Thieme Mumenthaler, Neurology - part 6 ppsx

7.3 EEG rhythms in various frequency ranges.Table 7.1 Pathological EEG rhythms and their clinical significance Focal slow activity Localized cerebral lesion – e.g., infarct, hemorrhage,

Trang 2

Injury Due to Ionizing Radiation

General Aspects

Radiation therapy can injure the

brain, the spinal cord, and the

periph-eral nerves The extent of injury

de-pends on:

> the radiation dose per session and

the total dose,

> the treatment field,

> and the timing of the treatment

sessions

An empirical measure of the injurious

potential of radiation therapy is given

by the NSD (normalized standard

dose), which is calculated according

to the following formula:

NSDRET= TD × N–0.24× T0.11

Here the NSD is expressed in RET (rad

equivalent therapy), TD stands for the

total dose in rads, N the number of

in-dividual doses, and T the duration of

treatment The latency of radiation

injury may be months or years,

de-pending on the NSD

Radiation Injury to the Brain

Mechanism

Radiation necrosis of the brain may

occur with a dose of 2800 rad (28 Gy)

or more As already mentioned, the

extent and latency of radiation injury

are strongly dose-dependent

Pathological Anatomy

Fibrinoid necrosis of blood vessels,

with extravasation of plasma and

erythrocytes, is accompanied by

lym-phocytic infiltration and massive

ne-crosis of nervous tissue, particularly

in the white matter

Differential Diagnosis

Because radiation therapy is usuallygiven to treat a tumor, radiation ne-crosis of the brain generally requiresdifferentiation from recurrent tumor.Cerebral ischemia is sometimes theindirect result of radiation therapy,when it is due to radiation-inducedocclusion of large vessels such as themiddle cerebral artery or the internalcarotid artery in the neck

Radiation Injury

to the Spinal Cord

The spinal cord, too, like the brain,can be injured by either conventionalphoton-beam or high-energyelectron-beam radiotherapy Signs ofspinal cord dysfunction generally ap-pear only if the dose used is 3500 rads

or higher, given over a period of

28 days or less Radiation myelopathyhas been described after radiotherapyfor tumors of the pharynx and neck,lymphoma, mediastinal tumors, andlung tumors It most commonly arisesabout 1 year after treatment, thoughthe latency may vary from 2 months

to 5 years, and rarely longer The thoanatomic changes, which mainlyaffect the white matter of the spinalcord, consist of spongiform demyelin-ation with astroglial reaction in theearly phase, and focal or diffuse de-myelination with necrosis in laterphases Vessel walls are regularly af-fected by changes ranging from fibri-noid necrosis with extravasation totelangiectasis The neurons are oftenrelatively well preserved

Trang 3

Clinical Features

The clinical presentation of radiation

myelopathy is highly varied Cervical

myelopathy, the most common

syn-drome, usually presents with

pares-thesiae in the legs, which may remain

the only symptom or may later be

ac-companied by Lhermitte’s sign (which

usually resolves spontaneously)

Other patients suffer from progressive

para- or quadriparesis More than half

of all patients develop a more or less

pure Brown-S´equard syndrome

Pro-prioception is disturbed more often

than superficial sensation

There is some evidence that radiation

therapy may induce a form of myelitis

accompanied by myoclonus in the

lower limbs This process, when it

oc-curs, may remain stable at a relatively

mild degree of severity, but

unfortu-nately tends to progress to a more orless complete spinal cord transectionsyndrome over a period of weeks tomonths About half of the affected pa-tients die months or years later fromthe complications of the myelopathy,while in others the myelopathy canremain stable or even regress

Generalized hypothermia is rarely the

result of cold exposure alone; usually

other factors are at work that have

rendered the patient unable to

pro-tect himself adequately against the

cold (e.g., alcohol or drug abuse or

mental illness)

Central nervous system The depth of

hypothermia determines the extent

to which the patient’s consciousness

is impaired and his pulse, blood

pres-sure, and respiratory rate are

de-pressed Severe hypothermia can

cause cardiac arrest The pupillary

flexes and the intrinsic muscle

re-flexes are diminished, while muscle

tone may be increased, and dal tract signs may appear Meningis-mus may develop even though theCSF is normal If the patient survives,there are generally no permanentneurologic sequelae other than thoseassociated with the underlying ill-ness, if any

pyrami-Peripheral nervous system Animal

experiments have shown that thermia alters the fine structure ofperipheral nerves and causes a slow-ing or blockade of impulse conduc-tion Weakness and sensory distur-bances due to hypothermic periph-eral nerve injuries were described insoldiers who fought in the trenchesduring the two World Wars, and inshipwreck survivors The thick, mye-linated fibers are most susceptible to

Trang 4

hypo-this type of injury Myocardial cooling

during open heart surgery causes

hy-pothermic injury to the phrenic nerve

in 7% of cases; such injuries are not

always fully reversible

Treatment

Resuscitation and warming are the

essential components of treatmentfor hypothermia Severely hypo-thermic patients may be re-

warmed by extracorporeal pulmonary bypass, if necessary

cardio-(993a) Therapeutic success is sible even in cases of extremelydeep hypothermia (343b)

Trang 5

7 Epilepsy, Other Episodic Disorders

of Neurologic Function, and Sleep

History

Epilepsy was well known in the

an-cient world, both in medical practice

and in everyday life The Greek term

epilepsia is derived from the verb

epilambanein, “to lay hold of, seize,

attack” (cf English seizure) It is easy

to see how the sufferer’s obvious lack

of self-control during the fit or

sei-zure gave rise, in many different

cul-tures, to the notion of possession by

a supernatural being – either an evil

spirit or, sometimes, a beneficent

one The Latin term morbus sacer

(“the holy disease”) reflects this

primitive conception Yet

Hippo-crates, the founder of rational

medi-cine (5th–4th cent BC), already

un-derstood epilepsy correctly as the

product of a sick brain The notion of

epilepsy as divine punishment

pre-vailed once again throughout the

Christian Middle Ages and was not

definitively discarded until the

En-lightenment

The Swiss physician Samuel Auguste Tissot described practically all forms

of epilepsy in his Trait´e de l’´epilepsie

of 1770 (491a) The British

neurolo-gist John Hughlings Jackson proposed

in 1873 that epilepsy was due to cessively strong electrical discharges

ex-of the gray matter ex-of the brain Two

years later, in Liverpool, Richard Caton

was able to confirm this hypothesis

by direct measurement of cerebralelectrical activity in rabbits and mon-keys In this era, too, the antiepilepticactivity of bromide was discovered(1857)

Further antiepileptic drugs were veloped in the first half of the 20thcentury – phenobarbital in 1912 anddiphenylhydantoin (phenytoin) in

de-1938 The first human EEG was

re-corded by Hans Berger of Jena,

Ger-many, in 1924 (who gave due credit toCaton) By mid-century, the Montreal

neurosurgeon Wilder Penfield, in laboration with the neurologists Her-

Trang 6

Fig 7.1 Incidence of

epilepsy by age (after

Schmidt and Elger;data from Camfield et

al and Forsgren et al.).The incidence of epi-lepsy is highest in thefirst year of life andafter age 65, and low-est in early adulthood

bert Jasper and William Lennox, had

succeeded in using direct

intraoperat-ive observation and

electroencepha-lography to correlate the normal

func-tion of various brain regions with the

clinical phenomenology of epilepsy

Etiology and Pathogenesis

Etiology

In principle, any brain – even a

healthy one – can generate an

epilep-tic seizure under certain conditions

that render the gray matter unusually

excitable A single febrile seizure in

early childhood, for instance, does not

qualify as “epilepsy.” The term, in its

proper sense, refers to a lasting

ten-dency to generate seizures The cause

may be a structural abnormality of

the brain, such as a developmental

anomaly, a scar due to trauma during

the birth process or at any later time,

ischemia, focal infection, or tumor In

other cases, epilepsy is due to a

meta-bolic disturbance, such as

hypoglyce-mia, or to a toxic condition, such as

alcoholism The cause of epilepsy

of-ten remains unidentified

Pathogenesis

Epilepsy reflects the abnormal tioning of cerebral neurons In gen-eral, a neuron receives both excit-atory and inhibitory influences fromother neurons, and fires an action po-tential only when the overall effect ofthe excitatory postsynaptic potentials(EPSPs) outweighs that of the inhibi-tory postsynaptic potentials (IPSPs).Intraneuronal recordings from epi-leptic foci have revealed a membranedepolarization of abnormally highamplitude that provokes the firing of

func-a series of func-action potentifunc-als func-at highfrequency, followed by hyperpolar-ization This type of electrical event,which can be considered a giant EPSP,

is called a paroxysmal depolarization shift (PDS).

A PDS occurring in the midst of apopulation of neurons is reflected onthe EEG by spikes followed by a slowwave (spike-wave complex) Suchcomplexes may be the initial EEG cor-relate of a clinically observable sei-zure It is not yet known with cer-tainty where these complexes arise;thalamocortical and intracortical

Trang 7

Fig 7.2a–d Electrode placement in the 10-20 system (a–c from K.F Masuhr and

M Neumann, Neurologie (Stuttgart: Hippokrates, 1992); d from H Kunkel, Das EEG in der

neurologischen Diagnostik, in H Schliack, H.C Hopf, Diagnostik in der Neurologie

(Stutt-gart: Thieme, 1988) The EEG recording from any given electrode reflects the electrical tivity of the underlying brain area Fig 7.2b–d g

ac-generation have both been

hypothe-sized The following processes play an

important role in neuronal

depolar-ization and repolardepolar-ization:

> calcium and sodium influx and

These processes are the basis of

vari-ous kinds of anticonvulsant therapy

Some medications lessen the sodium

influx, others potentiate GABA-ergic

inhibition, and others selectively

block calcium channels

Epidemiology

Epilepsy is one of the more common

types of neurologic disease It affects

0.5% to 1% of persons The onset of

epilepsy is more common in the first

year of life and after age 65 (Fig 7.1).

Persons with affected family bers are more likely to develop epi-lepsy If one parent suffers from idio-pathic epilepsy, the child’s risk is

mem-1 : 25; if one parent suffers fromsymptomatic epilepsy, the child’s risk

is 1 : 67 The risk is higher than 1 : 25

if both parents are affected

a Lateral aspect.

The electrodes aremounted at thespecified intervalsbetween the nasionand the inion

Ancillary Diagnostic Tests in Epileptology

We will first discuss the more tant diagnostic tests before proceed-ing to the classification and clinicalfeatures of epilepsy

Trang 8

b Frontal aspect The

preauricular points arethe reference sites forthe placement of thecentral transverse row

of electrodes C2 isthe intersection of thecentral transverse andlongitudinal rows

c Superior aspect.

Trang 9

Preauricular point

than the structure, of the brain It

reg-isters changes in electrical potential

that represent the net effect of the

EPSPs and IPSPs in the cerebral

cor-tex It also indirectly reflects the

func-tion of the thalamus and the

mid-brain reticular formation, which are

responsible for the maintenance of

the sleep-wake cycle

The standard EEG is recorded through

electrodes mounted on the scalp

ac-cording to the 10–20 system (Fig 7.2).

It is a general property of electrical

potential that it is not well-defined as

an absolute quantity, but can only be

measured as a difference between

two points Thus, the EEG is obtained

either as a bipolar recording (in which

potential differences are measured

between the scalp electrodes) or as a

so-called monopolar recording (in

which the difference is measured

be-tween each scalp electrode and a

ref-erence electrode) The ECG is

re-corded simultaneously with the EEG

on the same sheet of paper

Potential differences at the scalp are

on the order of 10–100 ‘ V, while tential differences at the surface ofthe brain (without the attenuationproduced by the skull and scalp) areabout ten times higher EEG activity

po-in different frequency ranges is ventionally designated by Greek let-ters, as follows:

Trang 10

Fig 7.3 EEG rhythms in various frequency ranges.

Table 7.1 Pathological EEG rhythms and their clinical significance

Focal slow activity Localized cerebral lesion – e.g., infarct, hemorrhage,

tumor, abscess, encephalitisIntermittent, rhythmic slow

waves Thalamocortical dysfunction; metabolic or toxic distur-bance, obstructive hydrocephalus, deep-seated

pro-cess near the midline, posterior fossa lesion; a cific finding in patients with generalized epilepsyGeneralized arrhythmic and

nonspe-polymorphic slow activity Diffuse encephalopathy of metabolic, toxic, infectious,or degenerative originEpileptiform discharges – e.g.,

focal or generalized spikes,

sharp waves, or

spike-slow-wave complexes

Focal or generalized epilepsy (or clinically silent position to seizures)

predis-Low-voltage activity Hypoxic-ischemic brain injury, degenerative brain

dis-ease, extra-axial lesion such as subdural hematoma(focal low voltage)

Flat-line EEG Consistent with, but not diagnostic of, death (“brain

death”)

Trang 11

R R R R R R R

A B C D E F G

B C D E F G

R

Fig 7.4a–c

Schematic illustration

of a sharp wave.

a A sharp wave is

pro-duced by the rapidrise and decline of a

“hill” of negativepotential at thebrain surface

b In a monopolar

re-cording, the

elec-trode directly overthe peak has thehighest potential

c In a bipolar

record-ing, phase reversal is

seen over the peak

frontal lobes, when the eyes are open,

during mental activity, or after the

in-gestion of barbiturates or diazepam

Slower (sub-\ , \ , and A ) activity is

seen during sleep or in the presence

of diffuse or generalized

patholo-gic processes Some degree of

tempo-ral A activity is normal in older

persons

Typical EEG rhythms in various

fre-quency ranges are shown in Fig 7.3.

Figure 7.4 shows how the site of

ori-gin of a sharp wave can be localized

in mono- and bipolar EEG recordings

The sharp wave is best understood as

a hill of (negative) potential centered

on a particular point on the surface of

the brain The spatial localization of aslow-wave focus is performed inanalogous fashion

Hyperventilation, photostimulation, and sleep deprivation are all provoca- tive methods by which focal distur-

bances of brain function can be centuated to increase the diagnosticyield of EEG (518a) Sleep deprivationputs most patients into a superficialstage of sleep, in which the likelihood

ac-of a paroxysmal electrical disturbance

is greatest

A number of pathological EEGrhythms and waves and their clinicalsignificance are summarized in

Table 7.1.

Trang 12

A valuable technique in the

evalua-tion of patients with epilepsy,

partic-ularly those for whom neurosurgical

treatment is under consideration, is

simultaneous EEG and video

monitor-ing By playing back each seizure at

reduced speed and noting the

elec-troencephalographic events

corre-sponding to each phase of the seizure,

the clinician can make a number of

valuable determinations, among

them the distinction between true

epileptic and psychogenic seizures

The former generally have an

un-changing, stereotyped pattern, while

the latter vary from seizure to

sei-zure

Subacute EEG recording and telemetry,

performed over days or weeks with

or without accompanying video

mon-itoring, maximizes the chance of

cap-turing a seizure for analysis (263)

Invasive neurosurgical treatment of

epilepsy is often preceded, as a final

diagnostic step, by EEG recording

through electrodes at deeper

loca-tions, placed by a semi-invasive

sur-gical procedure: the various types

used include sphenoidal electrodes,

foramen ovale electrodes, and

stereo-tactically implanted epidural or

intra-cerebral (“depth”) electrodes

Electro-corticography (ECoG) is the recording

of the EEG from the brain surface

it-self, either through a previously

im-planted strip or grid electrode, or

di-rectly during an open neurosurgical

procedure ECoG enables the

localiza-tion of abnormal electrical activity

with maximal accuracy

Magnetoencephalography

The electrical activity of neurons

gen-erates a magnetic field oriented

per-pendicularly to the direction of

cur-rent flow Variations in the magnetic

field can be detected with a conducting apparatus enclosed in aFaraday cage and displayed togetherwith the EEG or MRI in a single, su-perimposed image This enables thehighly precise localization of epilepticfoci, which is useful in the presurgicalevaluation of candidates for epilepsysurgery Magnetoencephalography isavailable in only a small number ofacademic centers

super-CT and MRI (pp 132 and 133)

CT and, especially, MRI are able studies for the detection ofstructural abnormalities of the brainand meninges They may reveal po-tential causes of epilepsy – including,for example, low-grade astrocytoma,cortical dysgenesis, cavernoma, ormesial temporal sclerosis

indispens-Functional MRI (fMRI) enables a

three-dimensional representation oflocal cerebral perfusion, which isknown to be correlated with electri-cal activity It can thus be used to de-tect an epileptogenic focus, or to lo-calize important functions (e.g., lan-guage) in the brain before resectivesurgery for epilepsy

Radioisotope Studies Isotope diagnosis SPECT and PET

both involve measurement of the w radiation (i.e., photons) emitted byintravenously administered radioac-tive isotope tracers

-Single photon emission computed mography (SPECT) SPECT enables

to-measurement of regional cerebralperfusion, oxygen and glucose con-sumption, and blood volume and canthus be used as a test of brain func-tion It makes use of radioactive tech-Mumenthaler, Neurology © 2004 Thieme

Trang 13

netium or iodine compounds as

trac-ers – e.g.,99mTc-HMPAO or133

I-iodo-amphetamine (IMP) Central

benzodi-azepine receptor ligands such as11

C-flumazenil can be used to detect

ar-eas of neuronal damage (425) SPECT

generally reveals increased regional

blood flow at the epileptogenic focus

during a seizure, and decreased

re-gional blood flow in the interictal

pe-riod

Positron emission tomography (PET).

This technique requires a cyclotron

close by for the production of the

short-lived radionuclides that emit

positrons, such as11C,14O, and18F It is

used to generate tomographic images

of local cerebral blood flow (CBF),

ce-rebral blood volume (CBV), oxygen

consumption (CMRO2), glucose

con-sumption (CMRGlu), and intracellular

pH (pHi) It enables the performance

of biochemical studies in vivo

Cou-pling of these radioactive tracers with

specific biologically active chemicals,

such as DOPA, enables the

investiga-tion of specific metabolic processes in

the brain (890)

PET and SPECT have vastly increased

our understanding of the

pathophysi-ology of numerous diseases of the

brain (65) Their primary use in

epi-leptology at present is as part of the

preoperative evaluation of candidates

for epilepsy surgery

– idiopathic, genetic, genuine

– symptomatic, due to an acquired

lesion of the brain

– cryptogenic

> by clinical pattern (Table 7.2):

– generalized– partial (focal, localized)– unclassifiable

– series of seizures, status ticus

epilep-> by site of epileptogenic focus:– frontal lobe seizures– temporal lobe seizures– parietal lobe seizures– occipital lobe seizures

> by EEG pattern

> by age of onset (e.g., late-onset lepsy, beginning after age 30).Epileptic seizures are episodic distur-bances of brain function When epi-leptic seizures occur repeatedly andwithout provocation, the patient is

epi-said to be suffering from epilepsy in

the proper sense of the term, whileseizures that occur only occasionallyand under special circumstances,such as sleep deprivation or alcohol

withdrawal, are called provoked zures A single seizure does not con- stitute epilepsy The suspicion of epi-

sei-lepsy may, nonetheless, be raised by asingle seizure if an EEG obtainedthereafter reveals the typical interic-tal pattern of a particular variety ofepilepsy

In focal (partial) epilepsy, the

abnor-mal electrical discharges are confined

to a portion of the cerebral cortex.Partial seizures are further subdi-

vided into simple and complex types:

consciousness is preserved in the mer, altered (usually impaired) in thelatter Partial seizures with secondarygeneralization may be impossible todistinguish from primarily general-ized seizures from their clinical ap-pearance alone

for-Epilepsy due to some other logic process, such as a tumor, is

patho-called symptomatic epilepsy Epileptic

Trang 14

Table 7.2 Classification of epileptic seizures as proposed by the International League

Against Epilepsy

1.1.1 With motor signs

Focal motor without Jacksonian march

Focal motor with Jacksonian march

Versive

Postural

Phonatory (vocalization without interruption of speech)

1.1.2 With somatosensory or specific sensory symptoms

1.1.4 With mental symptoms and/or disturbances of higher cerebral function

(almost always involving alteration of consciousness – i.e., generally seen

in complex partial epilepsy)

Dysphasia

Dysmnesia (e.g., d´ej`a vu)

Cognitive (twilight states, altered sense of time)

Affective (anxiety, excitement)

Illusions (e.g., dysmorphopsia)

Structured hallucinations

beginning with simple manifestations only)

1.2.1 simple partial onset, followed by disturbance of consciousness with

simple partial features, followed by disturbance of consciousness withautomatisms

1.2.2 Disturbance of consciousness at onset

Isolated disturbance of consciousness

Automatisms

Trang 15

Table 7.2 Classification of epileptic seizures as proposed by the International League

Against Epilepsy (continued)

seizures (= GTC seizures with partial or focal onset; partial seizures with ary generalization)

second-1.3.1 Simple partial seizures with secondary generalization

1.3.2 Complex partial seizures with secondary generalization

1.3.3 Simple partial seizures that develop into complex partial seizures and then

With mild clonic component

With atonic component

With tonic component

With autonomic component

Altered muscle tone may be more prominent

On- and offset often gradual

patients who are neurologically

nor-mal in between seizures and have no

structural abnormality on MRI are

said to have idiopathic epilepsy

(sometimes confusingly called

genu-ine epilepsy), which has a genetic

ba-sis in some, though by no means all,

cases Epilepsy is said to be

crypto-genic (“of hidden cause”) when it is

thought to be symptomatic, but the

underlying disorder cannot be mined with current diagnostic meth-ods

deter-The following sections provide anoverview of epileptology based on aclinical classification of seizure type.The revised classification of the Inter-national League Against Epilepsy is

reproduced in Table 7.2 The

designa-tions that have been chosen for many

Trang 16

types of seizure phenomena are quite

complicated and of debatable

useful-ness Each of the individual clinical

types of epilepsy is associated with

specific EEG characteristics and a

spe-cific etiology (or etiologies)

Individual Seizure Types

| Generalized Seizures

Somewhat less than half of all

sei-zures are generalized (the rest are

fo-cal) Tonic-clonic seizures are the

most common kind of generalized

seizure

| Generalized Tonic-Clonic

Seizures

These seizures, also known as grand

mal seizures and primarily

general-ized tonic-clonic seizures, are

charac-terized by sudden loss of

conscious-ness, tonic extension of the entire

body, and then generalized clonic

jerking (p 508) Some patients with

grand mal seizures have at least 90%

of their seizures within 2 hours of

waking up, while others have them

exclusively during sleep Generalized

tonic-clonic seizures may begin at

any age

Absence (Petit Mal) Seizures

Absence seizures, another type of

generalized seizure, are characterized

by a brief disturbance of

conscious-ness that ends as suddenly as it

be-gins Ninety percent of absence

sei-zures last less than 30 seconds Most

are accompanied by motor

phenom-ena such as eyelid flutter or mild

fa-cial myoclonus, and automatisms

may be seen in longer-lasting absence

seizures Motor phenomena are by no

means obligatory, however, and falls

are uncommon Absence seizures

ac-companied by abnormalities of cle tone or autonomic disturbances,and those in which consciousness isgradually rather than suddenly im-

mus-paired, are called atypical absence zures Absence seizures are most

sei-common in children of a particularage group The EEG shows character-istic changes Absence seizures re-quire specific medical treatment

Myoclonic Seizures

These are characterized by brief,rapid muscle twitches on one or bothsides of the body, which, when theyoccur bilaterally, may be either syn-chronous or asynchronous The clini-cal spectrum ranges from fine twitch-ing of the face, arm, or leg to massive,bilateral spasms of the entire body.Two age-dependent types of myo-

clonic seizure are impulsive petit mal seizures and myoclonic-astatic seizures.

Clonic, Tonic, and Atonic Seizures

Myoclonic and tonic seizures times occur as fragments of tonic-clonic seizures; tonic seizures also oc-cur as fragments of tonic-axial sei-zures Atonic seizures, also calleddrop attacks, involve a sudden loss ofmuscle tone, causing the patient(usually a child) to fall to the ground

some-A less severe atonic seizure maymerely cause a momentary bobbing

of the head Tonic and atonic seizuresare the main types of seizure thatcause falls

| Partial (= Focal) Seizures

The terms “partial” and “focal” zure are synonymous Seizures of thistype are caused by a focal abnormal-ity in the brain and are not associatedwith a loss of consciousness or with ageneralized tonic-clonic convulsionMumenthaler, Neurology © 2004 Thieme

Trang 17

(unless they become secondarily

gen-eralized) Simple partial seizures

in-volve either motor or sensory

phe-nomena (or both), while complex

par-tial seizures, by definition, involve an

altered state of consciousness,

per-haps with automatisms and

auto-nomic manifestations as well A

par-tial seizure of either type may

be-come secondarily generalized

| Simple Partial Seizures

Simple partial seizures are the

ex-pression of an ictal electrical

dis-charge that remains confined in or

near the cortical area in which it

arises (the epileptogenic focus)

Nearly any neurologic manifestation

can be the mode of presentation of a

simple partial seizure Purely sensory

simple partial seizures are evident

only to the patient and not to those

around him; such seizures are called

auras Motor simple partial seizures

are, of course, evident to other

per-sons as well

The manifestations of simple partial

seizures range from simple,

elemen-tary movements (Jacksonian seizure,

adversive seizure), to unilateral

sen-sory disturbances, to emotional

dis-turbances, hallucinations, and

mis-perceptions Any type of simple

par-tial seizure may develop secondarily

into a complex partial or generalized

seizure In such cases, the initial

sim-ple partial seizure is termed the aura

of the seizure that follows it

| Complex Partial Seizures

Complex partial (focal) seizures are

characterized by a disturbance of

consciousness and a bilateral spread

of seizure activity, at least in the

lim-bic system or frontobasal cortex

Pa-tients usually also manifest

automa-tisms, such as the stereotyped

repeti-tion of a particular movement, bing or wiping movements, chewing,lip-licking, lip-smacking, or abnormalbreathing There may be turning ofthe eyes, head, or torso to one side orcomplex stereotyped performances.There may also be involuntary pho-nation or vocalization, dysarthria, or

rub-speech arrest – i.e., inability to speak

while the ability to understand ken language is preserved

spo-Complex partial seizures usually last1–2 minutes The patients do not re-member these seizures afterward,but most do describe an aura at thebeginning of the seizure, most com-monly a vague feeling of warmth aris-ing in the epigastrium and ascendingretrosternally into the neck Rarertypes of aura include gustatory, olfac-tory, auditory, or visual hallucinations

or a “dreamy state” – i.e., a change inthe perceived familiarity of one’s sur-roundings: d éj à vu, jamais vu, d éj àentendu, jamais entendu Theseterms, by the way, should be used intheir original, scientific meaning,rather than as they are popularly mis-construed Thus, d éj à vu is the pa-tient’s (inaccurate) feeling that a cur-rently experienced, but unfamiliarthing has been seen somewherebefore It is not the reliving of an ear-lier experience

| Unclassifiable Seizures

The clinical history often provides aninsufficient basis for classification ofthe seizure type In such cases, theseizures may be termed (at least pro-visionally) unclassifiable

Trang 18

Clinical Patterns of Epilepsy

and Epileptic Syndromes

The initial diagnostic question in any

patient presenting with “seizures” is

Table 7.3 Questions for history-taking in

the aftermath of a seizure

1 About the current seizure:

> Family history of epilepsy?

> Past events possibly causing brain

damage?

– Perinatal injury (left-handedness,

strabismus, psychomotor delay)?

– Meningitis, encephalitis?

– Head trauma?

> History of impaired consciousness?

– Febrile seizure(s) in childhood?

– Unconsciousness?

– Bedwetting (possibly due to

noctur-nal grand mal seizures)?

– Twilight states? (ask specifically

about partial complex seizures and

d´ej`a vu)

> If there have been seizures in the past:

– When was the first one?

– When was the most recent previous

one?

– How frequent?

– What kind of seizure?

– EEG obtained? If so, with what

epi-asked of the patient himself, and of witnesses, if any, in the aftermath of a

seizure are listed in Table 7.3, while

the physical examination of the tient in the aftermath of a seizureshould include at least the elements

pa-listed in Table 7.4 Important

ques-tions for clinical history-taking in tients with known epilepsy are listed

pa-in Table 7.5; a model algorithm for

the classification of seizure type is

shown in Fig 7.5.

Table 7.4 Important points for physical

examination in the aftermath of a seizure

1 Evidence that a seizure has occurred

> Clinical:

– Tongue bite– Urinary or fecal incontinence– Conjunctival hemorrhage– External injury

– Fractured bone– Shoulder dislocation

> Laboratory:

– Elevated CK– Elevated prolactin (a few minutesafter the event)

2 Clues to the cause of the seizure:

> Laboratory:

– CT– EEG no sooner than 24 hours afterthe event (acute postictal changesare nonspecific)

Trang 19

Spikes, sharp waves, slow waves

Simple focal seizures, complex focal seizures (temporal), secondary GTC seizures

Simple focal seizures, generalized myoclonic seizures (bilateral)

Absence, generalized myoclonic seizures

Absence, generalized myoclonic seizures, simple focal seizures

Absence, generalized myoclonic seizures, primary GTC seizures (usually grand mal

on waking up), generalized atonic

Simple focal seizures, generalized myoclonic seizures

Simple or complex focal seizures, secondary GTC seizures

Absence, complex focal seizures (frontal), primary GTC seizures (usually grand mal on awakening)

Absence, complex focal seizures, GTC seizures

Complex focal seizures, generalized tonic-clonic

or tonic seizures Absence, complex focal seizures Simple focal seizures

Fig 7.5 Algorithm for the classification of individual seizures (after Schmidt and Elger)

Any particular type of seizure may

have a number of possible causes and

may be found in multiple epilepsy

syndromes Thus, the diagnosis of theparticular epilepsy syndrome that ispresent requires not only a phenome-

Trang 20

Table 7.5 Questions for history-taking in

a patient with known epilepsy

3 Previous ictal events

> Febrile seizure(s) in childhood?

> Bedwetting (possibly due to nocturnal

grand mal seizures)?

4 Details of previous seizures

> When was the first one?

> When was the most recent one?

nological classification of seizure

type(s), but also various ancillary

studies, to be described below

| Grand Mal Epilepsy

(Generalized Tonic-ClonicSeizures)

Grand mal epilepsy is the “classic”and most characteristic form of epi-lepsy and thus also the form bestknown to the general public Manypatients report nonspecific prodromalsymptoms such as anxiety, irritability,

a general feeling of not being well, ordifficulty concentrating, precedingthe seizure by minutes or hours Oth-ers report a more or less specific aurabefore the seizure, such as a feeling ofwarmth in the chest The seizure itselfbegins with sudden unconsciousnessand falling to the ground, sometimesaccompanied by a shout (produced byforceful, involuntary expulsion of airthrough the closed vocal folds) There

is generalized contraction of the cles, with respiratory arrest, cyanosis,rigidity, and extension of the body

mus-This tonic phase, lasting 10 seconds or longer, is followed by a clonic phase

with generalized, usually bilaterallysynchronous muscle twitching Thepatient foams at the mouth and maybite his or her tongue and become in-continent of urine or (rarely) stool.The clonic phase generally lasts2–5 minutes The patient briefly re-mains unconscious after the seizure,then passes through a phase of postic-tal confusion and finally regains nor-mal consciousness (Note: the word

“postictal” means “after a seizure”and does not by itself connote confu-sion or a neurologic deficit Inexactuse, as in “The patient was postictal,”should be avoided.) Afterward, thepatient remains amnestic for the sei-zure itself and the ensuing period ofconfusion, which may last 10 minutes

Trang 21

the patient immediately after a

sei-zure should look for a bite on the

lat-eral edge of the tongue, as this is

usu-ally the only abnormality present

Fo-cal neurologic signs in the postictal

period, such as an arm or leg paresis

that gradually resolves over a few

hours (Todd’s postictal paresis), are

evidence of a partial seizure with

sec-ondary generalization, and are thus

usually due to symptomatic, rather

than idiopathic, epilepsy

Patients with frequent seizures

grad-ually undergo a change of

personal-ity, characteristically becoming

cog-nitively slowed, complicated,

over-precise, and “sticky,” though

abnor-mal agitation and irritability may

also be found Such changes usually

do not arise in patients who respond

well to appropriate antiepileptic

medication

EEG and Other Ancillary Studies

EEG The interictal EEG is normal in

almost one-quarter of patients with

generalized epilepsy and shows

char-acteristic features of epilepsy in only

about 50% These consist of episodic,

synchronous, high-amplitude slow

waves in all leads, with a few sharp

waves and spikes (Fig 7.6) During a

grand mal seizure, however, the EEG

is abnormal throughout The ictal EEG

occasionally shows a focal, rather

than generalized, epileptic discharge

at first, even if the clinical seizure

phenomena are generalized from the

start (see below) If the EEG is normal,

the next diagnostic step is EEG after

sleep deprivation or subacute EEG

re-cording and video monitoring, with

special electrodes if necessary (see

p 508)

CSF examination In patients with

fre-quent generalized seizures, CSF cytosis is occasionally found, typi-cally with only a few cells but rarelywith as many as 100 per microliter

pleo-Serum tests The serum creatine

ki-nase concentration is elevated after agrand mal seizure, reaching its peak24–48 hours later The serum prolac-tin concentration is elevated20–60 minutes after a generalizedseizure (but never after a psychogenicseizure)

Etiology and Precipitating Factors

Grand mal seizures are often due to

an abnormality in the brain that isnot detectable by currently availablemethods of structural imaging (“gen-uine” epilepsy, primary generalizedepilepsy) Hereditary influences oftenplay a role in such cases Grand malseizures may also be symptomatic ofanother process, which may be of any

of the types listed below as possiblecauses of focal seizures; in such cases,the ictal EEG reveals a focal seizure

with secondary generalization nal influences are of varying impor-

Exter-tance in individual cases Possible

precipitating factors include sleep

deprivation and repetitive photicstimulation (strobe light in a disco-

th `eque, driving through an artificiallylit tunnel, television, etc.) Seizurestend to occur more frequently just af-ter the patient has woken up.The onset of epileptic seizures during

pregnancy is more common than that

of eclamptic seizures and usually curs between the 26th and 36thweeks of gestation Epileptic seizures

oc-in the puerperal period may be a ifestation of cerebral venous or venoussinus thrombosis (p 545) Pregnantwomen should be treated pro-

Trang 22

phylactically with folate and B

vita-mins, as both antiepileptic medication

(especially phenytoin) and pregnancy

itself can cause folate deficiency and

osteopenia (for antiepileptic drugs

and fetal malformations, see p 545)

Alcohol can precipitate seizures in

ep-ileptic patients and can itself be thecause of epilepsy Thirty percent ofpatients with delirium tremens haveepileptic seizures, usually before thedelirium sets in, and usually 12 or

Trang 23

more hours after the last

consump-tion of alcohol (“rum fits”)

Alcohol-ism can also lead to the development

of true epilepsy, with repeated

sei-zures

Other causes of generalized epileptic

seizures are discussed elsewhere in

this book under the heading of the

in-dividual disease entities For tumors,

see p 59; post-traumatic epilepsy,

p 55 and p 531; degenerative

eases, p 369; cerebrovascular

dis-eases, p 531 The treatment of

gener-alized epilepsy is discussed on p 532

Status Epilepticus and Death Due to

Epilepsy

Either primarily or secondarily

gener-alized epilepsy may be complicated

by status epilepticus (599d, 765c),

which is defined as a succession of

seizures occurring without any

inter-ruption in between, or without

re-gaining of full, normal function in

be-tween The seizures in status

epilepti-cus are not necessarily generalized in

all phases; there may be, for example,

twitching in a single limb only

Non-convulsive status epilepticus, without

any visibly abnormal motor activity,

can also occur Status epilepticus is a

life-threatening condition, as it

pro-duces central hyperthermia,

aspira-tion, electrolyte disturbances, and

hypoxic brain injury that may cause

death The mortality of status

epilep-ticus varies from 5% to 20%,

depend-ing on its etiology Its treatment is

discussed on p 543

Mortality in the first 9 years after the

onset of generalized epilepsy, in

pa-tients who continue to have seizures

despite medication, is elevated by a

factor of two to three in patients with

symptomatic epilepsy, and by a factor

of 1.6 in those with idiopathic

lepsy Patients with symptomatic

epi-lepsy who die usually do so as a result

of the underlying disease The morecommon causes of death related toepilepsy itself are (in order of de-creasing frequency) refractory statusepilepticus, death during a seizure,sudden, unexpected death, accidents,and suicide (181a)

It is thought that sudden, unexpected death in an epileptic patient may be

due to a seizure-related cardiac rhythmia, as these are sometimesseen during epileptic seizures (567b,1027a) Patients with both epilepsyand heart disease need especiallymeticulous follow-up for optimiza-tion of seizure control

ar-| Absence Seizures in Idiopathic Generalized Epilepsy (“Typical” Absence Seizures)

Grand mal seizures occur in cents and adults of any age; othertypes of generalized seizure are age-

adoles-specific (711c) Table 7.6 provides an

overview of the epilepsy syndromesthat predominantly affect childrenand adolescents

Absence epilepsy is often designated

“petit mal epilepsy of school age.”Most authors use the term “petit mal”for all minor generalized seizures oc-curring between the ages of 1 and

13 years

In an absence seizure, the affectedchild suddenly stops whatever activ-ity he or she was engaged in (includ-ing speaking), stares vacantly aheadfor a period of impaired conscious-ness that usually lasts no more than afew seconds, and then resumes activ-ity as before Such absence seizuresare sometimes mistaken for “day-dreaming.” The disorder affects girlsmore often than boys The seizures

Trang 24

Table 7.6 Epilepsy syndromes that are found mainly or exclusively in children

Often seen in damaged, retardedchildren TypicalEEG finding: hypsar-rhythmia

when febrile Later developmentof true epilepsy is

0–8 years Variable loss of

mus-cle tone (nodding tocollapse), very briefunconsciousness,frequent seizures

Usually in boys; zures of this typeoften occur in asso-ciation with tonicseizures

lasts several onds, falls are rare,minor motor phe-nomena are some-times seen (picking

sec-at clothes), vacantstare, many times aday, precipitated byhyperventilation

Pyknolepsy (whenabsences are thesole manifestation);possibly seen to-gether with grandmal seizures (mixedepilepsy); EEG typi-cally shows 3 Hzspike-wave pattern

Irregular rockingtwitches, more fre-quent on awaken-ing, no loss of con-sciousness

Later often bined with grandmal, usually grandmal on awakening

May be combinedwith absence andmyoclonic seizures

Benign focal

epi-lepsy of childhood

and adolescence

1st and 2nd decades Focal twitching,

usu-ally during sleep; tient is conscious inseizures occurringwhen he/she isawake; 1/5 also havegeneralized seizures

pa-Multiple subtypes;typical EEG change,biphasic centro-temporal spikes;good prognosis forspontaneous recov-ery

Trang 25

may be provoked by hyperventilation

(a useful test in the doctor’s office)

Patients who only have absence

sei-zures, and have no seizures of any

other type, are said to suffer from

pyknolepsy Falls or major motor

phe-nomena do not occur during absence

seizures So-called petit mal

automa-tisms are common, however; these

include movements of the mouth and

tongue, picking at clothes, or other

minor motor gestures

Absence seizures must be

distin-guished from temporal lobe seizures

(p 524), psychogenic tic, or simple

daydreaming In general, absence

sei-zures occur much more frequently

than temporal lobe seizures (perhaps

dozens of times per hour), and are

usually of shorter duration

Diagnostic Evaluation

The neurological examination reveals

no abnormality The EEG reveals an

ictal 3–4 Hz “spike and wave” pattern

that appears in primarily generalized

fashion, in all leads, after previously

normal baseline activity (Fig 7.7).

This EEG pattern is diagnostic of

ab-sence seizures and can be produced

by hyperventilation in 90% of

pa-tients Electroencephalographically

recorded events that last less than

3 seconds are not associated with

clinically evident absences On rare

occasion, analogous EEG changes are

found in children with focal brain

le-sions; this implies that the child’s

brain is particularly susceptible to

this type of abnormality

Frequency

Absence epilepsy accounts for less

than 10% of childhood epilepsy

About one-third of children with

ab-sence epilepsy have a family history

of epilepsy Thus, this form of lepsy may be due, in part, to a geneti-cally determined metabolic abnor-mality

epi-Prognosis

About one-quarter of patients taneously become free of seizuresaround the time of puberty Otherscontinue to have absence seizures ex-clusively, but more than half addi-tionally develop grand mal seizures,which usually occur on awakening

spon-Mixed epilepsy, with both petit mal

and grand mal seizures, can also ariseprimarily rather than as a later devel-opment of absence epilepsy Both sei-zure types are reflected in the EEG.For treatment, see p 534

| Absence Status

A permanently abnormal EEG is thediagnostic feature of this condition,also known as petit mal status or sta-tus pyknolepticus Affected patientsappear to be confused, dazed, or in adreamlike state; they react slowlyand answer questions inappropri-ately, but can often act in a fairly rea-sonable way Such states are alsoknown to occur in adults; particularly

in advanced age, de novo absence tus is not uncommon, usually be-cause of benzodiazepine or alcoholabuse

sta-| Other Types of Epilepsy with Absence Seizures

Aside from absence epilepsy of earlychildhood or school age (pyknolepsy),absence seizures also occur in a num-ber of other, rarer epilepsy syn-dromes:

> juvenile absence epilepsy,

> myoclonic-astatic epilepsy,

> juvenile myoclonus epilepsy,

Trang 27

> epilepsy with myoclonic absences,

> Lennox-Gastaut syndrome,

> epilepsy with continuous spikes

and waves during sleep

Absence seizures in the context of

symptomatic generalized epilepsy

are called atypical absence seizures.

These can arise in adults as well,

par-ticularly during benzodiazepine

withdrawal

| West Syndrome (Infantile

Spasms, Salaam Spasms,

Propulsive Petit Mal)

This epilepsy syndrome appears in

the first year of life and is apparently

due to an age-specific reaction of the

brain

Etiology

West syndrome has highly varied

causes, including developmental

mal-formations of the brain, perinatal

in-jury, congenital brain diseases,

tuber-ous sclerosis, leukodystrophy, and

others

The illness is clinically characterized

by myoclonus or tonic spasms

fol-lowed by rapid, jerky forward

move-ments Nodding of the head may

be accompanied by a simultaneous

thrust of the arms forward and

side-ways or by a sudden convulsion of the

entire body, with flexion and

eleva-tion of the arms and flexion of the

legs These attacks can occur as many

as 100 times an hour

The characteristic EEG pattern of

West syndrome consists of

high-amplitude slow waves with sharp

waves and spikes at varying locations

(hypsarrhythmia)

Prognosis

The prognosis is poor The mortality

in West syndrome is ca 25% Only20% or fewer of the surviving pa-tients are more or less normal; halfare severely retarded, and more thanhalf suffer from persistent seizures ofvarious types Positive prognosticfactors include the lack of a specificetiology, normal development up tothe time of assessment, and the ab-sence of other seizure types beforethe onset of infantile spasms Westsyndrome has been reported to un-dergo a transition to myoclonic-astatic petit mal epilepsy (see below)

in some cases

Treatment

West syndrome is treated with a

course of ACTH lasting several weeks and with antiepileptic medi-

cation (see Table 7.11).

| Myoclonic-Astatic Petit Mal Epilepsy (Lennox-Gastaut Syndrome)

This syndrome is characterized by thecombination of tonic seizures, dropattacks, and atypical absence sei-zures It mainly affects boys aged1–9 years (most commonly 1–3)

Etiology

Most cases are due to severe braindamage of some type In as many ashalf of all patients, Lennox-Gastautsyndrome is the further progression

of West syndrome

The seizures may be as minor as abrief nod of the head or may involve acollapse or violent fall to the ground.Falling may also be due to post-

Trang 28

myoclonic hypotonia Short seizures

do not impair consciousness

appre-ciably, but there may be brief

ab-sences or longer periods of confusion

even in the absence of a fall

Tonic-clonic or purely Tonic-clonic seizures are

also present in three-quarters of

cases Myoclonic-astatic status

epilep-ticus occurs in one-quarter of patients

and is highly associated with the later

development of dementia

The EEG reveals a generalized,

some-what irregular spike-wave pattern at

a frequency of about 2 Hz (“petit mal

variant”)

Treatment

See p 532

| Juvenile Myoclonus Epilepsy

(Impulsive Petit Mal Epilepsy,

Janz Syndrome)

The hallmark of this disorder is

bilat-eral myoclonus The seizures usually

begin in the second year of life and

become less frequent thereafter

Myoclonic epilepsy is rare in

adult-hood

The seizures consist of brief, forceful,

irregularly occurring twitches that

may be single or multiple,

indepen-dent or bilaterally symmetric and

usually involve the neck, shoulders,

and upper limbs They are more

com-mon just after awakening and can be

precipitated by sleep deprivation or

by intense emotion, sudden fright, or

a flickering light Consciousness is

preserved More than half of all

pa-tients later develop grand mal

sei-zures in addition, particularly in the

morning on awakening The

neuro-logical examination is normal, butpersonality disturbances are com-mon

The ictal EEG reveals multiple peaks

interrupted by high-amplitude slowwaves This pattern is particularlyprominent in photically induced sei-zures

Treatment

Valproic acid is the medication of

choice (p 538)

| Progressive Myoclonus Epilepsies

Progressive myoclonus epilepsy maydominate the clinical picture ofUnverricht-Lundborg disease, Laforadisease, neuronal ceroid lipofuscino-ses, or myoclonic epilepsy withragged red fibers (MERRF; p 905).These are hereditary diseases with anautosomal inheritance pattern, withthe exception of MERRF, which is amitochondrial disease They are not

to be confused with juvenile nus epilepsy

Trang 29

This syndrome is characterized by

grand mal seizures, progressive

de-mentia, and myoclonus The

myoclo-nus is asymmetric and usually

in-volves only portions of individual

muscles or muscle groups and does

not lead to large-scale movements It

is irregular rather than rhythmic and

can be precipitated by voluntary

movement or by sensory stimuli

Cer-ebellar ataxia develops later, and

sometimes also pyramidal and

extra-pyramidal signs and visual loss The

illness progresses, leading to death

| Epilepsy with Grand Mal

Seizures on Awakening

In this syndrome, more than 90% of

the seizures occur “on awakening” –

i.e., within 2 hours of awakening (by

definition); in general, more than

one-third of all grand mal seizures

are of this type A positive family

his-tory is found in some 15% of patients

with this syndrome It begins

be-tween the ages of 6 and 35 years,

usu-ally in the second decade of life The

seizures are generalized tonic-clonic,

and are not preceded by an aura They

may be precipitated by sleep

depriva-tion and can occur in combinadepriva-tion

with absence or myoclonic seizures

The neurological examination is

nor-mal The interictal EEG reveals

gener-alized spike-wave complexes in

40–70% of cases

Treatment

Some 80–90% of patients treated

with valproic acid are free of

Partial (Focal) SeizuresGeneral Aspects

The clinical manifestations of a focalseizure correspond to the function ofthe region of brain involved Partialseizures may have

> simple manifestations, such as focal

twitching, localized paresthesiae,visual hallucinations, or subjectiveauras; or

> complex manifestations, such as

twilight attacks, etc

Any type of partial seizure may come secondarily generalized

be-Etiology

Partial seizures are always due to afocal brain disturbance and are thus

symptomatic (rather than idiopathic).

Whenever partial seizures arise, theunderlying pathologic process must

be sought It must also be sized, however, that seizures appear-ing to be of primarily generalizedtype may be symptomatic as well

empha-Localization of the Epileptogenic Focus

The clinical phenomenology at theonset of the partial seizure is themost important clue to the localiza-tion of the epileptogenic focus Thenature of the seizures should be de-termined precisely by questioningand by direct observation The typicalseizure semiology associated withepileptogenic foci in various regions

Trang 30

18 17

9 8

6

Bowel Bladder

zation

Head/eyes/tru

nk to opposite side;

flexiontension synergy

of the contralateral lim bs

Toes Foot Calf Knee Central sulcus

Eyes to opposite side

Tongue Throat Chewing/licking/swallowing Vocalization/grunting

Complex visual sensations

Abdomen Chest Shoulder Arm Forearm Hand V IV II Thumb Neck Face

Eyes to opposite side

Thigh

Prim ary: rotation of head and eyes to opposite side Secondary: flexion synergy of the contralateral lim

bs

Prim

ary:

rotation of

Se

ndary:

Head/eyes/trunk

to opposite side;

Fig 7.8 Localization of focal epileptic seizures The type of attack depends on the site

of the focal lesion (adapted from Foerster)

Trang 31

Fig 7.9 EEG during a focal epileptic seizure.

Right central epileptogenic focus with spikes, sharp waves, and slow waves Phase reversal at electrode C4

Trang 32

Fig 7.10 Infrared video images of a frontal lobe seizure with onset during sleep.

The images on the left and right sides were taken during two different seizures Note theparallel, stereotyped course of the two seizures

Trang 33

of the brain is presented in Fig 7.8

Un-fortunately, the diagnostically

all-important initial phase, before the

sei-zure spreads and becomes generalized,

may be very short and therefore hard to

observe In this situation, the EEG and

video monitoring may afford further

help in demonstrating focal seizure

on-set (Figs 7.9, 7.10).

| Simple Partial Seizures

| Focal Motor and Sensory

Epilepsy

This form of epilepsy is clinically

characterized by tonic spasms, clonic

twitching, and/or paresthesiae

lim-ited to a particular region of the body

The more common sites of seizure

onset are the hands and the face, as

these are represented by a larger area

of cortex than the lower limbs The

seizure may begin with either motor

or sensory phenomena; frontal lobe

seizures may begin with a tonic

tor-sional movement of the head and

trunk or a fencing posture Other,

rarer initial symptoms include

sensa-tions of light or visual hallucinasensa-tions,

if there is a focal lesion in the

occipi-tal lobe (see below) Simple partial

seizures may last anywhere from a

few seconds to a few minutes

Con-sciousness is preserved Impairment

of consciousness occurs only later, if

at all, if the seizure spreads and

be-comes generalized

Hemiparesis may be observed in the

postictal period, for any of the

follow-ing reasons:

> Todd’s postictal paralysis is a

phe-nomenon directly related to the

seizure and is located on the same

side as the focal event; it regresses

within a few hours

> Persistent hemiparesis may be due

to epileptic activity continuing

af-ter the overt focal seizure hasended, sometimes recognizable asonly a very fine clonic twitching ofthe affected limb

> Preexisting hemiparesis in patients

with focal lesions causing both miparesis and seizures – e.g., chil-dren with perinatal brain injury(HHE syndrome = hemiconvulsivehemiplegic epilepsy)

he-> New hemiparesis due to a new,

acute lesion – e.g., infarction in theterritory of the middle cerebral ar-tery

A partial seizure may begin with

fo-cal paresthesiae or special sensory phenomena if the responsible brain

lesion is in a corresponding location;such phenomena include visual hal-lucinations, auditory sensations, andabnormal tastes and smells (see be-

low, also Fig 7.9) The initial seizure

phenomenon, whether it is motor orsensory, may be followed by differ-ent focal phenomena (as in a Jackso-nian motor seizure) or by secondarygeneralization to a grand mal seizure

with loss of consciousness Focal tus epilepticus, with a rapid suc-

sta-cession of focal seizures, can also

oc-cur The neurological examination

may reveal focal deficits in dance with the focal nature of thedisorder

accor-Diagnostic Evaluation

The interictal EEG may reveal

epilep-tiform activity at the focus, slowwaves, or, in many cases, no abnormal

findings Ictal EEG always reveals

sei-zure activity at the focus (see Fig 7.9).

| Jacksonian Epilepsy

In a Jacksonian seizure, tonic or clonicmotor activity usually begins in thefingers or hand, more rarely in the

Trang 34

face or foot, and then spreads to

neighboring parts of the body in

suc-cession (the “Jacksonian march”),

fi-nally involving the entire hemibody

or giving rise to a grand mal seizure

through secondary generalization

| Differential Diagnosis of Focal

Seizures

The differential diagnosis of

Jackso-nian epilepsy includes migraine with

aura (so-called migraine

accom-pagn´ee, p 811) This disorder usually

affects patients who already have

long-standing migraine Accompanied

migraine attacks almost always arise

before age 50, almost always begin in

the upper limb, and tend to spread

over a period of minutes, rather than

seconds as in Jacksonian epilepsy

Headache is present as a rule, and

clonic twitching is almost never seen

(again unlike Jacksonian epilepsy)

Such attacks may appear on

alternat-ing sides in the same patient

Focal spasms, twitching, or

paresthe-siae may be a manifestation of tetany

For tonic brainstem seizures, see

p 557 Repetitive, focal twitching in

the face is seen in hemifacial spasm

Hemimasticatory spasm, which

af-fects the masseter muscle, is a rarity

(45) (p 673) Psychogenic twitching

is almost never focal, but rather

prac-tically always unsystematic and

bilat-eral

| Epilepsia Partialis Continua

(of Kozhevnikov)

In this disorder, clonic or myoclonic

twitching persists in a limb or region

of the body for hours or days, during

sleep as well The EEG reveals strictly

focal epileptic discharges Such

sei-zures may arise many years after the

causative brain lesion

| Rasmussen’s Syndrome

This rare variety of chronic partial ilepsy mainly affects children The fo-cal seizures are accompanied by pro-gressive neurologic deficits, and theEEG reveals multiple contralateral ep-ileptogenic foci MRI and histopatho-logic study reveal encephaliticchanges; an autoimmune process can

ep-be demonstrated (antibodies againstglutamate receptors) Plasmapheresisoffers a chance of therapeutic benefit(729b)

| Benign Partial Epilepsy of Childhood and Adolescence, Rolandic Epilepsy (1029c) Clinical Features

These seizures are age-dependent,

arising usually around age 10, and cur mainly during sleep Those thatoccur during waking hours typically

oc-do not impair consciousness The zures usually begin with motor phe-nomena such as twitching of the face

sei-or sei-oropharynx, msei-ore rarely with matosensory or special sensory phe-nomena Only about one-third of sei-zures become secondarily general-ized Twenty percent of the affectedchildren or adolescents have only asingle seizure, and only one-thirdhave frequent seizures Patients withthis condition are usually neurologi-cally normal and undergo normalcognitive and behavioral develop-ment

so-Diagnostic Evaluation

The EEG almost always reveals

unilat-eral, centrotemporal, biphasic spikes

of high amplitude (“ ´epilepsie `apointes rolandiques,” rolandicspikes)

Trang 35

The differentiation of a single episode

of rolandic epilepsy from a single

fo-cal seizure, when the EEG is normal,

is probably no more than an arbitrary

matter of nomenclature

Prognosis

The prognosis is good The seizures

usually disappear during puberty,

and the EEG becomes normal A

sub-group of patients with this disorder

begin to experience seizures at the

age of 5 years or earlier, have absence,

myoclonic, and atonic seizures as

well, and show continuous,

general-ized spike-wave activity on their

sleep-EEG (711c); the seizures

appar-ently stop spontaneously once these

patients reach adulthood (243b) A

further type of benign childhood

epi-Table 7.7 Partial complex epilepsy: classification by site of origin

Site of origin,

type of epilepsy

Temporal lobe

Lateral temporal lobe Complex focal seizures, auditory or

vestibular aura

Supplementary motorarea Asymmetric tonic seizures, adversiveseizuresCingulate gyrus Absence-like complex focal seizuresFrontopolar area Complex focal seizures

Dorsolateral area Generalized tonic-clonic seizuresOrbitofrontal area Complex focal seizures

with sensory phenomena

Occipital lobe

lepsy (the Panayiotopoulos type),which constitutes one of the occipitallobe epilepsy syndromes, has a simi-larly favorable course (166b) Chil-dren with this syndrome have partialseizures with ictal vomiting, oculardeviation, and, occasionally, loss ofconsciousness and convulsions, andtheir EEG reveals occipital lobespikes

Treatment

Treatment is not always required

Sulthiame, carbamazepine, and

valproate are effective whenneeded (781a)

| Adversive Seizures

Adversive seizures are caused by a cus lying in the precentral area of the

Trang 36

fo-frontal lobe or in the supplementary

motor area on the medial surface of

the frontal lobe (see Fig 7.8) They are

clinically characterized by tonic

devi-ation of the eyes, head, and (often)

arm and shoulder to the side opposite

the cortical focus In some 10% of

pa-tients, however, the head turns to the

side of the focus Consciousness is

preserved at first but may be lost

sec-ondarily if the seizure becomes

gen-eralized A focus in the temporal,

oc-cipital, or parietal lobe may produce a

seizure beginning with a sensory

aura, in which consciousness is

im-paired before the adversive

move-ments take place

| Complex Partial Seizures

This form of epilepsy, also called

“fo-cal epilepsy with complex partial

sei-zures,” is further subclassified

ac-cording to the site of origin of

sei-zures (Table 7.7) Some 60-70% of

pa-tients with complex partial seizures

have a focus in the medial temporal

lobe The frontal lobe is the next most

common site; parietal and occipital

foci are rare

| Temporal Lobe Epilepsy

Medial temporal lobe epilepsy is

com-mon, while lateral temporal lobe

epi-lepsy is rare.

Medial Temporal Lobe Epilepsy

The seizures originate in the

amygdala-hippocampus complex, a

portion of the limbic system Earlier

synonyms for this type of epilepsy

were “psychomotor epilepsy” and

“temporal lobe epilepsy” (not further

specified) A current alternative name

is “mesiobasal-limbic epilepsy.”

Twi-light states, involving a clouding (but

not total loss) of consciousness, are

the clinical hallmark of medial poral lobe epilepsy

tem-Etiology and course Seizures of this

type are due to a lesion in the limbicsystem or the mediobasal portion ofthe temporal lobe They may first ap-pear in childhood, adolescence, oradulthood, but most commonly be-tween the ages of 10 and 20 It is notuncommon for a patient who sus-tained from one or more febrile sei-zures in childhood to develop medialtemporal lobe epilepsy in adoles-cence; in such cases, the underlyinglesion is usually hippocampal sclero-sis Other causes include hamartoma,arteriovenous malformation, tumorssuch as astrocytoma and oligodend-roglioma, and post-traumatic gliosis.Familial medial temporal lobe epi-lepsy can occur on a genetic basis

Clinical features The seizures

typi-cally consist of a twilight state thatbegins suddenly, lasts for a variableperiod from less than a minute to sev-eral hours, and then gradually sub-sides Common auras heralding theseizure include a sensation of warmth

or discomfort ascending from thestomach into the neck, nausea, olfac-tory and gustatory hallucinations, adream-like state, anxiety, a feeling offamiliarity (d ´ej `a vu) or unfamiliarity(jamais vu), followed by oral automa-tisms or grimacing, an arrest reaction,and a fixed, vacant stare Conscious-ness is mildly impaired The patientseems dazed Hand automatisms, or afixed posture of the contralateralhand, may appear In a left-hemi-spheric seizure, the patient cannotfollow commands, probably because

Trang 37

Various complexes of symptoms and

signs associated with medial

tempo-ral lobe seizures, to be described in

detail in the following sections, are

summarized in Table 7.8.

Sensory and perceptual disturbances.

Disturbances of this type may appear

by themselves or as auras heralding a

seizure They include dizziness,

dys-morphopsia (macropsia, micropsia),

gustatory sensations, or usually pleasant olfactory sensations (unci-nate fits, see p 624)

un-Autonomic phenomena These may

in-clude palpitations, nausea, (rarely)vomiting, salivation or dry mouth,hunger, or the urge to urinate Parox-ysmal abdominal pain has also beendescribed as a seizure equivalent, es-pecially in children Attacks of so-

Table 7.8 Clinical manifestations of complex partial seizures (medial temporal lobe

Often, ascending sation from stomach

in-appropriate behavior – e.g., picking

at clothes, senseless moving around

of objects, etc (twilight attacks);

long-lasting, semi-organized plex behaviors that may even in-volve travel over a long distance

com-(twilight states, fugue ´epileptique)

Amnesia for thesestates

fol-lowing one of the above ena, typically with only brief uncon-sciousness

Rare

Trang 38

called abdominal epilepsy last no

more than a few minutes and are

of-ten accompanied by clouding, though

not total loss, of consciousness The

EEG is almost always abnormal

Motor phenomena These consist of

tonic-clonic twitching or, more

fre-quently, complex motor behaviors

such as the stereotyped repetition of

a gesture, picking at clothes, and

rub-bing or wiping movements, then

mo-tor phenomena of a vegetative type

such as abnormal breathing, chewing

movements, sucking, lip-smacking,

gagging, and swallowing, urination,

etc Any temporal lobe seizure can

also become secondarily generalized

to a grand mal seizure

Behavioral and psychomotor

manifes-tations Diverse types of altered

con-sciousness are encountered Patients

may experience an unreal, dreamlike

state or have obsessive thoughts or a

subjectively increased clarity of

thinking They may have a feeling

that they have seen or experienced

their present situation before, though

this is actually not the case (d ´ej `a vu,

d éj à v écu) They may suffer from

groundless anxiety, rage, or other

emotions, or experience actual

hallu-cinations that differ from those of

schizophrenic psychosis only by their

sudden appearance during a seizure

Twilight states These states are a very

characteristic feature of

“psychomo-tor epilepsy.” The patient carries out

complex activities in apparently

orga-nized fashion, while remaining

con-scious These activities may be

rela-tively brief and more or less well

inte-grated into the behavioral context

(twilight attacks) A twilight state

may, however, last for hours or even

days The patient carries out highlycomplex activities – e.g., a long trip

(fugue ´epileptique), which he or she

cannot remember thereafter

Temporal syncope This term refers to

brief loss of consciousness and lapse, without other motor manifes-tations, due to an epileptogenic focus

col-in the temporal lobe A further ble manifestation of temporal lobe

possi-epilepsy is psychomotor status ticus.

epilep-Neurological examination and nostic studies There is usually no

diag-neurologic deficit, though the lying focal pathologic process in thetemporal lobe occasionally produces

under-a deficit such under-as under-a contrunder-alunder-aterunder-al upperhomonymous quadrantanopsia Verymild facial weakness, visible at thecorner of the mouth contralateral tothe focus, can be found in ca 70% of

patients MRI often reveals an

abnor-mal signal intensity in the pus, together with hippocampal atro-phy (made apparent by enlargement

hippocam-of the adjacent temporal horn) Rarerunderlying lesions include hamar-toma, arteriovenous malformation,tumor, gliosis, or tissue loss at the site

of an old temporal lobe contusion

The EEG is abnormal during

wakeful-ness in only 30% of patients, duringlight or deep sleep in 70% An epilep-togenic focus in the anterior temporallobe typically reveals itself throughhigh A and \ waves, as well as focal,sharp seizure potentials Bitemporalfoci are found in as many as 40% ofcases of medically intractable tempo-ral lobe epilepsy, possibly as the re-sult of secondary epileptogenesis(“kindling”) producing a so-calledmirror focus EEG recording during aseizure may be needed to determineMumenthaler, Neurology © 2004 Thieme

Trang 39

which of the two foci is responsible

for the seizures; in 25% of such

pa-tients, both foci produce seizures

in-dependently

Lateral Temporal Lobe Epilepsy

Seizures of this type originate in the

lateral temporal neocortex and often

begin with an aura consisting of

audi-tory or visual hallucinations, or

dizzi-ness The aura is frequently followed

by disorientation, protracted auditory

hallucinations, movement of the head

to one side, hand automatisms such

as picking at clothes, leg

automa-tisms, and (in the dominant

hemi-sphere) aphasia

Treatment

The first line of treatment for

tem-poral lobe epilepsy is

carbamaze-pine or valproate Surgical

treat-ment should be considered in

med-ically intractable cases (p 543)

Table 7.9 Frontal lobe seizures

sec-ondary generalization; status epilepticus is frequent

suddenly

Aura Rare, nonspecific; peculiar bodily sensation

Impairment of

ments of the upper limbs/hands, pedaling ments of the feet, rocking of the hips, (rarely) genitalmanipulation

| Frontal Lobe Epilepsy

lobe origin (Table 7.9, Fig 7.10) Frequency and Clinical Features

The seizures are brief (rarely longerthan 1 minute), begin and end sud-denly, and often occur in series of 20

to 50 seizures at a time, particularlyduring sleep Auras are rare and non-specific The patient may report anunusual bodily sensation Conscious-ness is usually only mildly impaired,

if at all An anxious facial expression

is typical Motor phenomena include

Trang 40

vocalizations and tonic versive

move-ments (adversive seizures, p 523)

Postural seizures are also typical,

with a fencing posture of the arm

contralateral to the focus The motor

automatisms may be grotesque or

bi-zarre, leading to an erroneous

im-pression of psychosis: flailing of the

arms and hands, pedaling

ments of the legs, rhythmic

move-ments of the hips, or, rarely, genital

manipulation

There is incomplete amnesia, or none

Frontal lobe seizures often occur

dur-ing sleep and have a marked

ten-dency to generalization (G 90%)

Sta-tus epilepticus is frequent The

fol-lowing clinical phenomena may be

seen, depending on the site of the

fo-cus (271):

> Central motor seizures are

charac-terized by contralateral twitching,

in a single limb at first, then

spreading to adjacent areas in a

Jacksonian march, sometimes to

the entire contralateral hemibody

> Supplementary motor seizures are

characterized by stereotypical

pos-tures with tonic components – e.g.,

elevation and abduction of the

con-tralateral and then the ipsilateral

arm, possibly accompanied by

high-frequency clonus

> If the seizure originates in the

fron-tal eye fields, there is versive

move-ment of the eyes to the opposite

side, possibly followed by

move-ment of the head

> If the seizure originates in Broca’s

area, there is iterative repetition of

single syllables without

impair-ment of consciousness or

postic-tal amnesia The patient is fully

responsive immediately

after-ward

> Seizures originating in the

premo-tor cortex consist of complex

move-ments such as rhythmic rocking orautomatisms involving the arms,legs, or entire body, with partialclouding of consciousness The pa-tient tries to follow verbal com-mands given during the seizure butusually fails because of persevera-tion Hypermotor seizures are alsoseen

> A continuum of seizure types links

the last-described type to lar, frontocingular and fronto- orbital seizures, all of which are

frontopo-characterized by highly varied, severating automatisms that mayappear psychogenic, and by an ex-cess of movement (hypermotorstate) The wide variety of seizurephenomena is due to the largenumber of directions in whichthe cortical seizure activity canspread

per-> Seizure activity usually spreads tothe limbic system, causing ictalclouding of consciousness andmarked postictal disorientation.Typical differences between frontaland temporal lobe seizures are listed

in Table 7.10.

Frontal lobe seizures may seem zarre to persons who observe them,and the patient’s description of the(subjective) aura preceding the sei-zure may seem no less bizarre It isthus not surprising, though unfortu-nate, that these seizures are oftenmisdiagnosed as schizophrenia, de-pression, bipolar affective disorder, oranother type of mental illness, or, ifthey occur during sleep, as night-mares, pavor nocturnus, or anothertype of parasomnia

Tiêu đề	Injury to the Nervous System by Specific Physical Agents
Trường học	Thieme Medical Publishers, Inc.
Chuyên ngành	Neurology
Thể loại	sách giáo khoa
Năm xuất bản	2004
Thành phố	New York

Định dạng
Số trang	101
Dung lượng	1,7 MB