Chapter 022. Dizziness and Vertigo (Part 3) doc

Dizziness and Vertigo Part 3 Recurrent unilateral labyrinthine dysfunction, in association with signs and symptoms of cochlear disease progressive hearing loss and tinnitus, is usually

Chapter 022 Dizziness and Vertigo

(Part 3)

Recurrent unilateral labyrinthine dysfunction, in association with signs and

symptoms of cochlear disease (progressive hearing loss and tinnitus), is usually due to Ménière's disease (Chap 30) When auditory manifestations are absent, the

term vestibular neuronitis denotes recurrent monosymptomatic vertigo Transient

ischemic attacks of the posterior cerebral circulation (vertebrobasilar insufficiency) only infrequently cause recurrent vertigo without concomitant motor, sensory, visual, cranial nerve, or cerebellar signs (Chap 364)

Positional vertigo is precipitated by a recumbent head position, either to the

right or to the left Benign paroxysmal positional (or positioning) vertigo (BPPV)

of the posterior semicircular canal is particularly common Although the condition may be due to head trauma, usually no precipitating factors are identified It generally abates spontaneously after weeks or months The vertigo and accompanying nystagmus have a distinct pattern of latency, fatigability, and

habituation that differs from the less common central positional vertigo (Table 22-1) due to lesions in and around the fourth ventricle Moreover, the pattern of nystagmus in posterior canal BPPV is distinctive When supine, with the head turned to the side of the offending ear (bad ear down), the lower eye displays a large-amplitude torsional nystagmus, and the upper eye has a lesser degree of torsion combined with upbeating nystagmus If the eyes are directed to the upper ear, the vertical nystagmus in the upper eye increases in amplitude Mild dysequilibrium when upright may also be present

Table 22-1 Benign Paroxysmal Positional Vertigo and Central Positional Vertigo

vertigo and nystagmus

Intensity of vertigo Severe Mild

a

Time between attaining head position and onset of symptoms

b

Disappearance of symptoms with maintenance of offending position

c

Lessening of symptoms with repeated trials

d

Likelihood of symptom production during any examination session.A

perilymphatic fistula should be suspected when episodic vertigo is precipitated by

Valsalva or exertion, particularly upon a background of a stepwise progressive sensory-neural hearing loss The condition is usually caused by head trauma or barotrauma or occurs after middle ear surgery

Vertigo of Vestibular Nerve Origin

This occurs with diseases that involve the nerve in the petrous bone or the cerebellopontine angle Although less severe and less frequently paroxysmal, it has many of the characteristics of labyrinthine vertigo The adjacent auditory division of the eighth cranial nerve is usually affected, which explains the frequent association of vertigo with unilateral tinnitus and hearing loss The most common cause of eighth cranial nerve dysfunction is a tumor, usually a schwannoma

(acoustic neuroma) or a meningioma These tumors grow slowly and produce such

a gradual reduction of labyrinthine output that central compensatory mechanisms can prevent or minimize the vertigo; auditory symptoms are the most common manifestations

Central Vertigo

Lesions of the brainstem or cerebellum can cause acute vertigo, but associated signs and symptoms usually permit distinction from a labyrinthine etiology (Table 22-2) Occasionally, an acute lesion of the vestibulocerebellum may present with monosymptomatic vertigo indistinguishable from a labyrinthopathy.Table 22-2 Features of Peripheral and Central Vertigo

Symptom

Peripheral (Labyrinth)

Central

Cerebellum)

Direction of

associated nystagmus

Unidirectional; fast phase opposite lesiona

Bidirectional or unidirectional

Purely

horizontal nystagmus

without torsional

component

Vertical or

purely torsional

nystagmus

Never present May be present

Visual fixation Inhibits nystagmus

and vertigo

No inhibition

Severity of

vertigo

Direction of

spin

Toward fast phase Variable

Direction of fall Toward slow phase Variable

Duration of

symptoms

Finite (minutes, days, weeks) but recurrent

May be chronic

Tinnitus and/or

deafness

Often present Usually absent

Associated

CNS abnormalities

(e.g., diplopia, hiccups, cranial neuropathies, dysarthria)

Common

causes

BPPV, infection (labyrinthitis), Ménière's, neuronitis, ischemia, trauma, toxin

Vascular, demyelinating, neoplasm