Chapter 028. Sleep Disorders (Part 9) pot

Most patients with restless legs also experience periodic limb movements of sleep, although the reverse is not the case.. Periodic Limb Movement Disorder PLMD Periodic limb movements of

Chapter 028 Sleep Disorders

(Part 9)

Restless Legs Syndrome (RLS)

Patients with this sensory-motor disorder report an irresistible urge to move the legs, or sometimes the upper extremities, that is often associated with a creepy-crawling or aching dysesthesias deep within the affected limbs For most patients with RLS, the dysesthesias and restlessness are much worse in the evening or night compared to the daytime and frequently interfere with the ability to fall asleep The symptoms appear with inactivity and are temporarily relieved by movement In contrast, paresthesias secondary to peripheral neuropathy persist with activity The severity of this chronic disorder may wax and wane over time and can be exacerbated by sleep deprivation, caffeine, alcohol, serotonergic antidepressants, and pregnancy The prevalence is 1–5% of young to middle-age adults and 10–20% of those >60 years There appear to be important differences in

RLS prevalence among racial groups, with higher prevalence in those of Northern European ancestry Roughly one-third of patients (particularly those with an early age of onset) will have multiple affected family members At least three separate chromosomal loci have been identified in familial RLS, though no gene has been identified to date Iron deficiency and renal failure may cause RLS, which is then considered secondary RLS The symptoms of RLS are exquisitely sensitive to dopaminergic drugs (e.g., pramipexole 0.25–0.5 mg q8PM or ropinirole 0.5–4.0

mg q8PM), which are the treatments of choice Opiods, benzodiazepines, and gabapentin may also be of therapeutic value Most patients with restless legs also experience periodic limb movements of sleep, although the reverse is not the case

Periodic Limb Movement Disorder (PLMD)

Periodic limb movements of sleep (PLMS), previously known as nocturnal myoclonus, consists of stereotyped, 0.5- to 5.0-s extensions of the great toe and

dorsiflexion of the foot, which recur every 20–40 s during NREM sleep, in episodes lasting from minutes to hours, as documented by bilateral surface EMG recordings of the anterior tibialis on polysomnography PLMS is the principal objective polysomnographic finding in 17% of patients with insomnia and 11% of those with excessive daytime somnolence (Fig 28-3) It is often unclear whether it

is an incidental finding or the cause of disturbed sleep When deemed to be the latter, PLMS is called PLMD PLMS occurs in a wide variety of sleep disorders (including narcolepsy, sleep apnea, REM sleep behavior disorder, and various

forms of insomnia) and may be associated with frequent arousals and an increased number of sleep-stage transitions The pathophysiology is not well understood, though individuals with high spinal transections can exhibit periodic leg movements during sleep, suggesting the existence of a spinal generator Treatment options include dopaminergic medications or benzodiazepines

Figure 28-3

Polysomnographic recordings of (A) obstructive sleep apnea and (B)

periodic limb movement of sleep Note the snoring and reduction in air flow in

the presence of continued respiratory effort, associated with the subsequent oxygen desaturation (upper panel) Periodic limb movements occur with a relatively constant intermovement interval and are associated with changes in the

EEG and heart rate acceleration (lower panel) Abbreviations: R.A.T., right

anterior tibialis; L.A.T., left anterior tibialis (From the Division of Sleep Medicine, Brigham and Women's Hospital.)

Evaluation of Daytime Sleepiness

Daytime impairment due to sleep loss may be difficult to quantify for several reasons First, sleepiness is not necessarily proportional to subjectively assessed sleep deprivation In obstructive sleep apnea, for example, the repeated brief interruptions of sleep associated with resumption of respiration at the end of apneic episodes result in daytime sleepiness, despite the fact that the patient may

be unaware of the sleep fragmentation Second, subjective descriptions of waking impairment vary from patient to patient Patients may describe themselves as

"sleepy," "fatigued," or "tired" and may have a clear sense of the meaning of those terms, while others may use the same terms to describe a completely different condition Third, sleepiness, particularly when profound, may affect judgment in a manner analogous to ethanol, such that subjective awareness of the condition and the consequent cognitive and motor impairment is reduced Finally, patients may

be reluctant to admit that sleepiness is a problem, both because they are generally unaware of what constitutes normal alertness and because sleepiness is generally viewed pejoratively, ascribed more often to a deficit in motivation than to an inadequately addressed physiologic sleep need