Other Parasomnias

Chapter 96 Other Parasomnias





Normal Sleep Phenomena


It should be remembered that some normal phenomena arising from REM or NREM sleep may be bothersome enough to a patient to seek medical attention.




Hypnagogic and Hypnopompic Hallucinations


Prominent vivid dreamlike mentation can occur at sleep onset, during light NREM sleep, and even during relaxed wakefulness.1 As with sleep paralysis, such sleep onset and sleep offset hallucinatory phenomena are quite common in the nonnarcoleptic population, and they may be combined with sleep paralysis (often referred to as the “old hag” phenomenon).2 As a matter of fact, the original meaning of the word nightmare referred not to the current use of the term (a dream anxiety attack arising from the sleep period) but rather to a combination of sleep paralysis and hypnagogic hallucinations occurring at sleep onset.3 Patients can be reassured that these hallucinations are normal sleep phenomena and not symptoms of psychiatric disease.



Sleep Starts (Hypnic Jerks)


Sleep starts are experienced by many normal persons during the transition between wake and sleep. The most common is the motor sleep start, a sudden jerk of all or part of the body, occasionally awakening the victim or bed partner. These are so prevalent as to rarely result in neurologic consultation.4 However, variations on this theme can result in neurologic consultation. These include visual (flashes of light, fragmentary visual hallucinations), auditory (loud bangs, snapping noises) or somesthetic (pain, tingling, floating, something flowing through the body) sleep starts. These sensory phenomena can occur without the body jerk.5


Sleep starts represent a normal (although not understood) physiologic event, and they should not be confused with seizures or other neurologic conditions. Explosive tinnitus, characterized by a loud crashing or banging noise occurring during sleep most likely represents an auditory sleep start.6 It is also likely that the exploding head syndrome (see later discussion) is a variant of a sensory sleep start. Sleep starts may be repetitive, and they should not be confused with epileptic phenomena. Familiarity with nonmotor sleep starts should eliminate unnecessary testing and pharmacologic treatment. There is a single case report of an auditory sleep start associated with insomnia due to a brainstem lesion.7 Management is simply reassurance.



Miscellaneous Primary Sleep Parasomnias


There remain a number of primary sleep phenomena that are poorly understood and appear not to respect sleep stages. (Bruxism is discussed in Chapter 99.) Box 96-1 outlines the various parasomnias.




Sleep-Related Expiratory Groaning (Catathrenia)


Groaning during sleep has been termed catathrenia (Video 96-1image).8 The groans occur intermittently during either REM or NREM sleep and are characterized by prolonged, often very loud, often socially disruptive groaning sounds during expiration. Catathrenia often begins in childhood, but generally it does not come to medical attention until the person plans to sleep in a dormitory environment, such as in college or the military, or when he or she begins to share a bed with another. It is poorly understood, and there is no known effective treatment. Although there have been some reports of a possible relationship with obstructive sleep apnea and response to treatment with nasal continuous positive airway pressure (CPAP), and there have clearly been a number of cases that did not respond to nasal CPAP.9 There is absolutely no evidence that catathrenia is related to any underlying psychological or psychiatric problems.



Enuresis


Enuresis was formerly classified as a disorder of arousal, implying a relationship with slow-wave sleep.10 However, enuresis can occur during either NREM or REM sleep, and the sleep of enuretic children is normal.11 Enuresis is very common in childhood, and it much more prevalent in adolescence and adulthood than generally appreciated (1% to 2% of 18 year-olds and 0.5% of adults).12,13 Many etiologies have been suggested, including genetic,14 behavioral and psychological, bladder size or reactivity abnormalities, lack of vasopressin release during sleep, and delayed development.15 Despite considerable literature, the causes of enuresis remain enigmatic. Local urologic abnormalities account for only 2% to 4% of pediatric cases.16 No specific psychopathology has been identified, and there is overwhelming evidence that enuretic children have no more behavioral or psychological problems than nonenuretic children and that genetic factors are important.17


Formal urologic evaluation is usually not indicated, and simple reassurance and understanding on the part of both the child and the parents are often sufficient. Conditioning with a bell-and-pad device is effective but may be transient.18 Psychotherapy is generally ineffective and indicated only if obvious psychopathology is present.12 Tricyclic antidepressants (imipramine or desipramine) are effective and may be employed for short-term treatment, but long-term pharmacologic treatment is to be discouraged. Their mechanism of action is not known, but it appears not to involve peripheral anticholinergic effects.19 Desmopressin, an intranasally administered vasopressin analogue, has been reported to be of benefit.20


Enuresis may be the sole manifestation of nocturnal seizures and can accompany obstructive sleep apnea or other primary sleep disorders.21 Formal polysomnographic study with a full seizure montage and enuresis detector is indicated in patients with atypical histories or failure to respond to conventional therapy.




Propriospinal Myoclonus


Propriospinal myoclonus is a spinal cord–mediated movement disorder, occasionally associated with acquired spinal cord lesions. It is characterized by repetitive jerks occurring during the transition from wake to sleep.31 Propriospinal myoclonus may be confused with restless legs syndrome or periodic limb movements in sleep, and it can serve to shed light on the pathophysiology of these two disorders.32 It has been described in various neurologic conditions such as restless legs syndrome, paraneoplastic syndromes, and cervical disk herniation, and in extreme cases it can result in life-threatening respiratory compromise.3336 The movements can appear during relaxation and can result in severe insomnia, particularly at sleep onset.37 Clonazepam or anticonvulsant medications may be effective in alleviating these movements.31 Propriospinal myoclonus may be related to segmental myoclonus, both spinal and palatal.38



Somniloquy (Sleeptalking)


Sleeptalking is very common in the general population, might have a genetic component,39 and can occur in either REM or NREM sleep.40 Most cases are not associated with serious psychopathology.41



Secondary Sleep Parasomnias


The secondary phenomena are parasomnias representing abnormal or excessive autonomic or physiologic events arising from specific organ systems and occurring preferentially during the sleep period. These can be approached by the offending organ system.



Central Nervous System Parasomnias




Headaches



Vascular Headaches


Although some headaches have historically been referred to as “vascular headaches,” there is now overwhelming evidence that the etiology of this headache type is not vascular, but rather a primary neurologic phenomenon.42 Many headache syndromes are sleep related.43 The headache symptoms of cluster headache, chronic paroxysmal hemicrania, and possibly migraines, in some cases, tend to be related to REM sleep, explaining the common report of sleep-related headaches in these conditions.44 This fact explains the worsening of these symptoms following the discontinuation of REM sleep–suppressing agents (which results in a rebound of REM sleep) such as tricyclic antidepressants, monoamine oxidase inhibitors, clonidine, alcohol, and amphetamines. Circadian rhythm abnormalities can play a role in cluster headache and chronic paroxysmal hemicrania.45,46 Episodic paroxysmal hemicrania might respond to calcium channel blockers or topiramate.47,48 Sleep-disordered breathing can serve as a risk factor for headaches in some persons with cluster headaches.49



Nonvascular Headaches


Although morning headaches may be more prevalent in persons with sleep complaints in general, headaches are not a reliable marker for sleep-disordered breathing.50 However, in some susceptible persons, obstructive sleep apnea can trigger cluster headaches, which respond to bilevel positive airway pressure (BiPAP).51 Headaches associated with sleep-disordered breathing are more commonly seen in patients with neuromuscular disease who experience REM sleep–related hypoventilation, with hypercapnia-induced migraines arising from the sleep period. Carbon monoxide poisoning must never be overlooked as a cause of morning headaches.

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Mar 13, 2017 | Posted by in NEUROLOGY | Comments Off on Other Parasomnias
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