Section 11 Sleep in Other Disorders
11.1 Neurologic Disorders
Findings
Accumulation of abnormal tau protein in CNS causes sleep problems
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Frightening and Disturbing to Observe
6 Which of the following statements regarding excessive daytime sleepiness (EDS) and myotonic dystrophy 1 (MD1) is true?
B EDS is exclusively found in the subpopulation of MD1 patients who also have either central or obstructive sleep apnea syndrome.
7 A 9-year-old girl presents with REM sleep behavior disorder. This condition is likely to herald the onset of:
1 A. This is a classic description of nocturnal paroxysmal dystonia. The other three conditions would be in the differential diagnosis. PPSM5, p 1056
2 D. Nocturnal paroxysmal dystonia is one of three diseases in the category of autosomal dominant nocturnal frontal lobe epilepsy (ADNFE): paroxysmal arousals, paroxysmal dystonia, and episodic wandering. Generally in these conditions, one parent is affected and patients have a mutation in the CHRNA4, CHRNB2, or CHRNA2 genes. PPSM5, p 1056; Hirose and Kurahashi, 2002-2010
3 C. Carbamazepine in small doses leads to remission or improvement in about 70% of patients with nocturnal paroxysmal dystonia. In patients with a specific mutation of the CHRNA4 gene, zonisamide (Zonegran in the United States) has been found to be more effective than carbamazepine. Genetic counseling should also be offered the patient and his or her family.
4 C. The patient is describing a hypnic jerk, also known as a sleep start. In ICSD2, hypnic jerks are classified as “isolated symptom, apparently normal variant and unresolved issues.” They are sudden brief contractions of the body occurring at sleep onset, often associated with a sensation of falling. There are three other conditions with a similar manifestation. Benign sleep myoclonus of infancy is manifested by myoclonic jerks occurring during sleep. It typically begins at birth and resolves spontaneously by 6 months. Hypnagogic foot tremor and alternating leg muscle activation can occur at sleep–wake transitions or during light NREM sleep. PSG shows recurrent EMG potentials in one or both feet that are in the myoclonic range (longer than 250 msec). Propriospinal myoclonus at sleep onset is a disorder of recurrent sudden muscular jerks in the transition from wake to sleep and is often associated with insomnia. PPSM5, pp 1098, 1100
5 B. Because hypnic jerks are common and benign and have no known negative consequences, reassurance is the goal of management. Such patients often worry they have epilepsy. Diagnosis should be made by the history and does not require a PSG. PPSM5, pp 1098
6 C. Although the severity of some myotonic dystrophy symptoms directly correlates with the number of abnormal CTG triplet repeats, this is not the case with excessive daytime sleepiness (EDS). EDS is present in 33% to 39% of patients with myotonic dystrophy 1 (MD1). Reduced mean latency and SOREMPs on MSLT are not uncommon findings in MD1. EDS may be found in MD1 in the absence of either obstructive or central sleep apnea syndromes. Gibbs et al, 2002
7 B. REM sleep behavior disorder (RBD) can herald onset of narcolepsy in the pediatric population. Unlike adult RBD, which can herald a synucleinopathy such as Parkinson’s disease, pediatric RBD is not associated with juvenile Parkinson’s disease. Nevsimalova et al, 2007
Summary
Parkinsonism (PPSM5, ch 87)
Stroke (PPSM5, ch 88)
Sleep-Disordered Breathing (SDB)
Findings
Neuromuscular Diseases (PPSM5, ch 89)
Alzheimer’s Disease (Atlas, ch 10.6)
Accumulation of abnormal tau protein in CNS causes sleep problems
