Traditional biomarkers in narcolepsy: experience of a Brazilian sleep centre

Narcolepsy: an interface among neurology, immunology, sleep, and genetics

Narcolepsy is a primary disorder of the central nervous system resulting from genetic, environmental, and immunological interactions defined as excessive daytime sleepiness plus cataplexy, hallucinations, sleep paralysis, and sleep fragmentation. The pathophysiology is not entirely known, but the interaction among genetic predisposition, environmental exposition, and immune component with consequent hypocretin-1 deficiency is the model to explain narcolepsy type I. The mechanism of narcolepsy type II is less understood. There is a delay of over ten years for the diagnosis of narcolepsy around the world. Patients with narcolepsy have many comorbidities with a negative impact on quality of life. The treatment of narcolepsy must contain an educational approach for the family, coworkers, and patients. Scheduled naps and sleep hygiene are essential to minimize the dose of medications. Much progress has been seen in the pharmacological treatment of narcolepsy with new stimulants, different presentations of oxybate, and recent studies with orexin agonists. Narcolepsy is a rare disease that needs to be more understood and highlighted to avoid delayed diagnosis and severe disabilities in patients.

HLA-DQB1*06:02 allele frequency and clinic-polysomnographic features in Saudi Arabian patients with narcolepsy

BACKGROUND

Narcolepsy is an uncommon neurological disorder characterised by irresistible spells of sleep associated with abnormal rapid eye movement (REM) sleep. The association between narcolepsy and human leukocyte antigen HLA- DQB1*06:02 has been established elsewhere but remains to be investigated among Saudi Arabian patients with narcolepsy.

METHODS

A total of 29 Saudi patients with type I or type 2 narcolepsy comprising of 23 (79%) males and 6 (21%) females with a mean age of 17.2 ± 9.6 years were included in this study. Type 1 or type 2 narcolepsy was diagnosed by full polysomnography followed by a multiple sleep latency test in accordance with International Classifications of Sleep Disorders-3 criteria. HLA typing for DQB1 alleles was performed by polymerase chain reaction and hybridization with sequence-specific oligonucleotide probes. Differences in clinical and sleep parameters were compared by univariable analyses. HLA-DQB1*06:02 frequency was systematically compared with the published literature.

RESULTS

Type 1 narcolepsy was diagnosed in 19/29 (65.5%) patients, whereas 10/29 (34.5%) patients had type 2 narcolepsy. DQB1*06:02 was present in 25/29 (86.2%) patients; 15/19 (78.9%) narcolepsy type 1 patients and 10/10 (100%) narcolepsy type 2 patients harboured the DQB1*06:02 allele. REM latency was significantly lower in DQB1*06:02-positive patients compared to DQB1*06:02-negative patients (17.6 ± 32.3 min vs. 106.0 ± 86.0 min; p = 0.025). Epworth Sleepiness Scale scores were significantly higher among type 1 than type 2 narcolepsy patients (19.7 ± 3.2 vs 15.3 ± 3.6; p = 0.02).

CONCLUSIONS

DQB1*06:02 allele frequencies among Saudi patients with narcolepsy were consistent with previously published data.

Sleepiness in Children: An Update

Sleep is essential for children's learning, memory processes, school performance, and general well-being. The prevalence of sleepiness in children is approximately 4%. Reductions of sleep duration have daytime consequences, including sleepiness, behavior problems, cognitive deficits, poor school performance, inflammation, and metabolic dysfunction. Chronic pain, movement disorders, and sleep-disordered breathing also may lead to daytime somnolence, inattention, hyperactivity, oppositional behaviors, and mood dysregulation. Parent-report questionnaires are useful tools to assess subjective sleepiness in children. Sleepiness in children may be secondary to a sleep problem, such as narcolepsy, central hypersomnia, Kleine-Levin disease, or circadian rhythm disorder.

The use of citalopram for the treatment of cataplexy

This is a series of cases describing the use of citalopram for the treatment of cataplexy in patients with narcolepsy. Cataplexy is the most specific symptom of narcolepsy, being characterized by a sudden and temporary loss of muscle tonus, triggered by episodes of emotion during vigil. Some antidepressants, besides gamma-hydroxybutyrate, are used for the control of cataplexy. As gamma-hydroxybutyrate is not available in Brazil, local treatment is usually done by the use of antidepressants. Citalopram is a selective inhibitor of serotonin reuptake, with reasonable price and with fewer side effects when compared with other drugs of the same type. In this study, we report a series of cases with patients with narcolepsy and cataplexy, treated with citalopram for the control of cataplexy.

Cataplexy as a side effect of modafinil in a patient without narcolepsy

Narcolepsy is a disease in which there is diurnal excessive sleepiness with sleep attacks and a prevalence in the general population of 1/4000 individuals. Classically, it is characterized by cataplexy, sleep paralysis, hypnagogic hallucinations and fragmented sleep. The use of modafinil in the treatment of narcolepsy is the first option of treatment for diurnal excessive sleepiness.

Although considered a safe drug for use in patients with narcolepsy, being utilized for more than 20 years, modafinil possesses a series of side effects, some of them still not fully researched or described.

Side effects such as headache, nausea, anxiety, insomnia, lumbago, diarrhea, dyspepsia, rhinitis and vertigo are the most frequent. However, the clinical follow-up of patients under treatment with modafinil must be intensive and the side effects ought to be noted and evaluated. The under-response to treatment or the unexpected side effects must always be directed to differential diagnostics.

The objective of this article is to describe an unexpected side effect of the use of modafinil in a patient with incorrect diagnosis of narcolepsy.

Moebius syndrome and narcolepsy: A case dissertation

Moebius syndrome (MS) is a congenital syndrome characterized by unilateral or bilateral aplasia of the VI and VII cranial nerves, with consequent convergent strabismus and bilateral peripheral facial paralysis. This syndrome might be associated with diurnal excessive sleepiness and muscular hypotony, mimetizing in this manner, narcolepsy. The diagnostic criteria for narcolepsy depend on the presence of REM sleep during the day. As with patients with MS we do not have ocular movements due to the VI nerve paralysis, the absence of horizontal ocular movements might make it difficult to confirm narcolepsy in these patients. The common clinical characteristics of these patients are due to a possible impairment of the same structures that are affected in the central nervous system. However, the mechanism by which it occurs remains to be fully understood. Further electrophysiological researches are necessary to better clarify the association of these two diseases. The objective of this dissertation is to describe and discuss a case of Moebius syndrome with diurnal excessive sleepiness as a differential diagnosis for narcolepsy.