Narcolepsy-cataplexy: is streptococcal infection a trigger?

Clinical Evaluation and Management of Narcolepsy in Children and Adolescents

While sleepiness is common among children, and particularly adolescents, profound sleepiness in the setting of apparently adequate sleep should prompt consideration of a central disorder of hypersomnolence. These disorders, which include narcolepsy, idiopathic hypersomnia, Kleine-Levin syndrome, and others, are likely underrecognized in the pediatric population. Narcolepsy in particular should be of interest to child neurologists as the unique signs and symptoms of this disease often prompt evaluation in pediatric neurology clinics. While sleepiness may appear to be a straightforward complaint, its evaluation requires a nuanced approach. Cataplexy, a hallmark of narcolepsy, can be confused for other neurologic conditions, though understanding its various manifestations makes it readily identifiable. Clinicians should be aware of these symptoms, as delay in diagnosis and misdiagnosis are common in childhood narcolepsy. While treatment options have been limited in the past, many new therapeutic options have become available and can result in significant improvement in symptoms. Given the age at presentation, paroxysmal and chronic features, diagnostic modalities, and available treatment options, the field of child neurology is well equipped to see patients with narcolepsy. In this review, I will focus on the presentation, evaluation, and management of pediatric patients with narcolepsy.

Narcolepsy following COVID-19: A case report and review of potential mechanisms

Key Clinical Message

The immune activation in COVID-19 may trigger narcolepsy in vulnerable patients. We suggest clinicians carefully evaluate patients with post-COVID fatigue and hypersomnia for primary sleep disorders, specifically narcolepsy.

Abstract

The patient is a 33-year-old Iranian woman without a significant past medical history with the full range of narcolepsy symptoms that started within 2 weeks after her recovery from COVID-19. Sleep studies revealed increased sleep latency and three sleep-onset rapid eye movement events, compatible with a narcolepsy-cataplexy diagnosis.

Central Hypersomnia

Sleepiness is not uncommon in the pediatric population. Although the etiology can be multifactorial, sleepiness due to increased sleep drive, also called central hypersomnia, is a common cause. The third edition of the International Classification of Sleep Disorders updated the diagnostic criteria for several of the central disorders of hypersomnolence, most notably narcolepsy. Although the International Classification Of Sleep Disorders-3 is not specific to pediatric patients, the peak incidence for many of the included disorders occurs during childhood or adolescence. As a result, recognition of these lifelong and potentially debilitating disorders is imperative for providers who evaluate pediatric patients. This review provides an update on recent advances in the field and highlights some of the diagnostic dilemmas, unique clinical features, and variable presentations associated with central disorders of hypersomnolence within the pediatric population.

Infancy narcolepsy: Streptococcus infection as a causal factor

Streptococcal infections are suggested as a risk factor for narcolepsy. This hypothesis is supported by the presence of anti-streptolysin antibodies in 65% of patients with narcolepsy. These infections are associated with the activation of general immunity and concomitant increased permeability of blood–brain barrier after T cell activation during inflammation and fever.

It has also been shown a significant association between birth order and narcolepsy in genetically susceptible patients, with positivity for HLA-DQB1⁎0602 allele. Watson and colleagues showed a significant association between birth order and narcolepsy in genetically susceptible patients, with positivity for HLA-DQB1⁎0602 allele. In that study, the disease was predominant in young children cases compared to controls.

We report here the case of a child diagnosed with narcolepsy with cataplexy, positivity for the HLA-DQB1⁎0602 and previous history of streptococcal infection.

Increased plasma level of tumor necrosis factor α in patients with narcolepsy in Taiwan

BACKGROUND

Narcolepsy is a neuropsychiatric disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and abnormal rapid eye movement (REM) sleep. Tumor necrosis factor α (TNF α) and its cognate receptors have been reported to be involved in the pathophysiology of narcolepsy in addition to the HLA antigen system. Our study aimed to determine if the TNF-α system was associated with narcolepsy in our patients.

METHODS

We first measured the plasma level of TNF α in 56 narcoleptic patients and 53 control subjects using a highly sensitive enzyme-linked immunosorbent assay. We next determined the genotype of three single nucleotide polymorphisms (SNPs) (T-1031C, C-863A, and C-857T) at the promoter region of the TNF-α gene and one missense SNP (T587G, M196R) at the exon 6 of the tumor necrosis factor receptor 2 gene, TNFR2, in a sample of 75 narcoleptic patients and 201 control subjects by direct sequencing analysis.

RESULTS

We found a significant elevation of plasma level of TNF α in patients with narcolepsy compared with the control subjects (4.64pg/mL vs 1.06pg/mL; P=.0013). However, we did not find significant differences between these two groups in the allelic and genotypic distributions of the investigated polymorphisms.

CONCLUSIONS

Our study suggests that an increased TNF-α level was associated with narcolepsy in our patients, and that chronic inflammation due to various factors might have led to the increased TNF-α levels found in our patients.