Abstracts

P17 Case Report of Common Occurrence of Narcolepsy Type 1 and Myasthenia Gravis in Adolescent Girl

Abstract

Introduction Narcolepsy with cataplexy and myasthenia gravis are both chronic neurological conditions causing symptoms of muscle weakness, often affecting facial muscles, and both attributed to an immune-mediated aetiology. Here we report an adolescent girl diagnosed with both conditions and discuss possible shared mechanisms and the diagnostic challenges presented by her case, to inform and aid clinicians managing children and young people with these rare conditions.

Case A ten-year-old girl was referred o the paediatric sleep clinic with a two year history of excessive daytime sleepiness and cataplexy, featuring full loss of postural tone. She was subsequently found to have narcolepsy with cataplexy based on positive PSG (figure 1) & MSLT findings with supporting HLA-DQB1*06:02 result. She was managed with methylphenidate, and later venlafaxine, but experienced unsatisfactory symptom control.

Two years later she represented to ophthalmology with ptosis and was subsequently found to have elevated acetylcholine receptor antibodies. She was referred to paediatric neurology and clinical examination demonstrated fatiguability consistent with myasthenia gravis and pyridostigmine was started with good effect.

Abstract P17 Figure 1
Abstract P17 Figure 1

Hypnogram generated from our patient‘s PSG demonstrating rapid sleep onset time (SOT), with first REM cycle arising from N1

Discussion Interesting comparisons between both conditions can be drawn: both cause weakness that can affect facial muscles and cause ptosis and both can be worse as the day progresses for different reasons; both have an immune-mediated aetiology with myasthenia gravis well recognised as antibody-mediated and narcolepsy shown to have increased T-cell activity; both have documented association with other autoimmune disorders.

Conclusion This case highlights an unusual presentation of two very rare conditions with both overlapping clinical features. Co-occurrence is incredibly rare, but caution and consideration of other differential diagnoses is advised if symptoms do not respond to treatment, or are not fully consistent with typical narcolepsy. The possible co-existence of other immune-mediated disorders should be borne in mind, with a low threshold to involve other expert professionals.

References

  1. Wise MS, Lynch J. Narcolepsy in children. Semin. Pediatr. Neurol. 2001;8:198–206

  2. Andlauer O, et al. Nocturnal rapid eye movement sleep latency for identifying patients with narcolepsy/hypocretin deficiency. JAMA Neurol. 2013;70:891–902

  3. Drakatos P, et al. First rapid eye movement sleep periods and sleep-onset rapid eye movement periods in sleep-stage sequencing of hypersomnias. Sleep Med. 2013;14:897–901

  4. Mignot E, et al. The role of cerebrospinal fluid hypocretin measurement in the diagnosis of narcolepsy and other hypersomnias. Arch. Neurol. 2002;59:1553–1562

  5. Miyagawa T, Tokunaga K. Genetics of narcolepsy. Hum. Genome Var. 2019;6:4

  6. Jayawant S. Myasthenia in children. (Mac Keith Press, 2020)

  7. Bassetti CLA, et al. European guideline and expert statements on the management of narcolepsy in adults and children. J. Sleep Res. 2021;30:e13387

  8. Pensato U, Pizza F, Plazzi G. Myasthenic or cataplectic facies? Ice pack test response in paediatric type 1 narcolepsy. Sleep Med. 2021;87:20–21

  9. El Sammak S, Cipriani V, Sahni A, Attarian H. Narcolepsy type 1 comorbid with myasthenia gravis: possible immunological link. J. Clin. Sleep Med. JCSM Off. Publ. Am. Acad. Sleep Med. 2022;18:1889–1890

  10. Latorre D, et al. T cells in patients with narcolepsy target self-antigens of hypocretin neurons. Nature 2018;562:63–68

  11. Giannoccaro MP, et al. Antibodies against hypocretin receptor 2 are rare in narcolepsy. Sleep 2017;40

  12. Mart nez-Orozco FJ, et al. Narcolepsy with cataplexy and comorbid immunopathological diseases. J. Sleep Res. 2014;23:414–419

  13. Aydinoz S, et al. Allergies and disease severity in childhood narcolepsy: preliminary findings. Sleep 2015;38:1981–1984

  14. Barateau L, et al. Comorbidity between central disorders of hypersomnolence and immune-based disorders. Neurology 2017;88:93–100

  15. Tajima Y, Yaguchi H, Mito Y. Non-motor comorbidity of Myasthenia Gravis: Myasthenia Gravis as a systemic immunological disorder involving non-motor systems. Intern. Med. Tokyo Jpn. 2019;58:1341–1347

Article metrics
Altmetric data not available for this article.
Dimensionsopen-url