Autonomic dysfunction in childhood hypersomnia disorders.

OBJECTIVE: Orthostatic intolerance (OI) is a common manifestation of autonomic dysfunction. It is characterized by light-headedness and palpitations in the upright position, with relief when supine. It can affect the quality of life. Other symptoms that may accompany OI include headache, fatigue, nausea, palpitations and abdominal pain. The prevalence and characteristics of autonomic symptoms in childhood hypersomnia disorders of childhood has not been examined, and hence were studied. METHODS: The medical records of children and adolescents with hypersomnia disorders were reviewed. Subjects had been diagnosed with narcolepsy types 1 or 2 (NT1 or NT2), idiopathic hypersomnia (IH) or the KLS, or hypersomnia related to medical conditions, were under 18 years of age at sleep diagnosis, and had been evaluated at our sleep center between 2000 and 2018. Those with comorbidities such as obstructive sleep apnea and major depression were excluded. The medical records were reviewed for symptoms at initial presentation suggestive of autonomic dysfunction, such as orthostatic intolerance, headache, fatigue, nausea, palpitations and abdominal pain. If these symptoms had been recorded, the chart was examined further to determine if an autonomic reflex screen (ARS) battery had been conducted. The ARS battery examines both sympathetic and parasympathetic function. It is composed of a tilt table test, heart rate and blood pressure responses to the Valsalva maneuver and deep breathing, a quantitative sudomotor axon reflex test and beat-to-beat blood pressure measurements during the Valsalva maneuver. Results of the ARS battery were interpreted by an autonomic neurology specialist (WS), who was not otherwise involved in the care of the patients. Medications taken at the time of autonomic testing were recorded. RESULTS: There were 89 patients with hypersomnia disorders. Forty six patients had NT1, 17 had NT2, 18 had IH, 1 with KLS, and 7 had hypersomnia associated with medical disorders. Thirty three of 89 subjects (37%) had the symptom of OI at initial presentation, hence had undergone autonomic reflex screen testing. The median age at diagnosis of hypersomnia in the 33 subjects with the OI symptom was 14.5 years (interquartile range 12-16) and similar (14.5 years, interquartile range 11.5-16) in the 56 subjects without OI. In the group with OI, 25/33 had not received medications for treating hypersomnia at the time of autonomic testing. OI was not related to the degree of sleepiness- the mean sleep latency in the subjects with OI was 5.3 ± 2.9 min while in those without OI it was 4.5 ± 3.8 min. The symptom of OI was not more likely to occur in any specific type of hypersomnia. OI however tended to occur predominantly in females - the female: male ratio in the OI subgroup was 2:1 (n = 33) while in the subgroup without OI, it was 1: 2.1 (n = 56; p = 0.0015). Additional symptoms recorded in the OI subgroup included lightheadedness in 25/33, palpitations in 6/33, nausea and vomiting in 4/33, fatigue in 25/33, headache in 15/33 and constipation in 3/33. The symptoms of OI were reproduced during the tilt table test in 17/33 subjects; 5 of these patients had a rise in heart rate consistent with postural orthostatic tachycardia syndrome (POTS). CONCLUSION: In this retrospective sample, one third of children with hypersomnia disorders exhibited the symptom of OI at initial presentation, with female predominance. A smaller subgroup met criteria for POTS. Screening for autonomic symptoms in children with hypersomnia is important because the former seems to be a treatable co-morbidity that impacts the sense of well-being.