0821 Postural Orthostatic Tachycardia Syndrome in Idiopathic Hypersomnia

Abstract Introduction Idiopathic hypersomnia (IH) is a chronic neurologic sleep disorder causing excessive daytime sleepiness despite normal or prolonged sleep durations, often impairing daily functioning. Autonomic symptoms are common in people with IH. Postural orthostatic tachycardia syndrome (POTS), a form of autonomic dysfunction, is marked by symptomatic increased heart rate upon standing. This study aimed to investigate whether IH with comorbid POTS represents a distinct subtype of IH based on symptoms, signs, and treatment responses. Methods This retrospective study analyzed clinical data from IH patients who had (POTS+) or had not (POTS-) been diagnosed with POTS. We compared clinical, demographic, and sleep features between POTS+ and POTS−, employing Chi-square, Fisher’s exact test, or t-tests, as indicated. Results Among 173 patients with idiopathic hypersomnia (IH), 75% were female, with a mean age of 43.1±15.3 years. Of these, 22 (12.7%) also had POTS. POTS+ patients were younger (38.3±10.7 vs. 43.8±15.8 years, p=0.04); gender distribution did not differ. At baseline, POTS+ patients had similar Epworth scores (16.3±4.9 for POTS+ vs 14.9±4.9 for POTS-, p=0.49), Functional Outcomes of Sleep scores (FOSQ, 9.4±4.0 vs 11.97±4.0, p=0.053), average weekday sleep durations (9.6±2.56 vs. 9.03±2.25 hours, p=0.46), and proportion with difficulty waking in the morning and cognitive symptoms. PSG sleep efficiency (89.3%±6.17% vs. 85.4%±10.63%, p=0.06), total sleep time (450.6±75.9 vs 424.2±80.9, p=0.27), and MSLT mean sleep latency (5.28± 2.53 vs 4.98±2.74, p=0.67) did not differ by group. Comorbidities such as Ehlers-Danlos syndrome (22.7% vs 1.3%, p=0.0004), fibromyalgia (22.7% vs 5.3%, p=0.01), and headaches (77.27% vs. 42.3%, p=0.002) were more common in POTS+, without significant differences for Hashimoto’s or mood disorders. The POTS+ group was more likely to have side effects from amphetamine-dextroamphetamine (58.3% vs 16.1%, p=0.004) and methylphenidate (41.7% vs 11.9% p=0.03) but not modafinil, armodafinil, solriamfetol or oxybates. Conclusion People with IH and comorbid POTS have similar IH symptom severity and PSG/MSLT findings to those with IH without POTS. However, those with POTS are more likely to also have comorbid Ehlers-Danlos, fibromyalgia, and headache. The presence of POTS may signal an increased risk of side effects with traditional psychostimulants used for treating IH. Support (if any) NS111280