P13. Childhood narcolepsy with cataplexy: Clinical characteristics of 4 cases

Introduction Childhood narcolepsy with cataplexy is a rare lifelong disorder which usually emerges in adolescence. Diagnosis is often delayed for many years due to poor awareness and gradual onset of symptoms. Excessive daytime sleepiness can be mistaken as a physiological phenomenon of the teenage years and cataplexy might be overlooked. Methods 4 proven cases of narcolepsy are presented that were referred to our outpatient clinic during the past 2 years. Results We report on 3 boys and 1 girl aged 6 to 13 years at disease onset. In all patients excessive daytime sleepiness was the main complaint. At the time of first presentation cataplexy was not reported but recognized by patients and parents when asked for. Loss of muscle tone affected the face and the trunk. None of the patients had drop attacks. 1 boy had major weight gain. The girl was the only patient who reported on night-time hallucinations and sleep paralysis and therefore presented with all disease defining symptoms. Rapid disease onset after a viral infection occurred in 2 boys. In 2 patients a peculiar facial expression with unusual tongue protrusion was reported and evident on physical exam. Mood changes and aggressive behaviour occurred in 2 patients. Polysomnography (PSG) and multiple sleep latency (MSLT) tests were performed in all patients and revealed typical findings of narcolepsy with sleep fragmentation, sleep onset REM and short sleep latency in 3 patients, while in 1 patient PSG and MSLT were normal. Carriage of the HLA-DQB1∗0602 haplotype and low CSF hypocretin levels were confirmed in the 3 boys. In one patient intravenous immunoglobulins were administered and lead to a transient symptom relief but failed to induce an increase of CSF hypocretin. Excessive daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS). All patients were treated with methylphenidate resulting in reduction of the ESS score. In 2 patients improvement is not yet considered as sufficient. As expected cataplexy did not respond to treatment. Conclusions Narcolepsy with cataplexy is a severely disabling, most probably autoimmune disease. Early diagnosis and treatment initiation may improve school performance and quality of life during the teenage years and hopefully also the longterm course. Treatment recommendations are adopted from adult medicine but are still controversial due to addictive potential and off-label use of some substances, as sodium oxybate in children.