Batten disease with Narcolepsy and Functional Neurological Disorder: A Case Report

Background Juvenile Batten disease, or neuronal ceroid lipofuscinosis type 3 (CLN3), is a rare neurodegenerative condition defined by progressive symptoms including seizures, vision impairment, motor decline, decaying cognitive function, and neuropsychiatric symptoms. The co-occurrence of functional neurological disorder (FND) and narcolepsy - conditions with significant clinical overlap with CLN3 symptoms - has not previously been reported in the literature. Case presentation: We describe a 17-year-old female with CLN3 who developed complex seizure-like events and profound daytime somnolence during adolescence. Her presentation was complicated by severe major depression, generalised anxiety, and suicidality. Elective video-encephalogram (EEG) monitoring confirmed a diagnosis of functional seizures. Subsequent Multiple Sleep Latency Testing (MSLT) confirmed a diagnosis of narcolepsy. Treatment with armodafinil resulted in marked and sustained improvements in energy, mood stability, and a dramatic reduction in functional seizure frequency, which had previously been resistant to standard psychiatric and anti-epileptic interventions. Conclusions This case highlights the previously unreported co-occurrence of FND and narcolepsy in patients with CLN3. These conditions can mimic core disease symptoms, leading to diagnostic overshadowing. Identifying and treating these comorbidities, particularly through stimulant therapy for narcolepsy, can significantly improve quality of life and functional outcomes in adolescents with juvenile Batten disease.