A teen's belief that strangers were one person in disguise traced to Moyamoya disease

Moyamoya disease narrows the distal internal carotid arteries and prompts the growth of fragile collateral vessels. Psychiatric symptoms are rarely reported with it, especially in children. This case report describes an early adolescent already diagnosed with the condition who developed abrupt psychosis after a febrile illness with headache and vomiting.

He had auditory hallucinations, persecutory delusions, emotional lability and Fregoli syndrome, the conviction that different strangers are really a familiar person in disguise. Imaging showed narrowing of both carotid arteries with extensive collaterals, while infectious, autoimmune and metabolic work-ups found nothing. He underwent a bypass procedure combined with synangiosis. His psychotic symptoms resolved after surgery, and he was back to baseline within a month.

This is a single case, so it cannot prove that the vascular disease caused the psychosis or that surgery cured it. Even so, the authors argue that cerebrovascular causes deserve consideration in sudden-onset childhood psychosis, even without major neurological deficits.