Porencephalic cyst: an unusual radiological finding in adult-onset seizure

Abstract

We report the case of a 39-year-old male who presented to the emergency department with a new-onset seizure, without prodromal symptoms, and with a remote history of neonatal bacterial meningitis without subsequent neurological follow-up. Physical examination revealed chronic distal left-sided hemiparesis, consistent with long-standing neurological sequelae. Cranial computed tomography demonstrated a large, well-defined hypodense cavity within the right cerebral hemisphere, CSF-attenuation, and communicating with the ipsilateral ventricular system, involving the frontal, parietal, and temporal lobes. These imaging findings are consistent with a porencephalic cyst, likely secondary to perinatal encephalic injury. A diagnosis of symptomatic structural epilepsy was established, and antiepileptic therapy with valproic acid was initiated, with referral for specialized follow-up. This case highlights the need to consider long-standing cerebral malformations or post-injury sequelae as potential etiologies of new-onset seizures in adulthood, particularly in patients with undocumented chronic neurological deficits.