Abstract

Objective: Periventricular nodular heterotopia (PNH) is a neurodevelopmental disorder often related to Filamin A gene mutation (FLNA). This mutation causes poor neural migration, manifesting as epilepsy with mild cognitive impairment in females and spontaneous abortion or early death in males. Recent research identified some PNH patients without FLNA mutation, dubbed posterior PNH. Typical presentation includes asymmetric ventricular nodules and additional malformations including cerebellar abnormalities, colpocephaly, and hippocampal malformations. Unlike PNH-FLNA, posterior PNH exhibits no sex-based differences but is often accompanied by cognitive impairment and epilepsy. This presentation discusses the pathophysiology of PNH and illustrates a typical case of posterior PNH condition seen in clinic. Method: A 22-year-old, left-handed, Ukrainian-American man who was a university student presented with refractory epilepsy and practical cognitive difficulties. Seizures appeared with fever at age 9 and persisted, usually absence with occasional falls. Imaging revealed bilateral PNH, cerebellar dysgenesis, reduced cortical volume, and possible mesial temporal sclerosis. Results: Examination revealed forward-tilting posture, tremulous upper face, vague/slowed speech and spatial disorientation. Data revealed borderline impaired IQ and deficits often observed with periventricular lesions, such as generalized slowing and significantly weaker visuospatial than verbal performances. Additional impairments included encoding and retrieval, naming, verbal fluency, mental flexibility, and construction. Close examination of imaging revealed primarily posterior, asymmetric nodules accompanied by multiple pathognomonic abnormalities. Conclusion(s): Imaging and cognitive data led to diagnosis of posterior PNH. The patient was deemed a poor surgical candidate due to non-localized seizure focus. This rather typical presentation of an unusual disorder provides differential diagnostic value with implications for treatment planning in posterior PNH.