Vigabatrin-Associated Brain Abnormalities on MRI in a Patient with PCDH19-Clustering Epilepsy

Background: Cluster epilepsy related to PCDH19 is a rare X-linked disorder that mainly affects females. Atypical presentations, such as infantile spasms, are exceptionally rare, leading to diagnostic and therapeutic challenges. Case Summary: An 8-month-old girl presented with early-onset, drug-resistant epilepsy from 4 months of age, displaying tonic and focal seizures, infantile spasms with hypsarrhythmia, and neurodevelopmental regression. Whole exome sequencing identified a novel heterozygous mutation, c.1072del (p.Val358SerfsTer10), in the PCDH19 gene. Following vigabatrin therapy for infantile spasms, the patient subacutely developed a movement disorders: dystonic movements and action tremor in forearm and hands. Brain Magnetic Resonance Imaging (MRI) revealed symmetrical restricted diffusion and cytotoxic edema in both the thalami and the internal capsules, confirming Vigabatrin-Associated Brain Abnormalities on MRI (VABAMR). Concurrently, a systemic carnitine deficiency was identified, which could additionally have compromised mitochondrial bioenergetics and intensified the tendency to cytotoxic cerebral edema. A strategic reduction in vigabatrin led to complete resolution of movement disorder and neuroimaging abnormalities. Conclusions: This case underscores the high phenotypic variability of PCDH19 mutations, and also the importance of early advanced genetic testing and the consideration of even rare side effects of drugs in differential diagnosis. It is unclear whether that baseline carnitine deficiency could potentially increase the risk of VABAMR.