Double Cortex Syndrome in an Adolescent Female with Refractory Epilepsy and Consanguineous Parentage: A Case Report

Double cortex syndrome, also known as Subcortical Band Heterotopia (SBH), is a rare X-linked dominant neuronal migration disorder caused by mutations in the Doublecortin (DCX) gene located at Xp22.3. It almost exclusively affects females, who present with variable degrees of epilepsy, developmental delay, and intellectual disability. We report an 18-year-old female born of second-degree consanguineous parentage who presented with multiple generalised tonic-clonic seizures and transient loss of consciousness. She had achieved normal developmental milestones until five years of age, when speech regression became apparent, followed by progressive learning difficulties and poor concentration during schooling. Physical examination confirmed global developmental delay. Electroencephalography (EEG) demonstrated epileptiform abnormalities. Computed Tomography (CT) of the brain revealed an abnormal band of grey matter deep to and paralleling the cortex bilaterally, raising the diagnosis of double cortex syndrome. Magnetic Resonance Imaging (MRI) of the brain confirmed bilateral symmetric subcortical grey matter bands isointense to normal cortex on all sequences, with frontoparietal cortical thickening and a thin intervening white matter layer creating the characteristic double cortex appearance. Antiepileptic therapy was initiated with referral for genetic counselling. This case underlines the critical role of MRI in the diagnosis of cortical malformations and the need for early genetic testing to guide management and family planning.