Dyke-Davidoff-Masson Syndrome Underlying Hemiplegic Cerebral Palsy in an Adolescent: A Case Report.

Dyke-Davidoff-Masson syndrome (DDMS) is a rare clinicoradiological syndrome involving unilateral cerebral hemiatrophy with compensatory calvarial changes. It typically presents with seizures, contralateral hemiparesis or hemiplegia, and developmental delay. The clinical manifestations may overlap with those of hemiplegic cerebral palsy, potentially delaying recognition of the underlying structural diagnosis. We report a 14-year-old male with longstanding right hemiplegic cerebral palsy and focal epilepsy who presented following a bicycle-related injury. During admission, non-contrast computed tomography of the brain was done to exclude intracranial pathology due to complaints of persistent headache. Imaging demonstrated extensive left frontoparietal encephalomalacia involving the middle cerebral artery territory, ex vacuo dilatation of the left lateral ventricle, ipsilateral Wallerian degeneration, and calvarial thickening, consistent with DDMS. No acute intracranial abnormality was identified. The patient recovered and was subsequently discharged with continued anti-seizure medications and multidisciplinary outpatient follow-up. This case highlights the importance of considering DDMS in patients with hemiplegic cerebral palsy and epilepsy. Recognition of DDMS provides an anatomical explanation for the patient's neurological phenotype, enhances understanding of the underlying cerebral injury, and supports long-term multidisciplinary management.