AbstractA 63-year-old female presents with a one-day history of abnormal twitching movements of the left upper extremity. Her past medical history of hypertension, type 2 diabetes mellitus, chronic systolic congestive heart failure, situs inversus with dextrocardia, seizures, gastroesophageal reflux disease, arthritis, and cervical degenerative disc disease presents with a one-day history of abnormal twitching movements of the left upper extremity. Physical examination was significant for left-sided hemiparesis and chronic mental impairment. Imaging was limited due to claustrophobia, but emergent CT showed no intracranial hemorrhage, mass effect, or midline shift. Multiecho multiplanar MRI of the brain performed under sedation before and after administration of gadolinium-based contrast showed long standing right cerebellar atrophy and decreased size of the right posterior fossa with associated calvarial thickening. A diagnosis of cerebellar hemiatrophy was established. Keywords: Dyke-Davidoff-Masson Syndrome; Cerebellar Hemiatrophy; Cerebral Hemiatrophy; DDMS; Radiology; Radiologic Findings; MRI; CT Dyke-Davidoff-Masson Syndrome