Basal Ganglia Intraparenchymal Cyst Revealed by a Movement Disorder.

Neuroepithelial cysts are rare, benign intracranial lesions most often detected incidentally due to their typically silent clinical course. We report the case of a 12-year-old right-handed girl who presented with progressive weakness of the left upper limb accompanied by involuntary movements of the left hemibody, including myoclonus and dystonia. Brain magnetic resonance imaging (MRI) demonstrated a well-defined intraparenchymal cystic lesion within the right basal ganglia, with cerebrospinal fluid-like signal characteristics and no contrast enhancement, radiologically suggestive of a neuroepithelial cyst. Manifestation as a movement disorder is exceedingly uncommon, particularly in the pediatric population. This case expands the clinical spectrum of basal ganglia intraparenchymal cystic lesions presenting with complex movement disorders and underscores the role of MRI in lesion characterization and clinico-radiological correlation.