Unilateral polymicrogyria

Unilateral polymicrogyria (unilateral PMG) is a brain malformation characterized by an excessive number of abnormally small gyri (folds) on the surface of one cerebral hemisphere. It belongs to the broader group of polymicrogyria disorders, which are classified as malformations of cortical development. In unilateral polymicrogyria, the abnormal cortical folding is confined to one side of the brain, distinguishing it from bilateral forms. The condition results from disrupted late neuronal migration or abnormal cortical organization during fetal brain development. The underlying causes can be genetic (involving various genes implicated in cortical development) or acquired (such as prenatal vascular insults, infections, or ischemic events), and in many cases the etiology remains unknown. The clinical presentation of unilateral polymicrogyria is variable and depends on the extent and location of the cortical malformation. Common manifestations include epilepsy (often focal seizures that may be drug-resistant), contralateral hemiparesis (weakness on the opposite side of the body from the affected hemisphere), developmental delay, and intellectual disability of varying severity. Some patients may also experience speech and language difficulties. Seizures frequently begin in infancy or childhood and represent one of the most significant clinical challenges. Neurological deficits tend to correlate with the size and location of the affected cortical region, with perisylvian involvement being particularly common. There is currently no cure for unilateral polymicrogyria. Treatment is symptomatic and supportive. Antiepileptic medications are the first-line therapy for seizure management, though refractory epilepsy may require evaluation for surgical intervention, including hemispherectomy or focal resection in carefully selected patients. Physical therapy, occupational therapy, and speech therapy are important components of management to optimize motor function, cognitive development, and communication skills. Regular neurological follow-up and multidisciplinary care are recommended to address the evolving needs of affected individuals.

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