Open-lip schizencephaly is a rare congenital malformation of cortical development characterized by a cerebrospinal fluid-filled cleft extending from the lateral ventricle to the subarachnoid space. The margins of the cleft are separated and lined by dysplastic gray matter, a defining feature that distinguishes schizencephaly from porencephaly. It may be unilateral or bilateral and is commonly associated with polymicrogyria, agenesis of the septum pellucidum or corpus callosum, and other developmental brain abnormalities.

The exact cause is not fully established. Proposed mechanisms include disruption of neuronal migration, genetic susceptibility, prenatal vascular injury, and intrauterine infections. Clinical manifestations vary according to the size, site, and laterality of the cleft. Patients may present with developmental delay, seizures, hemiparesis or quadriparesis, spasticity, speech impairment, and intellectual disability. Bilateral and large open-lip lesions are generally associated with more severe neurological deficits.

Magnetic resonance imaging is the investigation of choice because it accurately demonstrates the gray matter-lined cleft, its communication between the ventricular system and subarachnoid space, and associated cerebral malformations. Management is individualized and primarily supportive, including antiseizure medications, physiotherapy, occupational and speech therapy, developmental intervention, and educational support. Neurosurgical treatment, such as cerebrospinal fluid shunting, may be required when hydrocephalus is present.

Early diagnosis, multidisciplinary care, and long-term rehabilitation can improve functional outcomes and quality of life. Open-lip schizencephaly should be considered in children presenting with seizures, developmental delay, and focal neurological deficits, particularly when neuroimaging reveals a gray matter-lined cerebral cleft.