Unilateral megalencephaly: correlation of MR imaging and pathologic characteristics.
Unilateral megalencephaly is a rare and poorly understood malformation resulting in the enlargement of all or part of a cerebral hemisphere. The clinical and radiologic features of 12 patients with unilateral megalencephaly are presented; pathologic correlation was available in four. All patients had seizures and developmental delay. Two were in congestive heart failure as a result of arteriovenous shunting through the abnormal hemisphere. The affected hemispheres showed a wide spectrum of involvement. Anomalies of neuronal migration were present, and there was a roughly inverse correlation between the severity of hemispheric involvement and the magnitude of enlargement. This correlation is explained via a proposed mechanism of a mild hemispheric insult in the middle-to-late second trimester. One patient had an extremely anomalous hemisphere that did not have characteristics of a neuronal migration anomaly and may have been a hamartomatous malformation. Our correlation of the clinical, radiologic, and pathologic features of unilateral megalencephaly, together with a theory of pathogenesis, should help elucidate this rare malformation.
Department of Radiology, University of California School of Medicine, San Francisco 94143.
A J
AJ
Barkovich
S H
SH
Chuang
D000293:Adolescent; D000328:Adult; D001927:Brain Diseases / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000209:etiology; D005260:Female; D006429:Hemiplegia / Q000209:etiology; D006801:Humans; D006984:Hypertrophy / Q000175:diagnosis; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D012640:Seizures / Q000209:etiology; D014057:Tomography, X-Ray Computed