Variations in morphology of cerebral hemispheres and their clinical implications with special reference to polygyria

Polygyria is a developmental anomaly of the brain characterized by development of numerous small gyri. It is a neuronal migration cortical organization disorder which is often sporadic or genetic but is also seen secondary to vascular compromise. In the present study, 100 brain specimens fixed in 10% formalin were studied extensively in the department of Anatomy, Lady Hardinge Medical College, New Delhi and the pattern of sulci and gyri of the two cerebral hemispheres with their variations were identified and photographed. We observed an abnormal pattern of sulci and gyri in the form of polygyria on the medial surface of the cerebral hemisphere in the occipital and frontal lobes in 2% cases. The length of the corpus callosum and frontal-occipital pole diameter of one hemisphere was more than that of the other in 1% cases. The association of polygyria with unequal size of cerebral hemispheres is a rare presentation. These presentations are associated with numerous neurological deficits like mental retardation, seizures, spastic hemiparesis or quadriparesis etc. which may be of relevance to physicians, neurologists, neurosurgeons and radiologists.