Neurophysiological Basis of Mirror Movements in Schizencephaly: A Case Report

Mirror movements (MMs) are involuntary movements on one side of the body that mimic voluntary movements on the opposite side. Schizencephaly is an uncommon congenital neuronal migration disorder characterised by the presence of a trans-mantle column of heterotopic grey matter, with or without a full-thickness cleft filled with cerebrospinal fluid, which links the pial surface of the cerebral hemisphere with the ependymal surface of the lateral ventricle. We report a case of a 13-year-old child with unilateral schizencephaly who presented with MMs. Transcranial magnetic stimulation was used to understand the neurophysiology of MMs. Single-pulse and paired-pulse stimulation were done. The silent period was shortened with absent short-interval intracortical inhibition and reduced intracortical facilitation. This suggests reduced GABAergic and glutamatergic transmission in the brain. These altered neurophysiological parameters, along with motor cortex re-organisation, may account for MMs in our case.