Cortical reorganization of sensory, motor and language functions due to early cortical damage

Abstract 

During evaluation of a 22-year-old man for epilepsy surgery it was demonstrated that reorganisation of sensory, motor and language functions had occurred. Restricted perinatal lesions in the left frontal opercular region and in the hand primary sensory area had resulted in severe partial epilepsy and minor neuropsychological deficits, but no neurological deficits. The dominance for language and handedness was shifted to the right hemisphere but some language representation was still found in the left hemisphere. Threshold electrical stimulation via subdurally placed cortical electrodes revealed reorganisation of the hand sensory area in the left hemisphere. Hand sensory responses were electrically evoked close to the opercular region where also face sensory responses were recorded. Some of the sensory responses were located in the frontal lobe in the premotor cortex. The locations of the sensory representation areas differed from those expected neuroanatomically. The cortical motor responses were located around the presumed location of the precentral gyrus. These findings are considered to represent a functional intra- and interhemispherical reorganisation of cortical areas as a result of early cortical lesions, anatomically close to the somatosensory and language areas. A possible mechanism discussed is reorganisation of the thalamocortical projections.

Keywords:  Perinatal cerebral lesion, Cortical plasticity, Cortical reorganisation, Human epilepsy, Epilepsy surgery

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