Functional recovery in hemiplegic cerebral palsy: ipsilateral electromyographic responses to focal transcranial magnetic stimulation.

The patterns of functional recovery after unilateral cerebral damage occurring in the prenatal to infantile periods were studied in nine patients with hemiplegic cerebral palsy. Motor evoked potentials (MEPs) recorded from the small hand muscles were investigated using focal transcranial magnetic stimulation (TMS). The MEPs findings could be separated into three subtypes based on the features of ipsilateral MEPs elicited by TMS over the unaffected motor cortex. Bilateral MEPs of similar latency were obtained in three patients. These patients each having a congenital lesion invariably exhibited mirror movements and severe hemiparesis. Meanwhile, ipsilateral MEPs with markedly prolonged latency were demonstrated in two other patients, who exhibited synergistic associated movements and severe hemiparesis caused by an acquired lesion. In the remaining four patients, who showed mild hemiparesis without such abnormal interlimb coordinations, there were no ipsilateral MEPs. Thus, we suggest that TMS is useful for confirming the electrophysiological findings relevant to functional recovery in hemiplegic cerebral palsy underlying such abnormal interlimb coordinations. Specifically, bilateral MEPs of similar latency were considered consistent with compensatory mirror movements originating from bilateral motor representation in the unaffected motor cortex.