Dysfunction of transcallosally mediated motor inhibition and callosal morphology in patients with schizophrenia

Objective: In order to assess the functional integrity of motor pathways through the corpus callosum (CC) in patients with schizophrenia transcallosally mediated inhibition (TI) of voluntary tonic EMG activity, of first dorsal interosseus muscle following ipsilateral focal transcranial magnetic stimulation (fTMS) was investigated. In addition thickness and length of CC were calculated. Method: Twelve patients suffering from schizophrenia and 12 healthy controls were investigated. CC morphology was measured in midsagittal MRI-slices. Latency and duration of TI were calculated. Results: In schizophrenics the duration of TI was significantly prolonged, whereas latencies were not. In addition, a lack of TI was found unilaterally in three patients. Measurements of CC revealed a significantly reduction of the length and thickness in the anterior part of CC in patients. Conclusion: These findings indicate that measurement of TI could be used to detect clinical silent affection of transcallosal motor pathways in schizophrenics. The effect of neuroleptic drugs has to be explored.