Evaluation of thoracic myelopathy by transcranial magnetic stimulation

It is sometimes difficult to determine the appropriate surgical site in pat ients with thoracic myelopathy with diffuse or multisegmental lesions. To s olve this problem, a magnetic stimulation study was carried out. Seven pati ents with myelopathy and 10 healthy control subjects were examined. Transcr anial magnetic stimulation was applied and the motor evoked potentials (MEP s) of the intercostal muscles were recorded. The MEP latencies for the two groups were then compared. In patients with thoracic myelopathy, the MEP la tencies caudal to the lesion were more extended than those of the control s ubjects. This method could identify the levels at which myelopathy originat es in patients with a radiologically visible lesion. This method has the po tential to be used for deciding the surgical site at the level responsible for myelopathy in cases with multiple or diffused compression.