[Somatosensory evoked potentials in a patient with Parkinson's disease before and after cryothalamotomy]

To document changes in SEPs in PD we have chosen a patient with the idiopathic form of the disease. Because of drug intolerance and progressively deteriorating clinical course she was selected for thalamotomy. Before the operation we recorded oscillations in the range of 150-300 Hz superimposed on SEP over the area of the right hand cortical representation, an a low amplitude of the N20-P25-N34 components. Eight weeks after left thalamotomy the amplitude of oscillations recorded over the left hemisphere diminished. A new wave, P65, appeared and similar SEPs were seen in the right hemisphere ipsilateral to the stimulated median nerve. Following stimulation of the left median nerve unchanged SEPs were observed only in the right hemisphere. Sixteen weeks after the operation, SEPs from the left hemisphere had a similar sequence as before the procedure. There was a clear increase in amplitude of long latency waves recorded from the left scalp. Changes in SEP polarity and amplitude following operation are attributed to plastic reorganization of cortical connections.