Electrical spinal, internal capsular or cortical stimulation treatment for central (thalamic) pain

We studied the effectiveness of electrical stimulation treatment in 10 cases with central (thalamic) pain. Pain was caused by thalamic hemorrhage in 6 cases. There was one case each of putamino– thalamic, putaminal, pontine hemorrhage and thalamic infarct. We were able to achieve sufficient and long–term pain control by epidural spinal cord stimulation in all 4 cases in which pain was localized on the distal part of the upper or lower extremity. Pain control extended for a mean of 3.8 years in these cases. Precentral cortical stimulation treatment was carried out in 6 cases with diffuse pain (hemibody). Three cases were new, while 3 others were recurrent cases after thalamotomy. Sufficient pain relief was achieved in 3 cases. However, it was not obtained in the other 3 cases. In the former 3 cases, two were new with one recurrent case after thalamotomy. Pain was controlled during a mean of one year and 9 months. In all these cases, spontaneous pain was severe but hypesthesia mild. Electrical stimulation on the presumed precentral cortical area evoked a sensori–motor effect on the painful part of the body with low voltage stimulation. Regional CBF or rCMRglu decreased slightly and was localized in the affected thalamus. A MEG study demonstrated preservation of spino–thalamo–cortical function in one case. In the latter 3 cases in which we failed to obtain pain relief, one was new and the other two were recurrent cases after thalamotomy. In the 2 recurrent cases, we frequently encountered irregular burst discharges and positive spikes, but seldom found sensory responses of the sensory thalamus to peripheral natural stimulation during the operation. In one of these 3 cases, internal capsular (posterior limb) stimulation was performed, resulting in sufficient but short–term pain relief. In cases of localized thalamic pain, epidural spinal cord stimulation proved to be an effective treatment. In cases with diffuse pain, precentral cortical stimulation could be expected to ameliorate the intractable pain in those limited cases in which CVD had caused mild destruction of the pain conducting system and the spino–thalamo–cortical function was mostly preserved.