Stereotactic posterior capsulo-lentiform deafferentation as an effective treatment in central post-stroke pain. A new surgical method for intractable central pain control?

摘要

The authors present a case of a 72-year-old man with 3 years history of chronic 'burning' pain syndrome associated with allodynia, involving the hemiparetic left side of the body, due to right cerebral hemisphere stroke (post-stroke damage to the putamen, claustrum, external capsule and part of insular cortex). This pain has fullfilled all the criteria of 'central' pain. Stereotactic lesion disconnecting the posterior arm of the internal capsule and the lentiforme nucleus (including ansa lenticularis) was performed (based empirically on the results of intraoperative depolarizing macrostimulation tests) with the electrodes introduced subsequently into different possible target points. The clinical effects of stimulation tests were assessed and reported intraoperatively by the alert patient (under local anaesthesia). Two permanent high frequency lesions have been placed along the border between the posterior branch of the internal capsule and the lentiform nucleus. Only in this area was depolarising stimulation effective in controlling the pain in the whole left side of the body, including lower and upper limbs, the left side of the trunk and the left side of the face. Stimulation (depolarising macrostimulation) did not interfere with perception of the normal sensation in the affected parts of the body, or with voluntary movements. The central pain and allodynia disappeared immediately after lesioning. Postoperative MRI proved the proper positioning of the lesion. The duration of the immediate result has been proved at the 5-month follow-up. The patient is still pain-free. Immediately after the operation, hemiparesis was exaggerated, but then slowly resolved to the previous preoperative level. The sequel of surgery is increased spasticity of the left elbow joint and the decreased precision of movement coordination of the left limbs, with the preserved muscles strength at the preoperative hemiparetic level (Lovett's scale: grade 4). The authors discuss the possible neurophysiological explanation (interference with nociceptive information processing? lesion in the site of the excitatory efferent control of central sensation entry gate?) and the possible clinical implication of the reported procedure.