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Current targets for deep brain stimulation (DBS) for treatment of movement disorders include the ventrointermediate thalamic nucleus, the subthalamic nucleus, and the globus pallidus internus. There is interest, however, to expand this technology to other targets in order to increase efficacy and reduce side effects. The centre median-parafascicular (CM-Pf) complex, in particular, is considered to be a candidate target in patients with movement disorders. 1 There is some evidence from earlier reports on DBS and from centres performing medial thalamotomy that targeting the medial thalamus including the CM-Pf complex is efficient in controlling movement disorders. 2, 3 Furthermore, a recent study comparing the results between two teams performing thalamic DBS for parkinsonian tremor indicated that CM-Pf stimulation may have a beneficial effect on dyskinesias. 4
At present, we are conducting an open label prospective study on the effects of CM-Pf versus somatosensory thalamic stimulation for treatment of severe neuropathic pain. Here, we present the findings of CM-Pf stimulation in three patients who had concomitant movement disorders.
PATIENTS AND METHODS
Patients
Since December 1997, a total of 12 patients with chronic neuropathic pain have undergone bifocal contralateral stereotactic implantation of quadripolar electrodes in the CM-Pf complex and the somatosensory thalamus after having given informed consent. Preliminary results on the effect of CM-Pf DBS on neuropathic pain have been published elsewhere in abstract form. 5 The mean age at surgery was 56 years. There were six men and six women. The mean history of pain was nine years. All patients had participated in numerous medical trials with insufficient control of their pain. Pain was limited to one side of the face, body, or extremities in every instance.
Three patients had concomitant movement disorders: patient 1 had mild bilateral tremor at rest; patient 2 had mild choreoathetotic movements of the right foot; and patient 3 had amputation stump dyskinesias of his left thigh. The movement disorders in these patients did not result in additional disability and did not require medical treatment.
Methods
Bifocal quadripolar electrodes were implanted stereotactically under local anaesthesia in the CM-Pf complex and the ventroposterolateral (VPL) or the ventroposteromedial (VPM) thalamic nucleus contralateral to the side of the pain (Medtronic 3387; Medtronic Inc, Minneapolis, Minnesota, USA). The VPM thalamic nucleus was chosen in patients with...