Laminectomy versus percutaneous electrode placement for spinal cord stimulation.

OBJECTIVE: The purpose of this study was to compare the long-term effectiveness of spinal cord stimulation using laminectomy-style electrodes versus that using percutaneously implanted electrodes. METHODS: Forty-one patients underwent an initial trial period of spinal cord stimulation with temporary electrodes at Duke Medical Center between December 1992 and January 1998. A permanent system was implanted if trial stimulation reduced the patient's pain by more than 50%. Median long-term follow-up after permanent electrode placement was 34 months (range, 6-66 mo). Severity of pain was determined postoperatively by a disinterested third party using a visual analog scale and a modified outcome scale. RESULTS: Twenty-seven (66%) of the 41 patients participating in the trial had permanent electrodes placed. Visual analog scores decreased an average of 4.6 among patients in whom electrodes were placed via laminectomy in the thoracic region (two-tailed t test, P < 0.0001). Patients who underwent percutaneous placement of thoracic electrodes had an average decrease of 3.1 in their visual analog scores (two-tailed t test, P < 0.001). Electrodes placed through laminectomy furnished significantly greater long-term pain relief than did those placed percutaneously, as measured by a four-tier outcome grading scale (P = 0.02). CONCLUSION: Spinal cord stimulation is an effective treatment for chronic pain in the lower back and lower extremities that is refractory to conservative therapy. Electrodes placed via laminectomy in the thoracic region appear to be associated with significantly better long-term effectiveness than are electrodes placed percutaneously.

The Duke experience with the nucleus caudalis DREZ operation.

The nucleus caudalis DREZ operation has been performed in three phases at Duke. Between 1982 and 1988 radiofrequency (RF) lesions were made in the trigeminal nucleus extending from the C2 root to the obex using a straight electrode. Complications include ipsilateral arm ataxia due to spinocerebellar tract injury and ipsilateral lower limb weakness from the pyramidal tract. The former occurred at least transiently in 90% of cases. The electrode employed from 1988 to 1989 had proximal insulation protecting the spinocerebellar tract. Since 1989 a ninety degree bend has been added to the electrode to allow better placement. Two electrodes are used to accommodate the shape of the caudalis nucleus. A total of 101 procedures have been performed. The newest electrodes were used in 46 procedures. Ataxia is recognized in 39%. Overall pain relief was excellent in 34% and good in 40%. In post herpetic neuralgia 71% enjoyed excellent or good relief. Indications include post herpetic neuralgia, deafferentation pain (anaesthesia dolorosa, post-tic dysesthesia, stroke, MS, gasserian tumour, Gamma Knife radiation injury), facial trauma/surgery, atypical facial pain, and migraine/cluster headache. A study to compare this operation to deep brain stimulation prospectively for the above indications has been initiated.

The Duke experience with nucleus caudalis DREZ coagulation.

The results of 46 nucleus caudalis DREZ coagulations performed at Duke in the preceding 5 years are reviewed retrospectively, with a mean follow-up of 32 months. Fifteen (38%) of 39 patients with complete data indicated that they would undergo the procedure again. Fifteen (38%) described improved quality of life. Outcome was fair or better in 18 (46%). Complications in the form of ataxia were present in 21 (54%).

Ischemic damage to the spinal cord following end-to-side aortobifemoral bypass.

A patient presenting with urinary retention was found to have progressive spinal cord ischemia subsequent to an end-to-side aortobifemoral bypass for atherosclerotic disease. This serves as a vivid reminder of the possibility of this complication even in ischemic disease and that urinary retention may be the initial symptom of cord ischemia. A review of the literature on spinal cord ischemia following abdominal aortic surgery is presented.

Relief from chronic pelvic pain through surgical lesions of the conus medullaris dorsal root entry zone.

Dorsal root entry zone (DREZ) lesions are effective in treating specific pain syndromes, most notably post-brachial plexus avulsion. There is limited experience, however, with lesions in the conus medullaris. We review the case of a patient having pelvic pain and urinary retention who failed to improve despite multiple prior interventions. Her pain was completely relieved after DREZ lesions were placed bilaterally at S2, S3, S4 and S5. The intraoperative sensory and motor evoked potential monitoring used to define the level is described in detail.