John P. Gorecki

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 patients 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.

Spinal cord stimulation for failed back surgery syndrome.

Objective. The purpose of this study is to evaluate the effectiveness of modern spinal cord stimulation (SCS) for the treatment of failed back surgery syndrome (FBSS).

MRI-Guided Frameless Stereotactic Percutaneous Cordotomy

Background: Use of intraoperative myelography as a radiologic guidance for percutaneous cervical cordotomy (PCC) has been superseded by more modern imaging. The only significant advancement in cordotomy techniques over the last 30 years has been CT-guided PCC. The goal of this study was to demonstrate the feasibility of an MRI-guided frameless technique in high cervical cordotomy. Methods: We describe 6 patients with intractable pain treated using a frameless, MRI-guided, stereotactic, PCC technique in combination with standard physiological localization procedures. Results were compared with those from 32 patients who underwent PCC in the last 5 years using physiological localizing techniques only. Results: Six patients (100%) who underwent the frameless technique had excellent pain relief postoperatively. Patients in the non-stereotactic group, on average, required a higher number of lesions (2.5 vs. 1.2, p < 0.005), and 7 (22%) of these patients had unsatisfactory pain relief following PCC (p = 0.21). Five patients in the non-stereotactic group had weakness postoperatively and 1 had changes in bladder function. Postoperative weakness occurred in 1 patient undergoing the frameless technique. At an average of 6 months of follow-up (range 5–11), excellent pain relief was achieved in 83% (5/6) of MRI frameless PCC patients and 55% (16/29) of standard PCC patients (p = 0.20). Conclusions: Intraoperative frameless stereotaxy provides surgeons with accurate information that helps to guide the operative approach and precisely tailor the trajectory and depth of the electrode, potentially increasing the safety and efficacy of the operation.

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%).

Neurophysiological monitoring for the nucleus caudalis dorsal root entry zone operation.

OBJECTIVE The purpose of this report is to describe a neurophysiological monitoring technique that can decrease the incidence of complications while maintaining the effectiveness of the nucleus caudalis dorsal root entry zone (DREZ) operation. METHODS Needle electrodes were used to stimulate the supraorbital, infraorbital, mental, and median nerves after the nucleus caudalis was surgically exposed. The DREZ electrode was used to record responses from the various areas in and near the nucleus. The target site was localized. Before lesioning, the site was stimulated with the DREZ electrode and electromyographic activation was sought. If no activation was observed, a lesion was made. RESULTS Five patients underwent a total of seven nucleus caudalis DREZ procedures with complete neurophysiological monitoring. The mean number of lesions per procedure in this series was 5.4. Six procedures (86%) resulted in immediate pain relief, and five (71%) produced persistent benefit after a mean follow-up period of 12 months. Only one patient (20%) (one of seven procedures) who underwent a unilateral DREZ procedure had ataxia, which resolved within a few days. No complications were noted at follow-up. CONCLUSION Despite patients in this series receiving fewer lesions, the efficacy of the DREZ operation was comparable to that reported in earlier studies. There were fewer complications when neurophysiological monitoring was used. Such monitoring should be considered for nucleus caudalis DREZ operations.

Spontaneous and Evoked Dysesthesias Observed in the Rat after Spinal Cordotomies

Thirty-six rats have received surgical spinal cord lesions, 7 at a thoracic and 29 at a cervical level. More than 70% of rats with lesions which involved the lateral column (spinothalamic tract) developed spontaneous dysesthesias in the contralateral limb. Only high cervical (C1-C2) lateral column lesions were followed frequently by forelimb signs. Lesions restricted to the dorsal columns were not followed by dysesthesias.

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.

792 Standard Percutaneous Cordotomy Compared with a Novel MRI-guided Stereotactic Frameless Technique

The Emergence of Pain Medicine Fundamental approaches to the treatment of chronic pain are changing. Historically, the treatment of pain has been based upon the concept of pain management, which involves the treatment of pain as a symptom of disease or injury. Over the past two decades, a growing understanding of pain as a biopsychosocial disorder has led to the emergence of the concept of pain medicine. There are key differences between pain management and pain medicine. Pain management is appropriate for some types of pain, such as acute pain, which generally serves the useful purpose of signaling tissue injury (“eudynia,” good pain). In contrast, many chronic pain states are characterized by intractable pain that serves no useful biological purpose (“maldynia,” bad pain). The chronic pain, itself, becomes the disease. Overwhelming scientific data support the concept of maldynia as a neurobiological disorder and support the need for a new approach to the treatment of such pain. “Pain medicine” is the evolving field that transcends treatment of pain as a symptom by seeking to understand the causes of maldynia, and develop and provide appropriate treatment strategies for this malady. Neurosurgery and anesthesiology, and other medical specialties to a lesser extent (e.g., psychiatry, physical medicine and rehabilitation, neurology, internal medicine), have long histories in the practice of pain management. Some practitioners in these specialties provide excellent comprehensive care of chronic pain disorders but, for the most part, pain management physicians restrict the treatments they offer to those that reflect the bias of their parent specialties. Consequently, the typical chronic pain patient visits a succession of physicians and undergoes multiple isolated specific interventions as each physician provides only those treatments that are within the scope of his or her specialty. This approach is characterized by a lack of continuity of care and no coordination of care. Patients suffer as a result of this fragmented approach to pain treatment. Comprehensive training of pain physicians in the broad scientific and medical issues relevant to the treatment of maldynia can lessen the fragmentation of care these patients are subject to. Unfortunately, none of the primary specialties of the American Board of Medical Specialties (ABMS) offers such comprehensive training. Each specialty emphasizes pain therapies that are associated with its discipline. The American Board of Pain Medicine (ABPM), founded over a decade ago, was organized by neurosurgeons and other specialists in the field of pain management to remedy this problem. The ABPM recently submitted an application to the Liaison Committee for Specialty Boards (LCSB) of the ABMS, seeking recognition as a new primary medical specialty. The application was denied (by divided vote) but the importance of the issues raised by the ABPM has captured the attention of the ABMS. In response to the application, the LCSB will convene meetings between the ABPM and representatives of relevant primary ABMS boards to discuss development of a specialty of Pain Medicine. The development of a Pain Medicine specialty does not threaten neurosurgery or any other ABMS specialty that deals with pain disorders. To the contrary, a specialty of Pain Medicine can be a great asset. Pain Medicine is best conceptualized as a cognitive specialty rather than an interventional specialty such as neurosurgery or anesthesiology. Cognitive