Compensatory stepping in Parkinson's disease is still a problem after deep brain stimulation randomized to STN or GPi.

The effects of deep brain stimulation (DBS) on balance in people with Parkinson's disease (PD) are not well established. This study examined whether DBS randomized to the subthalamic nucleus (STN; n = 11) or globus pallidus interna (GPi; n = 10) improved compensatory stepping to recover balance after a perturbation. The standing surface translated backward, forcing subjects to take compensatory steps forward. Kinematic and kinetic responses were recorded. PD-DBS subjects were tested off and on their levodopa medication before bilateral DBS surgery and retested 6 mo later off and on DBS, combined with off and on levodopa medication. Responses were compared with PD-control subjects (n = 8) tested over the same timescale and 17 healthy control subjects. Neither DBS nor levodopa improved the stepping response. Compensatory stepping in the best-treated state after surgery (DBS+DOPA) was similar to the best-treated state before surgery (DOPA) for the PD-GPi group and the PD-control group. For the PD-STN group, there were more lateral weight shifts, a delayed foot-off, and a greater number of steps required to recover balance in DBS+DOPA after surgery compared with DOPA before surgery. Within the STN group five subjects who did not fall during the experiment before surgery fell at least once after surgery, whereas the number of falls in the GPi and PD-control groups were unchanged. DBS did not improve the compensatory step response needed to recover from balance perturbations in the GPi group and caused delays in the preparation phase of the step in the STN group.

A meta-regression of the long-term effects of deep brain stimulation on balance and gait in PD.

OBJECTIVE: Deep brain stimulation (DBS) alleviates the cardinal Parkinson disease (PD) symptoms of tremor, rigidity, and bradykinesia. However, its effects on postural instability and gait disability (PIGD) are uncertain. Contradictory findings may be due to differences the in stimulation site and the length of time since DBS surgery. This prompted us to conduct the first meta-regression of long-term studies of bilateral DBS in the subthalamic nucleus (STN) and globus pallidus interna (GPi). RESULTS: Eleven articles reported a breakdown of the Unified Parkinson's Disease Rating Scale score before and beyond 3 years postsurgery (mean 4.5 years). Random effects meta-regression revealed that DBS initially improved PIGD compared to the OFF medicated state before surgery, but performance declined over time and extrapolation showed subjects would reach presurgery levels 9 years postsurgery. ON medication, DBS improved PIGD over and above the effect of medication before surgery. Nevertheless, for the STN group, PIGD progressively declined and was worse than presurgery function within 2 years. In contrast, GPi patients showed no significant long-term decline in PIGD in the medicated state. Improvements in cardinal signs with DBS at both sites were maintained across 5 years in the OFF and ON medication states. CONCLUSIONS: DBS alone does not offer the same improvement to PIGD as it does to the cardinal symptoms, suggesting axial and distal control are differentially affected by DBS. GPi DBS in combination with levodopa seemed to preserve PIGD better than did STN DBS, although more studies of GPi DBS and randomized controls are needed.

Pathology of ilioinguinal neuropathy produced by mesh entrapment: case report and literature review.

Ilioinguinal neuropathy is a well-described complication of mesh inguinal herniorrhaphy. We report the first human case, to our knowledge, of ilioinguinal nerve mesh entrapment with neuropathological changes that suggest an inflammatory cause for this chronic pain syndrome.

Management of chronic severe pain: cerebral neuromodulatory and neuroablative approaches.

Two approaches are utilized when targeting the brain to treat pain. The first, a non-destructive approach, uses either electrical stimulation of brain targets thought to modulate the process of pain perception, or pharmacological agents are introduced into ventricular spaces to target pain modulating receptors. Electrical stimulation targets include; the thalamic nuclei, the periventricular and periaqueductal grey (PVG and PAG) matter or the motor cortex. Currently, the pharmacological agent of choice for intracerebroventricular injection is morphine. In general, electrical stimulation is used for nonmalignant type pain, and pharmacological modulation for malignant type pain. The second, a destructive approach, is usually employed with the goal of interrupting the signals that lead to pain perception at various levels. Neuroablation is usually performed on cellular complexes such as "nuclei, or gyri" or on tracts with the aim of disrupting the sensory and limbic pathways involved in the emotional processes associated with pain. Specific cerebral neuroablation targets include; the thalamic medial group of nuclei, the cingulated gyrus, and the trigeminal nucleus and tract. There are fewer reports in the literature detailing the brain, when compared to the spine, as a target to treat pain, and further research is required.

Management of chronic severe pain: spinal neuromodulatory and neuroablative approaches.

The spinal cord is the target of many neurosurgical procedures used to treat pain. Compactness and well-defined tract separation in addition to well understood dermatomal cord organization make the spinal cord an ideal target for pain procedures. Moreover, the presence of opioid and other receptors involved in pain modulation at the level of the dorsal horn increases the suitability of the spinal cord. Neuromodulative approaches of the spinal cord are either electrical or pharmacological. Electrical spinal cord modulation is used on a large scale for various pain syndromes including; failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), neuropathic pain, angina, and ischemic limb pain. Intraspinal delivery of medications e.g. opioids is used to treat nociceptive and neuropathic pains due to malignant and cancer pain etiologies. Neuroablation of the spinal cord pain pathway is mainly used to treat cancer pain. Targets involved include; the spinothalamic tract, the midline dorsal column visceral pain pathway and the trigeminal tract in the upper spinal cord. Spinal neuroablation can also involve cellular elements such as with trigeminal nucleotomy and the dorsal root entry zone (DREZ) operation. The DREZ operation is indicated for phantom type pain and root avulsion injuries. Due to its reversible nature spinal neuromodulation prevails, and spinal neuroablation is performed in a few select cases.

Microelectrode recording: lead point in STN-DBS surgery.

BACKGROUND: Microelectrode recording is an integral part of many surgical procedures for movement disorders. We evaluate the Lead point compared to the NeuroTrek system. We used NeuroTrek in 18 Parkinsonian patients, Lead point-4 in 12 patients, during STN-DBS surgery. We compared MR-Stir image with Microelectrode recording. METHOD: The MicroGuide system with its integrated screen display provides the user with all the information needed during the surgery on its screen. Microelectrode recordings showed characteristic neuronal discharges on a long trajectory (5-6 mm), intraoperative stimulation induces dramatic improvement of Parkinsonian motor symptoms. FINDINGS: Microrecording data of the Leadpoint showed high background activity, and firing rate of 14-50 Hz. The discharge pattern is typically chaotic, with frequent irregular bursts and pauses. DISCUSSION: The microelectrode recording of the neuroTrek and Lead point-4 showed unique results of the typical STN spike. The DBS effect is maximized associated by MER mapping.

Temporal lobe magnetic resonance spectroscopic imaging following selective amygdalohippocampectomy for treatment-resistant epilepsy.

OBJECTIVES: Magnetic resonance spectroscopic imaging (MRSI) may show circumscribed or extensive decreased brain N-acetyl aspartate (NAA)/creatine and phosphocreatine (Cr) in epilepsy patients. We compared temporal lobe MRSI in patients seizure-free (SzF) or with persistent seizures (PSz) following selective amygdalohippocampectomy (SAH) for medically intractable mesial temporal lobe epilepsy (mTLE). We hypothesized that PSz patients had more extensive temporal lobe metabolite abnormalities than SzF patients. MATERIALS AND METHODS: MRSI was used to study six regions of interest (ROI) in the bilateral medial and lateral temporal lobes in 14 mTLE patients following SAH and 11 controls. RESULTS: PSz patients had more temporal lobe ROI with abnormally low NAA/Cr than SzF patients, including the unoperated hippocampus and ipsilateral lateral temporal lobe. CONCLUSION: Postoperative temporal lobe MRSI abnormalities are more extensive if surgical outcome following SAH is poor. MRSI may be a useful tool to improve selection of appropriate candidates for SAH by identifying patients requiring more intensive investigation prior to epilepsy surgery. Future prospective studies are needed to evaluate the utility of MRSI, a predictor of successful outcome following SAH.

Interactions between deep brain stimulation and levodopa in Parkinson's disease.

OBJECTIVE: To quantify the effects of deep brain stimulation (DBS) of globus pallidus interna (GPi) and subthalamic nucleus (STN) on motor fluctuations and dyskinesia in PD and to determine how the response to levodopa was modified by DBS. BACKGROUND: Patients report that DBS reduces levodopa-induced motor fluctuations and dyskinesia throughout the day, but this has not been objectively measured. Further, the means by which DBS alters the response to levodopa to improve motor fluctuations is unknown. METHODS: Twelve subjects, six with bilateral GPi electrodes and six with bilateral STN electrodes, were studied 12 to 33 months after surgery. To quantify motor fluctuations and dyskinesia, subjects were monitored hourly throughout 2 waking days with their usual oral medications, 1 day with DBS on and 1 day with DBS off, with subjects and nurse raters blinded to DBS status. To examine the effects of DBS on levodopa pharmacodynamics, the effects of a 2-hour levodopa infusion were examined, 1 day with DBS on and 1 day with DBS off, again under double-blind conditions. Time course of variations in parkinsonism was evaluated by tapping speed, arising and walking speed, tremor scores, and dyskinesia scores. RESULTS: DBS raised the mean tapping speed and reduced the coefficient of variation during the waking day. This was achieved by increasing the lowest or trough tapping speed between doses of antiparkinson medications. Mean walking speed was modestly increased and mean tremor scores were reduced. DBS increased the drug-off tapping speed, but neither the peak response nor the duration of response to levodopa was affected by DBS. The study was not powered to detect differences between GPi and STN stimulation and the only difference that approached significance was that GPi reduced peak dyskinesia and STN tended to increase peak dyskinesia. CONCLUSION: DBS objectively reduces motor fluctuations. This is achieved by reduction of drug-off disability and not by alterations in levodopa pharmacodynamics. This finding suggests alleviation of interdose trough disability as an alternative strategy to prolonging the effects of each dose of levodopa as a means to reduce motor fluctuations.

A prospective study of long-term intrathecal morphine in the management of chronic nonmalignant pain.

OBJECTIVE: To examine in a prospective manner the long-term safety and efficacy of chronic intrathecal morphine in patients with severe, nonmalignant pain refractory to less invasive modalities. METHODS: Forty patients with severe, chronic nonmalignant pain poorly managed by systemic medications were identified as candidates for intraspinal trial of morphine. Thirty participants reported successful pain relief during trial and were implanted with an intraspinal delivery system. Standardized measures of pain and functional status were assessed before treatment was begun and at defined intervals during the subsequent 24 months. Intrathecal opioid use and pharmacological and device-related complications were also monitored. RESULTS: The participants had a mean age of 58 +/- 13 years and a mean pain duration of 8 +/- 9 years. Fifty-three percent of the study participants were women. Pain type was characterized as mixed neuropathic-nociceptive (15 of 30 patients, 50%), peripheral neuropathic (10 of 30 patients, 33%), deafferentation (4 of 30 patients, 13%), or nociceptive (1 of 30 patients, 3%). Forty-seven percent of the patients were diagnosed with failed back surgery syndrome. Significant improvement over baseline levels of visual analog scale pain was measured at each follow-up examination after implant. Overall, 50% (11 of 22 patients) of the population reported at least a 25% reduction in visual analog scale pain after 24 months of treatment. In addition, the McGill Pain Questionnaire, visual analog scale measures of functional improvement and pain coping, and several subscales of the Chronic Illness Problem Inventory showed improvement throughout the follow-up period. Pharmacological side effects were managed medically by morphine dose reduction, addition of bupivacaine, or replacement of morphine with hydromorphone. Device-related complications requiring repeat operations were experienced by 20% of the patients. CONCLUSION: Continuous intrathecal morphine can be a safe, effective therapy for the management of severe, nonmalignant pain among a carefully selected patient population and can result in long-term improvement in several areas of daily function.

Stereotactic ventral intermedial thalamotomy for the treatment of essential tremor: results of a series of 37 patients.

We have analyzed 43 ventral intermediate thalamotomies performed in our center for treatment of medically intractable essential tremor (ET) in 37 patients. The mean age of patients was 70.9 years (range 42-84), duration of symptoms 33.3 years (1-65). The surgery in all cases was performed with stereotactic technique using MRI or CT localization. Intraoperative neurophysiological confirmation of the target location was obtained using a macrostimulation technique. All patients experienced either complete abolition of the contralateral tremor or significant improvement in tremor intensity immediately after the surgery. At follow-up examination 1-13 months after the operation, 60.5% of patients had no tremor, and 13.9% had mild residual tremor without interference with daily life. Tremor recurrence was observed in 5 patients, all of whom underwent repeat ventral intermedial (VIM) thalamotomy with excellent results. Transient problems with speech and motor functions were observed after 15 thalamotomies, permanent hemiparesis and speech difficulties were seen in 6 patients. We conclude that VIM thalamotomy is a highly effective procedure for medically intractable ET and may be performed with no mortality and low morbidity rate.

Efficacy of transverse tripolar stimulation for relief of chronic low back pain: results of a single center.

The goal of this study was to evaluate the efficacy of the transverse tripolar spinal cord stimulation system (TTS) in providing relief of low back pain in patients with chronic non-malignant pain. Transverse tripolar electrodes were implanted in the lower thoracic region (T(8-9) to T(12)-L(1)) in 10 patients with chronic neuropathic pain, all of whom reported a significant component of low back pain in combination with unilateral or bilateral leg pain. One patient reported inadequate pain relief during the trial and was not implanted with a permanent generator. A visual analogue scale of low back pain showed a nonsignificant decrease from 64 +/- 19 to 47 +/- 30 (p = 0.25; paired t test) after 1 month of stimulation. Similarly, functional disability evaluated using Oswestry Low Back Pain Questionnaire was not improved (p = 0. 46; paired t test). We conclude that chronic low back pain is not particularly responsive to the transverse stimulation provided by the TTS system.

Psychological variables associated with outcome of spinal cord stimulation trials.

Study Design. This is a prospective study designed to identify psychological factors associated with response to spinal cord stimulation (SCS) trial. Summary of Background Data. In most centers, implantation of a permanent SCS system is preceded by a trial of a temporary stimulating electrode. Yet, even among those who report greater than 50% pain reduction during trial, a significant number of these patients fail to receive long-term pain relief from the permanent system. Because mood disorders can alter pain report, we hypothesized that refined definition of the psychological factors associated with SCS success could result in improved selection of candidates for SCS trial. Methods. The study sample consisted of 43 chronic pain patients (72% failed back surgery syndrome, 77% with radiating low back pain) who were referred for implantable pain management. Following psychological evaluation, patients were admitted for a three-day inpatient trial of SCS. Report of at least 50% pain relief during trial was considered a success and resulted in implantation of the permanent stimulator. Patients were retrospectively divided into two groups: those whose pretrial pain was relieved by at least 50% ("success") and those whose pain was relieved by less than 50% ("failure"). Results. Univariate t-test or chi-square analyzes of group means of an extensive psychological battery followed by a global, stepwise logistic regression model of trial outcome was used to analyze between group results of a psychological test battery. MMPI depression and mania subscores were found to be significantly elevated among the two outcome groups (p = 0.007 and 0.025, respectively). Conclusions. Patient mood state is an important predictor of trial outcome. Specific indicators of SCS trial outcome are the MMPI depression and mania subscale scores with successful trials being associated with individuals who are less depressed and have higher energy levels.

Prospective, multicenter study of spinal cord stimulation for relief of chronic back and extremity pain.

STUDY DESIGN: This prospective, multicenter study was designed to investigate the efficacy and outcome of spinal cord stimulation using a variety of clinical and psychosocial outcome measures. Data were collected before implantation and at regular intervals after implantation. This report focuses on 70 patients who had undergone 1 year of follow-up treatment at the time of data analysis. OBJECTIVES: To provide a more generalizable assessment of long-term spinal cord stimulation outcome by comparing a variety of pain and functional/quality-of-life measures before and after management. This report details results after 1 year of stimulation. SUMMARY OF BACKGROUND DATA: The historically diverse methods, patient selection criteria, and outcome measures reported in the spinal cord stimulation literature have made interpretation and comparison of results difficult. Although short-term outcomes are generally consistent, long-term outcomes of spinal cord stimulation, as determined by prospective studies that assess multidimensional aspects of the pain complaint among a relatively homogeneous population, are not well established. METHODS: Two hundred nineteen patients were entered at six centers throughout the United States. All patients underwent a trial of stimulation before implant of the permanent system. Most were psychologically screened. One hundred eighty-two patients were implanted with a permanent stimulating system. At the time of this report, complete 1-year follow-up data were available on 70 patients, 88% of whom reported pain in the back or lower extremities. Patient evaluation of pain and functional levels was completed before implantation and 3, 6, 12, and 24 months after implantation. Complications, medication usage, and work status also were monitored. RESULTS: All pain and quality-of-life measures showed statistically significant improvement during the treatment year. These included the average pain visual analogue scale, the McGill Pain Questionnaire, the Oswestry Disability Questionnaire, the Sickness Impact Profile, and the Back Depression Inventory. Overall success of the therapy was defined as at least 50% pain relief and patient assessment of the procedure as fully or partially beneficial and worthwhile. Using this definition, spinal cord stimulation successfully managed pain in 55% of patients on whom 1-year follow-up is available. Complications requiring surgical intervention were reported by 17% (12 of 70) of patients. Medication usage and work status were not changed significantly. CONCLUSIONS: This prospective, multicenter study confirms that spinal cord stimulation can be an effective therapy for management of chronic low back and extremity pain. Significant improvements in many aspects of the pain condition were measured, and complications were minimal.

Pallidotomy: a survey of current practice in North America.

Twenty-eight centers completed a survey about their current practice of pallidotomy. This sample represents a non-exhaustive survey of the current practice of pallidotomy in North America and is not a study of outcomes. 1015 patients underwent 1219 pallidotomies: 811 (80%) unilateral, 72 (7%) staged bilateral, and 132 (13%) simultaneous bilateral. Pallidotomy has long been an accepted procedure and the indications for this surgery, in the opinion of the responding centers, were rated on a scale of 1 (poor) to 4 (excellent) and demonstrated dyskinesia as the best indication (median = 4); on-off fluctuations, dystonia, rigidity, and bradykinesia as good indications (median = 3); and freezing, tremor and gait disturbance as fair indications (median = 2). Most centers used MRI alone (50%) or in combination with CT scan (n = 6) or ventriculopathy (n = 5) to localize the target. The median values of pallidal coordinates were: 2 mm anterior to the midcommissural point 21 mm lateral to the midsagittal plane and 5 mm below the intercommissural line. Microrecording was performed by half of the centers (n = 14) and half of the remaining centers were considering starting it (n = 7). Main criteria used to define the target included the firing pattern of spontaneous neuronal discharges (n = 13) and the response to joint movement (n = 10). Most centers performed motor (n = 26) and visual (n = 23) macrostimulation. Twenty four centers performed test lesions using median values of 55 degrees C temperatures for 30 s. Final lesions consisted of 3 permanent lesions placed 2 mm apart, each lesion created with median values of 75 degrees C temperatures for 1 minute. Median hospital stay was 2 days.

Prognostic factors of spinal cord stimulation for chronic back and leg pain.

Spinal cord stimulation (SCS) has been used for more than 20 years in the treatment of diverse pain conditions. Although recent studies have identified more clearly those conditions for which SCSoffers a favorable prognosis, the identification of a patient population in whom reasonably long-term success can be expected has been difficult. In an effort to improve patient selection and increase the overall success rate of treatment, we have examined various physical, demographic, and psychosocial variables as predictors of SCS outcome. The study population consisted of 40 patients with chronic low back and/or leg pain, 85% of whom were diagnosed with failed back surgery syndrome. Medical history and demographic data were collected as part of an initial assessment along with patient responses to the Minnesota Multiphasic Personality Inventory, the visual analogue pain rating scale (VAS), the McGill Pain Questionnaire, the Oswestry Disability Questionnaire, the Beck Depression Inventory, and the Sickness Impact Profile. Treatment outcomes were examined and found to improve significantly after 3 months of stimulation. Subsequent regression analysis revealed that patient age, the Minnesota Multiphasic Personality Inventory depression subscale D, and the evaluative subscale of the McGill Pain Questionnaire (MPQe) were important predictors of posttreatment pain status. Increased patient age and D subscale scores correlated negatively with pain status, as measured by the percentage of changes in pretreatment and posttreatment VAS scores, % delta VAS. In contrast, higher MPQe correlated with improved pain status. By the use of the following equation and the definition commonly associated with SCS success (at least 50% decrease in the VAS pain level), the success or failure of 3 months of SCS was correctly predicted in 88% of the study population. Our results suggest that patient age, Minnesota Multiphasic Personality Inventory depression, and MPQe may be clinically useful in the prediction of pain status after 3 months of SCS in patients with chronic low back and/or leg pain. % delta VAS = 112.57 - 1.98 (D)-1.68 (Age) + 35.54 (MPQe).

Thalamotomy for movement disorders.

VL thalamotomy is an excellent choice for the control of tremor in patients with a wide variety of disorders. Parkinson's disease and essential tremor are the best indications, but other disorders also respond. Improvement of bradykinesia and rigidity in Parkinson's disease is achievable but is not as dramatic as hyperkinetic symptoms. Morbidity from thalamotomy is most common with bilateral lesions, and innovative therapies such as thalamic stimulation may have a role when a second contralateral procedure is needed. Thalamotomy is an effective procedure that has probably been underused over the past two decades. With renewed interest in stereotactic neurosurgery, improved imaging, and well-established target localization techniques, the procedure is effective with a high degree of safety. The growing enthusiasm for brain grafting has also stimulated interest in the surgical treatment of movement disorders, and clearly this technique will evolve and progress as well. In the author's opinion, the results of ablative surgery still far exceed those of tissue implantation. For a select group of indications, thalamotomy should be considered in the forefront of options for patients with movement disorders.

The surgical treatment of painful traumatic neuromas.

Pain following suspected nerve injury was comprehensively evaluated with detailed examination including history, neurological evaluation, electrodiagnostic studies, quantitative sensory testing, thermography, anesthetic agents, and sympathetic nerve blocks. Forty-two surgically treated patients fell into four discrete groups: Group 1 patients had distal sensory neuromas treated by excision of the neuroma and reimplantation of the proximal nerve into muscle or bone marrow; Group 2 patients had suspected distal sensory neuromas in which the involved nerve was sectioned proximal to the injury site and reimplanted; Group 3 patients had proximal in-continuity neuromas of major sensorimotor nerves treated by external neurolysis; and Group 4 patients had proximal major sensorimotor nerve injuries at points of anatomical entrapment treated by external neurolysis and transposition, if possible. Patient follow-up monitoring from 2 to 32 months (average 11 months) was possible in 40 (95%) of 42 patients. Surgical success was defined as 50% or greater improvement in pain using the Visual Analog Scale or pain relief subjectively rated as either good or excellent, without postoperative narcotic usage. Overall, 16 (40%) of 40 patients met those criteria. Success rates varied as follows: 44% in 18 Group 1 patients, 40% in 10 Group 2 patients, 0% in five Group 3 patients, and 57% in seven Group 4 patients. Twelve (30%) of 40 patients were employed both pre- and postoperatively. It is concluded that: 1) neuroma excision, neurectomy, and nerve release for injury-related pain of peripheral nerve origin yield substantial subjective improvement in a minority of patients; 2) external neurolysis of proximal mixed nerves is ineffective in relieving pain; 3) surgically proving the existence of a neuroma with confirmed excision may be preferable; 4) traumatic neuroma pain is only partly due to a peripheral source; 5) demographic and neurological variables do not predict success; 6) the presence of a discrete nerve syndrome and mechanical hyperalgesia modestly predict pain relief; 7) ongoing litigation is the strongest predictor of failure; and 8) change in work status is not a likely outcome.

Pain medicine. State of the art, 1992.

Pain management has emerged as a mature medical discipline over the past few decades. Neurological surgery has provided, and will continue to provide, strong leadership in the field. More emphasis should be placed on multidisciplinary pain medicine in our training programs and continuing education environment. Our patients with acute, chronic, and cancer pain will be the beneficiaries of our pursuit of excellence in this important subspecialty of neurological surgery.

Painful nerve injuries: bridging the gap between basic neuroscience and neurosurgical treatment.

Pain which followed suspected nerve injury was comprehensively evaluated with detailed examination including history, neurologic exam, electrodiagnostic studies, quantitative sensory testing, thermography, anesthetic and sympathetic nerve blocks. Forty two patients treated surgically fell into four discrete groups: 1) Distal sensory neuromas treated by excision of the neuroma and reimplantation of the proximal nerve into muscle or bone marrow, 2) Suspected distal sensory neuromas in which the involved nerve was sectioned proximal to the injury site and reimplanted, 3) Proximal neuromas-incontinuity of major sensorimotor nerves treated by external neurolysis, and 4) Proximal major sensorimotor nerve injuries at points of anatomic entrapment treated by external neurolysis and transposition, if possible. Patient follow up was possible in 40/42 patients (95%) from 2-32 months (average F/U = 11 mo.). Surgical success was defined as: > or = 50% improvement in pain (VAS) or pain relief subjectively rated as good or excellent, and no postoperative narcotic usage. Overall, 40% (16/40) of patients met those criteria. Success rates varied as follows: Group 1 (n = 18) 44%, Group 2 (n = 10) 40%, Group 3 (n = 5) 0%, and Group 4 (n = 7) 57%. A total of 12 of 40 patients (30%) were employed both pre- and postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)