Prior Laminectomy Research Articles

Superior Cluneal Nerve Stimulator Lead Displacement to the Thigh: A Case Report and Management Recommendations.

An 82-year-old man with a history of lumbar spinal stenosis and prior laminectomy presented with chronic lower back pain and was treated with placement of bilateral superior cluneal nerve stimulators. At the 2-week follow-up, the patient reported loss of efficacy and new-onset paresthesia of the left lower extremity. Fluoroscopic evaluation revealed lead breakage and distal migration of the left-sided stimulator lead to the left anteromedial thigh. Lead breakage and migration remains a challenge in peripheral nerve stimulation. This report illustrates the case of a nerve stimulator lead breakage and migration resulting in treatment failure and new-onset sensory disturbance.

Osteomyelitis-Discitis at the Thoracolumbar Junction and the Development of Postinfectious Spinal Deformity: A Surgical Case Series

Progressive spinal deformity and neural compromise are the main indications for surgical management of vertebral osteomyelitis-discitis. However, when such pathology presents at the thoracolumbar (TL) junction, it remains unclear what the appropriate intervention is. The therapeutic dilemmas of decompression with or without instrumented fusion, the need for circumferential decompression and reconstruction, as well as the prognostic factors for progression of kyphosis, all remained ill-defined in the literature. The objective of this study is to evaluate risk factors for instrumentation at TL junction in spinal osteomyelitis-discitis. A review of patients at a single center with osteomyelitis-discitis at the TL junction between 2014 and 2018 was performed. Patients were 18 years or older with infectious pathologies at T10 to L2. Sixteen patients were included. Indication for instrumentation included progression of kyphosis following prior laminectomy/medical management. Of the 16 patients, 4 patients received laminectomy at initial treatment versus 12 patients receiving medical management alone. All 4 patients receiving laminectomy experienced progressive kyphosis requiring revision with instrumented fusion versus only 4 of 12 of the medically managed. Laminectomy, epidural compression, and vertebral body collapse were significant risk factors for kyphosis progression requiring instrumentation. The average time to surgical intervention for the indication of progressive kyphosis was 2.6 months after prior laminectomy and 6 months after initiation of medical management. Given the proclivity for kyphotic deformity at the TL junction, patients may benefit from long segment instrumentation in addition to decompression at the initial surgery. Laminectomy alone may hasten kyphosis progression.

Accuracy of Pedicle Screw placement in Revision Spine Surgery using Robotic Guidance

Introduction Pedicle screw instrumentation in revision spinal surgery can be challenging because of the altered anatomy and existing instrumentation. Malpositioned pedicle screws can result in surgical complications that may lead to persistent pain, dysfunction, and morbidity. Robotic-guided screw placement has been shown to be accurate in the setting of primary surgery, however, less is known about its accuracy in revision situations. The purpose of this study was to identify the accuracy rate of pedicle screws placed via robotic guidance in revision spine surgery. Patients and Methods Patients who underwent revision spinal instrumentation with robotic guidance during a 3-year period (2011–2014) at our institution were identified and included in the study if they had postoperative CT scans of the operated levels. Screw insertion was identified in revision levels and included for analysis if they were categorized as screw redirection, prior fusion without instrumentation, prior laminectomy, or a spinal level adjacent to a previously operated level. Postoperative CT scans were reviewed for pedicle screw accuracy by independent radiologists. Results A total of 36 patients met inclusion criteria (average age 61.6 years, 13 males and 26 females). Of the 682 total pedicle screws placed, 229 were placed in revision levels. Overall, 220 (96.1%) of the 229 revision screws were confirmed to be accurate by postoperative CT. Of the nine screws that were malpositioned, none were clinically significant nor required revision surgery. Of the nine malpositioned screws, there were five lateral breaches, and four medial breaches. One patient required revision surgery for cage migration at a similar level as a misplaced screw, however, pedicle screws were not revised. Conclusion Robotic-assisted pedicle screw placement in revision spinal surgery provides accuracy similar to other techniques in primary cases. In cases of previous laminectomy or fusion, robotic guidance can provide benefit to surgeons in navigating altered bony anatomy. Larger studies are needed to confirm these findings.

Surgical approach of severe fixed cervical kyphosis

Objective To investigate the radiographic features and surgical approach of severe fixed cervical kyphosis. Methods Seventeen cases of severe fixed cervical kyphosis from January 2007 to January 2012 were studied retrospectively. There were 8 males and 9 females, with an average age of 49.7 years. The etiologies were 3 cases of infection, 3 cases of degeneration, 3 cases of neurofibromatosis, 3 cases of prior laminectomy, 2 cases of idiopathic, 2 cases of trauma and 1 case of neuromuscular disease. The average length of kyphosis was 4.3±1.2 segments. All patients complained of severe neck pain (visual analogue scale, VAS, 7.6±1.5) or progressive cervical kyphosis. There were 4 cases with myelopathy, 2 with radiculopathy, 3 with difficulty of forward gaze and 1 with difficulty of swallowing. All patients were underwent dynamic flexion-extension radiographs and traction views. CT scans were carried out to identify the sites of fixed kyphosis. Continuous traction was performed after general anesthesia, and the surgical approach was decided according to spinal cord compression, length of kyphosis and the cause of fixed kyphosis. Surgical outcomes were assessed in terms of correction of Cobb angle and Odom criteria. Results All patients were followed-up for 2 to 5 years. According to the CT scans, the sites of fixed kyphosis were identified: anterior bony ankylosis in 7 cases, posterior in 6 cases and both anterior and posterior in 4 cases. The surgical approach were as following: anterior only in 4 cases, posterior only in 2 cases, anterior-posterior in 5 cases, posterior-anterior in 3 cases, anterior-posterior-anterior in 1 case and posterior-anterior-posterior in 2 cases. The Cobb angle was corrected from 49.3°±14.6° preoperation to 2.1°±6.8° at the latest follow-up, with an average correction of 47.2°. According to Odom criteria, there were 7 excellent outcome, 8 good, 2 fair and none poor outcome. Revision surgery was performed in 1 case due to proximal junctional kyphosis. At the latest follow-up, bony fusion was found in all patients. Conclusion CT scan is helpful in identifying the cause of fixed kyphosis. The surgical approach of fixed cervical kyphosis is decided by spinal cord compression, length of kyphosis and cause of fixed kyphosis. Anterior approach is suitable for anterior ankylosis, posterior approach for posterior ankylosis, combined approach for both anterior and posterior ankylosis. Key words: Cervical vertebrae; Kyphosis; Treatment outcome

Does Minimally Invasive Transsacral Fixation Provide Anterior Column Support in Adult Scoliosis?

BackgroundSpinal fusion to the sacrum, especially in the setting of deformity and long constructs, is associated with high complication and pseudarthrosis rates. Transsacral discectomy, fusion, and fixation is a minimally invasive spine surgery technique that provides very rigid fixation. To date, this has been minimally studied in the setting of spinal deformity correction.Questions/purposesWe determined (1) the fusion rate of long-segment arthrodeses, (2) heath-related quality-of-life (HRQOL) outcomes (VAS pain score, Oswestry Disability Index [ODI], SF-36), and (3) the common complications and their frequency in adult patients with scoliosis undergoing transsacral fixation without supplemental pelvic fixation.MethodsBetween April 2007 and May 2011, 92 patients had fusion of three or more segments extending to the sacrum for spinal deformity. Transsacral L5-S1 fusion without supplemental pelvic fixation was performed in 56 patients. Of these, 46 with complete data points and a minimum of 2 years of followup (mean, 48 months; range, 24–72 months; 18% of patients lost to followup) were included in this study. Nineteen of the 46 (41%) had fusions extending above the thoracolumbar junction, with one patient having fusion into the proximal thoracic spine (T3-S1). General indications for the use of transsacral fixation were situations where the fusion needed to be extended to the sacrum, such as spondylolisthesis, prior laminectomy, stenosis, oblique take-off, and disc degeneration at L5-S1. Contraindications included anatomic variations in the sacrum, vascular anomalies, prior intrapelvic surgery, and rectal fistulas or abscesses. Fusion rates were assessed by full-length radiographs and CT scanning. HRQOL data, including VAS pain score, ODI, and SF-36 scores, were assessed at all pre- and postoperative visits. Intraoperative and postoperative complications were noted.ResultsForty-one of 46 patients (89%) developed a solid fusion at L5-S1. There were significant improvements in all HRQOL parameters. Eight patients had complications related to the transsacral fusion, including five pseudarthroses and three superficial wound dehiscences. Three patients underwent revision surgery with iliac fixation. There were no bowel injuries, sacral hematomas, or sacral fractures.ConclusionsTranssacral fixation/fusion may allow for safe lumbosacral fusion without iliac fixation in the setting of long-segment constructs in carefully selected patients. This study was retrospective and suffered from some loss to followup; future prospective trials are called for to compare this technique to other, more established approaches.Level of EvidenceLevel IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Pleural effusion accumulating in the epidural space: Recurrent cord compression in a patient with progressive lung adenocarcinoma

Pleural effusions are common in patients with advanced carcioma, particularly of the lung and breast. While the spinal column ies adjacent to the pleura, to our knowledge there is no reported ase of a pleural effusion causing cord compression. The epidural pace is normally isolated from the pleural space by the parietal leura, spinal column, ribs, and associated soft tissue. Here we describe a patient with lung carcinoma and a prior horacic laminectomy for epidural metastasis who presented with ecurrent cord compression. She was found to have a large epidural uid collection in the region of the prior laminectomy, as well as large pleural effusion which had developed simultaneously. The pidural collection was thin in consistency and under high pressure, onsistent with pleural fluid. The pleural effusion became smaller fter drainage of the epidural collection, suggesting the presence f a pleural–epidural fistula.

Avaliação funcional e histológica da oxigenoterapia hiperbárica em ratos com lesão medular

OBJETIVOS: Avaliar a eficácia da aplicação da oxigenoterapia hiperbárica em ratos Wistar, com lesão medular contusa produzida por equipamento computadorizado para impacto por queda de peso, NYU Impactor. MÉTODOS: Avaliaram-se 17 ratos machos com peso variando de 265 a 426 g; realizaram-se impactos com peso de 10 g de uma altura pré-determinada de 12,5 mm ao nível da décima vértebra torácica, após realização de laminectomia prévia. Os ratos foram divididos aleatoriamente em grupo controle e grupo oxigênio hiperbárico. Este último, submetido à tratamento com oxigenoterapia em câmara hiperbárica, durante uma hora diária por um período de 30 dias. A avaliação da recuperação locomotora foi realizada no 2º, 9º, 16º, 23º e 30º dia pós-operatório, avaliados através de escala funcional e o sítio de lesão submetido à exame anatomopatológico. RESULTADOS: Demonstrou-se melhora da recuperação locomotora nos ratos tratados com oxigênio hiperbárico nas fases iniciais de avaliação mas no final da avaliação não havia diferença estatisticamente significante entre ambos grupos. O exame anatomopatológico comprovou as alterações estruturais da medula espinal nos dois grupos. CONCLUSÃO: A lesão medular leve provocada nos ratos evoluiu de maneira diferente no grupo da oxigenoterapia hiperbárica comparativamente ao grupo controle, na fase inicial.

Neuraxial Blockade in Patients with Preexisting Spinal Stenosis, Lumbar Disk Disease, or Prior Spine Surgery

Patients with spinal canal pathology, including spinal stenosis and lumbar disk disease, are often not considered candidates for neuraxial blockade because of the risk of exacerbating preexisting neurologic deficits or developing new neurologic dysfunction. In contrast, a history of spine surgery is thought to increase the likelihood of difficult or unsuccessful block. In this retrospective study we investigated the risk of neurologic complications and block efficacy in patients with preexisting spinal canal pathology, with or without a history of spine surgery, after neuraxial anesthesia. During the 15-year study period, all patients with a history of spinal stenosis or lumbar radiculopathy undergoing a neuraxial technique were studied. Patient demographics, preoperative neurologic diagnoses and neurologic findings at the time of surgery/neuraxial block, details of the neuraxial block including technique (spinal vs. epidural, single injection vs. continuous), injectate, technical complications (paresthesia elicitation, bloody needle/catheter placement, inability to advance catheter, accidental dural puncture), and block success were noted. New or progressive neurologic deficits were identified. All patients were followed until resolution or last date of evaluation. There were 937 patients included, 207 (22%) of whom had undergone spinal surgery. A history of spinal stenosis was present in 187 (20%), lumbar radiculopathy in 570 (61%), and peripheral neuropathy in 210 (22%) patients; 180 patients (19%) had multiple neurologic diagnoses. A majority of patients had active but stable neurologic symptoms at the time of surgery. Overall block success was 97.2%. A history of spine surgery did not affect the success rate or frequency of technical complications. Ten (1.1%; 95% confidence interval [CI] 0.5%-2.0%) patients experienced new deficits or worsening of existing symptoms. Three (1.4%) complications occurred in patients with a history of spinal surgery, and the remaining 7 (1.0%) in patients without prior surgical decompression or stabilization (P = NS). Although an orthopedic procedure was not a risk factor, in 5 of the 6 patients in which the surgery was a unilateral lower extremity procedure, the postoperative deficit involved the operative side. Likewise, in both patients undergoing bilateral orthopedic procedures who developed bilateral deficits, the outcome was worse on the previously affected side. A surgical cause was presumed to be the primary etiology in 4 (40%) of 10 patients. The primary etiology of the remaining 6 (60%) complications was judged to be nonsurgical (including anesthetic-related factors). The presence of a preoperative diagnosis of compressive radiculopathy (P = 0.0495) or multiple neurologic diagnoses (P = 0.005) increased the risk of neurologic complications postoperatively. We conclude that patients with preexisting spinal canal pathology have a higher incidence of neurologic complications after neuraxial blockade (1.1%; 95% CI 0.5%-2.0%) than that previously reported for patients without such underlying pathology. However, in the absence of a control group of surgical patients with similar anatomic pathology undergoing general anesthesia, we cannot determine whether the higher incidence of neurologic injury is secondary to the surgical procedure, the anesthetic technique, the natural history of spinal pathology, or a combination of factors and the relative contributions of each.

Surgical Treatment of Fixed Cervical Kyphosis With Myelopathy

A retrospective clinical study. To investigate clinical and radiographic outcomes following the surgical treatment of fixed cervical kyphosis with myelopathy. To our knowledge, a study specifically addressing the surgical treatment of fixed cervical sagittal deformity has never before been published. Sixteen patients treated surgically for fixed cervical kyphosis and myelopathy were followed for a mean of 4.5 years (range, 25-112 months). The study group consisted of 9 males and 7 females, with an average age of 52 years (range, 31-78 years). The principal etiologies of cervical deformity were prior laminectomy (63%), advanced spondylosis (19%), infection (6%), neuromuscular disease (6%), and metabolic disease (renal osteodystrophy) (6%). All patients were clinically evaluated by the Nurick classification and Odom criteria both before surgery and at the time of most recent follow-up. Radiographic analysis was performed using thin-cut CT scans, dynamic radiographs, and 14 x 36-inch scoliosis films. The mean preoperative cervical Cobb angle as measured from the C2-C7 was +38 degrees and improved to -10 degrees at final follow-up, yielding an average correction of 48 degrees . The mean number of anterior and posterior segments fused was 4.8 (range, 2-6) and 7.2 (range, 3-14), respectively. The mean Nurick score improved from 2.4 before surgery to 1.5 at the time of follow-up. According to Odom criteria, outcomes were as follows: excellent (38%), good (50%), fair (6%), and poor (6%). At the time of most recent follow-up, solid bony arthrodesis and maintenance of correction occurred in all patients; however, revision was required in one patient. The treatment of fixed cervical kyphosis with myelopathy using circumferential spinal osteotomies and instrumented reconstruction is technically demanding; however, restoration and maintenance of a neutral or lordotic cervical profile and excellent clinical outcomes are achievable.

Transforaminal Epidural Blood Patch

Spinal headache is an occasional, but painful complication of epidural injection procedures due to dural puncture that allows leakage of CSF from the thecal sac, thereby reducing intracranial pressure. In the event of failure of conservative management, (e.g. abdominal binder, fluids, acetaminophen), an epidural blood patch is often used. This case report describes a patient with spinal headache after a transforaminal selective epidural injection in a post laminectomy patient that was treated with a transforaminal epidural blood patch after the failure of conservative management. The patient underwent left transforaminal epidural injections at L5 and S1 for management of chronic low back pain secondary to post laminectomy syndrome. Three days later, the patient presented with a severe post lumbar puncture headache and failed to respond to conservative management. Interlaminar epidural approach for blood patch was not feasible secondary to prior laminectomy. Transforaminal epidural blood patch was performed utilizing 2 mL of autologous blood at each of the two sites. The patient recovered well without headache. In cases, with inability to perform interlaminar blood patch, a transforaminal approach may be considered.

Variation in Surgical Decision Making for Degenerative Spinal Disorders. Part I: Lumbar Spine

Survey-based descriptive study. To study relationships between surgeon-specific factors and surgical approach to degenerative diseases of the lumbar spine. Geographic variations in the rates of lumbar spine surgery are significant within the United States. Although surgeon density correlates with the rates of spine surgery, other reasons for variation such as surgeon age and training background are poorly understood. A total of 22 orthopedic surgeons and 8 neurosurgeons of varied ages and geographic regions answered questions regarding the need for surgery, surgical approach, and use of fusion and instrumentation for 5 simulated cases. Cases included: (1) multilevel stenosis without deformity or instability, (2) degenerative spondylolisthesis with stenosis, (3) isthmic (spondylolytic) spondylolisthesis with foraminal stenosis, (4) degenerative scoliosis with stenosis, and (5) recurrent stenosis following prior laminectomy without deformity or instability. The effects of surgeon age and training background on surgical decision making were analyzed using an independent samples t test and Fisher exact test, respectively. Significant variation in treatment approach among surgeons was noted for all cases except the patient with lytic spondylolisthesis, for whom all surgeons recommended fusion. Orthopedists recommended fusion and instrumentation more often than neurosurgeons for all cases, reaching significance for degenerative scoliosis with stenosis (P = 0.02 for both fusion and instrumentation). Younger surgeons were generally more likely to recommend instrumentation than their older peers, reaching significance for multilevel stenosis without deformity or instability and recurrent stenosis following prior laminectomy without deformity or instability (P = 0.05 and 0.01, respectively). Variations in surgical approach to lumbar degenerative diseases may depend on a patient's clinical condition. This study found strong agreement in the approach to lytic spondylolisthesis but significant variation for other degenerative conditions of the lumbar spine. In addition, recommendation for fusion and instrumentation varied with surgeon age and training background. Previously documented geographic variations may result in part from a lack of consensus on appropriate treatment techniques for specific lumbar degenerative conditions, as well as surgeon-specific factors.

Transthoracic disc excision and fusion for herniated thoracic discs.

Transthoracic discectomy and fusion were performed on 19 patients for a central or central-lateral herniated thoracic disc. At initial visit, 14 patients had evidence of myelopathy, 5 had bowel or bladder dysfunction, and 13 had pain. Previous laminectomy in three patients compromised the result of later anterior decompression. Coexistent multiple sclerosis was diagnosed in two patients, who had an atypical postoperative course. The overall results of transthoracic discectomy and fusion in patients without prior laminectomy or coexistent multiple sclerosis were excellent in six, good in six, fair in one, and poor in one, demonstrating that it is a safe and effective procedure.

Traumatic Charcot Spine

A case report of a trauma-induced neurologic injury of the spine that resulted in spinal arthropathy, without prior laminectomy, is presented. A review of Charcot joints of the spine is discussed, as well as the three other reported cases currently in the literature, only one of which was managed surgically. Charcot arthropathy can occur at sites distal to the quadra/paraplegic level in trauma patients. Careful radiographic analysis of these areas is important. Aggressive and modern surgical techniques are recommended to achieve spinal stabilization.

Epidural Steroids, Epidural Morphine and Epidural Steroids Combined with Morphine in the Treatment of Post-Laminectomy Syndrome

Epidural morphine injection followed by a steroid has been reported to be effective for the post-laminectomy pain ('failed back') syndrome. This double-blind, parallel study was undertaken to evaluate that mode of therapy. Twenty-two patients who had undergone at least one prior laminectomy, who were still symptomatic, were randomized to receive 50 mg of lidocaine epidurally with: (a) 75 mg triamcinolone diacetate (TR); or (b) 8 mg of preservative-free morphine (MP); or (c) both (TR and MP), at 1 month intervals for 3 consecutive months. The spinal interspace identified with the patients' pain complaint was the site of injection. For each treatment, patients were admitted to the Clinical Research Center for 24 h and their condition continuously monitored with a pulse oximeter and apnea monitor. Five to 7 patients in each group had pain relief for less than 1 month. No patient given morphine had pain relief for more than 1 month. Life-threatening ventilatory depression occurred in the group given triamcinolone and morphine. The use of morphine alone or combined with slow release triamcinolone does not appear to be appropriate for the treatment of the post-laminectomy pain syndrome.

Epidural steroids, epidural morphine and epidural steroids combined with morphine in the treatment of post-laminectomy syndrome

Epidural morphine injection followed by a steroid has been reported to be effective for the post-laminectomy pain (‘failed back’) syndrome. This double-blind, parallel study was undertaken to evaluate that mode of therapy. Twenty-two patients who had undergone at least one prior laminectomy, who were still symptomatic, were randomized to receive 50 mg of lidocaine epidurally with: 1. (a) 75 mg triamcinolone diacetate (TR); or 2. (b) 8 mg of preservative-free morphine (MP); or 3. (c) both (TR and MP), at 1 month intervals for 3 consecutive months. The spinal interspace identified with the patients' pain complaint was the site of injection. For each treatment, patients were admitted to the Clinical Research Center for 24 h and their condition continuously monitored with a pulse oximeter and apnea monitor. Five to 7 patients in each group had pain relief for less than 1 month. No patient given morphine had pain relief for more than 1 month. Life-threatening ventilatory depression occurred in the group given triamcinolone and morphine. The use of morphine alone or combined with slow release triamcinolone does not appear to be appropriate for the treatment of the post-laminectomy pain syndrome.

Cervical kyphosis and myelopathy. Treatment by anterior corpectomy and strut-grafting.

Between 1976 and 1984, fourteen patients who had severe cervical kyphosis and myelopathy were treated with anterior decompression and arthrodesis. Eight had had spondylosis; five, a traumatic injury; and one, a benign intradural tumor. In eight of the fourteen patients, the severe kyphosis and myelopathy had developed after a laminectomy of three, four, or five cervical vertebrae. The laminectomy had been done for the treatment of spondylosis in five patients, of a traumatic lesion in two, and of a tumor in one. Considering all fourteen patients, an average of 2.25 vertebral bodies was removed from each, and the average extent of the subsequent fusion was 3.25 levels. Eight patients (six of whom had spondylosis; one, a traumatic lesion; and one, a tumor) were treated with a fibular graft that spanned an average of 4.10 levels, and six patients (four of whom had a traumatic lesion and two, spondylosis) were treated with an iliac graft that spanned an average of 2.70 levels. Of the five patients who had a traumatic lesion, four were treated with anterior decompression and arthrodesis, combined with posterior arthrodesis that was performed during the same period of anesthesia. In three patients, the anterior graft dislodged during the immediate postoperative period. Two of the three patients had posterior instability due to a prior laminectomy, and in the third the graft dislodged because of technical difficulties. Two of these grafts were revised to restore stability. At the latest follow-up, twelve of the fourteen fusions were solid. In the other two patients, who died six and ten months postoperatively, the fusion had been solid, as shown by radiographs, before the time of death. The average amount of correction of the kyphotic deformities was 32 degrees, a reduction from an average of 45 degrees to an average of 13 degrees. All but one patient had some recovery of neural function; nine had complete and four, partial recovery. The remaining patient had relief of pain, but he continued to be completely quadriplegic although he had some sensory sparing. Of the four patients who had been unable to walk preoperatively, three were able to walk postoperatively. No patient lost neural function after the anterior decompression and arthrodesis. We concluded that, in the presence of severe cervical kyphosis and myelopathy, adequate anterior decompression of the spinal cord, correction of the kyphosis, and anterior arthrodesis using a strut graft can yield excellent results without undue risk.

Post-traumatic kyphosis. A review of forty-eight surgically treated patients.

We reviewed the cases of forty-eight patients who were treated surgically for symptomatic post-traumatic kyphosis of the thoracic or lumbar spine six months or longer after the initial injury. Presenting signs and symptoms included pain in 94 per cent, progression of kyphosis in 46 per cent, instability in 36 per cent, and increasing neural deficit in 27 per cent. Twenty-four patients had had a prior laminectomy. Posterior fusion (sixteen patients) and combined anterior and posterior fusion (twenty patients) always resulted in primary fusion. Anterior fusion alone was attempted in twelve patients, but failed in six. The average final correction of the deformity was 26 per cent. Pain was reduced significantly in 31 per cent of the patients and was relieved completely in 67 per cent. Fourteen of the forty-eight patients also had an anterior decompression, of whom five were neurologically improved, four were unchanged or stabilized, and four were immediately worse after operation. One patient was neurologically stable for twenty-three months postoperatively and then deteriorated again. No patients were neurologically improved following posterolateral decompression or repeat exploratory laminectomy.