Lumbar spinal stenosis

Lumbar spinal stenosis refers to a diversity of conditions that decrease the total area of the spinal canal, lateral recesses, or neural foramina. Lumbar stenosis is a common disorder that may be present in isolation, with or without associated disk bulge or herniation, or can be associated with degenerative spondylolisthesis or scoliosis. Symptomatic lumbar spinal stenosis is characterized by neurogenic claudication and/or lumbar or sacral radiculopathy. Sixty percent to 85% of properly selected patients have a satisfactory symptomatic improvement with surgical treatment.

The effect of limited interlaminar decompression versus complete laminectomy on intrathecal volume in degenerative lumbar spinal stenosis

INTRODUCTION

There is a controversial discussion about the adequate surgical procedure for degenerative lumbar spinal stenosis. Due to the observation that the degenerative lumbar spinal stenosis takes place predominantly at the interlaminar region on the level of the disc involving facets and bulging of the ligamentum flavum, resection of the whole lamina might not be necessary. A biomechanical study was designed to assess the effect of different decompression techniques using cadaver lumbar spine models.

METHODS

Twelve cadaver spines with CT verified degenerative lumbar spinal stenosis were dissected in order to measure the volume of the dural sac at different flexion and extension angles. Each segment (L3/4, L4/5) was decompressed first by limited interlaminar decompression and second by complete laminectomy. Intrathecal volume measurements were taken initially, after limited interlaminar decompression and after complete laminectomy.

RESULTS

Before surgical procedure, the cadaver spines showed an increase of the intrathecal volume in flexion and decrease in extension. After limited interlaminar decompression, there was a significant reduction of volume loss in extension. There was no significant additional reduction of volume loss in extension after complete laminectomy in comparison to limited interlaminar decompression.

CONCLUSION

The results allow to conclude that limited interlaminar decompression is efficient for decompression in degenerative lumbar spinal stenosis.

Impaired lumbar movement perception in association with postural stability and motor- and somatosensory-evoked potentials in lumbar spinal stenosis

STUDY DESIGN

A descriptive study of the associations between different neurophysiologic findings in patients with lumbar spinal stenosis.

OBJECTIVES

To evaluate the ability to sense a change in lumbar position and the associations between lumbar movement perception, postural stability, and motor-evoked potentials and somatosensory-evoked potentials.

SUMMARY OF BACKGROUND DATA

Patients with low back pain have impaired postural control and impaired lumbar proprioception. Altered motor-evoked potentials and somatosensory-evoked potentials have been often observed in lumbar spinal stenosis.

METHODS

The study included 26 patients with clinically and radiologically diagnosed lumbar spinal stenosis. Their ability to sense lumbar rotation was assessed in a previously validated motorized trunk rotation unit in the seated position. The abilities to indicate the movement direction and the movement magnitude were used as indexes of the ability to sense the lumbar rotatory movement. The postural stability was measured with a vertical force platform. The motor-evoked potentials were elicited by transcranial and lumbar stimulation and recorded from anterior tibialis muscles. The somatosensory-evoked potentials were elicited by transcutaneous electrical stimulation of the tibial nerve at the ankle.

RESULTS

Twenty patients (76.9%; P = 0.006) reported the wrong movement direction. Furthermore, the patients consistently localized the movement sensation in their shoulders instead of the lumbar region. The altered motor-evoked potentials and somatosensory-evoked potentials were observed in 11 and 16 patients, respectively. Abnormal motor-evoked potentials had inconsistent associations with impaired movement perception and postural stability and abnormal somatosensory-evoked potentials had no associations with other findings.

CONCLUSIONS

Many patients with lumbar spinal stenosis have difficulties in sensing the lumbar rotational movement, which may indicate impaired proprioceptive abilities. Abnormal motor-evoked potentials and somatosensory-evoked potentials are also frequent in lumbar spinal stenosis but do not necessarily occur in the same patients as the abnormal ability to sense trunk movement. These new findings add to our understanding of the pathophysiology of lumbar spinal stenosis.

"EMG disease" with bulbar muscle involvement: a case report

We report the first case of diffuse abnormal insertional activity with bulbar muscle involvement. Electromyography performed 5 months earlier reported multilevel radiculopathy. A repeat electromyography study revealed short trains of positive waves without fibrillation potentials, diffusely present in all tested muscles. Positive waves were also found in the bulbar innervated muscles; these included the trapezius, frontalis, and the orbicularis oculi. This entity is important to recognize because confusion with neuromuscular syndromes can occur.

Cervical spinal stenosis with cord neurapraxia: evaluations and decisions regarding participation in athletics

Cervical spinal cord neurapraxia (CCN) leads to transient episodes ranging from paresthesia to paresis to plegia (complete paralysis), and occurs in athletes with some demonstrable degree of cervical spinal stenosis. Determination of spinal stenosis requires demonstrating a sagittal diameter of the spinal canal less than 14 mm from C4 to C6. Because radiologic techniques vary affecting the accuracy of this measure, a ratio method was developed comparing the spinal canal to the vertebral body width, demonstrating that a ratio of less than 0.8 is indicative of cervical spinal stenosis. Although this has high sensitivity (93%), the low predictive value of 0.2% makes this a poor screening tool for athletic participation. Further complicating the challenge of determining which athletes are at risk for quadriplegia are data showing that athletes who suffered permanent injury did not recall transient episodes of CCN, and conversely none of the athletes with CCN later developed permanent neurologic injury. Nevertheless, 56% of football athletes returning to sport after an episode of CCN experienced a recurrence as determined by survey data. Those with CCN and documented ligamentous instability, magnetic resonance imaging evidence of cord defects or swelling, neurologic symptoms or signs for greater than 36 hours, or more than one recurrence have an absolute contraindication.

Interspinous bursa and spinal instability

STUDY DESIGN

This is a prospective study. Interspinous tissue was taken intraoperatively for pathological examination for the presence of bursa. The pathologist was unaware of the X-ray findings in each specimen. The presence of bursa was then correlated with X-ray evidence of hypermobility in each segment.

OBJECTIVE

To verify the pathogenesis of interspinous bursal formation.

SUMMARY OF BACKGROUND DATA

Interspinous bursa is common in the older population. It has been associated with degenerative lumbar diseases, aging and anatomical distance between the spinous process. However, no detailed exploration of the segmental instability as a cause of bursal formation has been done.

METHOD

The insterspinous tissue was taken intraoperatively from patients diagnosed as multilevelled spinal stenosis who underwent extensive decompression, fusion and instrumentation. The specimens were examined by the same pathologist for the existence of bursa. The presence of bursa was correlated with X-ray motion study of each spinal segment by student t-test.

RESULTS

The existence of bursal was significantly correlated with angular mobility of more than 10 degrees.

CONCLUSION

Angular mobility is a possible cause of interspinous bursa. On the contrary, the presence of insterspinous bursa may be evidence of segmental hypermobility.

Muscle sympathetic nerve activity in patients with lumbar spinal canal stenosis

The present study aimed to measure sensory nerve conduction velocity (SNCV) and muscle sympathetic nerve activity (MSA) in both normal subjects and patients with lumbar spinal canal stenosis (LSCS), and to determine what sensory and sympathetic nerve systems relate to the development of abnormal sensation in the lower limbs of the patients. The study population was 12 patients and 10 age-matched healthy control subjects. A statistical difference in the mean MSA intervals was found between the LSCS patients and the normal subjects. There was a fairly large difference between them in the values of the standard deviations as one of the parameters to determine the degree of fluctuation of MSA. These results suggest the LSCS patients have shorter MSA intervals and narrower fluctuations of MSA than normal subjects. As for the range of fluctuation of the MSA intervals and SNCV, the faster the SNCV, the wider the range of fluctuation of MSA intervals in the normal subjects. Many patients with LSCS seem to maintain a correlation between SNCV and MSA intervals. This suggests that even in cases of LSCS, human homeostasis works to keep the relationship between sympathetic nerve function and somato sensory nerve function to some extent. A few LSCS patients showed no correlation between MSA and SNCV. These patients were rather old, suffered spinal stenosis in the relatively higher levels of the spinal canal, and had suffered from the disease for longer than the mean period of all the patients. When the peripheral nerves or cauda epuina are chronically compressed, the nerve systems can not maintain the relationship between them, which finally results in failure. It is suggested that the disrupted coordination between sympathetic nerve function and somato sensory nerve function is one of the reasons why abnormal sensations occur in the lower extremities of LSCS patients.

Clinical symptoms and surgical outcome in lumbar spinal stenosis patients with neuropathic bladder

We evaluated the clinical and radiologic features of patients with lumbar spinal stenosis with neuropathic bladder. Based on cystometrogram analysis, the patients were divided into two groups--the neuropathic bladder (NB) group: the NB+ group (23 patients), and the nonneuropathic bladder group: the NB- group (14 patients). The symptom of incontinence was characteristic in patients in the NB+ group. Patients in the NB+ group had a more severe neurologic disturbance, compared with those in the NB- group. The more severe neurologic disturbance was caused by the more striking finding of degenerative spinal stenosis associated with developmental narrowing of the spinal canal. Decompressive surgery had a beneficial effect on the recovery of the neurologic symptoms in both groups. Residual urine volume was reduced after surgery. Postoperative cystometrogram was carried out in nine patients in the NB+ group. It showed a normal pattern in six patients; however, three patients remained in an underactive pattern. Furthermore, four patients still required clear intermittent self-catheterization after surgery.

Examination findings and self-reported walking capacity in patients with lumbar spinal stenosis

BACKGROUND AND PURPOSE

Spinal stenosis is a common, often disabling, condition resulting from compression of the cauda equina and nerve roots. This study was designed to: (1) characterize the impairments of patients with lumbar spinal stenosis (LSS) and (2) to identify predictors of self-reported walking capacity.

SUBJECTS

Forty-three patients with symptomatic LSS, from 3 specialty clinics, were evaluated. Twenty-eight subjects (65%) were female. The subjects' median age was 73.6 years (mean=72.4, SD=10.3, range=45.7-90.7), and the median duration of low back pain was 24 months (mean=36.6, SD=41.6, range=0-216).

METHODS

Demographic data, medical history, and information about low back pain and symptoms (eg, numbness, tingling, and lower-extremity weakness) were collected using a standardized questionnaire and physical examination.

RESULTS

Twenty-two subjects (51%) had lower-extremity weakness, primarily of the extensor hallucis longus muscle. Thirty-five subjects (81%) had absent or decreased neurosensory responses (eg, pinprick, vibration, reflexes), and 28 subjects (66%) reported that they were unable to walk farther than 2 blocks. Women were more likely than men to report difficulties walking, as were subjects with abnormal Romberg test scores and those with greater pain during walking.

DISCUSSION AND CONCLUSION

Pain and balance problems appeared to be the primary factors limiting ambulation in our subjects with LSS.

Laminoplasty versus laminectomy and fusion for multilevel cervical myelopathy: an independent matched cohort analysis

STUDY DESIGN

A matched cohort clinical and radiographic retrospective analysis of laminoplasty and laminectomy with fusion for the treatment of multilevel cervical myelopathy.

OBJECTIVES

To compare the clinical and radiographic outcomes of two procedures increasingly used to treat multilevel cervical myelopathy.

SUMMARY OF BACKGROUND DATA

Traditional methods of treating multilevel cervical myelopathy (laminectomy and corpectomy) are reported to have a notable frequency of complications. Laminoplasty and laminectomy with fusion have been advocated as superior procedures. A comparative study of these two techniques has not been reported.

METHODS

Medical records of all patients treated for multilevel cervical myelopathy with either laminoplasty or laminectomy with fusion between 1994 and 1999 at our institution were reviewed. Thirteen patients that underwent laminectomy with fusion were matched with 13 patients that underwent laminoplasty. All patients and radiographs were independently evaluated at latest follow-up by a single physician.

RESULTS

Cohorts were well matched based on patient age, duration of symptoms, and severity of myelopathy (Nurick grade) before surgery. Mean independent follow-up was similar (25.5 and 26.2 months). Both objective improvement in patient function (Nurick score) and the number of patients reporting subjective improvement in strength, dexterity, sensation, pain, and gait tended to be greater in the laminoplasty cohort. Whereas no complications occurred in the laminoplasty cohort, there were 14 complications in 9 patients that underwent laminectomy with fusion patients. Complications included progression of myelopathy, nonunion, instrumentation failure, development of a significant kyphotic alignment, persistent bone graft harvest site pain, subjacent degeneration requiring reoperation, and deep infection.

CONCLUSIONS

The marked difference in complications and functional improvement between these matched cohorts suggests that laminoplasty may be preferable to laminectomy with fusion as a posterior procedure for multilevel cervical myelopathy.

Lumbar canal stenosis: a cause of late neurological deterioration in patients with spina bifida

BACKGROUND

Patients diagnosed with spina bifida may show late deterioration. This worsening in their clinical symptoms has been attributed to a multiplicity of causes such as secondary tethering of the spinal cord, Chiari II anomaly, hydromyelia, diastematomyelia, arachnoid cysts, and dermoid tumors.

METHODS

We searched the clinical records of patients diagnosed with spina bifida who were treated at our hospital for a period of 25 years for the purpose of ascertaining the number and etiology of cases of late neurological deterioration.

RESULTS

Six of 144 patients with open spina bifida presented with late neurological deterioration. In one of these cases and in another patient with occult spina bifida the most relevant factor noted during surgery was the presence of marked lumbar canal stenosis.

CONCLUSION

We suggest that certain cases of late clinical worsening in spina bifida patients are because of lumbar canal stenosis and that this condition should be added to the list of causes that may produce delayed neurological deterioration in patients with spinal dysraphism.

Functional mobility performance in an elderly population with lumbar spinal stenosis

OBJECTIVES

To compare the functional mobility (FM) of elderly apparently healthy (AH) subjects and patients with lumbar spinal stenosis (LSS) and to evaluate the reliability and validity of the FM tests.

DESIGN

Using the test-retest paradigm, FM performance was assessed in AH subjects. A single FM assessment was conducted on a group of LSS subjects. Between-group performance comparisons were made with the AH subjects and the LSS patients.

SETTING

Orthopedic clinical practice (LSS subjects) and university laboratory (AH subjects).

PARTICIPANTS

Fifty-seven patients seen in an orthopedic clinical practice for LSS and 96 AH subjects who were volunteers identified from among participants of The Lifelong Learning Society at Florida Atlantic University.

INTERVENTIONS

Treadmill walk (TW) test (at 53.6 m/min, 1% increase in grade per min) until 70% of the predicted maximum heart rate was achieved or associated pain made participation uncomfortable. Three trials each of a sit-to-stand (SS, rise from chair as quickly as possible without using arms) and a weight-carrying (WC, walk 20 m as quickly as possible for time carrying 10% of the body weight evenly distributed in hand-held weights) test. The AH group repeated all tests on a separate day.

MAIN OUTCOME MEASURES

Time to walk treadmill, stand from sitting position, walk 20 meters, and analysis of variance between groups.

RESULTS

Significant between-group differences were found for the TW, SS, and WC tests. Test-retest r values of .839 for the TW, .848 for the SS, and .833 for the WC were observed.

CONCLUSIONS

The AH group demonstrated greater FM than the LSS group. The performance disparity between groups may suggest context validity, while the AH groups test-retest stability reflects reliability.

Motor and somatosensory conduction time between the cortex and the Erb point in patients suffering from cervical spinal stenosis and tumour

Motor and sensory conduction time between the cortex and the Erb point were examined in patients with cervical cord compression. Patients were divided into two groups: the compression was caused either by cervical extramedullary tumour (9 cases), or by cervical spondylosis or herniated disc (16 cases). In response to median nerve stimulation, pathological somatosensory evoked potentials were recorded in 66% of the patients suffering from tumour and in 60% of the patients suffering from spondylosis. All of the patients disclosed pathological motor evoked potentials. On the basis of these observations it could be concluded that, in cases of cervical spinal cord compression, the involvement of the motor system could be more reliably detected than that of the sensory system with electrophysiological methods.

Iliopsoas hematoma with femoral neuropathy presenting a diagnostic dilemma after spinal decompression

STUDY DESIGN

Case report of an iliopsoas hematoma with femoral neuropathy appearing 8 weeks after a posterior spinal decompression procedure.

OBJECTIVES

To describe a potential complication and differential diagnosis for nerve root symptoms following spinal decompression.

SUMMARY OF BACKGROUND DATA

Iliopsoas hematoma is usually a complication of anticoagulation, hemophilia, or trauma. It has not been described previously as a complication of posterior spinal decompression. Femoral neuropathy results from compression within the iliopsoas compartment.

METHODS

A 53-year-old woman reported pain in the right side of her groin and an increasing fixed flexion deformity of the right hip 8 weeks after a posterior, midline, spinal decompression. A femoral neuropathy later developed. Magnetic resonance imaging and computed tomography were performed.

RESULTS

Imaging studies demonstrated a diffusely enlarged iliopsoas. Exploration revealed a large hematoma, which was evacuated. The compartment was fully decompressed with resolution of the nerve root symptoms within 48 hours.

CONCLUSIONS

Iliopsoas pathology is a rare cause of nerve root symptoms and presented diagnostic difficulties after an apparently successful spinal decompression.

Model of neuropathic intermittent claudication in the rat: methodology and application

In the present study we characterize a rat neurogenic intermittent claudication model which was accomplished by placing two pieces of silicone rubber of various sizes into the lumbar (L4 and L6) epidural space. After induction of spinal stenosis walking function was measured using a treadmill apparatus and sensory functions were tested by measuring thermal and tactile withdrawal threshold (von Frey filaments) for the period of 28 days after stenosis. In addition, local spinal cord blood flow (SCBF) was measured, periodically, before and after induction of stenosis using laser Doppler. After implantation of two pieces of silicone rubber (width 1.25 mm, height 1.0 mm, length 4.0 mm) a significant running dysfunction, as evidenced by shortening of running distance, was measured as soon as 24 h after stenosis (178.5+/-59.1 m vs 681.3+/-70.2 m). This effect persisted for 28 days after surgery. Similarly, a significant tactile (but not thermal) hypersensitivity was measured for a period of 28 days (1.2+/-0.3 g vs 14.9+/-0.2 g). In this experimental group the measurement of local SCBF revealed a significant (30-50%) reduction in the territory of spinal stenosis measured at 3,7,14 or 28 days after surgery. Implantation of larger pieces of silicon rubber (1.5 mm width) caused a significant increase in the incidence of urinary retention and mortality rate. These data show that chronic partial spinal compression at L4 and L6 spinal level lead to the development of significant motor/sensory dysfunction which resemble those seen in patients with neurogenic intermittent claudication. The lack of motor dysfunction under resting conditions but its appearance during forced exercise also suggest that the development of local spinal ischemia can represent one of the mechanisms.

Cerebrospinal fluid flow in the cervical spinal canal in patients with chronic neck pain

PURPOSE

To measure the cerebrospinal fluid (CSF) velocity in the cervical spinal canal both above and below a stenotic segment in patients with cervical spinal stenosis. The cord velocity was also measured at the level of C2.

MATERIAL AND METHODS

Thirteen patients with chronic neck pain were examined with MR imaging. The degree of cervical spinal stenosis was assessed and measured on MR images and CSF velocity in the cervical spinal canal was measured using the phase MR flow quantification method at the level of C2 and below the stenotic segment. The cord motion was measured at the level of C2.

RESULTS

The peak velocities of CSF in front of the cord at the level of C2 were, on average, a little higher than behind the cord, but the interindividual variation was high. The caudal or rostral velocities of CSF above and below the stenotic segment could be measured in most cases and they were not dependent on the degree of stenosis when assessed visually. When the stenosis was assessed by relating the cord area to the dural sac area, a statistical correlation between narrow spinal canal and high velocities in the anterior CSF space below the stenotic segment was found.

CONCLUSION

Spinal stenosis does not alter the cord or CSF velocities at the C2 level, but increases the velocity of CSF in the anterior CSF space below the stenotic segment when the stenosis is assessed by cord and dural sac area measurements.

Test-retest reproducibility of the exercise treadmill examination in lumbar spinal stenosis

OBJECTIVE

To provide further validation of the treadmill test by assessing its "test-retest" reproducibility.

PATIENTS AND METHODS

In this prospective study, 28 patients with severe lumbar spinal stenosis underwent exercise treadmill testing, first at a walking speed of 1.2 mph and then at the patient's preferred walking speed. All patients had a second treadmill examination or "retest." No treatment intervention was performed between the initial test and the retest. Time to first symptoms (TFS) and total ambulation time (TAT) were measured. Differences between the baseline examination and the retest examination were assessed by using the concordance correlation coefficient (CCC) as well as graphically.

RESULTS

There was good reproducibility between baseline test and retest results for all 4 end points: 1.2 mph, TFS (CCC = 0.90); 1.2 mph, TAT (CCC = 0.89); preferred walking speed, TFS (CCC = 0.98); and preferred walking speed, TAT (CCC = 0.96). The median difference between trials was not significantly different from zero for any of the 4 outcomes.

CONCLUSIONS

Exercise treadmill testing has good test-retest reproducibility. There was no learning phenomenon associated with the test procedure. The study further validates the clinical utility of exercise treadmill testing in patients with lumbar spinal stenosis and neurogenic claudication.

Laminectomy for thoracic spinal canal stenosis

Stenosis of the thoracic spinal canal is a relatively rare disorder with numerous causes. Clinical manifestations include signs and or symptoms consistent with focal thoracic radiculopathy and/or myelopathy. Several surgical approaches for the decompression of the stenotic thoracic canal have been described. Laminectomy is typically reserved for only those cases in which dorsal compression of the neural elements is demonstrated; it is contraindicated when the epidural compression is primarily ventral in location.

The imaging of lumbar spinal stenosis

Lumbar spinal stenosis (LSS) is a relatively common condition of varied aetiology which results in chronic compression of the cauda equina. It becomes clinically relevant when giving rise to symptoms of neurogenic claudication or leg pain. Lumbar spinal stenosis can be classified based on anatomy or aetiology and the diagnosis in any single case should include a consideration of both the site and the cause. Plain radiography is of limited value. Myelography with erect lateral flexion/extension views will demonstrate the dynamic component of the stenosis which cannot be appreciated on plain computed tomography (CT) or magnetic resonance imaging (MRI). Therefore, in patients with a good history of symptomatic LSS, and a borderline stenosis on MRI, CT myelography is recommended as the definitive pre-operative imaging investigation.

Dynamic examination of the lumbar spine by using vertical, open magnetic resonance imaging

OBJECT

The aim of this study was to determine the relationship of different structures of the lower lumbar spine during interventional movement examination.

METHODS

Clinically healthy volunteers and patients suffering from degenerative disorders of the lumbar spine underwent vertical, open magnetic resonance (MR) imaging (0.5 tesla). Three functional patterns of lumbar spine motion were identified in 50 healthy volunteers (average age 25 years). The authors identified characteristic angles of the facet joints, as measured in the frontal plane. In 50 patients with degenerative disorders of the lumbar spine (41 with disc herniation, five with osteogenic spinal stenosis, and four with degenerative spondylolisthesis) the range of rotation was increased in the relevant spinal segments. Signs of neural compression were increased under motion.

CONCLUSIONS

Dynamic examination in which vertical, open MR imaging is used demonstrated that the extent of neural compression as well as the increasing range of rotation are important signs of segmental instability.

Neuropraxia of the cervical spinal cord following cervical spinal cord trauma: a report of five patients

Neuropraxia of the cervical spinal cord is a rare condition which is almost exclusively reported in American football players following cervical hyperextension or hyperflexion trauma. In this entity-neurological symptoms of both arms and legs for a period of up to 15 minutes are observed with complete recovery. We report the characteristics of five patients not involved in contact sport activities with a neuropraxia of the spinal cord following cervical trauma. In four of the five patients, this syndrome was associated with a cervical canal stenosis. Surgical decompression was performed in two patients with progressive neurological symptoms after an initial period of recovery. The cases illustrates that although neuropraxia of the spinal cord is usually seen in athletes, also other persons may be at risk for developing this condition, especially when a preexisting spinal stenosis is present. Patients who experienced neuropraxia of the spinal cord should thus be evaluated carefully for the presence of cervical spinal cord abnormalities.

Factors influencing the outcome of degenerative lumbar spinal stenosis

The objective of this study was to evaluate the influence of decreased dural sac cross-sectional area and baseline clinical parameters on the outcome of patients treated surgically or conservatively for lumbar spinal stenosis. Computed tomography or magnetic resonance imaging scans of 37 patients were digitized and the dural sac cross-sectional area was calculated. This parameter and baseline clinical, socioeconomic, and anthropometric data of the patients were correlated with 1-year and 2-year follow-up data. The decrease in dural sac cross-sectional area negatively affected walking capacity on follow-up controls in patients treated conservatively, whereas such a relation was not observed among surgically treated patients. Female sex was the main parameter that worsened the global outcome of degenerative lumbar spinal stenosis, particularly after surgical treatment.

Nonoperative treatment for lumbar spinal stenosis. Clinical and outcome results and a 3-year survivorship analysis

STUDY DESIGN

A cohort study of nonoperatively treated patients with lumbar spinal stenosis.

OBJECTIVE

To assess the effectiveness of aggressive nonsurgical treatment for lumbar spinal stenosis.

BACKGROUND DATA

While surgical treatment of lumbar spinal stenosis has been widely accepted, the natural history of this condition is poorly documented. Moreover, the effect of other available therapies is unclear.

METHODS

Forty-nine patients meeting radiographic and clinical criteria for spinal stenosis underwent nonsurgical intervention consisting of therapeutic exercises, analgesics, and epidural steroid injections. Patients were followed for an average of 33 months. Outcome was assessed using a recently developed patient questionnaire for assessment of patients with lumbar spinal stenosis. Survival analysis was used to assess the probability of surgical intervention over the follow-up period.

RESULTS

At 3 years following treatment, 9 of the 49 patients had undergone surgical intervention. Of the remaining 40 unoperated patients, it is reported that two suffered significant motor deterioration, one of whom still reported overall symptoms as mild improvement, and the other as definite worsening. Five of the 40 unoperated patients reported feeling overall symptoms as probably or definitely worse, 12 reported no change, 11 reported only mild improvement, and 12 reported sustained improvement. Twelve of the 40 unoperated patients also had none or only mild pain.

CONCLUSIONS

The authors conclude that aggressive nonoperative treatment for spinal stenosis remains a reasonable option.

Degenerative disease of the lumbosacral spine: disk herniation and stenosis

Degeneration of the intervertebral disk complex begins early in life and is a consequence of a variety of environmental factors as well as of normal aging. Degeneration of bone and soft tissue spinal elements is the most common cause of spinal stenosis. The term "degeneration" as commonly applied to the spine covers such a wide variety of clinical, radiological and pathological manifestations that the word is really only a symbol of our ignorance. Computed tomography and myelography have long been used for diagnosing the effects of degenerative diseases' of the lumbar spine. Despite the continuous improvement in magnetic resonance scanning for this purpose, computed tomography can provide excellent screening for disk herniation and spinal stenosis.

Stability and alignment of the cervical spine of hemodialyzed patients treated by canal-expansive laminoplasty

In this present study, four hemodialyzed patients with cervical myelopathy treated by canal-expansive laminoplasty are reported. The average duration of hemodialysis was 18 years, and the average follow-up was 16 months. Early results show maintenance of sagittal alignment and reduction of instability of the cervical spine with no progression of the destructive spondyloarthritis.

Predictors of surgical outcome in degenerative lumbar spinal stenosis

STUDY DESIGN

A prospective, observational study.

OBJECTIVES

To identify outcome predictors of surgery for degenerative lumbar spinal stenosis.

SUMMARY OF BACKGROUND DATA

Degenerative lumbar spinal stenosis is the most frequent indication for spine surgery in the elderly. More than 25% of surgical patients have a poor outcome, yet little is known about factors that predict the outcome of surgery.

METHODS

Surgery was performed on 199 patients with degenerative lumbar spinal stenosis, and they were observed for 2 years after surgery in four referral centers. Surgery consisted of decompressive laminectomy with or without arthrodesis. Outcomes included validated measures of symptom severity, walking capacity, and satisfaction with the results of surgery. Potential predictors of outcome included sociodemographic factors and physical examination, as well as radiographic, psychological, social, and clinical history variables.

RESULTS

The proportion of patients with severe pain decreased from 81% before surgery to 31% by 2 years afterward. The most powerful preoperation predictor of greater walking capacity, milder symptoms, and greater satisfaction was the patient's report of good or excellent health before surgery. Low cardiovascular comorbidity also predicted a favorable outcome.

CONCLUSIONS

Patient's assessments of their own health and comorbidity are the most cogent outcome predictors of surgery for spinal stenosis.

CT-guided epidural/perineural injections in painful disorders of the lumbar spine: short- and extended-term results

PURPOSE

Evaluation of short- and extended-term results of repeated epidural/perineural injections (EDT/PRT) of corticoids in painful afflictions of the lumbar spine.

METHODS

Thirty-two patients who had persistent radicular or low back pain for more than 6 weeks were treated with CT-guided injection therapy. By EDT/PRT, 40 mg of triamcinolonacetonid was injected either periradicularly or by a direct intraspinal epidural method at intervals of 3 weeks. Altogether, 140 EDT/PRT were performed in 32 patients (mean 4.4, range 2-8). In nine patients partial facet joint denervation with 1-2 ml of 50% alcohol solution was combined with EDT/PRT to reduce low back pain. Before and after treatment and at follow-up (mean 9.6 months), treatment success was evaluated on a visual analog scale and by physical examination (good = >50% improvement, moderate = 20%-50%, no improvement = <20%).

RESULTS

Short-term (end of therapy) good or moderate improvement was achieved in 91% of patients, extended-term (mean 9.6 months) in 56%. Regarding certain subgroups, those with disc herniations of the lumbar spine showed a better outcome with good or moderate improvement in 95% short-term and 69% extended-term than those with spinal stenosis who had 72% short-term and 28% long-term.

CONCLUSION

Results indicate that CT-guided EDT/PRT in combination with partial facet joint denervation is a safe and effective outpatient treatment.

Microdecompression for lumbar spinal canal stenosis

STUDY DESIGN

A description of the technique for lumbar microdecompression and a prospective study of the outcomes.

OBJECTIVE

To describe and analyze a technique that affords an excellent decompression while minimizing damage to surrounding tissues.

SUMMARY OF BACKGROUND DATA

Commonly used techniques of lumbar decompression that include bilateral takedown of paraspinal musculature and aggressive bony resection can result in significant iatrogenic sequelae. A less destructive alternative is needed.

METHODS

Unilateral limited takedown of multifidus was undertaken, and ipsilateral decompression performed. The contralateral side then was addressed under the midline structures with microscopic visualization--thereby preserving the supra-/interspinous ligament complex and the contralateral musculature. Thirty consecutive patients undergoing the procedure were analyzed prospectively and after a follow-up period by independent observers using a modified validated functional outcome score and patient satisfaction measures.

RESULTS

The technique affords an excellent decompression while minimizing destruction to tissues not directly involved in the pathologic process. Functional outcome scores doubled, and 87% of patients reported high satisfaction rates.

CONCLUSIONS

Lumbar microdecompression is a minimally invasive technique that appears to provide excellent functional outcomes.

Motor conduction alterations in patients with lumbar spinal stenosis following the onset of neurogenic claudication

The pathogenesis of neurogenic claudication is thought to lie in relative ischemia of cauda equina roots during exercise. In this study we will evaluate the effect of the transient ischemia brought on by exercise on motor conduction in patients suffering from lumbar spinal stenosis (LSS). We will also evaluate the sensitivity of motor evoked potentials (MEPs) in detecting motor conduction abnormalities before and after the onset of neurogenic claudication. Thirty patients with LSS and 19 healthy volunteers were enrolled in the study. All LSS patients had a history of neurogenic claudication and the diagnosis was confirmed with a CT myelogram. Both groups underwent a complete electrophysiological evaluation of the lower extremities. The motor evoked potential latency time (MEPLT) and the peripheral motor conduction time (PMCT) were measured. The subjects were asked to walk on a flat surface until their symptoms were reproduced. A new set of electrophysiological tests was then performed. Exercise did not produce claudication in any of the control group subjects. Twenty-seven patients did have claudication. The pre-exercise MEPLT and nerve conduction studies in the control group fell within the normal range. In the patient group, 19 patients had increased baseline values for MEPLT to at least one muscle. There was a significant difference between the MEPLT and the PMCT values measured before and after exercise in the patients with signs of neurological deficit. This difference was not found to be significant in patients without neurological deficits (t-test P < 0. 05). It may be concluded that exercise increases the sensitivity of MEPs in detecting the roots under functional compression in LSS.

The influence of spinal canal narrowing and timing of decompression on neurologic recovery after spinal cord contusion in a rat model

STUDY DESIGN

The effect of spinal canal narrowing and the timing of decompression after a spinal cord injury were evaluated using a rat model.

OBJECTIVE

To evaluate whether progressive spinal canal narrowing after a spinal cord injury results in a less favorable neurologic recovery. Additionally, to evaluate the effect of the timing of decompression after spinal cord injury on neurologic recovery.

SUMMARY OF BACKGROUND DATA

Results in previous studies are contradictory about whether the amount of canal narrowing or the timing of decompression after a spinal cord injury affects the degree of neurologic recovery.

METHODS

Forty adult male Sprague-Dawley rats were equally divided into a control group, in which spacers of 20%, 35%, and 50% were placed into the spinal canal after laminectomy, and an injury group in which the spacers were placed after a standardized incomplete spinal cord injury. After spacer removal, neurologic recovery in both was monitored by Basso, Beattie, Bresnahan (BBB) Locomotor Rating Scale (Ohio State University, Columbus, OH) motor scores and transcranial magnetic motor evoked potentials for 6 weeks followed by histologic examination of the spinal cords. Subsequently, 42 rats were divided into five groups in which, after spacer placement, the time until decompression was lengthened 0, 2, 6, 24, and 72 hours. Again, serial BBB motor scores and transcranial magnetic motor evoked potentials were used to assess neurologic recovery for 6 weeks until the animals were killed for histologic evaluation.

RESULTS

Spacer placement alone in the control animals resulted in no neurologic injury until canal narrowing reached 50%. All of the control groups (spacer only) exhibited significantly better (P < 0.05) motor scores compared with the injury groups (injury followed by spacer insertion). Within the injury groups the motor scores were progressively lower as spacer sizes increased from the no-spacer group to the 35% group. The results in the 35% and 50% groups were not statistically different. The results of the time until decompression demonstrated that the motor scores were consistently better the shorter the duration of spacer placement (P < 0.05) for each of the time groups (0, 2, 6, 24, and 72 hours) over the 6-week recovery period. Histologic analysis showed more severe spinal cord damage as both spinal canal narrowing and the time until decompression increased.

CONCLUSION

The results in this study present strong evidence that the prognosis for neurologic recovery is adversely affected by both a higher percentage of canal narrowing and a longer duration of canal narrowing after a spinal cord injury. The tolerance for spinal canal narrowing with a contused cord appears diminished, indicating that an injured spinal cord may benefit from early decompression. Additionally, it appears that the longer the spinal cord compression exists after an incomplete spinal cord injury, the worse the prognosis for neurologic recovery.

MR imaging of cerebrospinal fluid flow and spinal cord motion in neurologic disorders of the spine

In summary, MR imaging of CSF and cord motion helps to evaluate diseases affecting cord and CSF motion and to identify the specific pathophysiology involved. A number of significant points have been made. First, MR imaging flow studies can be useful in evaluating CSF spaces and cystic diseases. Second, longitudinal and transverse motions occur in the spinal cord and CSF. Traveling wave motion occurs along the length of the spinal cord. Third, spinal cord tethering is associated with decreased cord velocity and loss of cord displacement at tethering site. Decreased transverse velocities occur with lateral cord tethering to the spinal canal. Fourth, in spinal dysraphism, longitudinal cord velocity is decreased by tethering, and is normal in asymptomatic patients with low conus. Normal cord motion helps to rule out possible tethering in symptomatic dysraphism with hydromyelia. Fifth, in acquired and nonmyelodysplastic symptomatic tethering, spinal cord motion is decreased. Sixth, in symptomatic cord compression, CSF flow and cord motion decrease, but recover after surgical decompression and after compensatory atrophy. Seventh, in asymptomatic spinal stenosis, cord motion is normal or increased. Diffuse spinal stenosis with cord atrophy leads to diffuse cord acceleration and prolonged cord caudal velocity, possibly related to the loss of the transverse mobility of the cord. Finally, focal spinal stenosis leads to focal dynamic cord deformation and can be associated with prominent intramedullary deformations. When compression is severe or symptomatic, cord motion is significantly decreased. Postoperative cases demonstrate good recovery of cord and CSF motion, unless compression or obstruction is still present.

Laminoplasty--a possible treatment for cervicogenic headache? Some ideas on the trigger mechanism of CeH

Cervicogenic headache (CeH) has been treated successfully by ventral decompressive surgery and segmental fusioning. Usually ventral fusioning is performed during one operation on one or two neighbouring segments only. We performed dorsal decompressive laminotomy and laminoplasty on eight patients with more than two segmental degenerative diseases narrowing the cervical spinal canal. The bilateral sawn laminae were moved dorsally and fixed with miniplates and screws. Six patients were relieved from headache and two improved postoperatively. Ventral decompressive surgery and fusioning frees from irritating mechanisms all nociceptively innervated tissues such as disc, dorsal ligament, facet joint capsule, nerve root and dura. On the other hand, after dorsal laminoplasty only the dura is freed from irritation or compression. Relief of headache after this surgical treatment shows that the dura, with its nociceptive nerve fibres, could be an important trigger mechanism of CeH.

Intraoperative somatosensory evoked potential findings in acute and chronic spinal canal compromise

STUDY DESIGN

Early and long-term postoperative outcome were analyzed by retrospective record review and compared with results of intraoperative somatosensory evoked potential (SEP) findings in 70 patients with chronic lumbar stenosis.

SUMMARY OF BACKGROUND DATA

Adverse SEP changes occur in up to 2% of patients during scoliosis surgery and may reverse with intraoperative intervention. Little is known about the short- or long-term results of intraoperative intervention based on adverse SEP changes in patients with chronic lumbar stenosis during lumbar decompression and fusion.

OBJECTIVE

To compare intraoperative SEP changes with immediate and long-term neurologic outcome in patients undergoing lumbar decompression, instrumentation and fusion for chronic lumbar stenosis and to determine whether the early correlation between intraoperative SEP deterioration and clinical outcome persisted.

METHODS

Monitoring SEPs using an alternating arm and leg stimulation paradigm allowed rapid identification of intraoperative changes. Retrospective record review was conducted without knowledge of intraoperative SEP findings. Clinical and SEP findings were then compared, to determine whether the strong association between intraoperative SEP results and early clinical outcome persisted.

RESULTS

Nine of 12 patients who had unilateral intraoperative SEP deterioration that resolved with intervention had no adverse sequelae; the remaining three had new ipsilateral weakness that persisted during a 9-24-month follow-up. Intraoperative SEPs deteriorated in 15% of patients with normal and abnormal baseline SEPs. Intraoperative SEP deterioration could not be predicted by preoperative radicular pain, focal symptomatology or baseline SEP findings. 80% of patients with normal SEPs but only 54% with abnormal SEPs had immediate and sustained pain relief. SEP deterioration that reversed with surgical intervention or high-dose steroids resulted in no adverse neurologic outcome.

CONCLUSIONS

Acute, unilateral, unresolved intraoperative SEP deterioration was associated with long-term ipsilateral weakness not predicted by clinical or neurologic findings before surgery. Clinical improvement persisted in 92% of patients, 4% were unchanged, and 4% had persistent neurologic changes during an average 12-month follow-up period. The findings underscore the need for monitoring SEPs during surgery in all patients undergoing invasive lumbar surgery and for rapid identification and intervention should a unilateral SEP change persist.

Motor and somatosensory evoked potentials in asymptomatic spondylotic cord compression

To assess whether electrophysiological tests are of use in differentiating between patients with asymptomatic cervical stenosis and patients with clinical evidence of myelopathy, we studied motor evoked potentials (MEPs) to magnetic brain stimulation and somatosensory evoked potentials (SEPs) in patients with asymptomatic cervical cord compression and compared the results to healthy age-matched controls. The MEPs were normal in 23 of 25 patients and SEPs in 22 of 23 patients. Thus, MEPs and SEPs are normal in most cases of asymptomatic cervical stenosis. As previous studies have shown MEPs, and to a lesser extent SEPs, to be sensitive in the detection of spondylotic myelopathy, our data indicate that MEP and SEP may be clinically useful for differentiating patients with cervical stenosis who have myelopathy from those who have not.

Modified open-door laminoplasty for treatment of neurological deficits in younger patients with congenital spinal stenosis: analysis of clinical and radiographic data

OBJECT

Multilevel anterior cervical decompressive surgery and fusion effectively treats cervical myeloradiculopathy that is caused by severe cervical spinal stenosis, but degenerative changes at adjacent vertebral levels frequently result in long-term morbidity. The authors performed a modified open-door laminoplasty procedure in which allograft bone and titanium miniplates were used to treat cervical myeloradiculopathy in younger patients with congenital canal stenosis while maintaining functional cervical motion segments. Pre- and postoperative magnetic resonance imaging and/or computerized tomography myelography were performed to assess changes in cervical spinal canal dimensions. Pre- and postoperative flexion-extension radiographs were compared to determine the residual motion of the targeted operative segments.

METHODS

Twenty younger patients (average age 37.7 years) underwent modified open-door laminoplasty for treatment of myelopathy or myeloradiculopathy related to significant cervical spinal stenosis with or without associated central or lateral disc herniation or foraminal stenosis. These surgeries were performed during a 2-year period and follow-up review remains ongoing (average follow-up period 21.6 months). Reconstructive procedures were performed on an average of 4.1 levels (range three-six). Operative time averaged 186 minutes (range 93-229 minutes). Average blood loss was 305 ml (range 100-650 ml). No cases were complicated by neurological deterioration, infection, wound breakdown, graft displacement, or hardware failure. The patients' Nurick Scale grade improved from a preoperative average of 1.8 to a postoperative average of 0.5. Pre- and postoperative sagittal spinal diameter averaged 11.2 mm (8-14 mm) and 16.6 mm (13-19 mm), respectively. The sagittal compression ratio (sagittal/lateral x 100%) increased from 48% pre- to 72% postoperatively. The spinal canal area increased an average of 55% (range 19-127%). In patients in whom pre- and postoperative flexion-extension radiographs were obtained, 72.7% residual neck motion was maintained. No patient developed increased neck or shoulder pain. Neurological symptoms improved in all patients, with total relief of myelopathy in 50% and partial improvement in 50%.

CONCLUSIONS

Modified open-door laminoplasty with allograft bone and titanium miniplates effectively treats neurological deficits in younger patients with congenital and spinal stenosis. Although long-term results are unknown, short-term results are good and there is a low incidence of complications.

The effect of Lipo prostaglandin E1 on cauda equina blood flow in patients with lumbar spinal canal stenosis: myeloscopic observation

STUDY DESIGN

Myeloscopic examination was performed to observe the cauda equina in patients with lumbar spinal canal stenosis before and after treatment with Lipo prostaglandin E1, a strong peripheral vasodilator.

OBJECTIVES

The purpose of this study was to clarify the effects of Lipo prostaglandin E1 on blood flow in the cauda equina in patients with lumbar spinal canal stenosis.

SETTING

Japan, Kagoshima

METHODS

We performed myeloscopic observations of morphological changes in blood vessels running along the cauda equina in 11 patients with lumbar spinal canal stenosis before and after treatment with Lipo prostaglandin E1.

RESULTS

In six of these patients, dilation of the running blood vessels was observed immediately after administration. In all of the patients who exhibited a dilation of vessels on the surface of the cauda equina, intermittent claudication and lower extremity pain and/or numbness lessened immediately after examination. However, none of the patients who exhibited no morphological changes in the vessels along the cauda equina after administration of Lipo prostaglandin E1 experienced any improvement of symptoms at the time of examination.

CONCLUSION

Results of this study suggest that Lipo prostaglandin E1 may enhance blood flow in the cauda equina and improve clinical symptoms in some patients with lumbar spinal stenosis.

Axial loading of the spine during CT and MR in patients with suspected lumbar spinal stenosis

PURPOSE

To evaluate the effect of compressive axial loading in imaging of the lumbar spine in patients with clinically suspected spinal stenosis.

MATERIAL AND METHODS

A total of 84 patients were examined, 50 with CT (after intrathecal contrast administration) and 34 with MR. First the dural sac cross-sectional area (CSA) was determined with the patient in the supine psoas relaxed position (PRP). Then the CSA was determined during supine axial compression in slight extension (ACE), obtained with a specially designed loading device. A measurement error study was performed.

RESULTS

A minimum difference in CSA of 15 mm2 between PRP and ACE was found to be significant. In 40/50 (80%) of CT-examined patients and in 26/34 (76%) of MR-examined patients a significant difference in CSA was found. In 25/84 (30%) of the patients there was a significant difference at more than one level.

CONCLUSION

For an adequate evaluation of the CSA, CT or MR studies should be performed with axial loading in patients who have symptoms of lumbar spinal stenosis.

Motor deficit in lumbar spinal stenosis: a retrospective study of a series of 50 patients

Severe motor weakness is an infrequent symptom in the course of lumbar stenosis. The objectives of this study are threefold: to describe the motor deficit, evaluate the prognosis factors, and determine the type of stenosis most likely to be complicated by motor loss. Fifty consecutive patients with a mean age of 65 years, operated on for a lumbar stenosis and with a severe motor deficit, have been retrospectively studied with a mean follow-up of 38 months. The overall functional result was evaluated according to the Beaujon scoring system. The motor capacity was rated from 0 (complete paralysis) to 5 (normal strength). Prognosis factors were investigated with a multivariate analysis model. Motor weakness was rated as zero 11 times, as one 8 times, as two 8 times, and as three 23 times. According to our rating scale, the overall results were considered excellent in 25 cases, good in 17 cases, and fair in the 8 remaining cases. Regression of motor weakness was complete 15 times, partial 25 times, and null 10 times. In this study, favorable prognosis parameters of motor weakness recovery were as follows: association with a discal herniation, stenosis at one level, preoperative duration of motor weakness <6 weeks, age <65, and monoradicular deficit. In contrast, severity of the initial motor weakness, association with sphincter abnormalities, presence or not of degenerative spondylolisthesis, or of a complete block on the myelogram were not influential variables.

Dynamic changes of the spinal canal in patients with cervical spondylosis at flexion and extension using magnetic resonance imaging

RATIONALE AND OBJECTIVES

The authors determine the dynamic changes of the spinal canal during flexion and extension in patients with cervical spondylosis.

METHODS

Forty-six patients were studied inside a whole-body magnetic resonance (MR) scanner with between 50 degrees of flexion and 30 degrees of extension, using a positioning device. At neutral position (0 degree) and maximum flexion and extension sagittal T2-weighted turbo spin echo sequences were acquired.

RESULTS

A significant (P < or = 0.05) increase of spinal stenosis was found at extension (48%, 22 of 46 patients) when compared with flexion (24%, 11 of 46). Cervical cord compression was diagnosed at flexion in 5 patients (11%) and at extension in 9 patients (20%). Concerning the number of patients with cervical cord compression at flexion and extension, significant differences (P < or = 0.05) were found in patients with degenerative changes at four segments compared with patients with one segment involvement.

CONCLUSIONS

Magnetic resonance imaging identified a significant percentage of increased spinal stenosis at flexion and, especially, at extension, which was not observed at neutral position (0 degree). Flexion and extension MR imaging demonstrates additional information using a noninvasive technique concerning the dynamic factors in the pathogenesis of cervical spondylotic myelopathy.

The Henderson Trust Lecture. The development of the vertebral canal and associated neuro-physiological abnormalities

In this lecture I have attempted to demonstrate that the size of the lumbar vertebral canal has clinical importance. The canal develops very early in life, and impaired growth at this time affects other growing systems. The patient with spinal stenosis has more than a spinal disadvantage. Improved obstetric and childhood care has the potential not only to prevent some of the troublesome back problems, but also to influence the health and neurological status in adult life. I hope that the first Henderson Trustees would have been encouraged by this lecture. It supports some of the philosophy that stimulated an interest in Phrenology. In the lumbar spine at least, the container-the vertebral canal-seems to have an important relationship to the function of its neurological contents.

[Functional sequelae of surgical decompression of the lumbar spine--a biomechanical study in vitro]

PURPOSE

Dorsal decompression has become accepted as the standard surgical treatment for spinal stenosis. However, no consensus has been reached to date concerning the extent of resectioning required or the ensuing functional impairment of the segment. As a result, a discussion is now underway on the necessity of employing various additional methods for instrumented stabilisation. The aim of this biomechanical in vitro study is to objectify the functional impact of various defined decompression techniques.

METHODS

With the aid of a universal spine tester, the increasing defect situations following left hemifacetectomy, bilateral hemifacetectomy, left hemilaminotomy and laminectomy of the functional spinal unit L4/5 were assessed. A three-dimensional motion analysis was performed on six human lumbar spine specimens under the loading conditions flexion/extension, left/right bending and right/left rotation.

RESULTS

The results showed an increase in both the neutral zone and the range of motion under all the loading components. No significant differences were observed in coupled motions following decompression.

CONCLUSIONS

Laminectomy leads to a distinct instability and the question arises of how much additive stability achieved by instrumented stabilization will be adequate.

Laminectomy and functional impairment of the lumbar spine: the importance of muscle forces in flexible and rigid instrumented stabilization--a biomechanical study in vitro

Laminectomy is the accepted treatment for spinal canal stenosis in cases where conservative treatment has failed. Opinions diverge on the resulting clinical instability and the necessity of instrumented stabilization. The present biomechanical study was performed to determine the functional impairment following laminectomy and the stabilizing effect of flexible and rigid devices. This was the first time that the effects of agonist and antagonist intersegmental lumbar muscle forces acting on intact, unstable and instrumentally stabilized functional spinal units have been investigated. Six human cadaveric lumbar spines were tested in a spine tester. The coactivation of agonist and antagonist muscle forces resulted in increased stability under the load conditions of bending and rotation; a slight increase in the range of motion was noted during flexion. The functional impairment following laminectomy was corrected by ligamentoplasty and by means of muscle forces. Ligamentoplasty appears to be an alternative to decompression with spondylodesis, especially in patients with well-developed muscles.

A review of basic science issues in low back pain

This review article is based on a workshop, "New Horizons in Low Back Pain" that was held in November 1995 in San Diego, California. The current article follows the 1995 workshop format of a series of three case study models. Three classical clinical profiles were presented for consideration: lumbar radiculopathy, idiopathic (degenerative disk) low back pain, and degenerative stenosis. This article summarizes the basic science perspectives that were presented and discussed on each topic.

A physiological approach to the evaluation of lumbosacral spinal stenosis

It has been demonstrated that MR imaging of the lumbosacral spine may frequently show stenosis in an asymptomatic individual. This article discusses the value of a physiologic test--dermatomal somatosensory evoked potentials--to assist in the diagnosis of true neurogenic spinal stenosis in patients with back and leg complaints and to aid in the separation of these patients from those whose symptoms are caused by degenerative spine disease with referred pain.

Spontaneous remodeling of the spinal canal after conservative management of thoracolumbar burst fractures

STUDY DESIGN

Forty-two conservatively treated patients with a burst fracture of the thoracic, thoracolumbar, or lumbar spine with more than 25% stenosis of the spinal canal were reviewed more than 1 year after injury to investigate spontaneous remodeling of the spinal canal.

OBJECTIVES

To investigate the natural development of the changes in the spinal canal after thoracolumbar burst fractures.

SUMMARY OF THE BACKGROUND DATA

Surgical removal of bony fragments from the spinal canal may restore the shape of the spinal canal after burst fractures. However, it was reported that restoration of the spinal canal does not affect the extent of neurologic recovery.

METHODS

Using computerized tomography, the authors compared the least sagittal diameter of the spinal canal at the time of injury with the least sagittal diameter at the follow-up examination.

RESULTS

Remodeling and reconstitution of the spinal canal takes place within the first 12 months after injury. The mean percentage of the sagittal diameter of the spinal canal was 50% of the normal diameter (50% stenosis) at the time of the fracture and 75% of the normal diameter (25% stenosis) at the follow-up examination. The correlation was positive between the increase in the sagittal diameter of the spinal canal and the initial percentage stenosis. There was a negative correlation between the increase in the sagittal diameter of the spinal canal and age at time of injury. Remodeling of the spinal canal was not influenced by the presence of a neurologic deficit.

CONCLUSION

Conservative management of thoracolumbar burst fractures is followed by a marked degree of spontaneous redevelopment of the deformed spinal canal. Therefore, this study provides a new argument in favor of the conservative management of thoracolumbar burst fractures.

Lumbar spine stenosis: a common cause of back and leg pain

Lumbar spine stenosis most commonly affects the middle-aged and elderly population. Entrapment of the cauda equina roots by hypertrophy of the osseous and soft tissue structures surrounding the lumbar spinal canal is often associated with incapacitating pain in the back and lower extremities, difficulty ambulating, leg paresthesias and weakness and, in severe cases, bowel or bladder disturbances. The characteristic syndrome associated with lumbar stenosis is termed neurogenic intermittent claudication. This condition must be differentiated from true claudication, which is caused by atherosclerosis of the pelvofemoral vessels. Although many conditions may be associated with lumbar canal stenosis, most cases are idiopathic. Imaging of the lumbar spine performed with computed tomography or magnetic resonance imaging often demonstrates narrowing of the lumbar canal with compression of the cauda equina nerve roots by thickened posterior vertebral elements, facet joints, marginal osteophytes or soft tissue structures such as the ligamentum flavum or herniated discs. Treatment for symptomatic lumbar stenosis is usually surgical decompression. Medical treatment alternatives, such as bed rest, pain management and physical therapy, should be reserved for use in debilitated patients or patients whose surgical risk is prohibitive as a result of concomitant medical conditions.