The natural history and the results of surgical treatment of the spinal cord disorder associated with cervical spondylosis

Anterior cervical corpectomy in patients previously managed with a laminectomy: short-term complications

BACKGROUND

The purpose of this study was to evaluate the complications of anterior cervical corpectomy and arthrodesis in patients who had had a previous cervical laminectomy. The results of previous studies have suggested that these patients can be managed with anterior decompression and an arthrodesis with either plate fixation or immobilization in a halo vest. However, no studies that we are aware of have specifically focused on the complications of these types of procedures.

METHODS

The records and radiographs of eighteen patients who had been managed with a one to four-level corpectomy with strut-grafting were retrospectively reviewed. The reviews were independently performed by the three of us who were not involved in the original operation. The interval between the laminectomy and the corpectomy ranged from one month to twenty-two years (mean, eight years).

RESULTS

Eleven of the eighteen patients sustained a total of sixteen complications during the follow-up period, which averaged 2.7 years (range, seven months to six years and four months), and nine of the eleven had graft-related complications. Five grafts extruded or collapsed, or both. There were four reoperations. Immobilization in a halo vest did not prevent extrusions, as three of the four extrusions occurred while the patient wore a halo vest. Four patients had a pseudarthrosis. In three patients, the kyphosis increased by 10 degrees or more from the immediate preoperative period to the most recent follow-up evaluation. Two patients had respiratory distress that necessitated reintubation, one patient had a small dural tear, and one had transient dysphagia.

CONCLUSIONS

Our data suggest that anterior cervical corpectomy without instrumentation in a patient who has had a previous laminectomy is associated with a great risk of graft-related complications despite the use of a halo vest. This previously unreported finding is relevant in that it contradicts the recommendation previously made by Zdeblick and the senior one of us, who advocated postoperative immobilization in a halo vest for these patients. Anterior cervical corpectomy should be performed with caution and knowledge of the potential complications in a patient who has had a previous laminectomy.

Analysis of gait in cervical myelopathy

Gait disorders are a frequent symptom of cervical spondylotic myelopathy (CSM). Twelve patients with CSM underwent gait analysis before and after decompressive surgery. They were assessed on a walkway and a treadmill and compared with a healthy matched control group. The following features were observed in the CSM group before surgery: significantly reduced gait velocity and step length (P<0. 05), prolonged double support, increased step width, and reduced ankle joint extension during treadmill walking. Knee and hip kinematics did not differ from controls. Two months after surgery, spatio-temporal parameters had moved towards normal values, velocity, step length and cadence had increased significantly, and there was reduction of step width during treadmill walking, indicating improved equilibrium. Gait analysis is an objective tool to document functional recovery after decompressive surgery in CSM.

Cervical spondylotic myelopathy: patterns of neurological deficit and recovery after anterior cervical decompression

OBJECTIVES

We evaluated the specific pattern of pre- and postoperative neurological signs and symptoms and functional results in patients with cervical spondylotic myelopathy who underwent anterior decompressive operations. Additionally, we sought to determine which findings had predictive value for surgical outcome.

METHODS

We retrospectively reviewed the records of 76 patients with cervical spondylotic myelopathy caused by osteophytic ridge or intervertebral disc herniation who underwent anterior cervical decompression and fusion performed by one surgeon. The patients were evaluated postoperatively by office visits and/or telephone interviews. Outcome was assessed by objective neurological examination and scoring with multiple functional rating scales.

RESULTS

The most common preoperative symptoms were deterioration of hand use (75%), upper extremity sensory complaints (82.9%), and gait difficulties (80.3%). In the upper extremities, preoperative weakness was most common in the hand intrinsic muscles (56.6%) and triceps (28.9%), and in the lower extremities, preoperative weakness was most common in the iliopsoas (38.8%) and quadriceps (26.3%). In the lower extremities, individual muscle groups had strength improvement rates from 79.1 to 88.1 %; somewhat higher rates, from 81.3 to 90.9%, were observed in the upper extremities. When evaluated by using the Cooper myelopathy scale, lower extremity functional improvement occurred in 46.7% of the patients and upper extremity functional improvement in 75.4%. Overall functional improvement, evaluated by using a modification of the Japanese Orthopedic Association Scale, was noted in 79.7% of the patients who had abnormal scores preoperatively.

CONCLUSION

Strength improved at rates of approximately 80 to 90% in individual muscle groups after anterior cervical decompression. However, fewer than half of all patients experienced functional improvement in the lower extremities, a discrepancy that was probably caused by persistent spasticity rather than muscle weakness. Postoperative dysfunction in the upper extremities was caused by residual weakness as well as sensory loss. Recurrent symptomatic spondylosis at unoperated levels was calculated to occur at an incidence of 2% per year.

Cervical spondylotic myelopathy: functional and radiographic long-term outcome after laminectomy and posterior fusion

OBJECTIVE

To evaluate the long-term efficacy of cervical laminectomy with posterior lateral mass fusion/fixation in the treatment of patients with cervical spondylotic myelopathy (CSM).

METHOD

Twenty-five patients treated for CSM by laminectomy and lateral mass fusion at the Division of Neurosurgery at The Ohio State University between 1989 and 1994 were studied retrospectively. Only patients with longer than 2-year postoperative follow-up durations were included. At follow-up examination, each patient completed an SF36 questionnaire, underwent a physical examination, underwent plain radiography showing the spinal curvature with plate and screw position, and underwent magnetic resonance imaging of the cervical spine, which evaluated dural sac decompression and spinal cord abnormalities. Patient-generated data were used for outcome measurements.

RESULTS

The mean follow-up duration was 47.5 months. Good outcome was defined by the presence of three criteria: ability to walk unassisted (Grade IIIA or better), ability to write unassisted, and ability to manage buttons and/or zippers unassisted. The inability to meet these criteria was defined as a poor outcome. Two patients (8%) experienced complications that resulted from the surgery. There was no instability or progression to significant kyphosis. Lesions that were hyperintense on magnetic resonance images did not correlate with outcome. Eighty percent of the patients achieved good outcomes, and 76% had improved myelopathy scores. None of the patients had late neurological deterioration. Patients with better neurological statuses at the time of surgery (Grade IIIA or better) were more likely to improve (P < 0.0001); the likelihood of a change in status for those starting with poorer grades (IIIB or worse) was not statistically significant (P < 0.08).

CONCLUSION

Cervical laminectomy with posterior fusion/fixation proved useful in the treatment of patients with CSM with straight or lordotic spines and multilevel compression. This therapy addresses the dynamic and compressive forces that are important in the pathogenesis of CSM, resulting in minimal complications and possible improvement in long-term outcomes.

Modified Gallie technique versus transarticular screw fixation in C1-C2 fusion

The effectiveness of a modified Gallie technique versus Magerl and Seeman transarticular screw fixation was compared in the management of 27 patients with symptomatic atlantoaxial instability. Twelve patients were treated using a modified Gallie technique and postoperative halo vest immobilization. Atlantoaxial arthrodesis occurred in seven (58%) patients, stable fibrous union occurred in one patient, and pseudarthrosis with recurrent instability developed in four (33%) patients. Average followup was 6.9 years. All 15 patients treated using Magerl and Seeman transarticular screw fixation and postoperative soft collar immobilization had atlantoaxial arthrodesis develop. Average duration of followup was 4 years. One patient sustained vertebral artery injury during preparation for screw placement. Magerl and Seeman transarticular screw fixation provides stability and more reliably produces atlantoaxial arthrodesis than the Gallie technique provides in patients with atlantoaxial instability without the need for rigid postoperative bracing. Potential for vertebral artery exists despite apparent accurate screw placement. To ensure that safe transarticular screw placement is possible, preoperative fine cut axial computed tomography with reconstructions is required to assess vertebral artery position and C2 isthmus anatomy. A proportion of patients have anatomy unsuitable for screw placement. Traditional wiring techniques are indicated in these patients.

Functional outcome of plate fusions for disorders of the occipitocervical junction

Twenty-eight patients with average followup of 27 months (range, 12-51 months) required occipitocervical fusion with plates. A 1992 to 1996 consecutive case series enrolled patients prospectively from two institutions. Five surgeons participated. Sixteen patients had inflammatory arthritis; four, osteogenesis imperfecta; three, tumors; three, congenital anomalies; one, pseudarthrosis after odontoid fracture; and one, osteoarthritis. Twenty-two of 28 (78.6%) patients had serious comorbid medical conditions. Additional halo immobilization of 6 weeks was used in 16 of 27 patients. Four patients required revision surgery. No patients showed a decline in neurologic status and average neurologic improvement was one Nurick grade. Two-year followup showed 13 (50%) excellent, nine (34.6%) good, two (7.7%) fair, and two (7.7%) poor outcomes based on a functional outcome scale. There were three deaths during the followup period (overall mortality rate of 10.7%). One death was attributable to airway obstruction, one death 14 months postoperatively was attributable to late Methicillin resistant Staphylococcus aureus sepsis at the bone graft donor site, and one death 41 months postoperatively was attributable to a stroke. The overall fusion rate was 85.2% (23 of 27 patients), with a 96.3% (26 of 27 patients) occipitocervical fusion rate. Three patients had a possible asymptomatic end segment pseudarthrosis with screw loosening. Twenty-two of 26 (84.6%) interviewed patients would choose the surgery again if given the choice.

Multisegmental cervical spondylotic myelopathy and radiculopathy treated by multilevel oblique corpectomies without fusion

OBJECTIVE

The description of the technique of multilevel oblique corpectomy (MOC) without fusion in the treatment of spondylotic myelopathy and radiculopathy and the analysis of the results of this technique from a series of 101 cases are presented.

METHODS

MOC is performed using an anterolateral approach with control of the vertebral artery. The vertebral bodies are drilled obliquely from the lateral side toward the opposite posterolateral corner. More than half of the vertebral bodies are preserved, and no fusion procedure is required. The series of patients from 1992 through 1997 included 54 men and 47 women, with an average age of 57.9 years, who presented with myelopathy (n = 66) or radiculopathy (n = 35). MOC was realized on one to five levels from C2-C3 to C7-T1. Follow-up data were obtained by performing dynamic roentgenography, computed tomography, and magnetic resonance imaging 2 months, 1 year, and 3 years after surgery.

RESULTS

The results (Japanese Orthopedic Association score) were improvement in 82% of the patients, worsening in 8%, and stabilization in 10%. Better results were observed in younger patients (<50 yr). No relation between results and duration of symptoms or number of levels could be established. One death occurred as a result of multiorgan failure. No late deterioration was observed; however, three patients with particular features showed delayed instability requiring fusion.

CONCLUSION

MOC is a safe and efficient technique. It must be applied for patients with anterior compression and straight or kyphotic axis of the spine. No fusion is required regardless of the number of levels, providing there are no soft discs and there is no preoperative instability.

Surgery in the degenerative cervical spine

Degenerative changes of the cervical spine include changes of the bony and discoligamentous structures that can create mechanical alterations of the anatomy. Compressive syndromes and deformation or instability represent basic indications for surgery. In the upper cervical spine, osteoarthritis of the C1-C2 facet manifests with suboccipital pain syndrome caused by generally unilateral degenerative changes of the atlantoaxial facet. Fixation and atlantoaxial fusion represent the treatment of choice. In rare instances the presence of os odontoideum is responsible for atlantoaxial instability. Narrowing of the lateral recess in the subaxial spine produces radicular symptoms. The clinical symptoms should be supported with imaging methods such as computed tomography or magnetic resonance imaging. Selective decompression produces satisfactory results. Spondylotic cervical myelopathy requires the addition of neurophysiologic investigations. Posterior decompression with laminoplasty or anterior decompression procedures with corpectomy of the involved segments represent therapeutic options with comparable results. In the presence of axial neck pain, the exact location of the painful segment challenges clinicians and radiologists. Only in cases in which the clinical findings correlate with the radiologic changes should surgical fusion be considered as a last therapeutic means to resolve the painful condition.

Four-level cervical corpectomy

STUDY DESIGN

Retrospective analysis of 31 cases of cervical spondylotic myelopathy treated by four-level subaxial cervical corpectomy.

OBJECTIVE

To determine whether extremes of anterior decompression and fusion have inordinate or unique levels of morbidity.

SUMMARY OF BACKGROUND DATA

There is a paucity of data on experience with four-level corpectomy. However, counsel against such surgery can be found.

MATERIALS AND METHODS

The records and studies of 31 consecutive cases of cervical spondylotic myelopathy, treated by four-level corpectomy, were retrospectively analyzed. Patients in 26 cases were observed longer than 2 years. No hardware was used in the procedures. External orthosis, worn for 6 months, was a Philadelphia-type collar in 25 patients and a halo vest in 6.

RESULTS

Three patients died within 3 weeks of surgery (9.7%). Delayed radiculopathy occurred in four patients after surgery, three had acute graft complications, and one had pseudomeningocele, for a morbidity rate of 25.8%. There was no infection or worsened myelopathy.

CONCLUSIONS

No unique morbidity is associated with extremes of subaxial decompression when compared with surgery of lesser extent.

Submucosal hemorrhage of the esophagus associated with endoscopy in a patient with cervical osteophytes

Submucosal hemorrhage of the esophagus is an uncommon complication of endoscopy. It has a characteristic appearance and is most likely to occur in patients with cervical osteophytes. It is important to recognize the lesion so that unnecessary biopsies are not taken and other investigations are limited.

Anterior cervical corpectomy for cervical spondylotic myelopathy

OBJECTIVE

To evaluate the efficacy of anterior surgery for the treatment of cervical spondylotic myelopathy, we have reviewed our experience with anterior cervical corpectomy (ACC) at the University of Florida, specifically analyzing neurological outcomes and complications. These results have been compared with historical control subjects receiving laminectomy or "no treatment."

METHODS

Between 1982 and 1992, 93 ACC operations were performed for the primary diagnosis of cervical spondylotic myelopathy. This consecutive series of patients was reviewed retrospectively. Age, gender, pre- and postoperative myelopathy severity, number of levels decompressed, and neurological complications were assessed. Myelopathy severity was graded using the Nurick myelopathy grading system. The average follow-up period was 39 months (range, 2-137 mo).

RESULTS

Symptomatic improvement was achieved for 92% of patients (F = 28.9, df = 2172, P < 0.001). Nurick scores reflected improvement for 86% of patients, with the conditions of 13% remaining unchanged and only one patient showing worsening. Preoperative myelopathy severity was weakly correlated with age (P < 0.05) but was not correlated with gender or number of levels decompressed. Similarly, postoperative myelopathy severity was not significantly correlated with age, gender, preoperative myelopathy severity, or number of levels decompressed. ACC-treated patients showed an average improvement of 1.24 points on the Nurick scale, compared with an improvement of 0.07 points for patients treated with laminectomy (P < 0.001) and a deterioration of 0.23 points for patients undergoing conservative treatment (P < 0.001). Complications were slightly more likely to occur in older patients (P < 0.05). The number of levels decompressed was not significantly correlated with complications. Only one permanent neurological complication was seen in this series of patients.

CONCLUSION

We conclude that ACC is a safe and effective treatment for cervical spondylotic myelopathy. In an average of 39 months, ACC showed improved results in terms of myelopathy scores, compared with historical control subjects receiving either no treatment or laminectomy. Age, gender, preoperative myelopathy severity, and extent of disease were not negative predictors of clinical outcomes.

Anterior cervical decompression and arthrodesis for the treatment of cervical spondylotic myelopathy. Two to seventeen-year follow-up

We reviewed the cases of 108 patients with cervical spondylotic myelopathy who had been managed with anterior decompression and arthrodesis at our institution. Operative treatment consisted of anterior discectomy, partial corpectomy, or subtotal corpectomy at one level or more, followed by placement of autogenous bone graft from the iliac crest or the fibula. At the latest follow-up examination, thirty-eight of the eighty-two patients who had had a preoperative gait abnormality had a normal gait, thirty-three had an improvement in gait, six had no change, four had improvement and later deterioration, and one had a worse gait abnormality. Of the eighty-seven patients who had had a preoperative motor deficit, fifty-four had complete recovery; twenty-six, partial recovery; six, no change; and one had a worse deficit. The average grade according to the system of Nurick improved from 2.4 preoperatively to 1.2 (range, 0.0 to 5.0) postoperatively. A pseudarthrosis developed in sixteen patients, thirteen of whom had had a multilevel discectomy. Only one of thirty-eight arthrodeses that had been performed with use of a fibular strut graft was followed by a non-union. An unsatisfactory outcome with respect to pain was significantly associated with pseudarthrosis (p < 0.001). The development of complications other than non-union was associated with a history of one previous operative procedure or more (p = 0.005). Recurrent myelopathy was rare, but when it occurred it was associated with a pseudarthrosis or stenosis at a new level. The strongest predictive factor for recovery from myelopathy was the severity of the myelopathy before the operative intervention--that is, better preoperative neurological function was associated with a better neurological outcome. Anterior decompression and arthrodesis with autogenous bone-grafting can be performed safely, and is associated with a high rate of neurological recovery, functional improvement, and pain relief, in patients who have cervical spondylotic myelopathy.

Spinal deformity and instability after multilevel cervical laminectomy for spondylotic myelopathy

STUDY DESIGN

A retrospective radiographic and medical record analysis of 58 patients.

OBJECTIVES

To describe the incidence and consequences of cervical spinal deformity and instability after multilevel laminectomy in adult patients with myelopathy caused by cervical spondylosis and to determine the usefulness of preoperative dynamic roentgenographic films in the prevention of postoperative destabilization.

SUMMARY OF BACKGROUND DATA

Extensive cervical laminectomy has been widely used in the treatment of progressive myelopathy secondary to stenotic conditions. Complications of this procedure, including spinal instability, accelerated spondylotic changes, postoperative spinal deformity, and constriction of the dura mater by formation of extradural scar tissue formation have been recognized. However, the frequency of these complications is probably overestimated, and their effect on clinical outcome remains unknown.

METHODS

Fifty-eight patients older than 30 years who underwent a laminectomy at more than three levels without fusion for myelopathy secondary to cervical spondylosis were reviewed retrospectively with an average follow-up of 3.6 years. Functional results were evaluated according to the Japanese Orthopaedic Association's scoring system. Lateral views in neutral position, in flexion, and in extension of the preoperative cervical roentgenograms were analyzed in comparison with the last follow-up films to identify the changes in the curvature of the cervical column, in the range of motion of the neck, and in the intervertebral angular mobility and anteroposterior displacement of the vertebral bodies and finally to quantify the incidence of spinal instability.

RESULTS

In 18 patients (31%), postoperative changes in the type of cervical spine curvature developed. Fifteen patients (25%) had destabilization at one or more levels. Deformities of the cervical spine occurring after surgery do not appear to cause symptoms or neurologic abnormalities. Destabilization required repeat surgery in 3 patients. All the levels appearing to be destabilized on the postoperative films were hypermobile on the preoperative dynamic radiographs. Preoperative olisthesis Without hypermobility is not a factor of risk in postoperative destabilization.

CONCLUSIONS

The use of preoperative dynamic radiographs should improve the selection of patients undergoing laminectomy for the treatment of multilevel cervical cord compression. Dynamic radiographs may also reinforce the need for such adjunctive procedures as fusion and instrumentation, to prevent postoperative destabilization. Preoperative olisthesis with hypermobility in sagittal or horizontal planes must be fused and instrumented.

Motor evoked potential is useful for monitoring the effect of collar therapy in cervical spondylotic myelopathy

Motor and somatosensory evoked potential changes are reported in 20 patients with cervical spondylotic myelopathy following 6 and 12 weeks of collar therapy. The age of the patients ranged between 35 and 69 years and one of them was a female. Walking difficulty was present in 18 and their leg weakness ranged between grade 2 and 4 on the 0-5 MRC (Medical Research Council) scale. Joint position sense was impaired in 14 patients. Central motor conduction time to tibialis anterior (CMCT-TA) was prolonged in 18 patients (30 sides) and tibial somatosensory conduction time was abnormal in seven patients (11 sides), which was unrecordable in four (seven sides). Nineteen patients were followed up for 6 weeks and 10 for 12 weeks of collar therapy. One Nurick's grade improvement occurred in 12 and two grades in three patients at 6 weeks. The CMCT improvement was noted in 15 patients (25 sides) which was associated with clinical improvement in 12 patients. At 3 months, further clinical improvement occurred in four patients whereas CMCT improved in six (nine sides) out of 10 patients followed up. At 6 weeks follow-up, tibial CSCT improved in 11 patients (17 sides) which correlated with improvement in sensations in seven patients. At 12 weeks further improvement in tibial CSCT was noted in two patients only (two sides). Central motor conduction time was more sensitive compared to CSCT for the evaluation of spondylotic myelopathy and the improvement was more pronounced at 6 compared to 12 weeks after collar therapy.

Motor and somatosensory evoked potentials in cervical spondylotic myelopathy

We recorded upper and lower limb MEPs and SEPs in 55 patients with clinically suggestive and myelography-documented cervical cord compression due to spondylotic changes. MEPs were abnormal in biceps brachii of 21 patients (38%), in first dorsal interosseous muscle of the hand of 49 patients (89%) and in tibialis anterior of 47 patients (85%). Overall, MEP abnormalities were present in at least one muscle of 51/55 patients (93%). Median SEPs were abnormal in 20 cases (36%), ulnar SEPs in 24 (44%) and posterior tibial SEPs in 40 (73%). Overall incidence of SEP alterations was 73% (40/55) and SEPs detected clinically silent sensory dysfunction in 10 patients (18%). Among the 43 patients who underwent surgical decompression, first dorsal interosseous (FDI) MEPs and tibial SEPs remained abnormal in most cases 1 year after surgery, independently of clinical outcome. On the other hand, serial EP studies seemed useful to confirm and monitor the clinical evolution of unoperated patients.

Cervical radiculopathy: pain, muscle weakness and sensory loss in patients with cervical radiculopathy treated with surgery, physiotherapy or cervical collar. A prospective, controlled study

This prospective, randomised study compares the efficacy of surgery, physiotherapy and cervical collar with respect to pain, motor weakness and sensory loss in 81 patients with long-lasting cervical radiculopathy corresponding to a nerve root that was significantly compressed by spondylotic encroachment, with or without an additional bulging disk, as verified by MRI or CT-myelography. Pain intensity was registered on a visual analogue scale (VAS), muscle strength was measured by a hand-held dynamometer, Vigorometer and pinchometer. Sensory loss and paraesthesia were recorded. The measurements were performed before treatment (control 1), 4 months after the start of treatment (control 2) and after a further 12 months (control 3). A healthy control group was used for comparison and to test the reliability of the muscle-strength measurements. The study found that before start of treatment the groups were uniform with respect to pain, motor weakness and sensory loss. At control 2 the surgery group reported less pain, less sensory loss and had better muscle strength, measured as the ratio of the affected side to the non-affected side, compared to the two conservative treatment groups. After a further year (control 3), there were no differences in pain intensity, sensory loss or paraesthesia between the groups. An improvement in muscle strengths, measured as the ratio of the affected to the non-affected side, was seen in the surgery group compared to the physiotherapy group in wrist extension, elbow extension, shoulder abduction and internal rotation, but there were no differences in the ratios between the collar group and the other treatment groups. With respect to absolute muscle strength of the affected sides, there were no differences at control 1. At control 2, the surgery group performed some-what better than the two other groups but at control 3 there were no differences between the groups. We conclude that pain intensity, muscle weakness and sensory loss can be expected to improve within a few months after surgery, while slow improvement with conservative treatments and recurrent symptoms in the surgery group make the 1-year results about equal.

Wire fixation techniques of the cervical facets

STUDY DESIGN

The changes in the biomechanical responses of the cervical spine altered by multilevel laminectomy to various facet wiring techniques were evaluated.

OBJECTIVE

To determine the effectiveness of various proposed techniques of cervical facet wiring used to offer rigid internal fixation after multilevel laminectomy.

METHODS

Eight human cadaveric spine segments from C2-11 underwent combined flexion-compression loading. After testing intact and three-level laminectomy (C4-C6) preparations, two techniques of facet wiring fixation were evaluated in an identical manner. Force, displacement, and kinematics data at every level of the column were obtained.

RESULTS

The mean stiffness of the intact column was significantly greater than the mean stiffness for laminectomized specimens. Individual facet wiring to the bone graft and through the spinous process below the laminectomy failed to restore stiffness to the laminectomized preparations, whereas the Luque rectangle method restored the stiffness to that found in the intact column. The increases in segmental and overall sagittal rotations resulting from multilevel laminectomy were not decreased significantly by the individual facet wiring technique, but the Luque rectangle technique demonstrated a reduction of sagittal rotations compared with laminectomy without fixation.

CONCLUSIONS

The significant increases in total column flexibility and segmental flexural rotations after multilevel laminectomy were not corrected by techniques that depend on individual facet wires secured to an overlying strut, including wiring to the inferior intact segment. Crosslinking of the facet wire fixation above and below the laminectomized segments, as exemplified by the Luque rectangle technique, restored column stiffness and reduced segmental sagittal rotations.

Pathogenesis of cervical spondylotic myelopathy

OBJECTIVE

To determine whether either of two mechanical theories predicts the topographic pattern of neuropathology in cervical spondylotic myelopathy (CSM). The compression theory states that the spinal cord is compressed between a spondylotic bar anteriorly and the ligamenta flava posteriorly. The dentate tension theory states that the spinal cord is pulled laterally by the dentate ligaments, which are tensed by an anterior spondylotic bar.

METHODS

The spinal cord cross section, at the level of a spondylotic bar, is modelled as a circular disc subject to forces applied at its circumference. These forces differ for the two theories. From the pattern of forces at the circumference the distribution of shear stresses in the interior of the disc-that is, over the transverse section of the spinal cord-is calculated. With the assumption that highly stressed areas are most subject to damage, the stress pattern predicted by each theory can be compared to the topographic neuropathology of CSM.

RESULTS

The predicted stress pattern of the dentate tension theory corresponds to the reported neuropathology, whereas the predicted stress pattern of the compression theory does not.

CONCLUSIONS

The results strongly favour the theory that CSM is caused by tensile stresses transmitted to the spinal cord from the dura via the dentate ligaments. A spondylotic bar can increase dentate tension by displacing the spinal cord dorsally, while the dural attachments of the dentate, anchored by the dural root sleeves and dural ligaments, are displaced less. The spondylotic bar may also increase dentate tension by interfering locally with dural stretch during neck flexion, the resultant increase in dural stress being transmitted to the spinal cord via the dentate ligaments. Flexion of the neck increases dural tension and should be avoided in the conservative treatment of CSM. Both anterior and posterior extradural surgical operations can diminish dentate tension, which may explain their usefulness in CSM. The generality of these results must be tempered by the simplifying assumptions required for the mathematical model.

Intraoperative control by somatosensory evoked potentials in the treatment of cervical myeloradiculopathy. Results in 210 cases

Somatosensory evoked potentials (SEPs) were used for continuous monitoring of 210 patients during anterior surgery for cervical myeloradiculopathy, to test how effectively they help avoid irreversible neurological damage during surgery. The pathologies differed in severity and were treated by diskectomy or by extended corporectomy using the Senegas technique. Intraoperative SEP changes were recorded in 84 patients (40%); in 13 (6.2%) of these, changes in SEP amplitude and latency were caused by mechanical stress. SEPs revealed transient episodes of regional ischaemia or neurophysiological anomalies during anaesthesia (mainly hypotension) in 27 patients (12.8%). The traces detected incipient and potentially dangerous mechanical pressure on, or metabolic anomalies of, the spinal cord during manipulation and placement procedures of spinal fixation devices. They were particularly sensitive indicators of ischaemia; one of the most common causes of irreversible injury. The traces of 44 patients (21.0%) improved markedly during surgery. There were no false-negatives in this series and, thanks to the fact that SEPs gave immediate warnings of incipient ischaemia to the surgical team, we had no case of irreversible medullary or nerve-root deficit.

Development of a functional scoring system for rheumatoid arthritis patients with cervical myelopathy

OBJECTIVE

To be able to measure disability objectively in rheumatoid arthritis complicated by cervical myelopathy.

METHODS

The responses to the Stanford health assessment questionnaire disability index were recorded from 250 consecutive patients (group 1) referred to our unit for spinal surgery. Using principal components analysis the questionnaire was reduced from 20 questions to 10 questions. In the second part of the study, the results of the questionnaire for those patients undergoing surgery from the original group of 250 patients were analysed with respect to outcome.

RESULTS

The reduction in the number of questions results in no significant loss of information, reliability (internal consistency Cronbach's alpha = 0.968) or sensitivity. The new scale, the myelopathy disability index, measures only one dimension (Eigen value 6.97) and may be more finely tuned to the measurement of disability in these myelopathic patients. When administered to the 194 patients undergoing cervical spine (group 2) surgery the myelopathy disability index was an accurate predictor of neurological and functional outcome, as well as survival following surgery (P < 0.0001).

CONCLUSIONS

The myelopathy disability index provides a much needed objective and reliable means of assessing disability in patients with rheumatoid involvement of the cervical spine and also in predicting outcome following surgical intervention. It also provides information for both the patient and surgeon alike, on what to realistically expect from surgery. Its adoption should facilitate comparisons between different forms of surgical intervention.

Cervical spondylotic myelopathy. Clinicopathologic study on the progression pattern and thin myelinated fibers of the lesions of seven patients examined during complete autopsy

STUDY DESIGN

This study was designed to reveal the progression pattern and essential histological findings of the lesions in the spinal cord affected by cervical spondylotic myelopathy.

OBJECTIVES

The purpose of this study was to gain new information about symptom progression and recovery in cervical spondylotic myelopathy.

SUMMARY OF BACKGROUND DATA

The characteristics of the distribution and the progression pattern of the lesions and whether demyelination and remyelination processes actually occur in cervical spondylotic myelopathy remain unclear.

METHODS

Tissues from seven patients with cervical spondylotic myelopathy were taken during autopsy and examined macroscopically and microscopically. An ultrastructural examination of spinal cord from two patients was also performed.

RESULTS

The anterior horn and intermediate zone of the gray matter in the compressed segments showed atrophy in all the cases and in one, atrophy was limited to these areas. Atrophy and myelin pallor in the lateral and posterior funiculi were observed in six patients, and the lateral funiculi of two were severely affected. Many thin myelinated fibers and denuded axons were demonstrated ultrastructurally in the damaged white matter of two patients.

CONCLUSIONS

There appears to be a common pattern of lesion progression in cervical spondylotic myelopathy: atrophy and neuronal loss in the anterior horn and intermediate zone develop first, followed by degeneration of the lateral and posterior funiculi. Eventually, marked atrophy develops throughout the entire gray matter and severe degeneration occurs in the lateral funiculus. Furthermore, the existence of thin myelinated fibers in the white matter suggests focal demyelinating and remyelinating processes occur in cervical spondylotic myelopathy.

Intraoperative improvements of somatosensory evoked potentials: correlation to clinical outcome in surgery for cervical spondylitic myelopathy

STUDY DESIGN

Retrospective review of all patients who underwent surgical treatment of cervical spondylitic myelopathy and were monitored by somatosensory evoked potentials.

OBJECTIVES

To identify the patients who had recognizable improvements in somatosensory evoked potential signals intraoperatively and to correlate the changes in somatosensory evoked potential signals to the post-operative clinical status of the patients and compare this group of patients with those that had stable intraoperative somatosensory evoked potential recordings.

SUMMARY OF BACKGROUND DATA

Somatosensory evoked potentials are commonly used in the operating room to monitor potential injury to the spinal cord or alterations in spinal cord function. It may be possible to use intraoperative somatosensory evoked potentials to detect improvement in spinal cord function during the decompression of neural structures, as evidenced by an increase in amplitude or a decrease in the latency of the wave form.

METHODS

Thirty-two patients with moderate to severe cervical spondylitic myelopathy requiring multi-level anterior decompression and fusion were monitored intraoperatively with somatosensory evoked potentials. The median and posterior tibial nerves were stimulated at the wrist and ankle, respectively. Somatosensory evoked potential recordings were obtained from cervical and scalp electrodes by the Nicolet Pathfinder electrodiagnostic system, preoperatively, intraoperatively, and postoperatively.

RESULTS

Eleven of thirty-two patients demonstrated intraoperative improvement of somatosensory evoked potential signals after decompression. All patients had rapid recovery of motor strength, bladder control, and ambulatory capacity within days of surgery. The remaining twenty-one patients had stable somatosensory evoked potential recordings. Five had rapid resolution of their symptoms, 15 improved over the course of 6 to 8 weeks, and 1 did not improve. The motor recovery of this group at 8 weeks was equal to the group of patients that showed intraoperative improvements of evoked potential signals.

CONCLUSIONS

1) Multilevel anterior cervical decompression and fusion produced a significant improvement in the motor function of patients with cervical spondylitic myelopathy. 2) Patients with intraoperative increase in amplitude or shortening of latency had a more rapid clinical improvement than patients with stable recordings. 3) Long-term reassessment did not show any difference between patients with intraoperative somatosensory evoked potential improvement and those with stable somatosensory evoked potential recordings. Therefore, somatosensory evoked potential improvements cannot be used to determine prognosis at the present time. 4) A greater number of patients should be studied using more objective methods for quantifying gait patterns and motor function.

On the pathogenesis of the radiculopathy complicating multilevel corpectomy

Postoperative fifth cervical radiculopathy has been described after cervical corpectomy. One explanation for this complication is thought to be the factor of traction on cervical roots caused by a shifting of the spinal cord consequent to decompression. This theory is supported by our experience with 176 patients undergoing corpectomies for whom a lesser width of decompression all but eliminated the complication.

Anterior decompressive microsurgery and osteosynthesis for the treatment of multi-segmental cervical spondylosis. Pathophysiological considerations, surgical indication, results and complications: a survey

Surgical treatment of cervical myelopathy due to multi-segmental cervical spondylosis (MSCS) is currently performed by either anterior or posterior approaches. Considering the complex nature of the underlying disease involving more than one cervical segment, as well as the patho-biomechanical features of the spondylotic cervical spine, adequate decompression of the spinal cord and correction of hypermobility should be achieved by surgery in one stage, in order to achieve positive immediate and long-term benefit for the patient suffering from progressive myelopathy. Recently, anterior decompressive surgery, consisting of single or multi-level vertebrectomy, microsurgical epidural decompression and osteo-synthesis has emerged as an aggressive therapeutic approach for the treatment of MSCS. Based on the experience of a series of 92 patients with progressive cervical myelopathy due to MSCS operated on using the above described combined techniques, as well as the results from a limited number of clinical studies of anterior decompressive surgery in MSCS patients from the literature, the pathophysiological considerations, surgical indications, surgical technique as well as clinical results and complications of anterior surgery in patients with MSCS are reviewed and discussed.

Experimental chronic compressive cervical myelopathy: effects of decompression

Twelve dogs developed a delayed onset of neurological abnormalities from chronic cervical cord compression that was characteristic of myelopathy. The animals were divided into two groups and matched according to degree of neurological deficit. Six animals underwent decompression through removal of the anteriorly placed compressive device. Throughout the experiment, serial neurological examinations and somatosensory evoked potential studies were performed on each animal. Spinal cord blood flow measurements were obtained during each surgical procedure and at sacrifice. Magnetic resonance images were obtained after compression and before sacrifice. All animals in the decompressed group showed significant neurological improvement after decompression; no spontaneous improvement in neurological function was seen in the compressed group. On pathological examination, irreversible changes including large motor neuron loss, necrosis, and cavitation were seen in four of the animals in the decompressed group and five in the compressed group. Cervical spondylotic myelopathy in humans is known to respond to decompression; this study provides further evidence that this animal model for chronic compressive cervical myelopathy accurately reflects the disease process seen in humans.

Management of cervical spondylotic myelopathy and radiculopathy

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The treatment of spondylotic cervical myelopathy by ventral discectomy. Long term results on 121 patients

The pathophysiology of spondylotic cervical myelopathy is still a matter of discussion. This paper presents a series of 126 patients operated on using a ventral approach. In 47% of the patients only a spondylotic narrowing of the spinal canal was present and in 35% an additional disc herniation was found. In 13% of the cases however a soft disc without spondylotic spures was found and in 5% a dislocation of vertebral bodies. We found a marked male preponderance of 77%, mean age was 51.6 years, ranging from 25-50 years. Most patients were operated on at the levels of C4/5 and C5/6. Observation time covered a period of 3-10 years. The outcome was rated relatively to the preoperative degree of disablement using a questionnaire for the patients and their family doctors. We found a marked difference in the answers, especially in rating deterioration, which was stated by patients in 34%, by physicians only in 12%. Another finding was the time-related outcome. We found best results with 75% improvement and 5% deterioration between 3-6 months postoperatively, with increasing time the results decreased to 33% improvement, 33% identical statys and in 33% a deterioration related to the preoperative status must be noted.

Experimental chronic compressive cervical myelopathy

A canine model simulating both cervical spondylosis and its results in delayed progressive myelopathy is presented. This model allowed control of compression, an ongoing assessment of neurological deficits, and evaluation using diagnostic images, frequent electrophysiological tests, local blood flow measurements, and postmortem histological examinations. Subclinical cervical cord compression was achieved in 14 dogs by placing a Teflon washer posteriorly and a Teflon screw anteriorly, producing an average of 29% stenosis of the spinal canal. Four dogs undergoing sham operations were designated as controls. Twelve of the animals undergoing compression developed delayed and progressive clinical signs of myelopathy, with a mean latent period to onset of myelopathy of 7 months. Spinal cord blood flow studies using the hydrogen clearance method showed a significant transient increase in blood flow immediately after compression and a decrease before sacrifice. Somatosensory evoked potential studies indicated progressive deterioration during the period of compression. Magnetic resonance images revealed intramedullary changes. Histological studies showed abnormalities overwhelmingly within the gray matter, including changes in vascular morphology, loss of large motor neurons, necrosis, and cavitation. Axonal degeneration and obvious demyelination were rarely seen. The most profound morphological changes occurred at the site of greatest compression. It is proposed that a momentary arrest of microcirculation occurs during extension of the neck because of loss of the reserve space in the compromised spinal canal. This microcirculatory disturbance is predominant in the watershed area of the cord and mainly affects the highly vulnerable anterior horn cells, leading to neuronal death, necrosis, and eventual cavitation at the junction of the dorsal and anterior horns. Additional supportive evidence of this hypothesis was derived from the literature.

Spinal tumors: Experience at King Khalid University Hospital

This paper summarizes data on 30 consecutive spinal tumors treated at King Khalid University Hospital (KKUH) between 1984-1991. The male:female ratio was 2.75:1. Thirty percent of cases were less than 20 years of age while 71% were more than 60 years of age. The brain to spinal cord tumor ratio in our unit was 12.3:1. The ratio of Schwannoma to meningioma was 1.6:1. Metastatic carcinoma accounted for a mere 13% of cases and only 35% of tumors were located in the thoracic spine. Intramedullary tumors accounted for 17% of cases. An overall 63% of cases improved postoperatively while 37% remained unchanged.

The contribution of magnetic stimulation of the motor cortex to the diagnosis of cervical spondylotic myelopathy. Correlation of central motor conduction to distal and proximal upper limb muscles with clinical and MRI findings

Magnetic stimulation of the motor cortex and cervical spine was performed on 24 patients with cervical spondylotic myelopathy documented by MRI. Compound motor action potentials (CMAPs) were recorded from the biceps and thenar muscles to study the central motor pathways of two different myotomes, C5-C6 and C8-D1. Central motor conduction was abnormal in all 24 patients for thenar muscles and in 5 patients for biceps brachii. In patients with a single compression level, central motor conduction abnormalities were confined to the myotomes caudal to the site of compression documented by MRI, in both proximal and distal upper limb muscles in the patients with upper spondylotic compression, and in distal muscles only in the patients with lower compression. In the patients with multilevel compression, central motor conduction time was abnormal for thenar muscles and always normal for the biceps muscle, but its mean value was significantly greater than in the control subjects, suggesting a slight involvement of central motor pathways for proximal upper limb muscles and major damage of the lower cervical segments. Owing to their high degree of sensitivity, central motor conduction studies may be of considerable value in the functional assessment of central motor pathways in cervical spondylotic myelopathy.

Central corpectomy for cervical spondylotic myelopathy: a consecutive series with long-term follow-up evaluation

Since 1984, a consecutive series of patients with cervical spondylotic myelopathy has been treated by central corpectomy and strut grafting. This report focuses on 40 cases operated on between 1984 and 1987 and followed from 2 to 5 years. The perioperative complication rate was 47.5%, with a 7.5% incidence of persistent sequelae: severe C-5 radiculopathy in one patient, swallowing dysfunction in one, and hypoglossal nerve palsy in one. No single factor (age, duration of symptoms, or severity of myelopathy) was absolutely predictive of outcome; however, syndromes of short duration had the best likelihood of cure. Similar outcomes were associated, individually, with long duration of symptoms, age over 70 years, and severe myelopathy. After factoring a 5% regression of improvement, the long-term cure rate was 57.5% and the failure rate was 15%. Myelopathy worsening was not documented.

The treatment of spondylotic cervical myelopathy by multiple subtotal vertebrectomy and fusion

The authors report their experience in the treatment of cervical spondylotic myelopathy by multiple subtotal vertebrectomy and fusion. There were 27 cases with a mean age of 66.9 years. The clinical assessment was carried out using both the Nurick and the Japanese Orthopaedic Association (JOA) grading pre- and post-operatively at 6 months. The post-operative radiological assessment was done at 3 and 6 months. Two cases died from unrelated medical problems. There were three cases of graft dislodgement. Clinical improvement was detected in 80% of cases using the Nurick grading and in 88% of cases using the JOA scoring. No cases deteriorated neurologically after operation. Bony fusion was achieved in 96% of the surviving cases by 6 months. Multiple subtotal vertebrectomy and fusion is therefore an effective method for the treatment of cervical spondylotic myelopathy.

Anterolateral uncoforaminotomy for cervical spondylotic myeloradiculopathy

Thirty-five patients with cervical spondylotic radiculopathy and myeloradiculopathy had anterolateral uncoforaminotomy. Spondylotic spurs associated with radiculopathy were continuous from the uncovertebral joint to the posterior ridge of the vertebral body in 33 patients and to the posteriorly bulging disc with posterolateral bony spurs in 2 patients. Anterolateral uncoforaminotomy was found safe to remove the continuous type of spur, resulting in decompression of the cord-root complex, which shifted anteriorly after surgery. The outcome was satisfactory in 19 of 20 radiculopathy patients, and in all 15 myeloradiculopathy patients. Decompression of the cord-root complex is the most important factor in relieving neurologic manifestations of cervical spondylosis.

Clinical long-term results of anterior discectomy without fusion for treatment of cervical radiculopathy and myelopathy. A follow-up of 164 cases

Between 1976 and 1983, 251 patients underwent surgery for the treatment of cervical degenerative disc disease. Anterior microsurgical discectomy at one or more cervical segments without interbody fusion was performed in each case. 109 patients with radiculopathy and 55 patients with myelopathy were followed up clinically 1 to 8 years postoperatively. A soft disc lesion was found in 72, a hard disc lesion in 92 patients. Of all radicular symptoms and signs, brachialgia and motor deficits of the upper extremities showed the highest improvement rates. The medullary complaints were improved in 80%, the progression of the disease was arrested in 93% of myelopathic cases. An excellent or good long-term result was achieved in 82% of patients with radiculopathy and 55% of those with myelopathy. The outcome was best in cases with soft disc lesions, with monosegmental disease, in individuals under 50 years of age, and in patients with a sudden onset and a short duration of symptoms. These results are comparable with those obtained by other surgical methods.

Syringomyelia after decompressive laminectomy for cervical spondylosis

We describe a case of cervical spondylotic myelopathy in which deterioration occurred a month after decompressive laminectomy. Syringomyelia was then in evidence as seen by myelography and delayed metrizamide computed tomography scanning. The etiology of this finding and its possible relation to the course and treatment of cervical spondylotic myelopathy are discussed.

Tandem lumbar and cervical spinal stenosis. Natural history, prognostic indices, and results after surgical decompression

Spondylotic degeneration can give rise to concurrent stenosis of the lumbar and cervical portions of the spinal canal in tandem. Symptomatic tandem spinal stenosis (TSS) is characterized by the triad of intermittent neurogenic claudication, progressive gait disturbance, and findings of mixed myelopathy and polyradiculopathy in both the upper and lower extremities. Nineteen patients with clinically symptomatic and myelographically proven disease were studied retrospectively. Surgical intervention was directed at decompression of the stenotic lesions in both the cervical and lumbar regions. The most symptomatic level was usually treated first. After a mean follow-up period of 22 months, an excellent outcome was obtained in five patients (26%), four improved (21%), five deteriorated despite initial improvement (26%), and one was unchanged. Three patients could not be traced for follow-up review, and there was one postoperative death. Postoperative improvement correlated inversely with symptom duration. Sphincter disturbance, radiculopathy, myelography, cerebrospinal fluid analysis, and electrophysiological data were not prognostically significant. The presentation of TSS mimics amyotrophic lateral sclerosis and other forms of motor-neuron disease. In contrast to these conditions, however, TSS is amenable to treatment. Operative sequence and technique could not be related to outcome. Functional recovery in TSS depends on early diagnosis and timely surgical intervention.

Cervical spondylotic myelopathy and radiculopathy

A review of the extensive literature on cervical spondylotic myelopathy and radiculopathy shows that the clinical picture and pathology are well defined, and the complex pathogenetic mechanisms are better understood. With recent advances in investigative procedures: computed tomography, magnetic resonance imaging and somatosensory evoked potentials, the diagnosis can be more accurate and the assessment more complete. Careful selection of patients for the appropriate treatment modality (conservative, anterior or posterior surgery) is crucial to the success in management.

Surgical and conservative treatment of cervical spondylotic radiculopathy and myelopathy

One hundred and fourteen patients were admitted to our department for evaluation of their cervical spondylogenetic symptoms, including local cervical pain, radiculopathy and myelopathy. This retrospective study gives the results, expressed as improved, unchanged or worse, of anterior surgery, posterior surgery and conservative treatment. Local cervical pain improved in about half of the patients, without any difference between the groups. The effect of surgery on radiculopathy was superior to that of conservative treatment, 71 percent and 74 percent respectively, being improved after anterior and posterior surgery, compared to 19 percent in the conservatively treated group. The majority of patients with myelopathy were treated with posterior surgery and 69 percent had improved. The results were not influenced by the patients age or the duration of symptoms. It is argued that the positive effects of surgery on the radiculopathy are due to a segmental stabilisation rather then to decompression. The immediate post-operative improvement of the myelopathy is undoubtedly caused by the decompression while the long-termed improvement cannot with certainty be attributed to the operation.

Cervical disc prolapse in the elderly: an easily overlooked, reversible cause of spinal cord compression

It is important to distinguish cord compression due to cervical disc prolapse, which has a very favourable prognosis following surgery, from that due to cervical spondylosis. In the elderly the occurrence of cervical disc prolapse as a cause of spinal compression may be under-recognised because symptoms are too readily attributed to long standing degenerative changes on plain cervical X-rays. The difficulty of making an accurate diagnosis is complicated further in the elderly by the prevalence of other diseases which may mask the symptoms of cord compression. We report our experience with 19 patients over 60 who underwent anterior cervical discectomy for myelopathy due to intervertebral disc prolapse. There was generally a short history of walking difficulty, but the presence of 'numb clumsy hands', perhaps due to selective posterior column impairment, was often a more disabling complaint. Neck pain and disturbances of micturition were unusual. The prognosis after disc excision can be excellent. In this series all the severely disabled patients returned to an independent existence. Overall 16/19 patients made an excellent or good recovery.

Prolapse of a cervical disc in elderly patients with cervical spondylosis

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