Decompression For Cervical Spondylotic Myelopathy Research Articles

Indication for hypertrophy posterior longitudinal ligament removal in anterior decompression for cervical spondylotic myelopathy.

The retrospective study aimed to investigate the indication for hypertrophy posterior longitudinal ligament (HPLL) removal in anterior decompression for cervical spondylotic myelopathy (CSM). A total of 138 consecutive patients with CSM were divided into 2 groups with developmental cervical stenosis (DCS) (group S) and non-DCS (group N), according to the Pavlov ratio. These 2 groups were subdivided into 2 further subgroups, according to whether HPLL was removed or preserved: group SR (49 patients) and group SP (32 patients) in group S, group NR (21 patients) and group NP (36 patients) in group N. The modified Japanese Orthopedic Association score (mJOA), the modified recovery rate (mRR), quality of life (QoL), and relevant clinical data were used for clinical and radiological evaluation. The mJOA scores improved from 7.3 ± 2.2 to 15.0 ± 1.8 in the SR group and from 7.9 ± 2.3 to 14.2 ± 1.5 in the SP group (P = .036), with postoperative QoL significantly higher in the SR group than the SP group. A reduction in the diameter of enlarged spinal canals occurred at a significantly faster rate in the SP group compared with the SR group (P = .002). Multivariate regression analyses showed removal of HPLL correlated with mJOA scores (coefficient = 7.337, P = .002), mRR (%) (coefficient = 9.117, P = .005), PCS (coefficient = 12.129, P < .001), and MCS (coefficient = 14.31, P < .001) in the S group at 24 months postoperatively, while removal of HPLL did not correlate with clinical outcomes in the N group. The HPLL should, therefore, be removed when mobility was reduced and the spinal cord remained compressed after anterior decompression procedures in the patients with DCS. However, in non-DCS patients, it remains unclear as to whether removal of HPLL provides any clinical benefit, thus, HPLL removal may not be necessary.

Efficacy of Diffusion Tensor Imaging Indices in Assessing Postoperative Neural Recovery in Cervical Spondylotic Myelopathy.

Prospective observational cohort study. The aim of this study was to analyze the efficacy of diffusion tensor imaging (DTI) anisotropy indices in predicting the postoperative recovery in cervical spondylotic myelopathy (CSM) patients and to describe postoperative changes in the DTI indices based on neurological recovery after surgery. Surgical results of CSM are unpredictable and cannot be estimated based on preoperative MRI. DTI indices were found to have good sensitivity to detect changes in CSM, but their efficacy in predicting postoperative recovery and postoperative changes in DTI indices has not been studied before. Thirty-five patients who underwent surgical decompression for cervical spondylotic myelopathy underwent DTI evaluation preoperatively and postoperatively at 12 months. DTI indices-fractional anisotropy, apparent diffusion coefficient (ADC), relative anisotropy, volume ratio, and eigen vectors (E1, E2, and E3)-were obtained and clinical evaluations were made preoperatively and 12 months postoperatively. Twenty-six patients were available for final follow-up at 12 months. Twenty patients showed improvement by at least 1 Nurick grade, five maintained the preoperative Nurick grade status and one patient was noted to have deterioration by 1 grade. The preoperative DTI values could not predict neurological recovery patterns postoperatively. Although conventional MRI showed adequate decompression in all patients irrespective of the clinical outcome, DTI indices showed variable results. There were significant improvements in postoperative DTI indices for ADC (P = 0.002), E1 (P < 0.001), and E2 (P = 0.012) values in patients who showed neurological recovery at 12 months. Postoperative DTI indices for coefficients ADC, E1, and E2 in neurologically static/worsened individuals remained unchanged or insignificant (P = 0.05) CONCLUSION.: The DTI indices were sensitive enough to indicate postoperative neurological recovery observed following surgery. Preoperative DTI evaluation could not predict postoperative recovery for patients with cervical spondylotic myelopathy. 4.

Magnetic Resonance Imaging Biomarker of Axon Loss Reflects Cervical Spondylotic Myelopathy Severity.

A prospective cohort study. In this study, we employed diffusion basis spectrum imaging (DBSI) to quantitatively assess axon/myelin injury, cellular inflammation, and axonal loss of cervical spondylotic myelopathy (CSM) spinal cords. A major shortcoming in the management of CSM is the lack of an effective diagnostic approach to stratify treatments and to predict outcomes. No current clinical diagnostic imaging approach is capable of accurately reflecting underlying spinal cord pathologies. Seven patients with mild (mJOA ≥15), five patients with moderate (14≥mJOA ≥11), and two patients with severe (mJOA <11) CSM were prospectively enrolled. Given the low number of severe patients, moderate and severe patients were combined for comparison with seven age-matched controls and statistical analysis. We employed the newly developed DBSI to quantitatively measure axon and myelin injury, cellular inflammation, and axonal loss. Median DBSI-inflammation volume is similar in control (266 μL) and mild CSM (171 μL) subjects, with a significant overlap of the middle 50% of observations (quartile 3 - quartile 1). This was in contrast to moderate CSM subjects that had higher DBSI-inflammation volumes (382 μL; P = 0.033). DBSI-axon volume shows a strong correlation with clinical measures (r = 0.79 and 0.87, P = 1.9 x 10-5 and 2 x 10-4 for mJOA and MDI, respectively). In addition to axon and myelin injury, our findings suggest that both inflammation and axon loss contribute to neurological impairment. Most strikingly, DBSI-derived axon volume declines as severity of impairment increases. DBSI-quantified axonal loss may be an imaging biomarker to predict functional recovery following decompression in CSM. Our results demonstrate an increase of about 60% in the odds of impairment relative to the control for each decrease of 100 μL in axon volume. 3.

Clinical outcome of anterior vs posterior approach for cervical spondylotic myelopathy

ObjectiveThe aim is to demonstrate whether there is clinical difference between posterior vs anterior decompression in cervical spondylotic myelopathy. MethodsForty-two patient database was obtained from the Centro Medico Nacional de Occidente in Mexico, those who underwent surgical treatment for cervical myelopathy with a mean 1.4 year follow-up. ResultsPatients were divided; group A (45%) anterior approach and group B (55%) posterior approach, for mJOA, group A had a lower score compare with group B. While in the Nurick score group B got a higher score compare with group A. ConclusionsPosterior decompression resulted in better functional outcomes (p<0.05).

Riluzole Attenuates the Decompression-Induced Ischemia Reperfusion Injury and Enhances the Beneficial Impact of Decompression in Cervical Spondylotic Myelopathy

Riluzole Attenuates the Decompression-Induced Ischemia Reperfusion Injury and Enhances the Beneficial Impact of Decompression in Cervical Spondylotic Myelopathy

A Global Perspective on the Outcomes of Surgical Decompression in Patients With Cervical Spondylotic Myelopathy

Prospective, multicenter international cohort. To evaluate outcomes of surgical decompression for cervical spondylotic myelopathy (CSM) at a global level. CSM is a degenerative spine disease and the most common cause of spinal cord dysfunction worldwide. Surgery is increasingly recommended as the preferred treatment strategy for CSM to improve neurological and functional status and quality of life. The outcomes of surgical intervention for CSM have never been evaluated at an international level. Between October 2007 and January 2011, 479 symptomatic patients with image evidence of CSM were enrolled in the prospective, multicenter AOSpine CSM-International study from 16 global sites. Preoperative and postoperative clinical status, functional impairment, and quality of life were evaluated using the modified Japanese Orthopaedic Assessment Scale, Nurick Scale, Neck Disability Index, and Short-Form-36v2. Preoperative and 12- and 24-month postoperative outcomes were compared using mixed-model analysis of covariance for repeated measurements. The study cohort consisted of 310 males and 169 females, with a mean age of 56.37 ± 11.91 years. There were significant differences in age, etiology, and surgical approaches between the regions. At 24 months postoperatively, the mean modified Japanese Orthopaedic Assessment Scale score improved from 12.50 (95% confidence interval [CI], 12.24-12.76) to 14.90 (95% CI, 14.64-15.16); the Neck Disability Index improved from 36.38 (95% CI, 34.33-38.43) to 23.20 (95% CI, 21.24-25.15); and the SF36v2 Physical Component Score and Mental Composite Score improved from 34.28 (95% CI, 33.46-35.10) to 40.76 (95% CI, 39.71-41.81) and 39.45 (95% CI, 38.25-40.64) to 46.24 (95% CI, 44.94-47.55), respectively. The rate of neurological complications was 3.13%. Surgical decompression for CSM is safe and results in improved functional status and quality of life in patients around the world, irrespective of differences in medical systems and sociocultural determinants of health. 3.

Benefit of degenerative posterior longitudinal ligament removal during anterior decompression in cervical spondylotic myelopathy.

It remains controversial whether degenerative posterior longitudinal ligaments should be removed during anterior decompression procedures for cervical spondylotic myelopathy. Few data are available from studies that have compared removing and retaining the degenerative posterior longitudinal ligament. The goal of this retrospective study was to evaluate the benefit of degenerative posterior longitudinal ligament removal during such operations. Clinical data on 130 patients with confirmed degenerative posterior longitudinal ligament who underwent anterior cervical decompression surgery were retrospectively reviewed. All procedures were performed by the same senior orthopedic surgeon at the authors' spinal surgery center. The degenerative posterior longitudinal ligament was removed in 62 patients (group A) and retained in 68 patients (group B). The 130 patients were followed for 36 months. The Japanese Orthopedic Association score improved from 9.0±2.7 to 14.7±1.5 in group A and from 9.4±2.6 to 14.1±1.7 in group B (P=.028). The recovery rate for spinal cord neurologic function was 66.7% in group A and 61.3% in group B (P=.031). Operating time was longer (P=.002) and the sagittal median diameter of the vertebral canal was enhanced in group A (P<.001). Narrowing of previously enlarged canals occurred at a significantly higher rate in group B (P=.044). No significant difference was found in the rates of common complications between groups. Removal of the degenerative posterior longitudinal ligament in anterior decompression procedures for cervical spondylotic myelopathy appeared to be beneficial and provided more complete decompression and better postoperative outcomes than surgery without removal of the ligament. Although this procedure was generally safe, it required longer operating times, was more technically challenging, and required more experienced surgeons than surgery without removal of the ligament.

Cortical Reorganization Is Associated with Surgical Decompression of Cervical Spondylotic Myelopathy.

Background. Cervical spondylotic myelopathy (CSM) results in sensorimotor limb deficits, bladder, and bowel dysfunction, but mechanisms underlying motor plasticity changes before and after surgery are unclear. Methods. We studied 24 patients who underwent decompression surgery and 15 healthy controls. Patients with mixed upper and lower limb dysfunction (Group A) and only lower limb dysfunction (Group B) were then analysed separately. Results. The sum amplitude of motor evoked potentials sMEP (p < 0.01) and number of focal points where MEPs were elicited (N) (p < 0.001) were significantly larger in CSM patients compared with controls. For Group A (16 patients), sMEP (p < 0.01) and N (p < 0.001) showed similar findings. However, for Group B (8 patients), only N (p = 0.03) was significantly larger in patients than controls. Group A had significantly increased grip strength (p = 0.02) and reduced sMEP (p = 0.001) and N (p = 0.003) after surgery. Changes in sMEP (cMEP) significantly correlated inversely with improved feeding (p = 0.03) and stacking (p = 0.04) times as was the change in number of focal points (NDiff) with improved writing times (p = 0.03). Group B did not show significant reduction in sMEP or N after surgery, or significant correlation of cMEP or NDiff with all hand function tests. No significant differences in H reflex parameters obtained from the flexor carpi radialis, or central motor conduction time changes, were noted after surgery. Discussion. Compensatory expansion of motor cortical representation occurs largely at cortical rather than spinal levels, with a tendency to normalization after surgery. These mirrored improvements in relevant tasks requiring utilization of intrinsic hand muscles.

Transcranial magnetic stimulation of the motor cortex correlates with objective clinical measures in patients with cervical spondylotic myelopathy.

Prospective cohort study. To assess the correlation between central motor conduction time (CMCT) and various subjective and objective clinical assessment measures in patients undergoing decompressive surgery for cervical spondylotic myelopathy (CSM). CSM can cause a spectrum of neurological deficits among individuals. Subjective clinical assessments of disease severity may lack the sensitivity of objective tests. Transcranial magnetic stimulation provides objective electrophysiological data on the integrity of the corticospinal tracts, which may be useful for monitoring disease progression or neurological improvement after surgery. Patients undergoing surgical decompression for CSM underwent subjective and objective testing before surgery and at 1, 3, 6, and 12 months after surgery. Subjective measures included modified Japanese Orthopaedic Association score, Neck Disability Index, Nurick grade, and visual analogue scale score. Objective measures included CMCT as measured using transcranial magnetic stimulation, the 10-m walk test, the 9-hole peg task, and the grip and release test. Primary outcome was the correlation between CMCT and subjective or objective measures at preoperative and postoperative time points. Secondary outcome was the correlation between preoperative CMCT and performance in subjective or objective testing after surgical intervention. Improvement in both subjective and objective measures was observed after surgery. CMCT correlated with other objective measures (10-m walk test, 9-hole peg task, and grip and release test) both at baseline and after decompressive surgery in these 17 patients with CSM. Patients with high baseline CMCTs were associated with poor performance on the 10-m walk test, 9-hole peg task, and grip and release test. Modified Japanese Orthopaedic Association score correlated with CMCT at baseline but not after surgical intervention. CMCT was not associated with other subjective measures, such as Neck Disability Index, Nurick grade, and visual analogue scale score, at preoperative or postoperative time points. CMCT as measured by transcranial magnetic stimulation is a responsive objective assessment of CSM. It can be used to monitor disease severity and neurological function before and after surgical intervention. Prolonged baseline CMCT may be associated with worse surgical outcomes. 2.

Mild diabetes is not a contraindication for surgical decompression in cervical spondylotic myelopathy: results of the AOSpine North America multicenter prospective study (CSM)

Background contextCervical spondylotic myelopathy (CSM) is a chronic spinal cord disease and can lead to progressive or stepwise neurologic decline. Several factors may influence this process, including extent of spinal cord compression, duration of symptoms, and medical comorbidities. Diabetes is a systemic disease that can impact multiple organ systems, including the central and peripheral nervous systems. There has been little information regarding the effect of diabetes on patients with coexistent CSM. PurposeTo provide empirical data regarding the effect of diabetes on treatment outcomes in patients who underwent surgical decompression for coexistent CSM. Study design/settingLarge prospective multicenter cohort study of patients with and without diabetes who underwent decompressive surgery for CSM. Patient sampleTwo hundred thirty-six patients without and 42 patients with diabetes were enrolled. Of these, 37 were mild cases and five were moderate cases. Four required insulin. There were no severe cases associated with end-organ damage. Outcome measuresSelf-report measures include Neck Disability Index and version 2 of 36-Item Short Form Health Survey (SF-36v2), and functional measures include modified Japanese Orthopedic Association (mJOA) score and Nurick grade. MethodsWe compared presurgery symptoms and treatment outcomes between patients with and without diabetes using univariate and multivariate models, adjusting for demographics and comorbidities. ResultsDiabetic patients were older, less likely to smoke, and more likely to be on social security disability insurance. Patients with diabetes presented with a worse Nurick grade, but there were no differences in mJOA and SF-36v2 at presentation. Overall, there was a significant improvement in all outcome parameters at 12 and 24 months. There was no difference in the level of improvement between the patients with and without diabetes, except in the SF-36v2 Physical Functioning, in which diabetic patients experienced significantly less improvement. There were no differences in surgical complication rates between diabetic patients and nondiabetic patients. ConclusionsExcept for a worse Nurick grade, diabetes does not seem to affect severity of symptoms at presentation for surgery. More importantly, with the exception of the SF-36v2 Physical Functioning scores, outcomes of surgical treatment are similar in patients with diabetes and without diabetes. Surgical decompression is effective and should be offered to patients with diabetes who have symptomatic CSM and are appropriate surgical candidates.

Surgical Management of C5 Palsy Resulting from Posterior Spinal Decompression for the Treatment of Cervical Spondylotic Myelopathy

Objective: To assess the feasibility of anterior cervical procedures in the treatment of C5 palsy occurring after posterior cervical decompression procedures done for the treatment of cervical spondylotic myelopathy. Introduction: In this study we hypothesized that anterior cervical decompression would benefit these patients through widening the cervical foramen, directly by rongeurs and drills and indirectly by placing an intervertebral spacer (cervical cage). The aim of the study is to assess whether a more proactive approach would benefit these patients. Materials and methods: Between January 2005 and September 2011, 200 posterior cervical procedures have been done by the authors, for the treatment of cervical spondylotic myelopathy (CSM). The procedures done were laminectomy with or without instrumentation. Forty cases developed C5 palsy postoperatively (20%). 20 cases (50%) presented immediate postoperatively and the rest presented during the first week postoperatively. All the cases started a course of conservative treatment of steroids, analgesics and physiotherapy. Thirty patients (75%) improved on conservative treatment. Ten patients did not improve after more than one year of conservative management. Two cases had a single level anterior cervical discectomy and cage fusion (ACDF), 3 cases had single level ACDF with plate fixation and 3 cases had 2 levels ACDF with plate fixation. Two cases had 3 levels ACDF with interbody fusion and plate fixation. The operative choice was made in order to increase the lordotic curve and the foraminal diameter. Results: Immediately postoperatively all patients had improved radicular pain. Assessment of the motor power was made immediately postoperative and 3 months afterwards with continuous physiotherapy. There was no change in the C5 palsy in all cases on the immediate postoperative examination, whereas all cases showed improvement of at least 2 grades in the 3 months postoperative visits. All patients at the final follow up had an MMT (Manual Muscle Test) grade of at least 3. Six patients reached an MMT grade of 4 or more. One case had recurrent myelopathy 9 months after 3 levels ACDF and fixation. His MRI showed adjacent segment degeneration at a higher level and had led to myelopathy. He improved on conservative treatment. Two cases died during follow up period: one at 10 months postoperatively from complications of massive myocardial infarction and the other one 15 months postoperatively from bronchogenic carcinoma diagnosed 7 months after surgery. Conclusion: Postoperative C5 palsy following posterior decompression for cervical spondylotic myelopathy is not an uncommon occurrence and the majority of cases will respond to conservative treatment. Anterior decompression procedures may offer a safe and effective solution for those few patients who do not respond to a prolonged period of conservative management.

Comparison between anterior and posterior decompression for cervical spondylotic myelopathy: subjective evaluation and cost analysis

To compare anterior and posterior approaches for treating cervical spondylotic myelopathy (CSM) involving more than two levels, especially in regard to quality of life and cost effectiveness. The authors studied 116 CSM patients who underwent decompressive surgery by either an anterior or a posterior approach with instrumentation. In the anterior group, 1-3 levels subtotal vertebrectomy was followed by bone graft and Orion anterior cervical locking plate fixation. In the posterior group, multilevel laminectomy with posterior screw-rod fixation was performed. Follow-up, which included radiographic assessment, clinical examination and documentation of length of any hospitalization and cost and incidence of complications, was performed 1 day before discharge, 6 months after leaving hospital, and at final follow-up. Both groups had improved clinical outcomes. The anterior group showed greater satisfaction but lower visual analog scale scores than the posterior group, whereas SF-36 emotional role and mental health scores were higher in the anterior group. There was no marked difference between the two groups in length of hospitalization and most of the costs of treating CSM, however treatment and examination fees were significantly higher in the posterior group. Both anterior and posterior decompressions (with instrumentation) are effective procedures for improving the neurological outcomes of patients with CSM. However, although the two approaches have similar health care costs, anterior cervical corpectomy (with instrumentation) seems to be subjectively assessed by patients as better.

Approach-related complications after decompression for cervical ossification of the posterior longitudinal ligament

The surgical management of compressive cervical ossification of the posterior longitudinal ligament (OPLL) can be challenging. Traditionally, approach indications for decompression of cervical spondylotic myelopathy have been used. However, the postoperative complication profile after cervical OPLL decompression is unique and may require an alternative approach paradigm. The authors review the literature on approach-related OPLL complications and suggest a management strategy for patients with single- or multiple-segment OPLL with or without greater than 50% canal stenosis.

Use of Walking Data in Assessing Operative Results for Cervical Spondylotic Myelopathy

Retrospective case-control study. To study the role of surgical decompression in cervical spondylotic myelopathy (CSM). Fifty patients who received surgery, and 34 patients with myelopathy who were offered surgery but declined, or were not medically fit for surgery. We studied the role of surgical decompression in CSM by using a validated 30-m walking test in a group of patients to assess severity before surgery and at regular intervals over the following 3 years after surgery. Such patients were compared with a matched group of control patients with myelopathy but who did not undergo surgery. The walking data indicated a lasting benefit from surgery for at least 3 years after surgery. Patients gained a significant recovery of function which was maintained. In contrast, unoperated patients continued to deteriorate. More benefit was surprisingly seen when surgery was performed in older patients or with worse myelopathy. Surgical decompression is beneficial in the treatment of CSM. Improvements were generally seen by 6 months from operation. Older patients and greater degrees of myelopathy were not associated with a worse outcome, suggesting surgery should not necessarily be discouraged in such patients.

Compensatory cerebral adaptations before and evolving changes after surgical decompression in cervical spondylotic myelopathy

The goal of this study was to compare cortical sensorimotor adaptations associated with neurological deterioration and then recovery following surgical decompression for cervical spondylotic myelopathy (CSM). Eight patients with CSM underwent functional MR (fMR) imaging during wrist extension and the 3-finger pinch task, along with behavioral assessments before and 3 and 6 months after surgery. Six healthy control volunteers were scanned twice. Cervical spine MR imaging demonstrated successful cord decompression. The patients improved after surgery on the modified Japanese Orthopaedic Association score for the upper extremity, which correlated with the changes in task-associated activation in specific sensorimotor regions of interest. Pinch-related activation in sensorimotor cortex contralateral to the movement paradigm was reduced before surgery then increased toward the extent of healthy controls after surgery. Before surgery, patients showed broader activation in ipsilateral sensorimotor cortex during wrist extension than during pinch, but activations became similar to those of healthy controls after surgery. Pinch-related activation volume in the ipsilateral sensorimotor cortex and the magnitude of activation in the contralateral dorsal premotor cortex evolved linearly across time after surgery, along with wrist extension-related activation magnitude in the contralateral supplementary motor area. Serial fMR imaging studies in CSM can capture the adaptations in specific sensorimotor cortices that accompany clinical deterioration and postsurgical improvement in sensorimotor function associated with damage and partial recovery of conduction in corticospinal pathways. These adaptive regions can be monitored by serial fMR imaging to detect a critical loss of supraspinal reserve in compensatory plasticity, which might augment clinical information about the need for surgical decompression.

Prognostic relevance of the postoperative evolution of intramedullary spinal cord changes in signal intensity on magnetic resonance imaging after anterior decompression for cervical spondylotic myelopathy

Object Areas of intramedullary signal intensity changes (hypointensity on T1-weighted magnetic resonance [MR] images and hyperintensity on T2-weighted MR images) in patients with cervical spondylotic myelopathy (CSM) have been described by several investigators. The role of postoperative evolution of these alterations is still not well known. Methods A total of 47 patients underwent MR imaging before and at the end of the surgical procedure (intraoperative MR imaging [iMRI]) for cervical spine decompression and fusion using an anterior approach. Imaging was performed with a 1.5-tesla scanner integrated with the operative room (BrainSuite). Patients were followed clinically and evaluated using the Japanese Orthopaedic Association (JOA) and Nurick scales and also underwent MR imaging 3 and 6 months after surgery. Results Preoperative MR imaging showed an alteration (from the normal) of the intramedullary signal in 37 (78.7%) of 47 cases. In 23 cases, signal changes were altered on both T1- and T2-weighted images, and in 14 cases only on T2-weighted images. In 12 (52.2%) of the 23 cases, regression of hyperintensity on T2-weighted imaging was observed postoperatively. In 4 (17.4%) of these 23 cases, regression of hyperintensity was observed during the iMRI at the end of surgery. Residual compression on postoperative iMRI was not detected in any patients. A nonsignificant correlation was observed between postoperative expansion of the transverse diameter of the spinal cord at the level of maximal compression and the postoperative JOA score and Nurick grade. A statistically significant correlation was observed between the surgical result and the length of a patient's clinical history. A significant correlation was also observed according to the preoperative presence of intramedullary signal alteration. The best results were found in patients without spinal cord changes of signal, acceptable results were observed in the presence of changes on T2-weighted imaging only, and the worst results were observed in patients with spinal cord signal changes on both T1- and T2-weighted imaging. Finally, a statistically significant correlation was observed between patients with postoperative spinal cord signal change regression and better outcomes. Conclusions Intramedullary spinal cord changes in signal intensity in patients with CSM can be reversible (hyperintensity on T2-weighted imaging) or nonreversible (hypointensity on T1-weighted imaging). The regression of areas of hyperintensity on T2-weighted imaging is associated with a better prognosis, whereas the T1-weighted hypointensity is an expression of irreversible damage and, therefore, the worst prognosis. The preliminary experience with this patient series appears to exclude a relationship between the time of signal intensity recovery and outcome of CSM.

Prognostic relevance of the postoperative evolution of intramedullary spinal cord changes in signal intensity on magnetic resonance imaging after anterior decompression for cervical spondylotic myelopathy

Areas of intramedullary signal intensity changes (hypointensity on T1-weighted magnetic resonance [MR] images and hyperintensity on T2-weighted MR images) in patients with cervical spondylotic myelopathy (CSM) have been described by several investigators. The role of postoperative evolution of these alterations is still not well known. A total of 47 patients underwent MR imaging before and at the end of the surgical procedure (intraoperative MR imaging [iMRI]) for cervical spine decompression and fusion using an anterior approach. Imaging was performed with a 1.5-tesla scanner integrated with the operative room (BrainSuite). Patients were followed clinically and evaluated using the Japanese Orthopaedic Association (JOA) and Nurick scales and also underwent MR imaging 3 and 6 months after surgery. Preoperative MR imaging showed an alteration (from the normal) of the intramedullary signal in 37 (78.7%) of 47 cases. In 23 cases, signal changes were altered on both T1- and T2-weighted images, and in 14 cases only on T2-weighted images. In 12 (52.2%) of the 23 cases, regression of hyperintensity on T2-weighted imaging was observed postoperatively. In 4 (17.4%) of these 23 cases, regression of hyperintensity was observed during the iMRI at the end of surgery. Residual compression on postoperative iMRI was not detected in any patients. A nonsignificant correlation was observed between postoperative expansion of the transverse diameter of the spinal cord at the level of maximal compression and the postoperative JOA score and Nurick grade. A statistically significant correlation was observed between the surgical result and the length of a patient's clinical history. A significant correlation was also observed according to the preoperative presence of intramedullary signal alteration. The best results were found in patients without spinal cord changes of signal, acceptable results were observed in the presence of changes on T2-weighted imaging only, and the worst results were observed in patients with spinal cord signal changes on both Tl- and T2-weighted imaging. Finally, a statistically significant correlation was observed between patients with postoperative spinal cord signal change regression and better outcomes. Intramedullary spinal cord changes in signal intensity in patients with CSM can be reversible (hyperintensity on T2-weighted imaging) or nonreversible (hypointensity on T1-weighted imaging). The regression of areas of hyperintensity on T2-weighted imaging is associated with a better prognosis, whereas the T1-weighted hypointensity is an expression of irreversible damage and, therefore, the worst prognosis. The preliminary experience with this patient series appears to exclude a relationship between the time of signal intensity recovery and outcome of CSM.

Ventral Versus Dorsal Decompression for Cervical Spondylotic Myelopathy: Surgeonsʼ Assessment of Eligibility for Randomization in a Proposed Randomized Controlled Trial

Surgeons attending a Cervical Spine Research Society (CSRS) meeting were surveyed about the surgical approach to cervical spondylotic myelopathy (CSM). To elicit spine surgeons' opinions on the suitability of a panel of test cases for randomization in a proposed randomized controlled trial (RCT) of ventral versus dorsal decompression for CSM. The optimal surgical decompression strategy for CSM has not been defined. Specific eligibility criteria should be defined before a RCT is initiated. Twenty actual cases with images were prepared. Surgeons supplied demographic information, preferred surgical approach, and eligibility for randomization for 10 cases. A total of 91 of 239 (38%) surgeons completed the survey. Of 900 case-strategy responses, 51% recommended ventral surgery, 38% dorsal surgery, and 11% a combined approach. Both overall C2-C7 kyphosis >5 degrees and a segmental kyphotic deformity were inversely correlated with eligibility for randomization (P < 0.001 for both). Using these 2 criteria plus age over 85 years, ossification of the posterior longitudinal ligament, and congenital canal stenosis as additional exclusion criteria, 12 of 20 survey cases were considered potentially eligible for randomization. Orthopedic and neurologic surgeons were similar in determining a case's eligibility for randomization. These results measure surgeons' opinions on the suitability of cases for randomization and help to define entry and exclusion criteria for a RCT comparing ventral to dorsal strategies. Over 50% of CSM cases from a general spinal practice might be eligible for randomization.

Surgical Decompression for Cervical Spondylotic Myelopathy: Correlation Between Operative Outcomes and MRI of the Spinal Cord

Forty-two patients who underwent decompressive surgery for cervical spondylotic myelopathy were studied. The pre- and postoperative magnetic resonance imaging (MRI) findings and the Japanese Orthopedic Association score were analyzed to evaluate whether the different appearances of intramedullary high-signal intensity on T2-weighted MRI are related to the surgical prognosis. Magnetic resonance imaging signal intensities were classified as type 0 if no intramedullary high-signal intensity on T2-weighted images was noted, type 1 if high-signal intensity involved only one segment, and type 2 if high-signal intensity extended over two segments. Statistical analyses of the recovery ratio showed that type 0 and type 1 intramedullary high-signal intensity indicates better prognosis than type 2.

Recovery of spinal cord conduction after surgical decompression for cervical spondylotic myelopathy: serial somatosensory evoked potential studies.

We tested the utility of scalp-recorded median and tibial somatosensory evoked potentials (SEPs) as a measure of delineating the time course of postoperative recovery from cervical spondylotic myelopathy. We evaluated serial median and tibial SEP studies for 20 hands and 22 feet in 13 cervical spondylotic myelopathy patients during the first 6 mo postoperatively or longer. Serial sensory assessment of the hands and feet served to evaluate clinical correlation with the SEPs. The studies distinguished three recovery patterns of the SEPs based on the time course of the latencies of the N20 component for the median SEP and the P40 component for the tibial SEP. The latency started to decrease by 0.5 msec or more within 2 wk (seven hands and eight feet) or later than 2 wk (six hands and eight feet) postoperatively, or the change did not reach 0.5 msec (seven hands and six feet). In the late recovery group, the SEP improvement began as late as 10 wk postoperatively. Sensory recovery correlated with the SEP change in every group. An early onset of the SEP recovery predicts a favorable clinical course. The SEP may begin to improve later, and once it occurs, progressive return of function will follow.