Diagnosis Of Cervical Spondylotic Myelopathy Research Articles

Somatosensory evoked potentials (SEPs) for the evaluation of cervical spondylotic myelopathy: Utility of the onset-latency parameters

Objective Peak latencies have been traditionally employed for the evaluation of somatosensory evoked potentials (SEPs). Some authors have argued for the theoretical superiority of the onset latencies, which has never been verified in actual clinical cases. We aimed to investigate the utility of onset-latency parameters of median nerve SEPs in the cervical spondylotic myelopathy (CSM) patients, as well as several other issues concerned with the SEP diagnosis of CSM. Methods We retrospectively enrolled 42 CSM patients and investigated their SEP findings. Results The N9o (N9 onset)-P13/14o interval showed the highest sensitivity (83%) followed by N9o-N20o (74%). The sensitivities of corresponding peak latency parameters were lower (62% and 33%). The amplitude of the lower cervical N13 also showed the highest sensitivity (83%). The sensitivity of tibial nerve SEPs examined in 21 patients was lower (71%) than that of median nerve SEPs (90%). When clinical signs alone were used as the gold standard, the sensitivity of median SEPs was 90% whereas that of MRI was 88%. Conclusions Higher diagnostic yield of onset-latency parameters of median nerve SEPs has been documented in CSM. Significance SEPs are useful in the diagnosis of CSM having equal sensitivity and probably higher specificity than MRI.

Delayed diagnosis of cervical spondylotic myelopathy in a patient after traffic accident

Delayed diagnosis of cervical spondylotic myelopathy in a patient after traffic accident

Cutaneous silent periods in the evaluation of cord compression in cervical spondylosis

The clinical diagnosis of cervical spondylotic myelopathy (CSM) may be challenging in patients with cervical spondylosis (CS). Routine nerve conduction studies (NCS) may not evaluate cord compression adequately. We obtained cutaneous silent periods (CSP) in 26 consecutive patients presenting with clinical features of CS, in comparison with 30 normal controls. The results were also compared with transcranial magnetic stimulation (TMS) findings, and magnetic resonance imaging of the cervical cord as the gold standard. CSP findings showed similarly high sensitivity of up to 96% with TMS in evaluating cervical cord dysfunction. In specific clinical settings, CSP is of value for the diagnosis of CSM in CS. CSP measurement is advocated as a simple and rapid diagnostic adjunct to NCS in evaluating CS patients with possible cord compromise.

Analysis of the long-term outcome of anterior approach surgery on cervical spondylotic myelopathy

To investigate the long-term efficacy of anterior approach surgery on cervical spondylotic myelopathy and factors affecting prognosis. The data in 116 patients suffered from cervical spondylosis from January 1992 to December 2000 were reviewed, including 80 male cases and 36 female cases, whose age ranged from 36 to 76 years (mean, 51 years). The preoperative course of disease was 2 months to 20 years (mean, 19 months). There were 65 cases (56.0%) with single segments involved, 44 cases (37.9%) with two segments, 7 cases (6.0%) with three segments. Ninety-eight cases were onset slowly, 18 cases with no remote cause and aggravating quickly. Three kinds of surgeries were performed: anterior cervical decompression and autoiliac bone interbody fusion, anterior cervical decompression and fusion with threaded fusion cage, anterior cervical decompression and autoiliac bone interbody fusion with anterior screw-plate system. Improvement in spinal cord function was assessed using the Japanese Orthopaedic Association (JOA) scoring system, the long-term efficacy and influential factors were also analyzed. The mean follow-up time was 7 years and three months (5 - 12 years). The mean preoperative JOA score was 9.34 +/- 1.81. The mean postoperative JOA score was 10.35 +/- 1.85. At the final follow-up, the JOA score was 14.09 +/- 1.90 and the recovery rate was 63.2%. Among the total patients, 27 cases were excellent, 47 cases were fine, 23 cases were good, 19 cases were poor, the fineness rate was 63.8%. The long-term efficacy of anterior approach surgery has close correlations with time of course, age of onset, preoperative spinal cord function and the number of affected segments, but has no correlations with modes of fusion and internal fixation. The patients will be attentively observed while having a definite diagnosis of cervical spondylotic myelopathy. The good long-term results will be obtained after early anterior cervical decompression and fusion.

Characterization of Neurophysiologic Alerts During Anterior Cervical Spine Surgery

A retrospective review of neurophysiologic alerts during anterior cervical surgery. To examine incidence and types of neurophysiologic alerts and their correlation with new postoperative neurologic deficits after anterior cervical discectomy or corpectomy procedures. Although multimodality neurophysiologic monitoring has been shown to predict iatrogenic neurologic injuries in scoliosis surgeries, their role in degenerative or trauma-related anterior cervical spine surgery is still unclear. We retrospectively reviewed 1,445 patients who underwent anterior cervical discectomy or corpectomy and arthrodesis with neurophysiologic monitoring that included transcranial electrical motor-evoked potentials (tceMEP), somatosensory-evoked potentials (SSEP), and spontaneous electromyography (EMG). Intraoperative alerts were analyzed for type, perceived cause, actions taken to reverse or minimize the possible spinal cord injury, and any new postoperative neurologic deficits. There were 267 (18.4%) procedures that had either minor (spontaneous, sustained EMG) or major (tceMEP/SSEP amplitude reduction) alerts. Patients who underwent corpectomies had 28% increased risk of having a major neurophysiologic alert compared with those who had discectomies. Diagnosis of cervical spondylotic myelopathy or trauma increased the risk of having a major neurophysiologic alert 30% and 76%, respectively, compared with cervical radiculopathy. Eight surgeries were aborted due to persistent tceMEP/SSEP amplitude loss, but none resulted in new postoperative neurologic deficits. Two patients had halo-vest applied due to early termination of surgery. One of these patients ultimately could not receive definitive surgical stabilization. Diagnosis of cervical spondylotic myelopathy or trauma and cervical corpectomy procedures increase the risk for having major intraoperative alerts. In case of persistent tceMEP/SSEP amplitude loss, consider delaying potentially harmful interventions, such as premature termination of the procedure or methylprednisolone infusion, until a new neurologic deficit is verified with an awake-clinical examination.

Epidurally recorded spinal cord evoked potentials in patients with cervical myelopathy and normal central motor conduction time measured by transcranial magnetic stimulation

ObjectiveUse epidural recording of evoked spinal cord potentials (ESCPs) to investigate the pathology of cervical spondylotic myelopathy (CSM) in patients with normal central motor conduction time (CMCT) in upper and lower limbs. MethodsA total of 75 patients with CSM were studied. All patients were examined before surgery for motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS). They were also evaluated during surgery by epidurally recorded ESCPs following stimulation of the median nerve, brain and spine. ResultsSeven patients (9%) showed normal CMCT in upper and lower limbs upon TMS examination. Only the ESCPs following median nerve stimulation (MN-ESCPs) were abnormal in these patients. In 5 of the 7 patients, a marked block in conduction of MN-ESCPs was observed at the C3-4 intervertebral level. The remaining two patients showed attenuation in the amplitude of MN-ESCPs at mid-cervical levels. ConclusionsWe present 7 cases of CSM with negative CMCT findings. From the MN-ESCP results, we surmise that the pathology of CSM with normal CMCT is due predominantly to dysfunction of sensory systems involved in the upper limbs. SignificanceExamination by TMS is useful in the diagnosis of CSM but the possibility of negative CMCT findings upon TMS must be borne in mind. Multi-functional evoked spinal cord responses demonstrate that lesions in the sensory system are the major underlying pathology.

Functional Outcome after Central Corpectomy in Poor-grade Patients with Cervical Spondylotic Myelopathy or Ossified Posterior Longitudinal Ligament

We studied the long-term functional outcome in poor-grade patients (Nurick Grades 4 and 5) with cervical spondylotic myelopathy (CSM) or ossified posterior longitudinal ligament after central corpectomy (CC). We sought to determine whether there were any prognostic factors that could predict functional outcome in these patients. Functional outcome data were collected for 72 patients (68 men and 4 women; mean age, 49.7 yr; range, 30-67 yr) with CSM (60 patients) or OPLL (12 patients) of Nurick Grades 4 (55 patients) and 5 (17 patients). Uninstrumented CC was performed at 1 level in 12 patients, at 1 level combined with a discoidectomy at another level in 4 patients, at 2 levels in 50 patients, and at 2 levels plus a discoidectomy in 5 patients. The age at presentation (< or =50 yr or >50 yr), grade before surgery (4 or 5), the number of levels operated (1 or >1), diagnosis (CSM or ossified posterior longitudinal ligament), and duration of myelopathic symptoms (< or =12 mo or >12 mo) were studied for their effect on the functional outcome noted at the last follow-up. Functional outcome was graded as poor (no change in Nurick grade), fair (improvement of one Nurick grade), good (improvement of two Nurick grades), and cure (follow-up Nurick grade of 0 or 1). The follow-up ranged from 9 to 104 months (mean, 36.3 mo). One patient died 3 weeks after CC after surgery for a perforated duodenal ulcer. There was transient operative morbidity in 12 patients (16.9%). The mean Nurick score improved from 4.24 to 2.47 (P < 0.001). Of the 54 patients (76%) who improved in their Nurick grade, the functional outcome was graded as fair in 13 patients (18.3%), good in 24 patients (33.8%), and cure in 17 patients (23.9%). The functional outcome was poor in 17 patients (23.9%). Functional improvement after CC was uniformly correlated with myelopathic symptoms of 12 months' duration or shorter. The other favorable prognostic indicators for improvement after CC were a diagnosis of CSM and preoperative Nurick Grade 5; however, patients with a preoperative Nurick grade of 4 were more likely to experience a cure. More than three-fourths of patients with poor-grade CSM improve in their functional status after CC, with nearly 24% of patients obtaining a cure. Because patients with a duration of myelopathic symptoms of 12 months or less had the best functional outcome, early decompressive surgery should be offered to patients with poor-grade CSM.

Anterior cervical corpectomy for cervical spondylotic myelopathy.

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." 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). 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. 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.

S-10-4 Multichannel monitoring with various kinds of evoked potentials for spinal cord evaluation

Use epidural recording of evoked spinal cord potentials (ESCPs) to investigate the pathology of cervical spondylotic myelopathy (CSM) in patients with normal central motor conduction time (CMCT) in upper and lower limbs.A total of 75 patients with CSM were studied. All patients were examined before surgery for motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS). They were also evaluated during surgery by epidurally recorded ESCPs following stimulation of the median nerve, brain and spine.Seven patients (9%) showed normal CMCT in upper and lower limbs upon TMS examination. Only the ESCPs following median nerve stimulation (MN-ESCPs) were abnormal in these patients. In 5 of the 7 patients, a marked block in conduction of MN-ESCPs was observed at the C3-4 intervertebral level. The remaining two patients showed attenuation in the amplitude of MN-ESCPs at mid-cervical levels.We present 7 cases of CSM with negative CMCT findings. From the MN-ESCP results, we surmise that the pathology of CSM with normal CMCT is due predominantly to dysfunction of sensory systems involved in the upper limbs.Examination by TMS is useful in the diagnosis of CSM but the possibility of negative CMCT findings upon TMS must be borne in mind. Multi-functional evoked spinal cord responses demonstrate that lesions in the sensory system are the major underlying pathology.

Somatosensory evoked potentials after multisegmental upper limb stimulation in diagnosis of cervical spondylotic myelopathy.

Radial, median, and ulnar nerve somatosensory evoked potentials (SEPs) were recorded, with non-cephalic reference montage, in 38 patients with clinical signs of cervical myelopathy and MRI evidence of spondylotic compression of the cervical cord. Upper limb SEPs are useful in spondylotic myelopathy because SEPs were abnormal in all patients for at least one of the stimulated nerves and SEP abnormalities were bilateral in all patients but one. Reduction of the amplitude of the N13 potential indicating a segmental dysfunction of the cervical cord was the most frequent abnormality; it occurred in 93.4%, 84.2%, and 64.5% of radial, median, and ulnar nerve SEPs respectively. A second finding was that the P14 far-field potential was more sensitive than the cortical N20 potential to slowing of conduction in the dorsal column fibres. The high percentage of N13 abnormalities in the radial and median rather than in the ulnar nerve SEPs correlated well with the radiological compression level, mainly involving the C5-C6 vertebral segments. Therefore the recording of the N13 response is a reliable diagnostic tool in patients with cervical spondylotic myelopathy and P14 abnormalities, though less frequent, can be useful in assessing subclinical dorsal column dysfunction.

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 spondolytic myelopathy.

Early Diagnosis of Cervical Spondylotic Myelopathy

This is a retrospective study of 67 patients, seen during a 4-year period, with cervical pathology requiring surgical correction. The purpose of this study was to evaluate the usefulness of a new physical finding (dynamic Hoffmann's sign) in diagnosing early cervical myelopathy or in suggesting a narrow cervical canal clinically. Hoffman's sign was checked with the head in neutral (static) and during multiple active full flexion to extension as tolerated by the patient (dynamic). Forty patients had negative Hoffman's signs, 20 had positive static Hoffman's signs, and 7 had positive dynamic Hoffman's signs. Canal measurements were made on eight randomly selected negative patients on both plain films and myelographic studies, and on the seven positive patients. A positive dynamic Hoffmann's sign was consistent with a narrow sagittal diameter of the cervical canal, and aided clinically in making the diagnosis of early cervical spondylotic myelopathy or congenital cervical narrowing.

Magnetic transcranial motor evoked potentials (MEP) and seps in cervical spondylotic myelopathy (CSM) : Xian-Fu Tang and Zhu-Yuan Ren

Use epidural recording of evoked spinal cord potentials (ESCPs) to investigate the pathology of cervical spondylotic myelopathy (CSM) in patients with normal central motor conduction time (CMCT) in upper and lower limbs.A total of 75 patients with CSM were studied. All patients were examined before surgery for motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS). They were also evaluated during surgery by epidurally recorded ESCPs following stimulation of the median nerve, brain and spine.Seven patients (9%) showed normal CMCT in upper and lower limbs upon TMS examination. Only the ESCPs following median nerve stimulation (MN-ESCPs) were abnormal in these patients. In 5 of the 7 patients, a marked block in conduction of MN-ESCPs was observed at the C3-4 intervertebral level. The remaining two patients showed attenuation in the amplitude of MN-ESCPs at mid-cervical levels.We present 7 cases of CSM with negative CMCT findings. From the MN-ESCP results, we surmise that the pathology of CSM with normal CMCT is due predominantly to dysfunction of sensory systems involved in the upper limbs.Examination by TMS is useful in the diagnosis of CSM but the possibility of negative CMCT findings upon TMS must be borne in mind. Multi-functional evoked spinal cord responses demonstrate that lesions in the sensory system are the major underlying pathology.