New evaluation method using preoperative magnetic resonance imaging for cervical spondylotic myelopathy

A new method based on the score of preoperative magnetic resonance images (MRI) was devised to evaluate cervical spondylotic myelopathy and predict the results of cervical laminoplasty. On T1- and T2-weighted sagittal MRI, the intervertebral disc spaces at each level from the axis to the first thoracic spine were examined as to whether the anterior or posterior subarachnoid space would be maintained or not, and for the presence or absence of spinal cord deformity. The data were divided into six grades and rated, and the total score for all sites was regarded as the preoperative MRI cumulative score. In conclusion, our method was highly reliable and useful for a preoperative evaluation and prediction of results after cervical laminoplasty for cervical spondylotic myelopathy. Received: 18 December 2000     

Cervical extension magnetic resonance imaging in evaluating cervical spondylotic myelopathy

Background

Cervical spondylotic myelopathy (CSM) may be caused by static and dynamic spinal cord compression, particularly during neck extension. Dynamic compression may be better evaluated with dynamic magnetic resonance (MR) images. We performed a retrospective study to determine the clinical indication for dynamic MR imaging, and conducted a survey regarding image interpretation by clinicians.

Method

A total of 32 patients (M:F?=?20:12, 60.1?±?10.7 years) who had undergone neutral/extension cervical MR imaging were included. The study population consisted of 22 patients with signs of cervical myelopathy (M group) and 10 patients without signs of myelopathy (NM group). The number of compression levels (complete obliteration of the anterior and posterior subarachnoid space) was assessed at each level in mid-sagittal, T2-weighted, neutral and extension MR images. Reproduced images from 22 patients in the M group were randomly arranged, and four experienced spine surgeons at four different institutes interpreted them to reach a clinicians’ agreement. The agreements were then assessed with inter-rater correlation coefficients (ICC).

Results

Analysis with extension MR images found an increased number of compression levels in 23/32 (72 %) of patients; 20/22 in the M group and 3/10 in the NM group (p?<?0.01, chi-squared test), as compared to findings of the neutral MR images. Clinical factors for increased compression levels in extension MR images were age (p?<?0.01, 63.3?±?10.0 years vs. 51.9?±?8.1) and signs of myelopathy (p?<?0.01, odds ratio, 23.33). Clinician agreement was improved with extension MR images; ICC was 0.67 with neutral and 0.81 with extension MR images.

Conclusions

The evaluation of CSM may be improved with dynamic MR images. Dynamic MR scanning may be considered for elderly patients with signs of myelopathy, but an interpretation for asymptomatic spinal compression based exclusively on extension MR image should be made with caution.     

Postoperative myelography in spondylotic cervical myelopathy

Summary Thirty-five patients operated for myelopathy caused by cervical spondylosis were followed up from one to ten years. Of these patients 23 had posterior decompressive laminectomy and 12 had anterior intervertebral exploration followed by fusion. Satisfactory results were obtained in 76.9 percent after anterior operation and 72.3 percent after extensive decompressive laminectomy but the relative incidence of return to normal neurological status was higher in patients operated by the anterior approach. The preoperative myelograms of 21 patients (10 operated by anterior approach and 11 by laminectomy) were compared with postoperative myelograms. Several types of postoperative changes are described and correlated to the clinical symptoms. In the great majority of cases myelopathy seemed to be attributed to mechanical compression.     

Magnetic resonance imaging and cervical spondylotic myelopathy

Nineteen patients were examined for cervical spondylotic myelopathy with magnetic resonance imaging. Pre- and postoperative magnetic resonance scans were obtained in most cases. Surgical confirmation of the pathological condition was obtained for all 19 patients. On the T2-weighted scans, there was increased signal intensity within the spinal cord at the point of maximal compression. The exact cause of the increased signal intensity on the T2-weighted images is not known, but is suspected to represent edema, inflammation, vascular ischemia, myelomalacia, or gliosis. The increased signal intensity diminished postoperatively in the patients who improved clinically, and remained the same or increased in those whose conditions remained unchanged or worsened after decompression. The authors suggest that these T2-weighted images carry prognostic significance.     

Perfusion-weighted magnetic resonance imaging of the spinal cord in cervical spondylotic myelopathy

Principles of echo shifting with a train of observations was used to perform magnetic susceptibility-weighted magnetic resonance imaging with bolus-tracking in 14 patients with spondylotic myelopathy to assess changes in perfusion parameters of the spinal cord before and after decompression surgery for cervical spondylotic myelopathy. The mean transit time (MTT), bolus arrival time (T0), and time to peak (TTP) were obtained from regions of interest (ROIs) and assessed as the ratio between the spinal cord and the pons (MTT index = MTT(ROI)/MTT(pons), T0 index = T0(ROI)/T0(pons), TTP index = TTP(ROI)/TTP(pons)). The patients were divided into two groups according to percentage improvement on the Neurosurgical Cervical Spine Scale. The MTT index in patients with good recovery (> or =50%) was significantly reduced. The T0 index and TTP index showed no significant change in both groups. Reduction of MTT index may indicate improved perfusion of the spinal cord following surgery for cervical spondylotic myelopathy.     

A correlation between magnetic resonance imaging and electrophysiological findings in cervical spondylotic myelopathy.

STUDY DESIGN: Correlation between compressed spinal cords on magnetic resonance imaging (MRI) and electrophysiological findings in cervical spondylotic myelopathy patients. OBJECTIVE: To clarify the correlation between spinal-cord-evoked potentials and MRI measurements of compressed spinal cords in patients with cervical spondylotic myelopathy. SUMMARY OF BACKGROUND DATA: Compression of the spinal cord does not always cause clinical symptoms and it is difficult to infer the degree of dysfunction of the spinal cord from MRI findings. METHODS: Seventeen patients with cervical spondylotic myelopathy were examined with MRI and spinal-cord-evoked potentials before surgery. Using abnormality in spinal-cord-evoked potentials as indicators of spinal cord morphology, spinal-cord transverse area and compression ratios (central and 1/4-lateral) were measured on T1-weighted axial imaging. The correlations between these dimensions and electrophysiological findings were investigated. RESULTS: The mean preoperative transverse area of the spinal cord was 47.13 mm2.The mean preoperative central compression ratio of the spinal cord was 34.4%. The mean preoperative 1/4-lateral compression ratio of the spinal cord was 27.5%. A correlation (Spearman r=0.65, P < 0.01) was observed between the 1/4-lateral compression ratio of the spinal cord and the amplitude ratio of spinal-cord-evoked potentials after electric stimulation of the brain (Br(E)-SCEPs). CONCLUSIONS: The preoperative 1/4-lateral compression ratio of the spinal cord was found to reflect the degree of dysfunction of the corticospinal tracts.     

Surgical decompressive procedures for cervical spondylotic myelopathy. A study using magnetic resonance imaging

Twenty-two patients who underwent a surgical decompressive procedure for cervical spondylotic myelopathy were studied with magnetic resonance imaging to evaluate the effectiveness of their decompressive procedures. Twelve patients were judged as adequately decompressed by magnetic resonance imaging criteria. Ten patients exhibited evidence of residual cord indentation. This along with cord atrophy, gliosis, and abnormal spine curvature presumably contributed to residual deficit in several patients. One patient underwent a second decompressive procedure for residual cord indentation, which subsequently improved, as seen on his second postoperative magnetic resonance image. Magnetic resonance imaging was useful in distinguishing mechanical problems from intrinsic cord damage or atrophy. Magnetic resonance imaging should be used after operation in patients with residual deficit to detect patients who may be considered for a second decompressive procedure.     

Comparison of magnetic resonance imaging and computed tomography in the evaluation of head injury

Thirty-five patients who had incurred head trauma were studied with computed tomography (CT) and magnetic resonance imaging (MRI). CT was performed using a General Electric 8800 scanner. MRI was conducted with a Technicare Teslacon system using a 5.0 kG (0.5 T) magnetic field. Clinically, patients varied from those with mild concussions without focal neurological signs to those with severe neurological dysfunction including posttraumatic coma. MRI was superior to CT in imaging 23 of 41 extracerebral fluid collections, both in estimating the size of the collections and in diagnosing small collections. MRI was also superior to CT in distinguishing chronic subdural hematomas from hygromas. Further, MRI was superior to CT in visualizing nonhemorrhagic contusion in 15 of 21 lesions. Because of the potential failure of MRI to diagnose acute subarachnoid or acute parenchymal hemorrhage, CT remains the procedure of choice in diagnosing head injury less than 72 hours old.     

Comparison of magnetic resonance imaging and computed tomography in the preoperative evaluation of pituitary adenomas

Twenty surgically verified pituitary adenomas were imaged in a systematic comparative fashion with high field strength magnetic resonance imaging (MRI) and computed tomography (CT) before operation. The study group included 11 microadenomas, 4 macroadenomas, 2 recurrent microadenomas, and 3 recurrent macroadenomas. The MRI and CT examinations were evaluated for lesion detection, pituitary stalk displacement, cavernous sinus displacement or invasion, hemorrhage, cystic degeneration within the adenoma, bony erosion, detection of suprasellar extension, and displacement of suprasellar structures. T1 and T2 relaxation characteristics of the adenomas were evaluated on MRI examinations, and contrast enhancement characteristics were evaluated on CT examinations. MRI was superior to CT for detecting the extrasellar extent of tumor. Within the sella turcica, MRI and CT were equivalent with regard to lesion detection, except for 1 patient in whom CT was able to detect a surgically confirmed 3-mm microadenoma that was not visualized on the MRI examination.     

The surgical management of cervical spondylotic radiculopathy and myelopathy

Anterior fusion, laminectomy, and laminaplasty are recommended for the following conditions. For the treatment of one- or two-level spondylotic radiculopathy, anterior discectomy and fusion are preferred. For the treatment of spondylotic radiculopathy involving three or more levels, the open-door laminaplasty may be considered an alternative to anterior fusion. In this situation, laminaplasty is preferred for patients with developmental cervical canal stenosis, failed anterior fusion, or various prior anterior neck operations. Cervical laminectomy is indicated for patients with anterior bony ankylosis secondary to degenerative or inflammatory disorders and for patients in whom anterior fusion may be technically difficult, i.e., at C1-C3 or C7-T1. Anterior fusion is advisable for patients who have a structural reversal of the normal lordotic curve.     

Lumbar spinal stenosis assessment with computed tomography, magnetic resonance imaging, and myelography

Degenerative spinal stenosis of the lumbar spine is caused by many factors, some of which include: disc herniation, ligamentum flavum and facet hypertrophy, spondylolisthesis, and compression fracture. Most often the stenosis is caused by a combination of these factors. The imaging modalities in routine use to evaluate these conditions are computed tomography, magnetic resonance imaging and computed tomography-myelogram. They each have their advantages and disadvantages although any one of these modalities can adequately diagnose lumbar stenosis. The overall accuracy rate of computed tomography, magnetic resonance imaging, and computed tomography-myelogram has been reported to be similar and even complimentary. It is recommended that the least invasive modality be performed first. Magnetic resonance imaging should be the first choice because it does not require ionizing radiation or contrast injection. The aim of the current study is to present the common causes of lumbar stenosis. Where appropriate, each case is shown with images from each modality so that their similarities and differences can be highlighted.     

Surgical and conservative treatment of cervical spondylotic radiculopathy and myelopathy

Summary 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 symtoms. 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.     

Long-term outcome for surgically treated cervical spondylotic radiculopathy and myelopathy

Long-term follow-up results were examined to verify the efficacy of anterior osteophytectomy for cervical spondylotic myelopathy and radiculopathy, in particular the outcome for patients with developmentally narrow cervical canals and patients with associated ossification of the posterior longitudinal ligament (OPLL). One hundred thirty-nine patients who had undergone anterior osteophytectomy with interbody fusion between 1976 and 1990 were followed up for 1 to 22.5 years (mean 11.4 years). Overall results evaluated by the neurosurgical cervical spine scale scoring and grading showed significant improvement in both improvement score (2.7 +/- 2.3) and improvement rate (52.3 +/- 45.7%). Lower extremity motor function improved in 66.1% of patients, upper extremity motor function in 82.0%, and sensory/pain function in 70.5%. Improvement ranged from one to three grades. Severely affected patients showed good recovery. Outcome for patients with narrow cervical canals (41 patients, 29.5%) did not differ significantly from that for patients with normal canals (98, 70.5%). Patients with associated OPLL (32 patients, 23.0%) had approximately the same outcomes as those with only spondylosis (107, 77.0%). Fifteen patients (10.8%) underwent reoperation because of myelopathy due to disc degeneration adjacent to the fused level (11 patients) or OPLL (4 patients). Anterior osteophytectomy with interbody fusion can achieve good outcomes in patients with cervical spondylotic myelopathy and radiculopathy, regardless of the size of the spinal canal and association with OPLL.     

Comparison of nuclear magnetic resonance imaging and computed tomography in the diagnosis of upper cervical spinal cord compression

Because of its ability to visualize soft-tissue structures in greater detail than any previous radiographic modality, nuclear magnetic resonance (NMR) has been heralded as one of the greatest advances in recent years. It is particularly well suited in diagnosis of spinal disorders since it can visualize the spinal cord and cerebrospinal fluid without intrathecal contrast agents. This is a preliminary report of our experience of NMR examination in 106 patients studied since November 1982 at Case Western Reserve University Hospital. One of the best applications of NMR is for compressive lesions of the upper cervical spine because "functional" images can be obtained. The information from NMR was compared with computed tomography (CT) in 14 patients with various etiologies of neural compression--atlanto-occipital subluxation in Down's syndrome, fixed post-traumatic atlantoaxial subluxation, rheumatoid atlantoaxial subluxation and basilar impression of the odontoid, ossification of the posterior longitudinal ligament, Klippel-Feil syndrome, congenital spinal stenosis, cervical spondylosis, Arnold-Chiari malformation, etc. Unlike CT, NMR can directly image in the sagittal plane without computer reformatting of axial cuts. This readily provides direct images of the spinal cord in neutral, flexion, and extension to show the mechanism of neural compression. Disadvantages of NMR compared with CT include poorer image resolution, slightly increased imaging time, and no patients with intracranial aneurysm clips or cardiac pacemakers can be studied. Advantages include no radiation exposure, no intrathecal contrast agent is required to differentiate CSF from neural tissue, and direct sagittal, coronal, and oblique images can be obtained. As a result of this preliminary experience, computed tomography and nuclear magnetic resonance imaging appear to be complimentary studies--CT provides better osseous detail, whereas NMR offers superior soft tissue resolution.     

Magnetic resonance imaging in the preoperative evaluation of cervical radiculopathy

Forty patients with cervical radiculopathy were examined preoperatively with magnetic resonance imaging (MRI). MRI was used alone in 27 (68%) of the 40 patients; the remainder also had computed tomography in conjunction with myelography. The primary criterion on MRI for a clinically significant lesion was asymmetrical narrowing of the subarachnoid space in the region of the nerve root. Surgical confirmation of the abnormality was obtained in all 40 cases. The operative findings were a herniated nucleus pulposus (32 of 40 patients), spondylosis (2 of 40 patients), or a combination of the two (6 of 40 patients). MRI identified a surgical lesion (herniated nucleus pulposus, spondylosis, or both) in 37 of the 40 (92%) patients. We think MRI is the only preoperative imaging examination necessary in most cases of cervical radiculopathy.     

脊髓型颈椎病患者颈脊髓磁共振扩散张量成像的特点及临床意义

目的 :观察脊髓型颈椎病(cervical spondylotic myelopathy,CSM)患者磁共振扩散张量成像(diffusion tensor imaging,DTI)的特点,探讨DTI在评价颈脊髓慢性损伤的价值。方法:纳入2011年2月~2015年2月间收治的20例CSM患者(CSM组),并选择年龄匹配的42例健康志愿者作为对照组,均行颈椎磁共振DTI,测量CSM组病变节段以及对照组C2/3~C6/7节段颈脊髓的表观弥散系数(apparent diffusion coefficient,ADC)、各向异性分数(fractional aniostropy,FA)。比较对照组不同节段颈脊髓的ADC值和FA值,将CSM组和对照组颈脊髓的ADC值和FA值分别进行比较,并对CSM患者颈脊髓ADC、FA评分和颈椎改良JOA(m JOA)评分分别进行相关性分析。结果:对照组颈脊髓的ADC值自C2/3~C6/7节段呈上升趋势,而FA值呈下降趋势,C2/3节段颈脊髓的ADC值较C5/6和C6/7节段明显低,而FA值明显高(ADC:F=3.546,P=0.008;FA:F=13.82,P0.001)。CSM组颈脊髓的FA值与对照组比较显著性减小(P0.001),而ADC值则显著性增加(P0.001)。CSM组颈脊髓的ADC值与m JOA评分无显著相关性(r=-0.287,P=0.220),而颈脊髓的FA值与m JOA评分存在显著性正相关(r=0.359,P=0.005)。结论:CSM患者颈脊髓DTI与正常人群存在差异,其ADC值较正常人群升高,而FA值则明显降低;m JOA评分与FA值呈正相关。