CLASSIFICATION-SYSTEM BASED ON KINEMATIC MR-IMAGING IN CERVICAL SPONDYLITIC MYELOPATHY

BACKGROUND AND PURPOSE: Functional myelographic studies are often used to evaluate the dynamic changes of the cervical spinal canal during f lexion and extension. The purposes of this study were to use kinematic MR imaging to assess the dynamic changes of the cervical spine in pat ients at different stages of degenerative disease and to describe a cl assification system based on static and dynamic factors in the pathoge nesis of cervical spondylitic myelopathy. METHODS: Eighty-one patients with different stages (I-IV) of degenerative disease of the cervical spine were examined with MR imaging, In the neutral position (0 degree s) and at maximum flexion and extension, spinal stenosis was classifie d for each segment according to the following grading system: 0 = norm al, 1 = partial obliteration of the anterior or posterior subarachnoid space, 3 = complete obliteration of the anterior or posterior subarac hnoid space, and 3 cervical cord compression or displacement. RESULTS: At flexion and extension, the prevalence of spinal stenosis and cervi cal cord impingement increased as the stage of degenerative disease pr ogressed. With regard to a pincer effect (anterior and posterior cord impingement) and cord encroachment at multiple segments, statistically significant differences were observed at stages III and IV as compare d,vith stages I and II. Significant increase in cord impingement was s een in 22 (27%) of 81 patients at extension, as compared with four (5% ) of 81 patients at flexion. CONCLUSION: Regardless of the stage of de generative disease and grade of spinal stenosis at the neutral positio n (0 degrees), cervical spinal motion may contribute to the developmen t of cervical spondylitic myelopathy,