[A classification of the herniated cervical disc based on metrizamide CT].

In 202 surgical cases of anterior fusion of cervical spine, there were 150 cases in which disc herniation was the responsible lesion. According to metrizamide CT (met. CT) findings of these 150 cases, we proposed to classify the herniated cervical disc into 7 types. In the 150 cases there were 103 men and 47 women. Seventy-seven had single disc lesion, 57 had the two and 6 had three disc lesions. The most frequent involvement was of C 5/6 in 107 cases (51.2%). The next was of C 6/7 in 50 cases (23.9%) and the third was of C 4/5 in 36 (17.2%). Primarily herniated discs were classified into soft or hard disc. The soft discs were classified into medial, mediolateral and lateral type according to the direction of the protrusion of the disc. Each of the three types indicates that herniated disc compresses the median portion of the cord, lateral part of the cord and root simultaneously and root alone, respectively. The hard discs were classified into central, bilateral and unilateral types. The central type means the case in which the cord was compressed by the centromedian part of the posterior aspect of the vertebral body. The unilateral and bilateral type indicate that lateral portion of the cord and root were simultaneously compressed by the disc unilaterally or bilaterally. The other one was combined type. The combined type is that which belongs neither of the types noted above. In the soft disc group there were 37 cases (17.7%) of medial type, 28 (12.4%) of mediolateral and 8 (3.8%) of lateral type.(ABSTRACT TRUNCATED AT 250 WORDS)