Enlargement of cervical spinal cord correlates with improvement of motor function in upper extremities after laminoplasty for cervical myelopathy

OBJECTIVE: The correlation between postoperative spinal cord enlargement at the most compressive disc level and clinical outcome is controversial. The relationship between spinal cord enlargement at neurologically symptomatic disc level and clinical recovery has not been explored. The purpose of this study was to clarify the relationship between postoperative spinal cord enlargement at neurologically symptomatic disc level and neurologic outcome. METHODS: We studied 55 consecutive patients between 1995 and 2002. All patients underwent preoperative neurologic examination to determine the neurologically symptomatic disc level of the spinal cord and computed tomographic myelography twice before and 4 weeks after laminoplasty. The cross-sectional areas of both spinal cord and dural sac from C3/4 to C7/T1 disc levels were measured on computed tomographic myelography images. The Japanese Orthopedic Association scoring system was used for clinical evaluation before and 1 year after surgery. RESULTS: Total score improved significantly from 10.2+/-2.8 (SD) to 13.0+/-3.0 after operation. Motor and sensory function scores of upper and lower extremities also improved significantly. The enlargement of spinal cord area at the neurologically symptomatic disc level correlated significantly with improvement in motor function scores of upper extremities (rs=0.421 P=0.0052). However, there were no significant relationships between the enlargement of the spinal cord at the most compressive disc level or that at the dural sac and any categories of Japanese Orthopedic Association scoring system. CONCLUSION: Postsurgical enlargement of the cervical spinal cord at the neurologically symptomatic disc level at 4 weeks postoperatively correlated with recovery of motor function of the upper extremities at 1 year.