Cervical spondylotic myelopathy: patterns of neurological deficit and recovery after anterior cervical decompression

We evaluated the specific pattern of pre- and postoperative neurological signs and symptoms and functional results in patients with cervical spondylotic myelopathy who underwent anterior decompressive operations. Additionally, we sought to determine which findings had predictive value for surgical outcome.

We retrospectively reviewed the records of 76 patients with cervical spondylotic myelopathy caused by osteophytic ridge or intervertebral disc herniation who underwent anterior cervical decompression and fusion performed by one surgeon. The patients were evaluated postoperatively by office visits and/or telephone interviews. Outcome was assessed by objective neurological examination and scoring with multiple functional rating scales.

The most common preoperative symptoms were deterioration of hand use (75%), upper extremity sensory complaints (82.9%), and gait difficulties (80.3%). In the upper extremities, preoperative weakness was most common in the hand intrinsic muscles (56.6%) and triceps (28.9%), and in the lower extremities, preoperative weakness was most common in the iliopsoas (38.8%) and quadriceps (26.3%). In the lower extremities, individual muscle groups had strength improvement rates from 79.1 to 88.1 %; somewhat higher rates, from 81.3 to 90.9%, were observed in the upper extremities. When evaluated by using the Cooper myelopathy scale, lower extremity functional improvement occurred in 46.7% of the patients and upper extremity functional improvement in 75.4%. Overall functional improvement, evaluated by using a modification of the Japanese Orthopedic Association Scale, was noted in 79.7% of the patients who had abnormal scores preoperatively.

Strength improved at rates of approximately 80 to 90% in individual muscle groups after anterior cervical decompression. However, fewer than half of all patients experienced functional improvement in the lower extremities, a discrepancy that was probably caused by persistent spasticity rather than muscle weakness. Postoperative dysfunction in the upper extremities was caused by residual weakness as well as sensory loss. Recurrent symptomatic spondylosis at unoperated levels was calculated to occur at an incidence of 2% per year.