Causes of neurologic deterioration following surgical treatment of cervical myelopathy.

Neurologic deterioration was analyzed in 110 patients with surgically treated cervical myelopathy secondary to soft disc hernia or spondylosis. Follow-up periods ranged from 2 to 14 years, with an average of 6 years. Of 110 patients, 29 suffered neurologic deterioration. In most of the patients, deterioration occurred within the first year after surgery. Causes of deterioration were divided into three categories: direct trauma to neural tissue during surgery (a preventable complication); instability of the spine, progression of spondylotic changes above or below the level of fusion, and non-union (apparently unpreventable but treatable); and nonsurgery-related accidental trauma (unavoidable and often irreversible). Countermeasures for the deterioration are discussed.