Incidence and characteristics of spinal decompression surgery after the onset of symptoms of amyotrophic lateral sclerosis.

OBJECTIVE: The high incidence of spondylosis in patients at the mean age of onset (55.7 yr) of amyotrophic lateral sclerosis (ALS) can make recognition of ALS as a cause of weakness difficult. METHODS: To assess the impact of this diagnostic dilemma on neurosurgical practice, we performed a retrospective analysis of a database of more than 1500 patients with motor neuron disease. RESULTS: Of 1131 patients with typical, sporadic ALS, 47 (4.2%) underwent decompressive spinal surgery after the onset of retrospectively recognized symptoms of ALS. Among 55 operations in 47 ALS patients, 86% yielded no improvement, 9% produced minor improvement, and only 5% provided significant benefit. Cervical decompression was performed in 56%, lumbar in 42%, and thoracic in 2%. Foot drop was a symptom prompting surgery in 11 patients, and in 10, this finding was subsequently attributed solely to ALS. No differences between ALS patients who underwent spinal decompression and other ALS patients were noted regarding age at symptom onset, severity of impairment at time of diagnosis, or rate of disease progression. Not surprisingly, patients who had spinal surgery tended to have a longer interval between retrospectively recognized symptom onset and diagnosis of ALS. CONCLUSION: A small but significant number of patients with unrecognized ALS undergo spinal surgery that in retrospect may be inappropriate. The possibility of ALS must be considered in the evaluation of patients with weakness even in the presence of radiographic evidence of spondylosis and nerve root or spinal cord impingement.