A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part I: Clinical features related to radiographic findings.

STUDY
DESIGN: A prospective study of consecutive patients undergoing surgery for central lumbar spinal stenosis.
OBJECTIVES: To evaluate symptoms and signs in patients undergoing surgery for central spinal stenosis and to correlate the findings to age, preoperative duration of symptoms, and radiographically detected constriction. SUMMARY OF BACKGROUND DATA: The degree of constriction of the spinal canal considered to be symptomatic of lumbar canal stenosis is not clear, nor is the relation between the clinical appearance of the disease and the degree of radiographically verified constriction.
MATERIAL AND METHODS: One hundred five consecutive patients scheduled for decompression surgery were included in a prospective study. The day before surgery, all patients were interviewed and examined, using a defined protocol that included data on age, gender, preoperative duration of symptoms, walking ability, and occurrence of pain at rest and at night. Included were data recording straight leg raising test results, reflex disturbance, and extensor hallucis longus muscle weakness. All radiographs were examined by a neuroradiologist. The anteroposterior diameters at each site from L1-L2 to L5-S1 were recorded. For the computer analysis, the site of and width at the narrowest site was registered, as well as the number of sites with an anteroposterior diameter of less than 10 mm. A statistical analysis was performed using chi-square analysis, nonparametric tests, analysis of variance, and logistic regression.
RESULTS: Pain at rest and at night was reported by 68 and 60 patients, respectively, and was more common in younger patients (P = 0.065 and 0.015, respectively). A severe reduction of walking ability (< 0.5 km) was reported by 70 patients. The straight leg raising test results were negative in 70 patients, positive > 60 degrees in 16, positive 30-60 degrees in 14, and positive < 30 degrees in 5. Younger patients had a positive straight leg raising result (P = 0.028, analysis of variance) more often. Reflex disturbances correlated to patient age: Older patients had reflex disturbances more often. There was no correlation between preoperative duration and pain or neurologic disturbances: Patients with longer preoperative duration of symptoms did not demonstrate more severe symptoms. There was a total myelographic block of the spinal canal in 13 patients. The mean value of the antero-posterior diameter in the other patients was 6.8 mm (range, 4-11 mm). In patients younger than 70 years L4-L5 was the site for the most pronounced constriction, whereas L3-L4 was the narrowest site in the older patients. Degenerative spondylolisthesis was found in 32 patients, and they had a more pronounced constriction of the spinal canal (5.6 mm compared with 6.7 mm in those without displacement, P = 0.02). There was a (nonsignificant) tendency toward more walking disturbances in patients with a more pronounced constriction of the spine. There was no correlation between reflex disturbances or extensor hallucis longus weakness and radiographically detected constriction.
CONCLUSION: Pain was more intense and positive straight leg raising test results were more common in younger patients, whereas reflex disturbances were more common in the elderly. The vertebral site for the lowest anteroposterior value was higher with higher age. Preoperative duration did not affect the severity of symptoms or signs. Patients with more pronounced stenosis tended to have a more severe reduction of walking ability. There was no correlation between symptoms and signs and radiographically detected constriction.