SEVERE MOTOR WEAKNESS ASSOCIATED WITH LUM BAR SPINAL STENOSIS - A SERIES OF 61 CASES

Purpose of the study Severe motor weakness is a rather infrequent symp tom in the course of lumbar stenosis. The objectives of this study are three fold : describe the motor deficit, evaluate the prognosis facto rs and determine the type of stenosis the most likely to be complicate d by motor loss. Material and methods 61 consecutive patients with a m ean age of 63 years, operated on for a lumbar stenosis and with a seve re motor deficit have been retrospectively studied, The mean follow-up was 38 months. The overall functional result was evaluated according to a rating scale, specially developped in our unit for the follow-up of lumbar stenosis. The motor capacity was rated from 0 (complete para lysis) to 5 (normal strength). According to that scale the motor weakn ess was rated as 0, 11. times as 1, 11 times, as 2, 11 times and as 3, 28 times. The deficit was unilateral in 79 per cent of cases and mult iradicular in 58 per cent of patients. Sphincter abnormalities were al so present in 9 cases. In 9 out of 10 patients the motor deficit was i n the L5 territory, Stenosis was extended to 3 levels in 30 cases and was focal in the remaining cases. Degenerative spondylolisthesis was d isclosed in 20 patients. In 3 out of 4 cases decompression was perform ed after 3 weeks of motor weakness and within 3 weeks in the remaining cases. Results According to our rating scale the overall results were considered excellent in 29 cases, good in 21 cases and fair in the ?I remaining cases, There was no complication, and no postoperative wors ening of the deficit was observed. Regression of motor weakness was co mplete 22 times, partial 29 limes and null 10 times. In the eleven com plete deficits with a 0 cotation one receded completely, 7 receded par tially and no improvement was noted in the 3 remaining cases. 6 out of the 9 patients with sphincter abnormalities recovered complety, in th is study favourable prognosis parameters were as follows : age under 6 2 years, monoradicular deficit, stenosis at one level and association with a discal herniation. In contrast, severity of the initial motor w eakness, association with sphincter abnormalities, presence or not of degenerative spondylolisthesis, or of a complete block on the myelogra m were not influential variables. Chances of recovery were statistical ly diminished when decompression was performed after 6 weeks. Discussi on and conclusion No study dealing specifically with the postoperative outcome of motor deficit caused by lumbar stenosis has been published , However the rate of motor recovery (complete or partial) disclosed i n our series is comparable with that found in other series dealing mor e generally with the overall post-surgery outcome. At our last follow- up, 82 per cent of our patients were considered as having an excellent or good result. II can be concluded that the existence of a motor def icit is not a major pejorative factor of the overall final functional result. Motor weakness is more frequently observed in eldery patients, in cases with degenerative spondylolisthesis, or when a discal hernia tion is associated with a bony compression. Chances of recovery are be tter, when the deficit is monoradicular, when the stenosis is focal, o r associated with a discal herniation and when the patient is relative ly young.