Shape of the spinal canal is not associated with success rates of microsurgical unilateral laminotomy and bilateral decompression for lumbar spinal canal stenosis.

Shape of the spinal canal is not associated with success rates of microsurgical unilateral laminotomy and bilateral decompression for lumbar spinal canal stenosis.

World Neurosurg. 2018 Mar 27;:

Authors: Schatlo B, Horanin M, Hernandez-Durán S, Solomiichuk V, Rohde V

Abstract
INTRODUCTION: Lumbar spinal stenosis (LSS) is one of the most frequent neurosurgical affections. It has been reported that the anatomical shape of the spinal canal (oval, round, trefoil) predicts outcome of bilateral decompression performed in an undercutting technique via a unilateral laminotomy in monosegmental LSS. The poorest results were observed in a trefoild spinal canal, leading to the proposal of using a bilateral instead of a unilateral laminotomy. We have been routinely performing a unilateral microsurgical approach with undercutting to decompress both sides of the spinal canal for more than a decade. Subjectively, we were not under the impression that shape was of relevance to surgical outcome. Therefore, the aim of the current study is to re-assess whether this anatomical distinction into oval, round and trefoil-shaped spinal canal indeed is of relevance to surgical treatment of the LSS.
METHODS: We performed a retrospective chart review of patients undergoing lumbar decompression surgery. Spinal canal configuration was assessed on preoperative CT-scans based on maximal transverse and anterior-posterior diameter and shapes were classified accordingly into oval, trefoil and round. Associations between canal shape and outcome improvement (aggregate of walking distance and leg pain) were tested using receiver-operator curve analysis and Chi2 with a significance level defined as a p-value of <0.05.
RESULTS: A total of 236 lumbar levels were decompressed in 159 patients. Mean age was 73+-8 years. Mean BMI was 29+-6 and the average number of operated segments was 1.3+-0.6. Oval shaped configurations were detected in 155 (65%; L1/2: 67%, L2/3: 96%, L3/4: 73%, L4/5: 58%, L5/S1: 0%). Round shaped segments constituted 11 (5%; L1/2: 0%, L2/3: 0%, L3/4: 8%, L4/5: 3%, L5/S1: 0%) and trefoil-shaped segments 70 (30%; L1/2: 33%, L2/3: 4%, L3/4: 19%, L4/5: 39%, L5/S1: 100%) levels. Postoperative improvement was recorded in 91.7% of patients. Spinal canal shape had no influence on surgical outcome (Oval: Area under the curve (AUC) 0.529, p-value 0.672; trefoil:AUC 0.500, p-value 0.997; round: AUC 0.471, p-value 0.670).
CONCLUSION: Our results suggest that the configuration of the spinal canal, particularly the nomenclature of oval, round and trefoil is an anatomical function varying in frequency with lumbar segment. Our results do not support the notion that the classification should influence surgical decision making.

PMID: 29602004 [PubMed - as supplied by publisher]

https://ift.tt/2JaRiLi