Measurement of the lateral recess angle as a possible alternative for evaluation of the lateral recess stenosis on a CT scan

Stenosis of the lateral recess in the lumbar spinal canal is a clinical pro blem, especially in terms of surgical management. Criteria for the diagnosi s and surgical treatment of lateral recess stenosis (LRS) are not clearly d efined. Several authors have suggested measurement of the lateral recess he ight (LRH) on computed tomography (CT) scans as a helpful tool for making d ecisions in regard of management. The present study is based on the assumpt ion that measurement of the lateral recess angle (LRA) may be useful in the clinical management of lateral recess stenosis. The reliability and signif icance of the results have been analyzed, in 35 patients, the stenosis was confirmed by intraoperative measurement of the lateral recess height. Fifty -three affected lateral recesses were analyzed. Before surgery, the heights on CT scans were measured. The mean value was 3.3 mm (SD = 0.9 mm), while 41 of them were 3.6 mm or less. Furthermore, the angles on CT scans were ev aluated. The mean value was 25.9 degrees (SD = 4.9 degrees), 48 of them wer e 30 degrees or less and only 5 of them achieved more than 30 degrees. Resu lts reveal that the best quantitative determination of a lateral recess ste nosis is a CT scan angle measurement with a critical value of 30 degrees. A CT scan height of 3.6 mm or less is also indicative of stenosis. Statistic al evaluation of the data by multiple regression analysis revealed agreemen t between intraoperative findings and measured heights (p = 0.02), while ev en better results were noted for angles (p < 0.01). Interfacet distance (IF ) was found to be least predictive (p = 0.04).