L5 Radiculopathy due to Foraminal Stenosis Accompanied With Vacuum Phenomena of the L5/S Disc on Radiography Images in Extension Position

Study Design.Retrospective study for L5 radiculopathy due to foraminal stenosis with vacuum phenomena (VP) at the L5/S disc.Objective.To investigate the influence of the L5/S VP on L5 radiculopathy, due to L5/S foraminal stenosis.Summary of Background Data.Foraminal stenosis has often been detected via images. However, although this condition is well known, it is occasionally overlooked during diagnosis, because spinal nerve compression is not always visible on stationary images.Methods.Patients who underwent lumbar spine surgery were examined to determine the presence of foraminal stenosis (n=194). The presence of VP and the range of motion of the L5/S disc were assessed on radiography with the lumbar spine in the extended and flexed positions. The shapes of the L5/S foramina were confirmed using sagittal magnetic resonance imaging. Patients who showed VP were divided into 2 groups: patients with (group A) and without (group B) symptomatic foraminal stenosis. The relationship between the VP and symptomatic foraminal stenosis was examined.Results.In total, 35 cases of VP at the L5/S disc were noted on lateral radiography. L5 radiculopathy due to L5/S foraminal stenosis was identified in 14 of these 35 cases. The ranges of L5/S angles were 10 degrees 4 degrees and 5 degrees 3 degrees in groups A and B, respectively, and these values were significantly different (P<0.01). 11 (48%) of 23L5/S foramina that showed VP of the L5/S disc and were completely occupied by a disc below the caudal edge of the vertebra had symptomatic foraminal stenosis.Conclusion.Our results indicated that VP, which showed a large range of motion angle between flexion and extension, triggered symptoms of foraminal stenosis at the L5/S disc. The dynamic motion of the VP should thus be considered for the diagnosis of L5/S foraminal stenosis.Level of Evidence: 3