Analysis Of 34 Cases Of Far Lateral Lumbar Disc Herniations

Objective: To summarize the clinical features of 34 far lateral lumbar disc herniation (FLLDH) out of 369 cases of LDH treated in our department from 2002.1 to 2007.4 retrospectively, and to explore the incidence, clinical features and the reasons of misdiagnosis of FLLDH.Methods: 34 cases in this group, there were 18 males and 16 females; the average age was 55.7 years old (rang, 45~71); 2 cases had trauma history, others had no obvious inducement; mean course was 14.6 months (rang, 7d～96months). The preliminary diagnosis was FLLDH in 22 cases; postlateral LDH in 5 cases; lumbar canal stenosis in 2 cases; lumbar muscle strain in 2 cases, and pyriformis syndrome in 3 cases. 14 cases only took the usually intervertebral disc scanning of CT, among which there wasn't any founding in 5 cases. All took the routine and dynamic X-ray test, multilayer CT and MRI scanning for vertebral body and intervertebral disc. Selected JOA score system as the clinical objective evaluation criterion. Classify the FLLDH into intervertebral foramen type, extra intervertebral foramen type and the mixed type according to the imaging features.Results: The incidence of FLLDH was 9.21% in all the LDH patients. According to the CT and MR imaging, there were 15 cases of L3/4 FLLDH, 16 cases of L4/5 and 3 cases of L5/S1. All the FLLDH were found in the single intervertebral space. 14 cases belonged to intervertebral foramen type; 8 cases belonged to extra intervertebral foramen type; 8 cases of mixed type had a postlateral LDH at the same segment, another 4 cases of mixed type had a postlateral LDH at upper segment. There were 2 cases with stenosis of intervertebral foramen and 2 cases with stenosis of spinal stenosis. The blocks which had the same density with the nucleus pulposus can be found in all CT films of the 34 cases, among them 5 cases can found calcification. We can find the same signal blocks with the nucleus pulposus in (out of) the intervertebral foramen from the transverse plane, and dehydrate and degeneration intervertebral disc and low signal blocks in (out of) the intervertebral foramen from the sagittal plane. The 3 types of FLLDH did not have a significant difference in VAS low back pain scores (p>0.05); the intervertebral foramen type had a significant difference with the other two in VAS low limb pain scores (p<0.01) and JOA scores (p<0.05) while the other two didn't have a significant difference (p>0.05).Conclusion: FLLDH has a significant incidence in the LDH, so we should treat it seriously. We can decrease the misdiagnosis with knowing it better and using the whole lumbar CT and MRI.