Radiological Significance of Ligamentum Flavum Hypertrophy in the Occurrence of Redundant Nerve Roots of Central Lumbar Spinal Stenosis

Abstract

ObjectiveThere were previous reports of redundant nerve roots (RNRs) focused on their clinical significance and pathogenesis. In this study, we investigated the significant radiologic findings that correlate with RNRs occurrence. These relations would provide an advanced clue for clinical significance and pathogenesis of RNRs.MethodsRetrospective research was performed with data from 126 patients who underwent surgery for central lumbar spinal stenosis (LSS). Finally, 106 patients with common denominators (inter-observer accuracy : 84%) were included on this study. We divided the patients into two groups by MRI, patients with RNRs and those with no RNRs (NRNRs). Comparative analyses were performed with clinical and radiologic parameters.ResultsRNRs were found in 45 patients (42%) with central LSS. There were no statistically significant differences between the two groups in severity of symptoms. On the other hand, we found statistically significant differences in duration of symptom and number of level included (p<0.05). In the maximal stenotic level, ligamentum flavum (LF) thickness, LF cross-sectional area (CSA), dural sac CSA, and segmental angulation are significantly different in RNRs group compared to NRNRs group (p<0.05).ConclusionRNRs patients showed clinically longer duration of symptoms and multiple levels included. We also confirmed that wide segmental angulation and LF hypertrophy play a major role of the development of RNRs in central LSS. Together, our results suggest that wide motion in long period contribute to LF hypertrophy, and it might be the key factor of RNRs formation in central LSS.

Redundant nerve roots in lumbar spinal stenosis: inter- and intra-rater reliability of an MRI-based classification

“…1). In the remaining 40% of patients, redundant nerve roots (RNRs) of the cauda equina are evident on preoperative magnetic resonance images (MRIs) [2][3][4][5]. RNRs were first described by Verbiest [6] in 1954, and they were named 14 years later by Cressman and Pawl [7].…”

Tumor Occupation in the Spinal Canal and Clinical Symptoms of Cauda Equina Schwannoma: An Analysis of 22 Cases

“…A number of studies have analyzed cross-sectional areas of intracanal-occupying lesions, such as lumbar disc herniation, burst fracture, ligamentum flavum, and ossification of the posterior longitudinal ligament [3456]. Some authors have reported a correlation of clinical symptoms with both the cross-sectional area of the dural sac and the extent of lumbar canal stenosis [78910111213].…”

“…Furthermore, because cauda equina schwannomas may move craniocaudally, we should consider the influence of tumor mobility in the dural sac [41516171819]. Hence, further investigation examining tumor mobility is needed.…”

“…Another limitation of this study is that we did not consider the shape or hardness of the tumors or deviations in the spinal canal [4252627]. Age, the existence of congenital/degenerative spinal canal stenosis, and vertebral disc pathologies are also important factors that may strongly affect clinical symptoms [9132223].…”

Electrodiagnostic characteristics of upper lumbar stenosis: Discrepancy between neurological and structural levels

“…We conducted a retrospective study of patients who underwent EDX because of neurological symptoms of the lower extremity and lumbosacral MRI for suspected spinal structural lesions between July 2014 and August 2017. The inclusion criteria were (1) an interval of less than 3 months between EDX and MRI; (2) abnormal EDX findings necessarily including abnormal spontaneous activity (positive sharp waves or fibrillation potentials) in lower extremity muscles; and (3) upper lumbar (L1/2, L2/3, or L3/4) central canal stenosis, defined as a CSA of the dural sac of <100 mm 2 on lumbar spine MRI . The exclusion criteria were (1) concomitant peripheral polyneuropathy suspected by clinical manifestations and diagnosed by a nerve conduction study (NCS); (2) structural lesions on MRI at the L4/5 or L5/S1 level in the spinal canal or the neural foramina that could explain the EDX abnormalities; and (3) acute cauda equina syndrome, characterized by a rapid progression of neurological deficits, including bladder and bowel dysfunctions or sensory changes in the perineal area; and (4) a history of lumbar spine surgery whose current symptoms developed before the surgery or within 1 year after surgery.…”