Redundant Nerve Roots of the Cauda Equina, MRI Findings and Postoperative Clinical Outcome: Emphasizing an Overlooked Entity

Abstract

Study Design: Retrospective study. Objective: To describe the MRI findings of RNRs in patients with low back pain, and observe the imaging findings and the clinical outcome post decompression surgery. Methods: The lumbar spine MRI of 202 patients (122 females) with proven RNRs were retrospectively reviewed. The morphology and the location of the RNRs in relation to the level of stenosis were described. The level(s), grade and cause of lumbar canal stenosis were recorded. The persistence of symptoms and the imaging findings on follow up post decompression surgery were recorded. The imaging findings were correlated among each other and with patients’ demographics. Results: Two distinctive morphological appearance of the RNRs were noted: loop (56.4%), and serpentine-shaped. In the majority of the cases the RNRs were located above the level of stenosis (79.7%). Eighteen patients underwent decompression surgery, only 4 patients remained symptomatic post decompression surgery. The RNRs changed in shape and location after decompression surgery. Age was a strong predictor value in the location of the RNRs. There was no correlation between the shape and location of the RNRs, or with the gender of the patients. Conclusion: RNRs is not an uncommon finding on lumbar spine MRI with lumbar canal stenosis. Its importance remains a controversy. A common language between the radiologists and the clinicians is mandatory to aid in the management planning.

Effectiveness of caudal block in patients with spinal stenosis accompanied by redundant nerve root syndrome

“…This result is also consistent with the findings reported by Nathani et al. 11 , 18 It may be assumed that more degenerative changes of the spine occur over time, resulting in the development of RNRS. Among the MRI parameters, the dural sac AP diameter, left ligamentum flavum thickness, and right foraminal AP diameter were significantly correlated with RNRS.…”

Redundant nerve roots on magnetic resonance imaging can predict ongoing denervation in patients with lumbar spinal stenosis

“…The difference in our study may be attributed to initial selection bias caused by inclusion of patients who underwent an EDX study for several reasons, primarily severe neurological symptoms. Neurogenic symptoms were more prevalent in our study than in the prior study, 3 even in the non-RNR group.…”

“…As RNRs were initially described by myelographic findings, they were mainly classified by their morphology as serpentine or loop type. Several studies have explored the clinical significance of RNR morphology 3,6,12,22 . Yokoyama et al, 22 who followed up 33 patients with LSS who had RNRs for 1 year after decompression laminectomy, reported that loop‐type RNRs were more frequent in patients with poorer functional outcomes.…”

“…They were first described as a filling defect on myelography in 1954, 1 and the term RNR was subsequently coined in 1968 2 . With advances in diagnostic modalities, the presence of RNRs is now recognized on T2‐weighted sagittal and/or axial magnetic resonance imaging (MRI) 3–7 …”

“…3,12 According to Ono et al,12 sagittal T2-weighted MRI was inferior to myelography for detection of RNRs, and serpentine-type RNRs (23.5%) were particularly more difficult to identify on MRI compared to loop-type RNRs (97.6%). Thus, distinguishing the shape of RNRs may have low specificity and limited clinical significance.…”