Identifying lumbosacral plexus nerve root abnormalities in patients with sciatica using 3T readout-segmented echo-planar diffusion weighted MR neurography

Osamah M Abdulaal,Dearbhail O’Driscoll,Peter J Macmahon,Marie Galligan,Louise Rainford,Valerie Reid,Allison Mcgee

doi:10.1186/s13244-021-00992-w

Abstract

ObjectivesTo investigate the accuracy of Diffusion Weighted Imaging (DWI) using the Readout Segmentation of Long Variable Echo-trains (RESOLVE) sequence in detecting lumbosacral nerve abnormalities.MethodsFollowing institutional ethics committee approval, patients with sciatica-type lower limb radicular symptoms (n = 110) were recruited and prospectively scanned using 3T MRI. Additional participants (n = 17) who underwent neurophysiological testing (EMG/NCV), were also prospectively studied. In addition to routine lumbar spine MRI, a DWI-RESOLVE sequence of the lumbosacral plexus was performed. Two radiologists, blinded to the side of patient symptoms, independently evaluated the MR images. The size and signal intensity changes of the nerves were evaluated using ordinal 4-point Likert-scales. Signal-to-noise ratio (SNR), apparent diffusion coefficient (ADC) and size were measured for affected and normal nerves. Inter-observer agreement was determined with kappa statistics; κ.ResultsIn patients who did not undergo EMG/NCV testing (n = 110), the DWI-RESOLVE sequence detected lumbosacral nerve abnormalities that correlated with symptoms in 36.3% (40/110). This is a similar percentage to patients who underwent EMG/NCV testing, which was positive and correlated with symptoms in 41.2% (7/17). Inter-observer agreement for evaluation of lumbosacral nerve abnormalities was excellent and ranged from 0.87 to 0.94. SNR and nerve size measurements demonstrated statistically significant differences for the L5 and S1 nerves (p value < 0.05) for patients who did not undergo EMG/NCV testing.ConclusionThe DWI-RESOLVE sequence is a promising new method that may permit accurate detection and localization of lumbar nerve abnormalities in patients with sciatica.

Highlights

Sciatica, which refers to pain that conforms to the sciatic nerve distribution, is a common cause of disability worldwide [1]
We investigated a tailored Diffusion Weighted Imaging (DWI)-Readout Segmentation of Long Variable Echo-trains (RESOLVE) sequence for the lumbosacral plexus, that would not add excessive time to a typical lumbar spine magnetic resonance imaging (MRI)
For patients on whom an EMG/Nerve conduction velocity (NCV) was not performed (n = 110), the MRI findings demonstrated that only 36.3% (40/110) of patients had findings on DWI-RESOLVE images consistent with a lumbosacral nerve abnormality

Summary

Introduction

Sciatica, which refers to pain that conforms to the sciatic nerve distribution, is a common cause of disability worldwide [1]. Identifying the cause of sciatica-type symptoms can be problematic. The majority of patients with sciatica have a herniated intervertebral disc on magnetic resonance imaging (MRI); it may not be clear which disc level is symptomatic [2, 3]. Sciatica-type symptoms may be non-discogenic in origin. Fracture, synovial cysts, sacroiliitis, hip joint pathology, gluteal tendinopathy and other conditions may be confused with true sciatica [4]. Radiculopathy symptoms can be investigated using electromyography and nerve conduction velocity (EMG/ NCV) testing; these examinations are invasive with limited sensitivity [5, 6]

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