541: Bilateral Sciatic Nerve Impairment in Patients with Unilateral Chronic Painful Radiculopathy

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic neuropathic pain, Developing methodology/technology, Assessment and Measurement of Pain/Nociception, Imaging (e.g. fMRI, PET, MRS)

Background and Aims: Painful radiculopathy is a common neuropathic pain condition. Patients with chronic painful radiculopathy may present with bilateral nerve impairments. A comparison of both sides of a patient with a matched control could clarify whether the sciatic nerve is impaired bilaterally. This study aimed to compare the cross-sectional area (CSA) and skin-to-nerve distance (SKN) of the sciatic nerve between patients with probable neuropathic pain and matched asymptomatic controls.

Methods: A case-control study was conducted with 31 participants presenting unilateral painful radiculopathy and 31 matched asymptomatic controls. We prospectively recruited asymptomatic adults matched for age, sex, and affected side. The current study focused on data comparing the morphology (measured by CSA) and response to increased tension (measured by SKN) from patients and controls. Ultrasound evaluation of the sciatic nerve was performed at the posterior mid-thigh under two tension conditions: hip flexed with knee flexed (lesser tension position), and hip flexed with knee extended plus ankle dorsiflexion (greater tension position). Group comparisons were performed with repeated measures two-way analysis of variance.

Results: Patients with radiculopathy demonstrated significantly greater CSA bilaterally compared to controls (p ≤ 0.001). Within-patient comparisons revealed no significant differences in CSA between symptomatic and asymptomatic sides. CSA decreased under greater neural tension in the radiculopathy group (p < 0.0001) but not in controls. A two-way repeated measures ANOVA revealed a significant interaction effect for CSA [F(2,90) = 5.015, p < 0.01]. SKN analysis showed significant group and positional effects (p < 0.0001), with controls presenting greater values than patients in both positions. A repeated measures two-way ANOVA revealed a non-significant interaction effect for SKN [F(2,90) = 1.469, p = 0.24].

Conclusions: Participants with neuropathic pain exhibited bilaterally significantly greater CSA than controls in both positions. The control group showed the sciatic nerve to be more superficial in both positions when compared to the patients` symptomatic and asymptomatic sides. The control group sciatic nerve demonstrated a different response to the increase of tension in the CSA and a similar response to the SKN when compared to the patients’ sides. The similarities between both sides of the patients and the differences compared to the control group suggest bilateral sciatic morphological alterations in patients with chronic painful radiculopathy.

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Presenting Author: Leandro Calazans Nogueira
Submitting Author: Leandro Calazans Nogueira

Senior Author: Leandro Calazans Nogueira

IASP 2026 Global Year theme of Neuropathic Pain: Yes

• Rayssa de Vilhena Moreira: MSc - Augusto Motta University Centre
• Ricardo Liberalli Miguez: MSc - Augusto Motta University Centre
• Maria Alice Mainenti Pagnez: PhD - Augusto Motta University Centre
• Luiza Ferreira Moreira: PT - Augusto Motta University Centre
• Louise Acalantis Pereira Pires Fernandes: MSc - Augusto Motta University Centre
• Stephanie Mathieson: PhD - The University of Sydney
• Juliana Valentim Bittencourt: PhD - Augusto Motta University Centre