High-Resolution Ultrasonography in the Assessment of Lumbar Radiculoplexus Neuropathy in Diabetics: Preliminary Results of a Case-Control Study

Abstract

Background The traditional diagnosis of lumbar radiculoplexus neuropathy (LRN) is based on a classical sequence of symptoms and targeted electrodiagnostic examination by means of electromyography. Ultrasonography reliably indicates the level of lumbar radiculopathy by assessing edema mesial to the site of compression. Materials and Methods This case-control study was undertaken at a tertiary care hospital between July 2017 and June 2019 on 15 diabetic patients with symptoms of LRN. Fifteen healthy volunteers with no symptoms or clinical signs of LRN were included in the control group. The diameter (D) and transverse diameter (TD) of L1 nerve root (L1NR), L2NR, L3NR, and L4NR were measured, and their cross-sectional areas (CSAs) were calculated based on location in the lateral zone, where the NRs were visualized. On high-resolution ultrasonography, femoral nerve was localized lateral to the femoral artery in the femoral triangle beneath the inguinal ligament. Additionally, the CSA (calculated as CSA [mm 2 ] = D × TD × π/4), the diameter (mm), and transverse diameter (mm) of bilateral femoral nerves at the level of L3-L4 were calculated. Results The difference attributed to CSAs between affected NRs in LRN group and unaffected NRs in controls at levels L1-L4 was considered statistically significant (p < 0.05). Receiver operating characteristic analysis revealed mean values to be 8 mm 2 (CSA) for L1NR, 11.2 mm 2 (CSA) for L2NR, 13.6 mm2 (CSA) for L3NR, and 17.8 mm 2 (CSA) for L4NR. There was significant difference between ΔCSA of LRN patients and controls at L1 to L4 levels (p < 0.05). CSA measurements of lateral femoral cutaneous nerve (8 mm 2) and femoral nerve (58 mm 2) performed on high-resolution ultrasonography were significantly larger on the affected side as compared with the unaffected side. Conclusion Radiculoplexus neuropathy of the lumbar plexus can be reliably diagnosed on high-resolution ultrasonography that can reveal nerve thickening. The laterality of affected NRs was significantly greater in LRN group when compared with controls.