Ultrasonographic Evaluation of Peripheral Nerves for Early Diagnosis of Guillain-Barré Syndrome: A Case-Control Study.

Background and Aim: Guillain-Barré syndrome (GBS) is an acute immune-mediated neuropathy in which early diagnosis remains challenging because nerve conduction studies (NCS) may appear normal in the first few days after onset. Ultrasonography (US) has recently gained attention as a non-invasive tool for evaluating peripheral nerve pathology. This study aimed to assess the usefulness of ultrasonographic cross-sectional area (CSA) measurement of peripheral nerves for the early diagnosis of GBS in Iranian patients within 2 weeks of GBS symptom onset. Methods: In this case-control study, 150 participants were enrolled, including 75 patients with GBS and 75 healthy controls matched for age and sex. Patients were referred to Golestan Hospital (Ahvaz, Iran) between November 2023 and June 2025 with less than 2 weeks of GBS onset. All participants underwent demographic and clinical assessments, NCS, and US evaluations of the ulnar and median nerves. Results: Each group of participants (patients or controls) comprised 47 men and 28 women. The mean age of the patients with GBS was 43.8 ± 10.9 years. Statistically significant mean differences were found in all measured variables of the ulnar and median nerves, including ultrasonographic CSAs and NCS parameters (F-wave latency and persistence, motor nerve conduction velocity (MCV), sensory nerve conduction velocity (SCV), sensory nerve action potentials (SNAP), distal motor latency (DML), and compound muscle action potential (CMAP)), between patients with GBS and those in the control group ( Conclusion: Sonographic measurement of the CSA of the ulnar and median nerves differentiates early-stage GBS patients from healthy controls and may support early diagnosis. The combination of US and NCS provides complementary information that facilitates early recognition of GBS.