Diagnostic Utility of the H-Reflex in Clinically Diagnosed Diabetic Polyneuropathy: A Cross-Sectional Study

Abstract

Background: Diabetic polyneuropathy (DPN) is a prevalent and debilitating complication of diabetes mellitus. Early detection is critical to prevent progressive morbidity, but routine physical examinations and standard nerve conduction studies (NCS) have practical limitations. This study evaluated the diagnostic accuracy of soleus H-reflex recording as an accessible electrophysiological modality in clinically diagnosed DPN.

Methods: In this cross-sectional study, 60 patients with type 2 diabetes mellitus were evaluated: 30 with clinically diagnosed DPN (Toronto criteria) and 30 age- and sex-matched diabetic controls without clinical neuropathy. Bilateral soleus H-reflex latency, amplitude, and evoke-ability were assessed using standard surface electrophysiological protocols. Diagnostic metrics, receiver operating characteristic (ROC) curves, and multivariate logistic regression were computed against clinical diagnosis.

Results: H-reflex abnormalities (prolonged latency \ge 30\text{ ms} or absent responses) were present in 85.0% (25.5/30) of patients in the DPN group and 30.0% (9/30) in the non-DPN group. The diagnostic sensitivity was 85.0% (95% CI: 67.4–94.8%), specificity was 70.0% (95% CI: 50.6–85.3%), PPV was 73.5% (95% CI: 55.6–87.1%), and NPV was 82.7% (95% CI: 64.2–94.2%). The mean H-reflex latency was significantly prolonged in the DPN group (33.4 \pm 2.8\text{ ms}) compared to controls (28.2 \pm 1.6\text{ ms}; p < 0.001). The area under the ROC curve (AUC) for H-reflex latency was 0.88 (95% CI: 0.79–0.96; p < 0.001).

Conclusion: Soleus H-reflex is a sensitive, objective, non-invasive electrophysiological tool that effectively identifies large-fiber sensorimotor dysfunction and aids in detecting subclinical neuropathy in outpatient diabetic populations.