Neurophysiological, Autonomic, and Sonographic Assessment of Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is a prevalent and disabling complication of diabetes, associated with pain, sensory deficits, gait instability, and increased risk of foot ulcers and amputation. Conventional diagnostic methods, such as nerve conduction studies, primarily identify established disease and may overlook early or autonomic involvement. A multimodal assessment integrating neurophysiological, autonomic, and sonographic techniques offers the potential for earlier detection, improved diagnostic accuracy, and optimized patient management.

• Nerve conduction study (Diagnostic test): Nerve conduction studies (NCS) are widely regarded as the gold standard for evaluating large-fiber peripheral nerve function. They measure conduction velocity, latency, and amplitude, providing objective evidence of axonal loss or demyelination. While highly specific, NCS often detect abnormalities only in established diabetic peripheral neuropathy, limiting their sensitivity for early or subclinical disease.
• Nerve ultrasound (Diagnostic test): High-resolution ultrasound (HRUS) is a non-invasive imaging tool that allows structural evaluation of peripheral nerves. It can measure cross-sectional area (CSA), visualize fascicular pattern, and detect nerve enlargement or structural abnormalities. In diabetic peripheral neuropathy, HRUS provides complementary information to functional tests and may identify early or subclinical changes.
• Autonomic assessment (Diagnostic test): Autonomic testing provides insight into small-fiber and autonomic nervous system function, often impaired early in diabetic peripheral neuropathy. Heart rate variability (HRV) during deep breathing and postural change is a simple, non-invasive method to detect cardiovascular autonomic dysfunction

Primary outcomes

• Sensitivity of nerve conduction studies for diagnosing diabetic peripheral neuropathy [Baseline (single study visit)]: Percentage of participants with clinically diagnosed diabetic peripheral neuropathy who have abnormal nerve conduction study results (reduced amplitude and/or reduced conduction velocity) at the baseline visit.

Secondary outcomes

• Correlation between tibial nerve cross-sectional area and tibial motor conduction velocity [Baseline (single study visit)]: Correlation coefficient between tibial nerve cross-sectional area measured by high-resolution ultrasound and tibial motor nerve conduction velocity at the baseline visit.

Sex: All, ages: 18 Years to 75 Years, accepts healthy volunteers

Inclusion Criteria:

Adults aged 18-75 years with type 1 or type 2 diabetes (with or without diabetic peripheral neuropathy), and age and sex-matched healthy controls

Exclusion Criteria:

* Other causes of neuropathy (e.g., CIDP, trauma, toxins, vitamin deficiencies), advanced renal failure,thyroid disease,chronic alcohol use, pregnancy,
* presence of implanted cardiac devicesthat may interfere with autonomic testing

• Nageh Fouly, Study chair, Department of Neurology , Assiut University, Egypt