Tibial Nerve Elastography in Chemotherapy-Induced Neuropathic Pain

Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting side effect observed in 30-40% of patients receiving neurotoxic chemotherapy. CIPN typically presents with sensory symptoms such as paresthesia, numbness, balance disturbances, heightened pain sensitivity, and deep tendon reflex loss. The severity and progression of neuropathy vary widely among patients.

The diagnosis of peripheral neuropathy is based on clinical symptoms and is often supported by nerve conduction studies such as electromyography (EMG). However, EMG can be time-consuming and may be insufficient in advanced cases due to loss of nerve action potentials. Furthermore, subclinical cases of neuropathy may go undetected by EMG.

Recent evidence suggests that pathophysiological changes in CIPN may lead to increased nerve stiffness. Shear Wave Elastography (SWE), a non-invasive ultrasound-based technique, allows for quantitative evaluation of tissue elasticity by measuring shear wave velocity (V value in m/s) and calculating stiffness (E value in kPa). Unlike strain elastography, SWE does not require manual compression, making it more objective and reproducible.

This observational, case-control study aims to assess tibial nerve elasticity using SWE in patients diagnosed with CIPN and to compare the findings with healthy controls. A total of 25 patients with CIPN (defined as a DN4 score ≥4) and 25 age-matched healthy volunteers without neuropathy symptoms will be included. All participants will undergo ultrasound and SWE measurements of bilateral tibial nerve.

Parameters recorded will include the anteroposterior and lateral-medial diameter, cross-sectional area, distance from the skin, and the mean shear wave velocity (V value) obtained from three repeated measurements. In addition, demographic and clinical data such as age, gender, chemotherapy protocol and duration, comorbidities, and current medications will be collected.

The primary objective is to investigate whether tibial nerve elasticity differs significantly between CIPN patients and healthy individuals. This study aims to explore SWE as a potential supportive diagnostic tool for early detection or monitoring of CIPN.

Inclusion criteria

• Age between 18 and 75 years
• DN4 score ≥4
• Anatomical suitability for tibial nerve ultrasound and SWE assessment
• Providing written informed consent

Exclusion criteria

• Presence of diabetes mellitus
• Alcohol use
• Polyneuropathy due to genetic or toxic causes
• Fracture, skin lesion, or edema in the lower extremity
• Severe systemic diseases (e.g., liver, kidney, heart, or lung)
• Inability to visualize the tibial nerve anatomically
• Cognitive or psychiatric disorders preventing cooperation