This randomized controlled trial aims to investigate the immediate effects of paraffin wax therapy on muscle stiffness and pain among patients diagnosed with Carpal Tunnel Syndrome (CTS). The intervention involves immersing the hand and forearm in paraffin wax at 42-44 °C for 20 minutes. Stiffness will be measured using the MyotonPro device, and pain will be evaluated using standard visual scales.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper limb and may alter the passive mechanical properties of forearm and hand muscles, contributing to pain and functional limitation. Handheld devices such as MyotonPro allow non-invasive, point-of-care assessment of muscle stiffness, elasticity and viscoelastic behaviour in clinical settings. Paraffin wax therapy is widely used as a superficial heat modality in hand rehabilitation and has been shown to reduce pain and improve function in various hand conditions, but its immediate effects on objectively measured muscle stiffness in CTS remain unclear. This parallel-group randomised controlled trial will examine the immediate effects of a single paraffin wax session on muscle stiffness and pain in adults with CTS. Physically active adults aged 18-65 years with clinically diagnosed CTS will be recruited from university-based facilities in Erzurum, Türkiye, and randomly allocated (1:1) to paraffin wax therapy or a control condition. A priori power analysis indicated that a total sample of 24 participants (12 per group) would provide adequate power to detect between-group differences in pre- to post-intervention change. Mechanical properties of selected forearm and hand muscles (e.g. APB, FDS, ECRB, FCU) will be assessed using MyotonPro immediately before and after the intervention. In the intervention group, the affected hand and forearm will receive 20 minutes of paraffin wax therapy at approximately 42-44 °C using a standardised brush-on technique and safety checks for skin integrity and temperature. Pain intensity in the affected region will be recorded pre- and post-session using a validated numeric rating or similar pain scale. The primary outcome is the between-group difference in immediate change in MyotonPro stiffness parameters, with secondary outcomes including change in pain and exploratory relationships between changes in stiffness and pain. Mixed model repeated measures ANOVA will be used to compare pre- to post-intervention changes between groups. Findings from this study may help clarify the short-term neuromuscular and symptomatic effects of paraffin wax therapy in CTS and inform future rehabilitation protocols.

Inclusion Criteria:

• Clinically diagnosed carpal tunnel syndrome.
• Age between 18 and 65 years.
• Apparently healthy, without a known chronic systemic disease (other than CTS).
• No history of other chronic musculoskeletal or neurological disorders.

Exclusion Criteria:

• Previous surgery on the affected wrist or hand.
• Systemic conditions affecting nerve function (e.g., diabetes mellitus, thyroid disease)
• Cardiovascular disease or uncontrolled hypertension.

There is no plan to share individual participant data (IPD) from this trial. Summary results and aggregate data will be disseminated through peer-reviewed publications and conference presentations.