This study aims to evaluate the diagnostic accuracy of ultrasonographic measurements of the median nerve in patients with Carpal Tunnel Syndrome (CTS). While ultrasound is a common diagnostic tool, various physical factors can influence its results. The researchers will investigate how a patient's absolute body weight and Body Mass Index (BMI) affect the size of the median nerve cross-sectional area across different stages of disease severity. The goal is to determine if absolute body weight plays a 'masking' role that could lead to more precise diagnostic interpretations in clinical practice.

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy, and while electrodiagnostic studies (NCS/EMG) remain the gold standard, ultrasonography (USG) has gained popularity as a non-invasive diagnostic tool. However, the correlation between median nerve cross-sectional area (CSA) and electrophysiological severity can be inconsistent due to anthropometric variations.

In this prospective observational study involving 120 participants, the researchers will perform high-resolution ultrasonographic measurements of the median nerve at the level of the pisiform bone. All patients will undergo standardized nerve conduction studies to be classified into mild, moderate, or severe CTS stages according to AAEM criteria.

The study specifically focuses on the 'masking hypothesis,' which suggests that absolute body weight may have a more significant impact on nerve morphological changes than the ratio-based BMI, particularly during the progression from mild to moderate stages. By analyzing these relationships using non-parametric statistical methods, the study seeks to improve the reliability of USG-based diagnostics in diverse patient populations.

Inclusion Criteria:

• Patients aged between 18 and 75 years.
• Clinical diagnosis of Carpal Tunnel Syndrome (CTS) based on symptoms (numbness, tingling, nocturnal pain in the median nerve distribution).
• Electrophysiological confirmation of CTS according to the American
• Association of Neuromuscular & Electrodiagnostic Medicine (AAEM) criteria.
• Ability to provide written informed consent.

Exclusion Criteria:

• Secondary causes of CTS (e.g., Diabetes Mellitus, Hypothyroidism, Rheumatoid -Arthritis, Chronic Renal Failure).
• Coexisting neurological conditions (e.g., Cervical Radiculopathy,
• Polyneuropathy, Brachial Plexopathy).
• History of previous wrist surgery, trauma, or local corticosteroid injection within the last 6 months.
• Pregnancy or lactation.
• Congenital anatomical variations such as a bifid median nerve or persistent median artery (detected during USG).

The study population consists of adult patients who were admitted to the Physical and Rehabilitation Medicine (PMR) outpatient clinic with complaints of hand numbness and tingling. The cohort includes individuals from a diverse range of occupational backgrounds and body compositions to evaluate the impact of anthropometric measurements on median nerve morphology.

Individual participant data (IPD) will not be shared with other researchers to ensure the confidentiality and privacy of the study participants in accordance with local ethical guidelines and national data protection laws (KVKK). The aggregated results and statistical analyses will be made available through the final publication. Specific requests for data may be evaluated by the Principal Investigator upon reasonable request and institutional approval.