The effect of insulin resistance, serum IGF-1 level and them on peripheric electrophysiological findings in carpal tunnel syndrome

Carpal tunnel syndrome is defined as the loss of median nerve function as a result of increased pressure within the carpal tunnel. However, its pathophysiology has not been clearly explained. Insulin resistance (IR) is defined as impaired physiological response to endogenous or exogenous insulin. Insulin resistance has a wide clinical presentation. Blood glucose levels of patients with insulin resistance may be normal or high, even some studies have found low blood glucose levels. In a study conducted in 2011, prediabetes and insulin resistance were found to be risk factors for carpal tunnel syndrome. The insulin-like growth factor-1 (IGF-1) is an endogenous molecule in a small peptide construct that resembles a proinsulin found in human, whose primary amino acid sequences and usually local effects and stimulate growth in specific cells. Studies have shown that there are two hormone receptors in skeletal muscle and both are able to stimulate protein synthesis and cell hypertrophy in skeletal muscle, but IGF-1 is a more potent mitogen for myoblasts. Study in 2009, a negative correlation was found between IGF-1 levels and BMI, body weight and waist circumference. As insulin level and insulin resistance increased, IGF-1 levels decreased. In our study, we wanted to examine the relationship between CTS and insulin resistance and IGF-1 levels. Our study included 50 CTS patients and 50 healthy volunteers control group aged 20-50 years. At the beginning of the study, physical examinations and routine biochemical tests of the patients were performed. Complete blood count, liver transaminase (ALT) and aspartate transaminase (AST), urea, creatinine, vitamin B12 and thyroid stimulating hormone (TSH) levels were evaluated. In addition, fasting blood glucose, blood insulin and serum IGF-1 tests were requested after 12 hours fasting to determine insulin resistance. HOMA-IR index results of all participants were recorded. All the participants underwent diagnostic ENMG and their results were recorded. All participants were filled in the Boston Symptom Violence Scale, Boston Functional Severity Scale questionnaires, and hand grasping force with hand dynamometer were recorded. HOMA-IR results were significantly different between group 1 and group 2 (p = 0.006). There was a significant difference in fasting blood glucose levels between group 1 and group 2 (p = 0.038). There was no significant difference between IGF-1 levels in group 1 and group 2. When the patients in Group 1 were separated according to the HOMA-IR results, the serum IGF-1 level of the patients with HOMA-IR test was found lower than the HOMA-IR test negative group and this difference was found to be statistically significant (p = 0.013). Negative correlation was found between IGF-1 levels and insulin levels and HOMA-IR scores in patients with Group 1. No statistically significant difference was found between the results of HOMA-IR and serum IGF-1 and nerve conduction studies. When the patients in Group 1 were separated according to the presence of insulin resistance, the Boston symptom severity scale and Boston function severity scale of the patients with insulin resistance were higher than those without insulin resistance. The difference of BSVS between the groups was statistically significant (p = 0.014). Keywords: Carpal tunnel syndrome, insülin resistance, insülin like growth hormone-1