T111. Median nerve area in diabetic carpal tunnel syndrome patients: a retrospective review of 1030 cases

Abstract

Association of CTS and diabetes mellitus (DM) is very common. DM is a known risk factor for CTS, but the impact of DM on the median nerve cross-sectional area augmentation remains uncertain. This is a retrospective review of patients presenting to the Duke Electromyography (EMG) Laboratory during 2013–2014 with a final diagnosis of CTS. US diagnosis of CTS was based upon median nerve cross-sectional area of >9 mm2 and/or wrist-to-forearm ratio of >1.4. EDx studies were the gold standard for diagnosis. The objective of this study is to determine if median nerve CSA is higher in diabetic CTS patients as compared to non-diabetic CTS patients. A total of this is a retrospective review of 1030 consecutive patients presenting to the Duke EMG Laboratory during 2013–2014 with a final EDX diagnosis of CTS were examined. Median nerve CSA at the wrist We analyzed wrist-CSA (W-CSA) and, forearm (F-CSA) were measured-CSA and a wrist-forearm ratio (WFR) calculated. Statistical analysis was performed in diabetic and non-diabetic CTS patients with ANCOVA test and Bonferroni correction using as covariates: age, gender, pregnancy, handedness, and body mass index (BMI). The mean age was 56 ± 14.0 (range from 20 to 90 years). 263 were men (36.8%) and 451 were women (63.2%, 10 women were pregnant). 41.9% of patients were diabetic. 521 were Caucasians, 162 African-Americans and 31 other ethnicities (Asians, Indians, Hispanic). 539 were right-handed, 174 left-handed and 1 was ambidextrous. The mean body mass index (BMI) was 32.2 ± 8.0 (range from 15.5 to 112.1), and the patients were classified in groups I-V following international classification (underweight + normal weight, preobese, obese, severely obese and morbidly obese).The CSA of the median nerve in diabetic patients: (1) At the wrist was 12.8 ± 4.7 mm2 on the right and 11.7 ± 4.8 mm2 on the left. (2) At the forearm, median nerve CSA was 6.5 ± 2.2 mm2 on the right, and 6.1 ± 2.3 mm2 on the left. (3) Mean WFR was 2.1 ± 0.9 on the right and 2.0 ± 0.8 on the left. We had 43 bifid median nerves, and 3 with persistent median artery. There was no difference between wrist CSA (W-CSA) of non-diabetic and diabetic patients (right W-CSA p = 0.992, left W-CSA p = 0.253), and the same was observed with forearm-CSA (right forearm-CSA p = 0.498, left forearm-CSAp = 0.181) and WFR (right-WFR p = 0.706, left WFR p = 0.444 mean = 2.0 ± 0.8), and Bonferroni-correction p-values were also non-significant (value = 1) for all the analysis. There was no difference in CSA or WFR considering the severity of CTS between non-diabetic and diabetic patients (right hand p = 0.237 and left hand p = 0.458). There is no correlation between higher median nerve CSA and diabetes in patients with CTS.