Usefulness of combination of grey-scale and color Doppler ultrasound findings in the diagnosis of ulnar nerve entrapment syndrome

Ulnar nerve entrapment (UNE) has been diagnosed with clinical examination and electrodiagnostic studies. This study was designed to determine the value of a combination of grey-scale and color Doppler ultrasound findings in the diagnosis of patients with UNE. During May to August 2013 41 patients with UNE (proven by electrodiagnostic studies) and 44 healthy volunteers were evaluated by ultrasound study. Three cross sectional area (CSA) of ulnar nerve around cubital fossa was determined and measured in both groups. The maximum and minimum diameter of ulnar nerve was measured for calculating flattening ratio index (FRI). Vascularity of ulnar nerve around cubital fossa was also examined in proper color Doppler setting. The mean CSA of nerve at all proximal, middle and distal levels were greater in patients with UNE than in controls (P = 0.02, <0.001 and 0.34 respectively). A cut-off point of 10.5 mm2 for CSA (in the level of the cubital fossa) yielded a sensitivity and specificity of 92.7% and 93.2%, respectively. Mean FRI was 3.1 ± 0.6 in patients with UNE group and 1.4 ± 0.2 in the control group with a significant difference (P < 0.001). FRI with cutoff point 2.15 has been shown as an important parameter for the detection of UNE. The vascularity in UNE has a sensitivity and specificity of 66% and 93.2%, respectively, and has a higher probability of being positive in severe UNE. Combination of grey-scale and color Doppler ultrasound may provide valuable diagnostic criteria and severity assessment of UNE.