The relationship between diffusion tensor imaging and the clinical classification of cubital tunnel syndrome

The purpose of the study was to investigate the relationship between diffusion tensor imaging (DTI) and the clinical classification of cubital tunnel syndrome (CuTS). Ten patients with CuTS (7 men and 3 women; mean age: 52.7 years) and 5 patients without ulnar neuropathy (2 men and 3 women; mean age: 38.0 years) were enrolled in this retrospective study. Fifteen patients were clinically classified into three groups: "Normal", "1 and 2A", and "2B and 3" by an orthopedic surgeon using the modified McGowan stages. DTI was acquired using a 3.0-T MRI. Fractional anisotropy (FA) of the ulnar nerve was measured in slices covering 20 mm proximal to 20 mm distal to ulnar sulcus. Median FA values in each group were compared by Kruskal-Wallis and Steel-Dwass test (P < 0.05). Five patients with CuTS were classified as "1 and 2A" and five patients as "2B and 3". The FA values, proximal 12 mm to the ulnar sulcus were 0.486 ± 0.117, 0.425 ± 0.166 and 0.298 ± 0.0386 in the "Normal", "1 and 2A" and "2B and 3" groups, respectively. The FA values of patients classified as "Normal" were significantly higher than those classified as "2B and 3" (P = 0.0326 in Steel-Dwass test). FA proximal to the ulnar sulcus might be associated to the modified McGowan stages for the clinical classification of CuTS.