Preoperative Magnetic Resonance Imaging Findings in Patients with Tarsal Tunnel Syndrome and Postoperative Outcomes.

Abstract

Tarsal tunnel syndrome is an entrapment neuropathy at the tarsal tunnel. The diagnosis and the prediction of the surgical outcome are difficult. We compared preoperative magnetic resonance imaging findings with the postoperative results. We examined preoperative magnetic resonance imaging findings in 38 consecutive patients with Tarsal tunnel syndrome (47 feet); their mean age was 73.8 years. We inspected the nerve width on the slice showing the most compressed nerve, and the hyperintensity of that nerve on preoperative T2* fat-suppressed axial magnetic resonance imaging images and examined the role of magnetic resonance imaging in the diagnosis and of the surgical outcomes in patients with Tarsal tunnel syndrome. Postoperatively, there was significant symptom improvement. On preoperative magnetic resonance imaging scans the mean width of the most compressed nerve was 0.99 ± 0.37 mm. There was no significant correlation between the preoperative symptom severity and postoperative symptom improvement. In 29 feet (61.7%) we observed hyperintensity of the compressed nerve. In all but one foot the hyperintense area was displayed on 3 axial slices adjacent to the strongest nerve compression point. There was no significant difference in the preoperative symptom severity in patients with (group 1, n = 29) or without hyperintensity (group 2, n = 18). The nerve width at the point of greatest compression was significantly thinner, and postoperative symptom improvement was significantly greater in group 1 patients. Although there was no correlation between the preoperative nerve compression severity and the surgical results, nerve hyperintensity on magnetic resonance imaging scans may help with the diagnosis of Tarsal tunnel syndrome.