Takatoshi Aoki MD, Presenter: Nothing to Disclose

Takahisa Oshige, Abstract Co-Author: Nothing to Disclose

Hodaka Ohki, Abstract Co-Author: Nothing to Disclose

Shunsuke Kinoshita, Abstract Co-Author: Nothing to Disclose

Hiroyuki Takahashi, Abstract Co-Author: Nothing to Disclose

Yukunori Korogi MD, Abstract Co-Author: Nothing to Disclose

Yoshiko Hayashida MD, Abstract Co-Author: Nothing to Disclose

Akinori Sakai, Abstract Co-Author: Nothing to Disclose

Although patients with carpal tunnel syndrome (CTS) are often treated with steroid injection (SI) into carpal tunnel, predictive indicator of SI response has not been clarified. The purpose of this study is to correlate median nerve T2 signal and shape at the carpal tunnel with SI response in CTS patients and to determine if high-resolution MRI can be used to predict SI response in these patients.

Fifty-seven consecutive patients with CTS (24 men, 33 women; age range, 37-87 years; mean age, 64.9 years) were prospectively evaluated with 3T MRI and nerve conduction study using needle electrode examination. Both wrists were examined in all but one patient and the diagnosis of CTS was confirmed in 92 wrists by clinical criteria and nerve conduction studies. All patients underwent axial high-resolution MRI (in-plane resolution of 0.25×0.25 mm) covering the carpal tunnel, including T2-weighted imaging (repetition time msec/echo time msec, 3000/81.1) and intermediate weighted image with fat suppression (2000/18.4). Median nerve T2 signal measured by using T2-weighted contrast-to-noise ratios and median nerve flattening ratio at the hook of hamate level were evaluated as diagnostic signs. The CTS wrists were classified into 3 groups according to the nerve T2 signal and the flattening ratio: high and oval, group 1; high and flat, group 2; and low and flat, group 3. Clinical response to SI was evaluated at 6 months after injection. A forward stepwise logistic regression model was used to identify variables that predicted SI response.

Fifty-three of 92 (57.6%) wrists responded well to SI. The percentage of good response was 84.4% (27/32) in group 1, 52.6% (20/38) in group 2, and 27.3% (6/22) in group 3 (p < 0.01). On stepwise logistic regression analysis of all variables including nerve conduction study and duration of disease, high-resolution MRI was the only significant independent factor for SI response in CTS patients (p < 0.05).

High-resolution MRI correlates well with SI response in CTS patients and seems to be able to use for predicting SI response.

Nerve T2 signal and shape on high-resolution MRI can predict a favorable outcome after SI in CTS patients and therefore can be crucial in deciding appropriate care and avoiding unnecessary surgery.

Aoki, T, Oshige, T, Ohki, H, Kinoshita, S, Takahashi, H, Korogi, Y, Hayashida, Y, Sakai, A, Usefulness of High-Resolution MRI for Prediction of Steroid Injection Response in Carpal Tunnel Syndrome Patients.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12029509.html