The diagnostic value of MRI scans for the diagnosis of chronic exertional compartment syndrome of the lower leg

Objective. A prospective descriptive study to determine the value of magnet ic resonance imaging (MRI) as an aid in diagnosing (chronic) exertional com partment syndrome. Design and patients. MRI was performed in 21 patients (41 anterior compartm ents) with chronic compartment syndrome at rest and following physical exer cise. Median (T2-weighted) signal intensity on the MRI scan was determined in the anterior and the (superficial) posterior compartment of the lower le g before and after exercise. Postexercise increases in the signal intensity in these two compartments were compared. After fasciotomy, a second MRI sc an was performed in 13 patients (25 anterior compartments) on the basis of the same protocol. MR studies were performed in 12 normal controls (24 ante rior muscle compartments) on the basis of the same protocol. Results. T-2-weighted signal intensity increased by 27.5% (range 13.6-38.6% ) following exercise in the anterior compartment of patients with a chronic compartment syn-drome. In the posterior compartment this increase amounted to 4.25% (range 0-10.2%). Following fasciotomy, the increase in the anteri or compartment was 4.1% (range 1.0-5.2%), while the increase in the posteri or compartment amounted to 5.6% (range 0-11.0%), In normal controls, the in crease in the anterior compartment was 7.6% (range 0-9.1%), while in the po sterior compartment it was 4.0% (range 0-7.2%). Conclusions. In patients with a chronic compartment syndrome, the affected (anterior) compartment shows a statistically significant increase in (T2-we ighted) signal intensity during exercise compared with both the (superficia l) posterior compartment and the anterior compartment of normal controls. T his effect disappeared after fasciotomy. In view of the substantial increas e in T2-weighted signal intensity, MRI can be used in diagnosing chronic co mpartment syndrome.