Chronic exertional compartment syndrome of the forearm in motocross racers: findings on MRI

The purpose of this prospective study was to demonstrate the findings of MRI in motocross racers with chronic exertional compartment syndrome (CECS) of the forearm. Racers with proven CECS and without CECS and male individuals not involved in strenuous activities with the forearm were included. Signal intensity (SI) and signal-to-noise ratio (SNR) obtained before and after exercise were compared (D-SNR). Magnetic resonance imaging after exercise showed an increase in SI and SNR in the muscles on T2-WI. The SI increase was obvious in the flexor digitorum superficialis (FDS) and profundus (FDP) in all CECS patients. In addition, a minor SI and SNR increase in the extensor carpi radialis longus (ECRL) was noted. In the non-symptomatic group of motocross racers, there was only a minor increase in SI and the SNR, which was similar in the FDP and ECRL muscles. In the untrained individuals a remarkable increase in the SI and SNR of the FDS/FDP-ECRL was noted. This increased SI and SNR was not present in the majority of non-symptomatic racers. Post-exertional MRI produces significant findings in CECS of the forearm. The motocross racers without post-exertional oedema in the FDP/FDS had no CECS. (orig.)