Presentation
This athlete experiences severe pain in the lower legs, predominantly on the left, when exercising. He was referred to a vascular surgeon with 'intermittent claudication.' There were no risk factors of peripheral vascular disease. The clinical suspicion was that of exercise-induced compartment syndrome.
Patient Data
Axial T1 and STIR of both lower legs show normal structures bilaterally without evidence of muscle edema, interstitial fluid or focal abnormality.
The patient was asked to run up and down the stairs between ground floor and second floor where the MRI scanner is located, and to promptly report to the radiographers upon onset of pain in the lower legs.
The patient was scanned immediately after onset of pain.
While the muscles of the right calf appear normal on the postexercise imaging, there is a definite interval change in the signal intensity of the muscles in the left extensor and peroneal compartments manifesting as increased signal on STIR and consistent with muscle edema.Side-by-side comparison of pre- & post exercise MRI STIR
Following exercise, there has been an interval increase in signal intensity in the anterior and lateral compartments of the left lower leg, involving tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus longus and peroneus brevis muscles. The appearances are therefore consistent with exercise induced compartment syndrome.
Case Discussion
Chronic exertional compartment syndrome usually occurs in competitive athletes, long distance runners, skiers, basketball and soccer players. It is characterized by pain induced during exercise, most typical occurring at a specific distance or time (i.e. predictable by the patient).
Although previously thought to be a form of shin splints, it is now recognized as a completely different entity.
In this case, the patient was made to exercise outside the scanner until pain occurred, and then was immediately scanned.
There are also in-scanner exercise protocols where the patient's feet get strapped to a custom-made resistance plate, allowing continuous plantar- and dorsiflexion against resistance with little motion of the lower legs otherwise (legs in a birdcage-type transmit-receive coil).1
See also
Achnowledgements
Thanks to Dr E Heffernan, Consultant Radiologist at St. Vincent's University Hospital, Dublin
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