Young athlete with bilateral exertional calf pain

Background/significance: 15 year old male, multi-sport athlete, with one year of bilateral exertional calf pain, associated with paresthesias and no pain with rest. Neurologically intact, 2 out of 4 patellar and ankle reflexes, 5 out of 5 strength without muscle atrophy, negative slump and straight leg raise. Bounding dorsalis pedis pulse bilaterally, however with active flexion and passive dorsiflexion, pulse was not palpable. Purpose: To evaluate the etiology and work-up of calf pain and intermittent claudication in a young athlete. In this case, the working diagnosis of popliteal artery entrapment syndrome (PAES) proved to be wrong. Therefore, clinicians should be aware of functional popliteal artery entrapment syndrome and the associated work-up and treatment. Methods: MEDLINE search was conducted to determine the differential diagnosis of exertional calf pain in a young athlete. Additionally, specifically reviewed the presentation, diagnosis and treatment for functional popliteal artery entrapment syndrome versus popliteal artery entrapment syndrome. Results: The differential diagnosis included exertional compartment syndrome, popliteal artery entrapment syndrome (PAES), myopathy or lumbar radiculitis. Doppler US obtained during the initial visit supported PAES given the complete cessation of flow through the popliteal arteries bilaterally with active plantar flexion. Given that MRI is the current diagnostic modality, this was obtained, however surprisingly it was negative for anatomical variants in the gastrocnemius muscles and showed no focal filing defects of the popliteal arteries bilaterally. Due to this, exertional and compartment testing was completed, which were negative for compartment syndrome. Given the results of the work-up above, the final diagnosis was functional popliteal artery entrapment syndrome. Conclusion: There was no anatomic variation in the gastrocnemius muscles or stenosis of the popliteal arteries on MRI/MRA to support PAES. However, entrapment was demonstrated with doppler ultrasound on the initial office visit. The diagnosis of functional popliteal artery entrapment syndrome was later confirmed with ABI testing. Going forward, is ultrasound a clinically reliable way to diagnose functional popliteal artery entrapment syndrome