27M with reproducible unilateral leg numbness and weakness after ~20 minutes of running — thoughts?
27-year-old male with no significant PMHx presented with a very reproducible episode of left lower-extremity numbness and motor weakness that occurs specifically with running.
He initially feels completely normal, but at approximately the 20-minute mark, he develops numbness in the left leg below the knee, followed by progressive motor weakness. At its worst, he describes it as essentially complete paralysis of the lower leg and says it feels like his “knee is slipping.”
The symptoms resolve with rest, with sensation and motor function returning to baseline after approximately 5–7 minutes.
A few additional details:
No pain associated with the episodes
No symptoms at rest
No similar symptoms in the right leg
No other neurologic symptoms
No significant PMHx
Denies current smoking; previously vaped for approximately 1 year
Rare alcohol use
Denies recreational drug use
The reproducibility with exertion and relatively rapid resolution with rest caught my attention.
What would be on your differential? Would you approach this primarily as a vascular, neurologic, or musculoskeletal/compartment-related issue?