De Quervain Syndrome (De Quervain's Syndrome; Washerwoman's Sprain) By David R Steinberg, MD, Perelman School of Medicine at the University of Pennsylvania Reviewed / Revised Apr 2022 | Modified Sep 2022 View Patient Education Treatment De Quervain syndrome is stenosing tenosynovitis of the short extensor tendon (extensor pollicis brevis) and long abductor tendon (abductor pollicis longus) of the thumb within the first extensor compartment.