Findings
The radiographs in this case are not particularly contributory. The MRI demonstrates tenosynovitis of the first extensor compartment manifest by fluid/synovitis distention of the tendon sheaths. Multiple tendon slips are present of the abductor pollicis longus (APL) and with severe tendinosis seen of one of the tendon slips. Other areas of slightly increased signal and tendinosis are present of the components of the APL. Noted is a somewhat prominent septum separating the more dorsal extensor pollicis brevis (EPB) from the APL.
Diagnosis: DeQuervain’s Tenosynovitis
The first extensor compartment of the wrist contains the abductor pollicis longus or APL (slightly more volar) and the extensor pollicis brevis or EPB (slightly more dorsal). Tenosynovitis of this compartment is known by the eponym of DeQuervain’s tenosynovitis. In addition to tenosynovitis, tendinosis, and partial tearing can be seen. Complete disruption of the tendons is extremely uncommon. More common in women than men, this can affect almost any age patient. It is typically seen in individuals who perform repetitive gripping maneuvers or thumb overuse as can be seen in gripping a golf club or racket. The symptoms are frequently able to be managed with rest and ultrasound guided injections. Recalcitrant cases may require surgical intervention.
This case in particular highlights some of the normal variants of the first extensor compartment which can be confusing as well as clinically important. The APL can have multiple tendon slips with the insertion mostly being to the base of the thumb metacarpal but with additional insertions found of the trapezium and occasionally other thenar muscles. With additional tendinosis and partial tearing, this can become particularly confusing.
There can also be a partial or complete septum between the APL and EPB. This can particularly come into play with injections and positioning the needle into both sub-compartments to ensure that both tendons are bathed in the injectate.
References
Benjamin Plotkin, MD, Srihari C. Sampath, MD, PhD, Srinath C. Sampath, MD, PhD, and Kambiz Motamedi, MD. MR Imaging and US of the Wrist Tendons. RadioGraphics Volume 36, Number 6 https://doi.org/10.1148/rg.2016160014
Christopher G. Larsen, MD, Michael J. Fitzgerald, MD, Kate W. Nellans, MD, MPH, Lewis B. Lane, MD. Management of de Quervain Tenosynovitis
A Critical Analysis Review. JBJS Reviews Review Articles with Critical Analysis Component September 2021; 9 (9): e21.00069 DOI 10.2106/JBJS.RVW.21.00069