This middle aged lady came in for an ultrasound scan of the wrist. She complained of radial wrist pain reminiscent of a De Quervain’s syndrome. However the symptoms were somewhat different. The main area of pain was 4 cm proximal of the radial styloid process. Resisted testing was more painful on extension but was not worse when adding ulnar deviation which is usually the case with De Quervain’s tenosynovitis.

Finkelstein’s test was only mildly positive. Ultrasound revealed some tenosynovitis of the extensor pollicis brevis at the radial styloid. When moving proximal with the US probe transverse to 1^st extensor compartment the tenosynovitis became more pronounced where the EPB crossed over he second compartment. The APL seemed to be relatively unaffected. This syndrome has been described as Intersection syndrome of the wrist. The few articles that I could find on intersection syndrome very much supported my clinical and ultrasound findings.

I have clinically diagnosed this syndrome several times however on previous occasions there was no sign of tenosynovitis but it clinically resembled  myotendinous junction syndrome with pain over the muscle rather than tendon. The severity of the symptoms correlated well with degree of tenosynovitis as seen on ultrasound.

As it seemed to be more related to the overuse/provocation of the extensor component of the 1^st extensor compartment i.e the EPB rather than APL it seems sensible to focus more on avoiding repeated extension stress rather ulnar deviation stress which is the predominant complaint in De Quervains tenosynovitis.

An interesting paper was written by Montechiarello et al (2010) which summaries the use of MSK US in Intersection syndrome. Also, this case study by Shiraj et al (2013) is another useful resource.