A 46-year old female, keen gardener presented to the ED with a firm, hot swelling on the dorsum of her right distal forearm on the radial side. She commented that finger movements were painful and it came on after a vigorous few days of garden work. CRP was raised to 26, all other blood work normal.
Transverse high resolution USS of the dorsum of the distal radial forearm
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Images demonstrate normal and abnormal side by side.
On the right, there is gross swelling of the tendons of the 1st extensor compartment as it crosses over the 2nd extensor compartment in the distal forearm, radial side.
The left side is normal by comparison.
Intersection syndrome is a friction / overuse tenosynovitis affecting the crossover point of the 1st and 2nd extensor compartments on the dorsum of the distal, radial aspect of the forearm.
It is an often confused diagnosis because the palpable lump and pain is more proximal to the expected site in De Quervain's tenosynovitis. This makes it an important differential diagnostic consideration when carrying out a wrist ultrasound.
The condition is best appreciated in the transverse plane by sweeping a high resolution linear probe back and forth across the intersection site. It is always advised that comparison is made with the asymptomatic side.
Signs of intersection syndrome on ultrasound are:
- thickening of either or both of the 1st/2nd extensor tendon compartments (tendinitis)
- thickening of the surrounding tendon sheaths with oedema (tenosynovitis)
- hypervascularity on power Doppler assessment (hyperaemia)
Ultrasound can be effectively used in the diagnosis of intersection syndrome.
Ultrasound guided injection of steroid / local anaesthetic into the inflamed tendon sheaths at the level of the intersection provides effective relief for this condition. Wrist splinting is recommended after injection, followed by specialist physiotherapy.
- Montechiarello, S., Miozzi, F., D’Ambrosio, I., & Giovagnorio, F. (2010). The intersection syndrome: Ultrasound findings and their diagnostic value. Journal of Ultrasound, 13(2), 70–73. http://doi.org/10.1016/j.jus.2010.07.009