Intersection syndrome

Case contributed by Daniel Fascia
Diagnosis certain

Presentation

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.

Patient Data

Age: 46
Gender: Female

Dorsum distal radial forearm

ultrasound

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.

Annotated image

Annotated images. Right is abnormal in the setting of intersection syndrome. 

Case Discussion

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.

Ultrasound tips

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 edema (tenosynovitis)
  • hypervascularity on power Doppler assessment (hyperemia)

Ultrasound can be effectively used in the diagnosis of intersection syndrome.

Interventional treatment

Ultrasound-guided injection of steroid / local anesthetic 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.

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