Intersection syndrome

Intersection syndrome is a painful inflammatory condition on the thumb side of the wrist and forearm, on the back of the arm. It occurs where the compartment holding the thumb muscles crosses over the compartment holding the muscles that extend the wrist, and it is a type of tenosynovitis that develops gradually. The usual mechanism of injury is repetitive resisted extension, as in rowing, weight lifting or pulling. Symptoms are pain, tenderness and swelling, most severe about 4 to 8 cm above the radial styloid, and crepitus may be felt in severe cases. Diagnosis is clinical, with ultrasound or MRI used when the presentation is unclear. It is often confused with De Quervain syndrome, whose pain sits closer to the thumb. The condition is rare overall, with fewer than one case per 100,000 patients each year.