Disclaimer: The following case is for education purposes only and does not depict any actual person or patient.
A 16-year-old male has developed achy wrist pain over the past two weeks while participating in high school marching band. He reports no traumatic injury. He has been preparing for the football band season with practices for 2-3 hours per day. He reports dull achy pain with general activities of daily living. He has mild pain when the wrist is at rest. His primary instrument is the snare drum and he has been playing since middle school.
On physical exam, he has no noted deformity or instability of the distal radial ulnar joint. There is noted swelling and tenderness to palpation over the radial aspect of the distal forearm. He has full flexion/extension as well as supination/pronation of the wrist. He is able to extend his digits against resistance without difficulty. He does report a mild reproduction of his pain with resisted extension of the thumb. The Finklestein test is negative.
X-rays obtained at the initial visit showed no osseous abnormalities
MRI of the distal forearm illustrates the diagnosis
Clinical Approach
What is the is pathophysiology behind this injury?
In the cases of intersection syndrome, the underlying mechanism is a mechanical friction between the dorsal tendons of the wrist as they cross in the distal forearm. Typically it is an overuse phenomenon due to the anatomic positioning of the extensor compartments. A key concept is that friction causes a tenosynovitis, or irritation of the synovium that surrounds the tendon, rather than a true tendonitis in most cases.
What is the difference between distal and proximal intersection syndrome?
Proximal intersection syndrome (this case) occurs approximately 4-5 cm proximal to the wrist joint. It involves the site where the first extensor compartment, abductor pollicus longus (APL) & extensor pollicus brevis (EPB) cross over the tendons of the extensor carpi radialis brevis and longus (ECRB & ECRL. Distal intersection syndrome occurs at the wrist joint and involves the site where the extensor pollicus longus (EPL) cross the tendons of the extensor carpi radialis brevis and longus. If you rewatch the MRI video above you can see the tendons crossing just above the surface of the radius.
What is the general treatment plan?
I will typically recommend the patient undergo conservative treatment including relative rest as well as simple bracing to limit movement of the tendons. I don't generally obtain an MRI in this case, as it is a pretty straightforward diagnosis. However, if the patient was not improving or swelling was out of proportion to the injury, I would consider ultrasound versus MRI. If the diagnosis was confirmed I would likely proceed with ultrasound-guided injection.
Clinical Pearls
Intersection syndrome is pretty uncommon in adolescents, however, it should be considered in cases of repetitive wrist motions such as drumming or rowing.
Differential diagnosis includes extensor tendonitis, ganglion cysts, and DeQuervain's tenosynovitis.
The diagnosis is frequently misdiagnosed as DeQuervain's tenosynovitis, but can be further differentiated with pain being more proximal than would be expected for DeQuervain's.
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