Intersection Syndrome

Intersection syndrome was first described in the literature by Alfred-Armand-Louis-Marie Velpeau, a French anatomist and surgeon, in 1841. However, the term was later officially coined by James H Dobyns at the Mayo Clinic in 1978. Although intersection syndrome is the commonly accepted term today, it has historically been described in the medical literature by other names, such as , crossover syndrome, abductor pollicis longus bursitis, abductor pollicis longus syndrome, and peritendinitis crepitans. This condition affects the first and second compartments of the dorsal wrist extensors, which are part of a collective of 6 dorsal compartments that are variably responsible for wrist and digital extension. The specific compartments include (see . Dorsal Forearm Anatomy): First compartment: Abductor pollicis longus and extensor pollicis brevis. Second compartment: Extensor carpi radialis longus and extensor carpi radialis brevis. Third compartment: Extensor pollicis longus. Fourth compartment: Extensor digitorum communis and extensor indicis proprius . Fifth compartment: Extensor digiti minimi. Sixth compartment: Extensor carpi ulnaris. The abductor pollicis longus and extensor pollicis brevis tendons of the first dorsal compartment of the wrist have a unique anatomical pathway where they cross over the extensor carpi radialis longus and extensor carpi radialis brevis of the second dorsal compartment proximal to the extensor retinaculum and radial styloid. The inflammatory process and resulting tenosynovitis occur at this intersection, approximately 4 to 6 cm proximal to Lister tubercle along the dorso-radial distal forearm. Although this is generally accepted as the underlying cause of intersection syndrome, researchers have also suggested that the condition may reflect pathology isolated to the second compartment (without contribution or involvement from the first dorsal compartment).