Intersection syndrome:
report of two cases and review of the literature

 

G. GEORGIADES1, T. TSAVDARIDIS[1], N. GEROSTATHOPOULOS[2], A. SKAMAKIS[1]
[1]Orthopedic Department of Limnos Hospital, Limnos
[2]Microsurgery and hand surgery clinic, KAT Hospital, Athens

ABSTRUCT
Intersection syndrome is a painful and disabling condition of the radiodorsal aspect of the forearm that is infrequently diagnosed. We present two cases of intersection syndrome, describing its characteristic clinical and anatomic features and highlighting matters concerning its pathology, diagnosis, differential diagnosis and treatment.

Key words: Forearm intersection syndrome, De Quervain syndrome, anatomy of forearm.

INTRODUCTION
Intersection syndrome of the forearm is a soft tissue inflammatory condition of the radiodorsal aspect of the forearm. It presents with pain, localized tenderness, swelling, redness, increased warmth and crepitus over the radiodorsal aspect of the forearm, 4-8cm proximal to Lister's tubercle. It is located at the area where the musculotendinous junctures of the abductor pollicis longus and the extensor pollicis brevis cross over the underlying tendons of the extensor carpi radialis longus and brevis (figure 1). The tendons at this area are lined only with peritendon without any tenontosynovial tissue and the overlying extensor fascia of the forearm closely approximates them to one another.
The basic pathology in intersection syndrome is still a matter of disagreement. Most authors believe that the basic pathology is the friction between the musculotendinous junctures of the abductor pollicis longus and the extensor pollicis brevis and the underlying tendons of the extensor carpi radialis longus and brevis[1]. This situation leads to inflammation of the soft tissues at the intersection area causing bursitis, peritendinitis, tendinitis and myositis[5,10,11]. Confined beneath the extensor fascia inflammation and swelling around these tendons increase their surface friction, contributing to a cycle of additional swelling and friction. Some authors implicate stenosing tenosynovitis of the second dorsal compartment that contains the tendons of the extensor carpi radialis longus and brevis as the causative mechanism[3,9]. According to them, this tenosynovitis is encased in a tight compartment that's why physical findings does not present in this area but more proximal.

CASES REPORT
We present two cases with intersection syndrome of the forearm. Both patients were males, 31 and 45 years old. They were workers whose activities involved repetitive wrist motion, mostly wrist extension and radial deviation. Both patients reported the onset of a new activity a few days before the syndrome's development. The dominant hand was involved in both patients. The diagnosis was based on the history and the physical examination. Patients presented with pain, swelling and redness over the radiodorsal aspect of the forearm approximately 4cm proximal to the radial styloid (figure 2). The findings were readily seen when the affected and non-affected sides were compared (figure 3). Palpation at this area revealed tenderness, increased warmth and crackling crepitance. Wrist motion increased pain and discomfort and detected palpable and audible crepitus.
Differential diagnosis included De Quervain's stenosing tenosynovitis, tenosynovitis of the second or third dorsal compartments, entrapments of the superficial sensory branch of the radial nerve (Wartenberg's syndrome), blunt local trauma and local cellulitis. The pain and swelling were located more proximal and dorsal on the forearm that would be found with De Quervain's stenosing tenosynovitis. A Finkelstein's test was positive but the site of pain was localized at the intersection area. Also the tenderness and the pain detected with wrist motion were located more proximal that would be found with tenosynovitis of the second or third dorsal compartments. Tinel's sing and parasthesia at the dorsal aspect of the thumb absence, precluded entrapments of the superficial sensory branch of the radial nerve as it emerges beneath the brachioradialis. The patients denied any recent direct trauma to the area while the limitation of the swelling and the erythema at the intersection area turned away the possibility of a cellulitis.
Management of the patients included rest, work activities modification, oral nonsteroidal anti-inflammatory drugs and immobilization by a splint that kept the wrist in 15° of extension. At follow-up, two weeks later a minimal improvement was noted and the patients received an injection therapy with an anesthetic-steroid combination to the area of maximal tenderness. The symptoms were eliminated within 10 days of the injection. One year later the patients were free of symptoms.

Figure 1.


Figure 2.


Figure 3.

DISCUSSION
Dobyns et al introduced the term intersection syndrome[2] for a condition that was first described by Velpeau in 1841. In the past, this syndrome has been referred to as peritendinitis crepitans[5], abductor pollicis longus bursitis[11], crossover tendinitis, bugaboo forearm[7], Oarsman's wrist and subcutaneous perimyositis.
Intersection syndrome is an overuse syndrome that is relatively uncommon in the general population8. It is seen most commonly in workers whose activities involve repetitive wrist motion mostly wrist extension and radial deviation. It tends to occur with the onset of a new activity rather than after a prolonged exposure to daily activities[5,6]. Also, it often occurs in athletes who participate in weight lifting, rowing, canoeing, helicopter skiing and other sports that involve repetitive use of the wrist[7,10,12].
The intersection syndrome of the forearm is infrequently diagnosed mostly because it is frequently confused with De Quervain's stenosing tenosynovitis[4]. However, its signs and symptoms are more proximally and dorsally located on the forearm.
The treatment of intersection syndrome is similar to the treatment of most overuse syndromes, including rest, work activities modification, topical ice-pack placement, oral nonsteroidal anti-inflammatory drugs and immobilization by a splint. In most cases, conservative treatment provides a satisfactory outcome. Those cases that fail to respond after two to three weeks of splinting and anti-inflammatory medication may benefit from an injection therapy with an anesthetic-long acting cortisone combination. The injection is made at the intersection area, at the point of maximal tenderness, rather than into the second dorsal compartment. The improvement of the patients after the injection suggests that the primary site of the pathology is the intersection area.
In rare cases, surgical treatment may be necessary. Williams has successfully treated this condition by simple surgical decompression of the sheath of the abductor pollicis longus and the extensor pollicis brevis and thus of the underlying tendons of the extensor carpi radialis longus and brevis[10]. Grundberg and Reagan report relief of symptoms by decompression of the second dorsal compartment without decompression of the proximal structures[3]. Because the actual site of pathology in intersection syndrome remains controversial both the intersection area and the second dorsal compartment should be examined and, if necessary, released.

REFERENCES
1. Allison D.M. Pathologic anatomy of the forearm: Intersection Syndrome (letter). J Hand Surg. 1986; 11A, 913-4.
2. Dobyns J.H., Sim F.H., Linscheid R.L. Sports stress syndromes of the hand and wrist. Am J Sports Med. 1978; 6, 236-54.
3. Grundberg A.B., Reagan D.S. Pathologic anatomy of the forearm: Intersection syndrome. J Hand Surg. 1985; 10A, 299-302.
4. Hanlon D.P., Luellen J.R. Intersection syndrome: A case report and review of the literature. The Journal of Emergency Medicine. 1999; 17,6, 969-71.
5. Howard N.J. Peritendinitis crepitans JBJS 1976; 19A, 447-59.
6. Idler R.S., Strickland J.W., Creighton J.J. Intersection Syndrome Indiana Med. 1990; 83, 658-9.
7. Palmer D.H., Lane-Larsen C.L. Helicopter skiing wrist injuries. A case report of "Bugaboo Forearm". Am J Sports Med 1994; 22, 148-9.
8. Pantukosit S., Petchkrua W., Stiens S.A. Intersection syndrome in Buriram Hospital: a 4-yr prospective study. Am. J Phys Med & Rehabil. 2001; 80, 656-61.
9. Thorson E., Szabo R.M. Common tendinitis problems in the hand and forearm. Orthop Clin North Am 1992; 23, 65-74.
10. Williams J.C.P. Surgical management of traumatic non-infective tenosynovitis of the wrist extensors. JBJS. 1977; 59B, 408-10.
11. Wood M.B., Linscheid R.L. Abductor pollicis longus bursitis. Clin Orthop. 1973; 93, 293-6.
12. Wood M.B., Dobyns J.H. Sports-related extraarticular wrist syndromes. Clin Orthop. 1986; 202, 93-102.

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G. GEORGIADES
Orthopedic Department of Limnos Hospital, Limnos