Intersection Syndrome


Article Author:
Nicholas Michols


Article Editor:
John Kiel


Editors In Chief:
Susan Jeno
Sarah Fabiano


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Frank Smeeks
Kristina Soman-Faulkner
Trevor Nezwek
Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
4/2/2019 10:28:58 PM

Introduction

Intersection syndrome is a condition that affects the first and second compartments of the dorsal wrist extensors. The condition is thought to occur as a result of repetitive friction at the junction in which the tendons of the first dorsal compartment cross over the second, creating a tenosynovitis. This is typically noted as a pain just proximal and dorsal to the radial styloid, or also noted anatomically by 4 cm - 6 cm proximal to Lister's tubercle.[1][2][3]

Etiology

The first dorsal compartment of the wrist is comprised of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB). These tendons have a unique anatomical pathway proximally in which they cross over the second dorsal compartment tendons just proximal to the extensor retinaculum and radial styloid. The second dorsal compartment of the wrist is comprised of the extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL).[1][2][4]

Epidemiology

The syndrome is typically the result of repetitive extension and flexion exercises or activities. It is commonly seen in sporting activities such as rowing or canoeing, skiing, racquet sports, and horseback riding. There is no significant difference in injury pattern found in men versus women.[1][4][2]

Pathophysiology

The repetitive extension-flexion results in a friction injury at the crossover junction of the first dorsal compartment (abductor pollicis longus and extensor pollicis brevis) and the second dorsal compartment (extensor carpi radialis brevis/extensor carpi radialis longus) tendons leading to an inflammatory response and subsequently a tenosynovitis. The presentation is typically one that the patient complains of pain or tenderness over the dorsal aspect of the wrist proximal to the radial styloid. There may also be swelling and crepitus that is palpable on the exam with wrist and/or thumb extension.[4][2]

History and Physical

Intersection syndrome was first described in the literature by Alfred-Armand-Louis-Marie Velpeau a French anatomist and surgeon in 1841. He is also credited for the first accurate description of leukemia. The term of intersection syndrome was first coined by James H. Dobyns in 1978 at the Mayo Clinic. Although the accepted vernacular is intersection syndrome, it has been described in the medical literature by many other names: Oarsmen's wrist, crossover syndrome, squeaker's wrist, abductor pollicis longus bursitis, abductor pollicis longus syndrome, subcutaneous polymyositis, and peritendinitis crepitans. [1][2]

Evaluation

Intersection syndrome is a clinical diagnosis, although a musculoskeletal ultrasound can easily confirm it. The initial steps for diagnosis include a focused physical exam of the elbow, wrist, and hand.[1][2][5]

As with all musculoskeletal exam, you must have a structured approach that includes inspection, a range of motion, palpation, muscle testing, and other special tests. Each joint above and below the injury should be tested in all motions. Look for swelling over the distal forearm as there can be some cases that present with a palpable finding on exam 4 cm - 6 cm proximal to Lister's tubercle. Crepitus is a very common finding on the exam over the site of irritation. This is a finding that is specific to intersection syndrome. As the two dorsal compartments cross the movements of pronation and supination, create friction resulting in the exam finding of crepitus. Pronation is typically found more uncomfortable than supination.[1][2][5]

When developing or working through your differential diagnosis, resisted pronation that leads to the recreation of the patient's pain, along with the palpable finding of crepitus about 2 cm - 3 cm proximal to the radial styloid, can help differentiate from tenosynovitis of De Quarvein Syndrome. De Quarvein Syndrome is a condition that also involves the first dorsal compartment of the wrist extensors. This condition is noted below the radial styloid and can be classically tested via the Finkelstein maneuver.[1][2]

Plain film imaging and CT will not be helpful in the diagnosis of Intersection syndrome. MRI would give excellent soft tissue picture and diagnosis, although MRI would not be a cost- or time-effective choice.[4][3]

Ultrasound technology has pushed musculoskeletal medicine forward in both diagnosis and treatment provided by physicians. There have been some that say it can be as specific as MRI in the hands of the skilled user. Remember that as in most musculoskeletal conditions, the anatomy is mostly superficial. Therefore a linear ultrasound probe is utilized. When observing Intersection syndrome under ultrasound, the ideal image is in the transverse plane in short axis. The findings that would correlate to the diagnosis would be a hypoechoic area in between the two dorsal compartments as they are on top of each other. This represents swelling/edema as caused by friction. There also may be a thickening of the tendon sheaths.[5][3]

Treatment / Management

Treatment is conservative management with rest and activity modification. Corticosteroid injection has shown significant improvement and is a known next best step if little or no improvement has been made with other conservative treatment. [1][2]

Anti-inflammatory medications are maybe useful for acute injury and pain relief. Common medications are ibuprofen, naproxen, meloxicam or diclofenac.[2] Acetaminophen also may be utilized for pain relief as well. Typically rest and activity modification will be more effective. Ice is also an effective treatment. A temporary splint for protection and comfort at night may also be beneficial. There is no compelling evidenced based rehab protocol for intersection syndrome at this time. One may consider extrapolating the use of eccentric strengthening and stretching for rehab protocols.

When conservative measures are not effective corticosteroid injection under ultrasound guidance can be utilized. Using the ultrasound visualization technique noted in the evaluation process; confirm the diagnosis. The typical injection is a one to one mixture of a corticosteroid and anesthetic (0.5ml to 1ml of steroid, commonly used is triamcinolone 40mg/1ml along with a local anesthetic of choice at 0.5ml to 1ml). A 23 to 25 gauge needle at a length of 1 to 1.5 inch is preferred. [5]Using the in-plane or out of plane needle injection technique, guide the needle to where the first dorsal compartment (abductor pollicis longus and extensor pollicis brevis) is crossed over the second dorsal compartment (extensor carpi radialis brevis/extensor carpi radialis longus).[5] After the injection is completed, have the patient pronate and supinate the wrist, observe for crepitus and tenderness with palpation. Resolution of the pain can help solidify the diagnosis. The steroid will take the time to reach full potential. We recommend that rehab exercises be used in tandem with the injection after day 3 to 5. 

In rare, recalcitrant cases surgical debridement and release is indicated.

Pearls and Other Issues

  • Intersection syndrome is inflammatory tenosynovitis at the intersection of the 1st dorsal compartment (APL, EPB) and 2nd dorsal compartment (ECRL, ECRB) of the wrist
  • Patients report pain over dorsal forearm and wrist
  • Examination reveals ttp dorsal radial forearm about 4-6 cm proximal to joint, worse with resisted wrist extension, thumb extension
  • Diagnosis is primarily clinical but supported by US and MRI
  • Treatment is primarily non-operative with medicine, splinting, corticosteroid injections, and very rarely surgical debridement or release

Enhancing Healthcare Team Outcomes

A team of the clinician and nursing splinting the injury and providing close follow up will result in the best outcome. [Level V]


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Intersection Syndrome - Questions

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The intersection syndrome is most likely to be seen in which group of people?



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A rower complains of pain in his wrist that started after his last race last week. He admits it was a tough race and a very windy day on the water. Upon exam, pain with resisted wrist extension and pronation is noted as well as tenderness just proximal to the radial styloid. There also seems to be crepitus with wrist pronation. What is the most likely diagnosis?



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A 22-year-old collegiate tennis player presents wrist pain. She notes her pain is worse with her backhand. She has been working with her coaches on improving her swing. After an exam, you diagnose her with intersection syndrome. What would be an appropriate initial treatment?



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A 20-year-old competitive rower returns to the clinic with complaints of mild improvements since starting rehabilitation. He is noted to have intersection syndrome in his right wrist in which he was given activity modification and appropriate exercises. What is an appropriate adjunct treatment?



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A 20-year-old active duty sailor presents with dorsal forearm pain and crunching with use. She notes the discomfort is hindering her work. She works in an industrial setting onboard a naval ship. On exam, there is crepitus with pronation and supination of the forearm. She is diagnosed with intersection syndrome. What is most likely to be seen on ultrasound examination?



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Intersection Syndrome - References

References

Intersection syndrome of the forearm., Browne J,Helms CA,, Arthritis and rheumatism, 2006 Jun     [PubMed]
Rowing injuries., McNally E,Wilson D,Seiler S,, Seminars in musculoskeletal radiology, 2005 Dec     [PubMed]
Wrist pain from overuse: detecting and relieving intersection syndrome., Servi JT,, The Physician and sportsmedicine, 1997 Dec     [PubMed]
Ultrasound findings in intersection syndrome., Giovagnorio F,Miozzi F,, Journal of medical ultrasonics (2001), 2012 Oct     [PubMed]
MRI features of intersection syndrome of the forearm., Costa CR,Morrison WB,Carrino JA,, AJR. American journal of roentgenology, 2003 Nov     [PubMed]

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