Posterior interosseous nerve syndrome

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Top Contributors - Lyn Bruyndonckx, Deborah Huart, Liena Lamonte, Claire Knott and Wanda van Niekerk  Deborah Huart


Posterior interosseous nerve syndrome is a compression of the posterior interosseous nerve that is located nearby the shaft of the humerus and the elbow. This nerve is the deep motor branch of the radial nerve. Proximal to the supinator arch, the radial nerve is divided into a superficial branch and posterior interosseous branch. The radial nerve supplies the majority of the forearm and hand extensors. Damage to the branch of the radial nerve results in a posterior interosseous nerve syndrome. The syndrome may result in paresis or paralysis of the digital and thumb extensor muscles. The patient is unable to extend the thumb and fingers at their metacarpophalangeal joints. The only movement patients may be able to do is the dorsoradial direction(2) (Level of Evidence: 4) . A posterior interosseous nerve syndrome can be caused by a traumatic injury, tumors, inflammation and anatomic injury. Traumatic injury is a term which refers to physical injuries of sudden onset and severity which require immediate medical attention. The insult may cause systemic shock called “shock trauma”, and may require immediate resuscitation and interventions to save life and limb. Traumatic injuries are the result of a wide variety of blunt, penetrating and burn mechanisms. They include motor vehicle collisions, sports injuries, falls, natural disasters and a multitude of other physical injuries which can occur at home, on the street, or while at work and require immediate care. With repeated pronation and supination a dynamic compression of the nerve in the proximal part of the forearm can be created. (1) (Level of Evidence: 5)

Clinically Relevant Anatomy

Posterior interosseous nerve syndrome is a neuropathic compression of the posterior interosseous nerve, that is situated where this nerve (RN) passes through the radial tunnel(4) (Level of Evidence: 4) .
The radial tunnel is a space that extends 5 cm from the radial head to the distal margin of the supinator. This tunnel is attached laterally to the brachioradialis (BR), extensor carpi radialis longus and extensor carpi radialis brevis (MW – mobile wad) and medially to the biceps tendon and brachialis. The floor is formed by the deep head of the supinator (S) and the capsule of the radiocapitellar joint, while the roof is formed by the superficial head of the supinator and the radial recurrent vessels.(11) (Level of Evidence: 4)
At the level of the lateral epicondyle, between the brachioradialis and brachialis muscles, the radial nerve, which has its origin in the plexus brachialis, divides into its 2 terminal branches: the superficial radial nerve (SRN) and the posterior interosseous nerve (PIN).(12) (Level of Evidence: 3B)
The superficial radial nerve ends proximal to the radial tunnel. The posterior interosseous nerve is much longer and enters the radial tunnel underneath a musculotendinous arch, the arcade of Frohse (*). The arcade of Frohse, which is the most common point of compression, is a connection between the deep and superficial heads of the supinator and is fibrotendinous in 30% of the population. The PIN continues in the radial tunnel through the supinator, as it goes from the anterior to the posterior surface of the forearm.
The posterior interosseous nerve is a motor nerve and sequentially innervates supinator, extensor carpi radialis brevis, extensor digitorum communis, extensor digiti minimi, extensor carpi ulnaris, abductor pollicis, extensor pollicis brevis, extensor pollicis longus, and extensor indicis.(11),(19) (Level of Evidence: 4,4)

Epidemiology /Etiology

Posterior interosseous nerve syndrome usually develops spontaneously(4) and is caused by a compression of the arcade of Frohse. It’s the area where the nerve enters the supinator muscle (3) (Level of Evidence: 3A) and is the most common place for a compression of the nerve. However, it can also occur following trauma such as a blow to the proximal dorsal region of the forearm, forearm fractures, crush injuries, … . When you have a humeral shaft fracture, there is a 12% chance that it is associated with radial nerve paralysis. Impingement of the radial nerve results in posterior interosseous nerve syndrome(13) (Level of Evidence: 3B). Compression of the PIN is associated with repetitive activities that involve wrist supination and pronation, with a component of wrist extension(14) (Level of Evidence: 2C)
Compressive injuries to the upper extremity can result in posterior interosseous nerve damage(15) (Level of Evidence: 2C)
It also can be iatrogenic following reduction of radial fracture, transposition of the ulnar nerve or release of the extensor origin for lateral epicondylitis(4).(Level of Evidence: 4) The causes of posterior interosseous nerve syndrome include intrinsic nerve abnormalities and extrinsic compression(2) (Level of Evidence: 4)

Characteristics/Clinical Presentation

Most nerve entrapments occur usually due to an osseoligamentous tunnel narrowing. In the case of a posterior interosseous nerve entrapment, the compression occurs within the musculo-tendinous radial tunnel. In 69.4%, the nerve is compressed by the fibrous arcade of Frohse(5) (Level of Evidence: 3B) . In a normal situation the nerve dives under the arcade of Frohse (proximal edge of the supinator).

There is a very slow development of the symptoms. The duration of symptoms averaged 2.3 years before a definitive diagnosis 1) could be made. Symptoms of nerve entrapment syndromes are generally involving pain, sensory and motor changes, sensations of popping, paresthesias, and paresis.

But the posterior interosseous nerve is characterized by motor deficits in the distribution of the posterior interosseous nerve(5 (Level of Evidence: 3B)). While the PIN does have afferent fibres that transmit pain signals from the wrist, it does not carry any cutaneous sensory information that can help distinguish a PIN palsy from cervical radiculopathy. The clinical presentation of posterior interosseous nerve syndrome is characterized by the loss of function due to variable degrees of weakness involving ulnar deviation.

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Differential Diagnosis

The PIN syndrome is one of the pathologies that can cause lateral elbow pain. The other pathologies that are associated with lateral elbow pain are:

Pigmented villonodular synovitis (PVNS) (17) (Level of Evidence: 4)
• Lateral epicondylitis (18) (Level of Evidence: 4)
• Radial nerve injury (18)
• Cervical radiculopathy (18)
• ECRB Tendinose (19) (Level of Evidence: 4)
• Cervical spine C5-C7 (19)
• Extensor tendon rupture(6) (Level of Evidence: 3B)
Trigger finger
• Sagittal band ruptures
• Inflammatory involvement of the MCP joints
• Anconeus muscle tendonitis (20) (Level of Evidence: 3B)
• Supinator syndrome (20)
• Brachialis neuritis (20)
• Artirits/artrose of the radiohumeral joint
• Meniscus of the radiohumeral joint
Olecranon bursitis
• Neuralgic amyotrophy
• Tennis elbow (4)
• Rupture of the intermetacarpal space (6)

Diagnostic Procedures

Careful clinical and electrophysiological examination is important and essential for a reliable diagnosis(3). (Level of Evidence: 3A) EMG (electromyography) and NCV (nerve conduction velocity) can help to set the diagnose. It is a pre-operative examination to ensure that the patient has the syndrom (4) (Level of Evidence: 2A), it can establish the topography of the lesion and the severity of the muscular denervation (3) (Level of Evidence: 3A)

Outcome Measures

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Physical examination

<span style="font-size: 19.92px; line-height: 1.5em; background-color: initial;" />The diagnosis of posterior interosseous syndrome can be based on the findings of the patients history and the limitations or deficits that the patient might have during physical examination.
Tests that might be positive are:

1) Palpation:
Abnormal tenderness is expected over the arcade of Frohse and eventually over the lateral epicondyle.

2) Neural tension test:

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3) Muscle testing (with resistance): (10),(11)
There is a partial or complete paralysis of the wrist extensors.
- The patient is unable to extend the thumb and other fingers of the affected side at the metacarpophalangeal joints.
- Dorsiflexion is possible but only with a dorso-radial direction, due to the weakened exten-sor carpi ulnaris.
- Resisted supination and pronation of the forearm can produce pain, as well as resisted ex-tension of the middle finger.
- The brachioradialis, extensor carpi radialis longus and extensor capri radialis brevis are innervated by more proximal branches of the radial nerve, so may be spared.

Medical Management 

There are several medical ways to treat the posterior interosseous nerve syndrome.

Non-surgical Treatment
For the treatment of the posterior interosseous syndrome we begin with wrist and/or elbow splints, NSAID’s and activity modification to reduce local inflammation and swelling around the nerve5(C).(21) (Level of Evidence: 2C) The other most commonly used medications are corticosteroid injections, ultrasound massages and therapy.(23) (Level of Evidence: 4) Furthermore heat applications, rest and a mild range-of-motion can be used to reduce synovitis. (22) (Level of Evidence: 4)

Surgical Treatment
The surgical treatment will be used if there is no improvement of the conservative treatment or if the pain is still present after 12 weeks. The aim of the surgery is to obtain full recovery. There are different ways to treat the posterior interosseous nerve syndrome depending on how and on where the radial nerve is pinched. They can release the arcade of Frohse, resect the lesions, release the PIN and the superficial branch of the radial nerve,(24) (Level of Evidence: 2B) lengthening the supinator and perform a synovectomy.(22) (Level of Evidence: 4)

Physical Therapy Management

The physical therapy involves the use of cryotherapy, ultrasound, TENS (transcutaneous electrical nerve stimulation), deep tissue massage, dry needling, neural mobilizations, manual therapy(23) (Level of Evidence: 4)and strengthening exercises for weakened musculature 5(C)(5).
• Dry needling and cryotherapy can be used for short duration and will only be used to re-duce the tone of the local muscles and to increase the extensibility.
• Deep tissue massage (DTM) and stretching are necessary to improve extensibility of the muscles who surround the brachial plexus and radial nerve. It’s necessary to focus on the thoracic outlet, M. pectoralis minor, M. triceps, M. brachioradialis, M. supinator and M.extensor carpi radialis longus and brevis. (26)  (Level of Evidence: 3B)
• The extensor muscles of the fingers were completely paralysed. Because supination was absent, it meant that the supinator needed to be stretched. Furthermore, the radial exten-sors of the wrist were weak. Neural mobilization was used to reduce mechanical extra and intra neural adhesion and to assist the neuromodulation of symptoms.(26) (Level of Evidence: 3B)
• Manual therapy is needed to regain mobility of the elbow.
• The arm can be put in an above-elbow cast for ten days with the elbow flexed at 90°, the forearm supinated and the wrist in neutral position. (27) (Level of Evidence: 3B)

Exercises (9):
- Immobilize your wrist on the table, your other hand is fixated on your bad wrist. Now you move your upper body above your wrist.
- Put your hands together with their palms against each other. You push your hands together.

- Wave with your hand, the movement must come from the wrist and not from the elbow. This is a good exercise for radial deviation.
- Special for the fingers is to bring your fingers to the back of your hand with your other hand.
You should follow the therapy for approximately 3-6 months with regular re-assessment of signs and symptoms. If there is no response to therapy, evidence of denervation, or persistent paralysis, surgical decompression should be considered (5).  (Level of Evidence: 3B)

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see adding references tutorial.

1. A. E. Portilla Molina et Al. The posterior interosseous nerve and the radial tunnel syndrome: an anatomical study. International Orthopaedics, number 2, volume 22, p102-106. Level of evidence: 5
2. Alexander J. Chien et Al. Sonography and MR Imaging of Posterior Interosseous Nerve Syndrome with Surgical Correlation. The American Journal of Roentgenology, number 1, volume 181, July 2003, p219-221. (Level of Evidence: 4)

3. Bionka M. et Al. Interventions for treating the posterior interosseus nerve syndrome: a systematic review of observational studies. Journal of the Peripheral Nervous System, number 2, volume 11, 15 JUNE 2006, p101-110. Level of evidence: 3A
4. C. Vrieling et Al. Posterior interosseous nerve syndrome: literature review and report of 14 cases. Eur J Plast Surg, volume 21, 1998, p196-202. Level of evidence: 2A
5. Saratsiotis John et Al. Diagnosis and treatment of posterior interosseous nerve syndrome using soft tissue manipulation therapy: A case study. Journal of Bodywork and Movement Therapies, number 14, 2010, p397-402. Level of evidence: 3B
6. Lewis H. et Al. Posterior interosseous-nerve syndrome secondary to rheumatoid synovitis. The Journal of Bone and Joint Surgery, number 55, June 01 1973, p753-757. Level of evidence: 3B
9. Cursus Functionele trainingstherapie.
Evidence level: D
10. Vijay A. Singh et al. , Case report: Posterior Interosseous Nerve Syndrome from Thermal Injury, 6 march 2014. Level of evidence: 3 B
11. Cha et al. Posterior Interosseous Nerve Compression., Interesting Case, 31 January 2014 Level of evidence: 4
12. Bevelaqua A-C. et al. , Posterior Interosseous Neuropathy : Electrodiagnostic Evaluation,
hospital for special surgery, 24 January 2012 Level of evidence: 3B

13. R. Quignon, E. Marteau, A. Penaud, P. Corcia, and J. Laulan, “Posterior interosseous nerve palsy. A series of 18 cases and literature review,” Chirurgie de la Main, vol. 31, no. 1, pp. 18–23, 2012. Level of evidence: 3 B
14. Rosenbaum R. Disputed radial tunnel syndrome. Muscle & Nerve. 1999. Level of evidence: 2 C
15. G. Andreisek, D. W. Crook, D. Burg, B. Marincek, and D. Weishaupt, “Peripheral neuropa-thies of the median, radial, and ulnar nerves: MR imaging features,” Radiographics, vol. 26, no. 5, pp. 1267–1287, 2006 Level of evidence: 2 C
16. P. Kaveh Mansuripur et al. , Nerve Compression Syndromes of the upper Extremity: Diagnosis,
Treatment, and rehabilitation , May 2013, Rhode Island Medical Journal. Level of evidence: 2C
17. K. Kohyamaa,, H. Sugiurab, K. Yamadab et al. Posterior interosseous nerve palsy secondary to pigmented villonodular synovitis of the elbow: Case report and review of literature, Orthopaedics & Traumatology: Surgery & Research (2013) 99, 247—251 : level of evidence: 4
18. Anna-Christina Bevelaqua, MD&Catherine L. Hayter et al. Posterior Interosseous Neuropathy: Electrodiagnostic Evaluation HSSJ (2012) 8:184–189, level of evidence: 4
19. Richard A Ekstrom and Kari Holden. Examination of and Intervention for a Patient With Chronic Lateral Elbow Pain With Signs of Nerve Entrapment.PHYS THER. 2002; 82:1077-1086; Level of evidence: 4
20. Kaswan et al. Radial Tunnel Syndrome Complicated by Lateral Epicondylitis in a Middle-Aged Female. Interesting Case, November 4, 2014; level of evidence: 3 B
21. P. Kaveh Mansuripur, et al. ; Nerve Compression Syndromes of the Upper Extremity: Diagnosis, Treatment, and Rehabilitation ; May 2003; Rhode island medical journal, level of evidence: 2C
22. Lennig W. Chang, et al. ; Entrapment Neuropathy of the Posterior lnterosseous Nerve ,A Complication of Rheumatoid Arthritis; Arthritis and Rheumatism, Vol. 15, No. 4 (July-August 1972)Level of evidence: 4
23. Nicola Maffulli, Francesco Maffulli; Transient entrapment neuropathy of the posterior interosseous nerve in violin players, Journal of Neurology, Neurosurgery, and Psychiatry 1991;54:65-67; Level of evidence: 4
24. H. Hashizume, et al. ; non-traumatic paralysis of the posterior interosseous nerve; VOL. 78-B, NO. 5, SEPTEMBER 1996; Level of evidence: 2 B
25. Carl-olof Werner et al., ;Lateral Elbow Pain and Posterior Interosseous Nerve Entrapment; Department ofOrthopaedic Surgery; Level of evidence: 1A
26. John Molloy.Posterior interosseous nerve enrapement.2006;vol33:48-52; Level of evidence: 3B
27. Nicola Maffulli, Francesco Maffulli , Transient entrapment neuropathy of the posterior
interosseous nerve in violin players, April 17 2015, Journal of Neurology, Neurosurgery, and Psychiatry 1991;54:65-67 Level of evidence: 3 B