Posterior Interosseous Nerve Syndrome

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 7 min read
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Posterior interosseous nerve syndrome is a chronic neuromuscular compressive or nerve compression neuropathy of the posterior interosseous nerve which innervates the extensor compartment of the forearm. It usually has an insidious onset, sudden often presenting with weakness in finger and thumb extension. Posterior interosseous nerve syndrome may...

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বাংলা রোগী নোট এখনো যোগ করা হয়নি। পোস্ট এডিটরে “RX Bangla Patient Mode” বক্স থেকে সহজ বাংলা সারাংশ যোগ করুন।

এই তথ্য শিক্ষা ও সচেতনতার জন্য। এটি ডাক্তারি পরীক্ষা, রোগ নির্ণয় বা প্রেসক্রিপশনের বিকল্প নয়।

Article Summary

Posterior interosseous nerve syndrome is a chronic neuromuscular compressive or nerve compression neuropathy of the posterior interosseous nerve which innervates the extensor compartment of the forearm. It usually has an insidious onset, sudden often presenting with weakness in finger and thumb extension. Posterior interosseous nerve syndrome may be a neuropathic compression of the posterior interosseous nerve where it passes through the radial tunnel this might end in paresis or paralysis...

Key Takeaways

  • This article explains Anatomy in simple medical language.
  • This article explains Causes in simple medical language.
  • This article explains Symptoms in simple medical language.
  • This article explains Diagnosis in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
Reviewed content workflowUse writer and reviewer profiles for stronger trust.
Emergency safety firstUrgent warning signs are highlighted below.

Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

Emergency now

Use emergency care for severe, sudden, rapidly worsening, or life-threatening symptoms.

2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

Learn safely

Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

Posterior interosseous nerve syndrome is a chronic neuromuscular compressive or nerve compression pain, numbness, tingling, or weakness. সহজ বাংলা: স্নায়ুর ক্ষতি/সমস্যা।" data-rx-term="neuropathy" data-rx-definition="Neuropathy means nerve damage or irritation causing pain, numbness, tingling, or weakness. সহজ বাংলা: স্নায়ুর ক্ষতি/সমস্যা।">neuropathy of the posterior interosseous nerve which innervates the extensor compartment of the forearm. It usually has an insidious onset, sudden often presenting with weakness in finger and thumb extension.

Posterior interosseous nerve syndrome may be a neuropathic compression of the posterior interosseous nerve where it passes through the radial tunnel this might end in paresis or paralysis of the digital and thumb extensor muscles, leading to an inability to increase the thumb and fingers at their metacarpophalangeal joints. Wrist extension is preserved thanks to the action of the extensor carpi radialis longus innervated by the nervus radialis.

Anatomy

The posterior interosseous nerve may be a branch of the nervus radialis, which comes off the posterior cord of the plexus brachialis. With nerve roots C5 to T1, the nervus radialis travels down the arm and divides into superficial and deep branches within the proximal forearm. Normally the deep branch of the nervus radialis dives into the posterior forearm through the heads of the supinator to emerge because of the posterior interosseous nerve. Anatomical variants include the deep nervus radialis passing through the Arcade of Frohse to become the posterior interosseous nerve. This variant can increase susceptibility to impingement. The posterior interosseous nerve supplies motor innervation to the posterior forearm. The terminal branch of the posterior interosseous nerve travels distally into the ground of the 4th dorsal compartment of the wrist to innervate the dorsal wrist capsule.

Compression neuropathies of the nervus radialis distal to the elbow include radial tunnel syndrome, posterior interosseous nerve syndrome, and Wartenberg syndrome. Each of those has distinct symptoms, which may help with identifying the right diagnosis. Posterior interosseous nerve syndrome may be a compressive pain, numbness, tingling, or weakness. সহজ বাংলা: স্নায়ুর ক্ষতি/সমস্যা।" data-rx-term="neuropathy" data-rx-definition="Neuropathy means nerve damage or irritation causing pain, numbness, tingling, or weakness. সহজ বাংলা: স্নায়ুর ক্ষতি/সমস্যা।">neuropathy of the posterior interosseous nerve which innervates the extensor compartment of the forearm it always has an insidious onset, often presenting with weakness in finger and thumb extension. However, there should be preservation in wrist extension thanks to the nervus radialis innervated extensor carpi radialis longus its often self-limiting and resolves with conservative measures. However, symptoms that are refractory to nonoperative treatment may require surgical decompression.

Causes

  • Posterior interosseous nerve syndrome can result from trauma, gunshot wound, sudden fall, space-occupying lesions like
  • pain, swelling, stiffness, or reduced movement. সহজ বাংলা: জয়েন্টের প্রদাহ।" data-rx-term="arthritis" data-rx-definition="Arthritis means joint inflammation causing pain, swelling, stiffness, or reduced movement. সহজ বাংলা: জয়েন্টের প্রদাহ।">arthritis: Rheumatoid arthritis is an autoimmune joint disease causing infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।" data-rx-term="inflammation" data-rx-definition="Inflammation is the body’s response to injury, infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।">inflammation, pain, and swelling. সহজ বাংলা: রোগপ্রতিরোধ ব্যবস্থার ভুল আক্রমণে জয়েন্টের প্রদাহ।" data-rx-term="rheumatoid arthritis" data-rx-definition="Rheumatoid arthritis is an autoimmune joint disease causing inflammation, pain, and swelling. সহজ বাংলা: রোগপ্রতিরোধ ব্যবস্থার ভুল আক্রমণে জয়েন্টের প্রদাহ।">Rheumatoid arthritis,
  • Muscle weakness
  • Motorbike driving, mechanical work such as range use to tight or loose any pars
  • Brachial neuritis, and injury
  • Spontaneous compression.
  • The most common site of compression is at the arcade of Frohse (the proximal edge of the supinator).
  • Repetitive pronation supination activities in your daily life activity can also can posterior interosseous nerve syndrome.

Symptoms

  • Pain
  • numbness. সহজ বাংলা: ঝিনঝিন/অবশ/জ্বালাভাব।" data-rx-term="paresthesia" data-rx-definition="Paresthesia means abnormal feelings such as tingling, pins and needles, burning, or numbness. সহজ বাংলা: ঝিনঝিন/অবশ/জ্বালাভাব।">Paresthesia, numbness, itching in the affected area,
  • Sensory disturbances are present
  • Muscle spasm, weakness
  • It usually has a sudden onset, often presenting with weakness in finger and thumb extension. However, there should be preservation in wrist extension movement due to the radial nerve innervated extensor carpi radialis longus.
  • Insidious onset of weakness, numbness in finger extension at the MCP joint.
  • Weakness in extension and abduction of the thumb joint.
  • Deep ache in the proximal forearm may develop.
  • It may often be associated with lateral elbow pain that is exacerbated by pronation and supination.
  • Wrist drop is not a symptom as the extensor carpi radialis brevis and longus remain intact.
  • When asked to make a fist, the wrist may deviate radially due to extensor carpi ulnaris weakness.
  • Positive Tinel’s sign in severe injuries may be found
  • A possible positive radial nerve tensioning test may be positive.

Diagnosis

Physical examination

  • History
  • Functional limitations of movement or deficits
  • Palpation: muscle weakness, motor function weakness. Abnormal pain when an area is touched or pressed. সহজ বাংলা: চাপ দিলে ব্যথা।" data-rx-term="tenderness" data-rx-definition="Tenderness means pain when an area is touched or pressed. সহজ বাংলা: চাপ দিলে ব্যথা।">tenderness is expected over the area of Frohse and eventually over the lateral epicondyle
  • Neural tension test
  • Muscle testing (with resistance): There is partial or complete paralysis, weakness of the wrist extensors
    • The patient is unable to extend the thumb and other fingers of the affected side metacarpophalangeal joints
    • Wrist extension is possible, typically in a radially deviated direction, due to the preservation of the extensor carpi radialis longus the weakened extensor carpi ulnaris muscle
    • Resisted supination and pronation of the forearm can cause pain, as well as the resisted extension of the middle finger
    • The brachioradialis and the extensor carpi radialis longus are innervated by the most proximal branches of the radial nerve, so may be spared

Radiography can assist in including underlying fractures, dislocations, dislocated problems, instability, or arthrosis as an underlying cause of the compression.

Ultrasound can be useful in both localizing and quantifying the degree of constriction. The most commonly seen finding is posterior interosseous nerve enlargement problem or swelling, discolor at the proximal aspect of the compression site.

Imaging diagnosis based primarily on muscle denervation pattern; nerve injury abnormal signal intensity or atrophy in muscles innervated by the posterior interosseous nerve. MRI can also be used to identify any extrinsically compressive lesions, evaluate potential compression sites, and ultimately for surgical planning if intervention is appropriately done.

Electromyography (EMG)

The evaluation may include an electromyography (EMG) and nerve conduction study (NCS).[10] This study may show denervation changes within the muscles innervated by the posterior interosseous nerve. there’ll be sparing of muscles innervated by the nervus radialis, including triceps, anconeus, brachioradialis, and extensor carpi radialis longus (ECRL). there’ll even be normal nerve nerve impulse of the superficial nervus radialis.

Treatment

Treatment of posterior interosseous nerve syndrome starts with non-surgical management, which may include splinting, physiotherapy, activity modification, and surgery is reserved for those refractory to conservative management for a minimum of 3 months.

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

Conservative management

  • Reduction of local inflammation and swelling around the nerve
    • Wrist and/or elbow splints
      • 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
      • In cases with more significant weakness, extension assist outrigger component maybe added to aid in passive finger extension for improved hand function.
    • NSAID’s
    • Activity modification to reduce local inflammation and swelling around the nerve
  • Corticosteroid injections
  • Therapeutic ultrasound
  • Physiotherapy
  • Reduction of synovitis:
    • Heat
    • Rest
    • Mild range of motion

Surgery

Surgical decompression focuses on releasing areas of compression. Areas that will be decompressed include releasing fibrous bands superficial to the radiocapitellar joint, the fibrous fringe of extensor carpi radialis brevis (ECRB), ligating the leash of Henry (radial recurrent artery), releasing the arcade of Frohse, and therefore the distal fringe of the supinator.

  • Indication:
    • No improvement with conservative management after 3-6 months
    • Pain present after 12 weeks
    • Surgical decompression may be indicated to prevent further nerve damage.
  • Aim: To obtain full recovery
  • Recovery and outcomes: Will depend on the extent of nerve damage with the vast majority of neuropraxic problems resolving. Treatment of a patient after they have a decompression includes a gradual return to activities over a 6 weeks period.
  • Surgery: Depends on how and where impingement is present
    • Arcade of Frohse release
    • Resection of lesions
    • Posterior interosseous nerve release
    • Release of superficial radial nerve
    • Lengthening of supinator
    • Synovectomy

Physiotherapy Management

Conservative management

3-6 months of physiotherapy with regular re-assessment of signs and symptoms is recommended. If there is no response to therapy, evidence of denervation, or persistent paralysis, surgical decompression should be considered.

Physiotherapy should include a multimodal approach. The following can be considered based on the patient presentation:

  • Cryotherapy: Increase extensibility and reduce tone of local muscles
  • Ultrasound
  • TENS
  • Deep tissue massage and stretching exercises: Improve extensibility of the muscles who surround the brachial plexus and radial nerve
    • Focus on:[30]
      • Thoracic outlet
      • Pectoralis minor
      • Triceps
      • Brachioradialis
      • Supinator
      • Extensor carpi radialis longus and brevis
  • Dry needling: Increase extensibility and reduce tone of local muscles
  • Neural mobilizations:[30]
    • Reduce mechanical extra- and intra-neural adhesion
    • Assist the neuromodulation of symptoms
  • Manual therapy[9]: Regain elbow mobility
  • Strengthening[20] and range of motion exercises
  • Stretching exercises:
    • Focus on supinator
    • Passive wrist extensions stretches:
      • Place hand on table and move upper body over wrist
      • Prayer stretch

Post-surgical rehabilitation

  • Commence active range of motion from day 3-5
    • Incorporate stretching of extensors
  • Commence strengthening from week 3-4

Patients can return to light duty work between week 2 and 3 post-operatively, while return to baseline function can take between 6 and 12 weeks.

References

Doctor visit helper

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A simple rural-patient checklist to help you explain symptoms clearly, ask better questions, and avoid unsafe self-treatment.

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Doctor / qualified healthcare provider
Tests to discuss with doctor
  • Basic vital signs: temperature, pulse, blood pressure, oxygen level if needed
  • Relevant blood, urine, imaging, or specialist tests only after clinical assessment
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Posterior Interosseous Nerve Syndrome

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

Ask a health question safely

Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area from the RX Article Professional Blocks panel.

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