Brachial Neuritis – Parsonage-Turner Syndrome: Causes, Symptoms, and Recovery

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Brachial neuritis is also known as:

Neuralgic Amyotrophy (NA)
Parsonage-Turner Syndrome
It is a condition characterized by severe shoulder pain that typically radiates down the arm and up to the neck and scapula. The pain is sudden, intense, and may last for weeks.

This pain often wakes patients from sleep and usually occurs spontaneously without a history of trauma. It is more common in males and can affect individuals of any age.

The position of comfort is shoulder adduction with elbow flexion, known as the Adduction/Flexion Sign of Acute Brachial Neuritis.

Neck movement and Valsalva’s maneuver do not exacerbate the pain; however, moving the arm increases it. Despite its sudden and severe nature, this condition is often underdiagnosed, misdiagnosed, or diagnosed late.

Muscle weakness may not be present in the acute phase but develops as the pain subsides. The degree of weakness correlates with the severity of the initial pain.

Commonly Affected Muscles
Supraspinatus and Infraspinatus (External Rotators): The suprascapular nerve is the most commonly involved.
Deltoid (Shoulder Abductor): Innervated by the axillary nerve.
This condition may affect both sides (bilateral) or be subclinical (detectable only on imaging).

Sensory Changes
No sensory loss is a classic finding that helps confirm the diagnosis.
Decreased sensation is present in many cases.
The lateral antebrachial cutaneous nerve is commonly involved.
Motor deficits are more prominent than sensory changes.
The condition can involve the brachial plexus from C5-T1, leading to variable degrees of weakness.
Multiple nerve branches may be affected, with characteristic patterns seen on MRI.
Prognosis
A benign, self-limiting condition, with 90% of patients recovering near-normal function within 3 years.
Only about one-third of patients recover within 1 year.
Etiology
The exact cause is unknown, but possible triggers include:

Viral infections
Shoulder trauma or overuse
Autoimmune responses
Stress
Immunization
Genetic predisposition: A rare autosomal dominant form exists.
Imaging
MRI may show hyperintense signals in the affected muscles (supraspinatus, infraspinatus, deltoid).
In advanced cases, muscles may show atrophy or fatty infiltration.
Electrodiagnostic Studies (EMG & Nerve Conduction Studies)
Helpful for diagnosis and prognosis.
First 4 weeks: Acute denervation of nerve roots and peripheral nerves.
EMG abnormalities can persist for up to 7 years after diagnosis.
Differential Diagnosis
Cervical radiculopathy from a herniated disc → Imaging of the cervical spine can exclude this.
Adhesive capsulitis (frozen shoulder).
Lyme disease.
Notable Clinical Presentations
Bilateral Anterior Interosseous Nerve Palsy

Caused by viral brachial neuritis (documented cases).
Patients lose the ability to perform the O.K. sign.
Motor loss follows intense shoulder pain and usually resolves over time, especially if due to neuritis.
Winging of the Scapula

Serratus anterior muscle involvement may cause a dull ache and scapular winging.
If scapular winging is associated with acute, severe pain, consider acute brachial neuritis affecting the C7 nerve root.
C7 nerve root → Long thoracic nerve → Serratus anterior muscle.
Severe shoulder pain + Winging of the scapula → Rule out Brachial Neuritis.
Treatment
Rest
Observation
Steroid injections
Avoid using a sling, as it may lead to shoulder contracture (flexion/internal rotation) and elbow stiffness.
Expected Recovery
Most patients recover over time, though the process can be prolonged.
QUIZZES
1. What is another name for Brachial Neuritis?
✅ Neuralgic Amyotrophy
A) Thoracic Outlet Syndrome
B) Neuralgic Amyotrophy
C) Cervical Radiculopathy
D) Rotator Cuff Tear
Explanation: Brachial neuritis is also known as Neuralgic Amyotrophy or Parsonage-Turner Syndrome.

2. Which nerve is most commonly involved in Brachial Neuritis?
✅ Suprascapular nerve
A) Median nerve
B) Ulnar nerve
C) Suprascapular nerve
D) Radial nerve
Explanation: The suprascapular nerve, which innervates the supraspinatus and infraspinatus muscles, is most commonly affected.

3. What is a hallmark feature of pain in Brachial Neuritis?
✅ Severe, sudden onset, radiating to the neck and arm
A) Gradual onset with mild discomfort
B) Severe, sudden onset, radiating to the neck and arm
C) Associated with trauma
D) Pain worsens with Valsalva maneuver
Explanation: Pain is sudden, severe, and radiates but is not aggravated by Valsalva maneuver or neck movement.
4. What is the typical position of comfort in acute Brachial Neuritis?
✅ Shoulder adducted with elbow flexed
A) Shoulder abducted with elbow flexed
B) Shoulder adducted with elbow flexed
C) Shoulder neutral with elbow extended
D) Shoulder internal rotation with elbow extended
Explanation: Patients prefer shoulder adduction and elbow flexion, known as the Adduction/Flexion Sign.