Brachial Neuritis Following Vaccination
Diagnosis
This patient has brachial neuritis (also called neuralgic amyotrophy), a recognized complication of vaccination that presents with severe shoulder and arm pain followed by weakness, and the diagnosis is primarily clinical. 1
Clinical Features to Confirm Diagnosis
- Pain pattern: Severe, acute-onset shoulder and upper arm pain that typically precedes weakness by days to weeks 2, 3
- Timing: Symptoms develop within days to weeks after vaccination (typically 4-12 hours to several days), distinguishing this from anaphylaxis which occurs within minutes 1, 2
- Motor involvement: Weakness appears as pain subsides, most commonly affecting the deltoid, spinati, serratus anterior, biceps, and triceps muscles 3
- Nerve distribution: The C5 or C6 nerve roots and/or upper trunk are always involved, with frequent involvement of suprascapular, long thoracic, and axillary nerves 4
- Sensory findings: Paresthesias and sensory loss are inconstant features 3
Diagnostic Workup
- Electromyography (EMG): Shows fibrillation potentials and positive waves in a pattern indicating combined nerve-root and peripheral nerve involvement; frequently reveals bilateral involvement even when clinically unilateral 3
- MR neurography: Can document abnormal signal consistent with inflammatory changes in the brachial plexus and associated muscular denervation edema, and may identify hourglass constrictions in affected nerves 4, 5
- Laboratory studies: Serve only to exclude other causes of shoulder pain 3
Critical Differential Diagnosis Pitfall
Do not confuse brachial neuritis with rotator cuff pathology, adhesive capsulitis (frozen shoulder), shoulder arthritis, or cervical spondylosis—all more common diagnoses that can delay appropriate management 6
Treatment
Initiate conservative management immediately with symptomatic pain control, as brachial neuritis is self-limited with spontaneous recovery expected in most cases. 1, 2
Acute Phase Management
- Pain control: Provide aggressive symptomatic pain management during the acute phase, which typically lasts weeks to months 2
- Physical therapy: Institute supportive care and physical therapy as tolerated to prevent contractures and maintain range of motion 3
- Monitoring: Follow clinically and with EMG for prognostic assessment 3
Prognosis and Recovery
- Expected outcome: Complete recovery occurs in 90% of patients within three years 3
- Recovery timeline: Some patients begin improving within weeks, but full recovery may take months to years 2, 3
- Recurrence: Uncommon 3
Future Vaccination Guidance
The Advisory Committee on Immunization Practices explicitly states that brachial neuritis is NOT a contraindication or precaution for subsequent tetanus toxoid-containing vaccines (or other vaccines), and future vaccinations can and should be administered when indicated. 1, 2
Key Points for Patient Counseling
- Brachial neuritis does not preclude future use of the same vaccine in the same person 1
- The condition is usually self-limited with expected recovery in the majority of cases 1, 2
- This is a recognized compensable event through the Vaccine Injury Compensation Program (VICP) 1
Adverse Event Reporting
Document this as a vaccine adverse event and report to the Vaccine Adverse Event Reporting System (VAERS) 2
Important Caveat
While the Institute of Medicine concluded that evidence favors a causal relationship between tetanus toxoid-containing vaccines and brachial neuritis, the ACIP considers this a rare event that does not warrant avoiding future vaccination 1