Brachial Plexus Injury After Regional Block

Brachial plexus injury after regional block is damage to roots, trunks, divisions or cords of the plexus during interscalene, supraclavicular, infraclavicular or axillary blocks. It presents with persistent arm weakness or sensory loss.

Epidemiology. Persistent symptoms occur in about 0.05% to 0.2% of brachial plexus blocks, and transient symptoms in 1% to 10%. Interscalene block carries a higher rate of neurological symptoms in shoulder surgery (about 1 in 100 to 1 in 20 at 1 to 4 weeks), commonly attributed to surgical stretch or positioning (beach chair).

Risk factors. Intraneural injection (particularly within the nerve root), small nerve diameter at interscalene level, sitting (beach chair) position with hypotension, shoulder surgery, diabetes, pre-existing neuropathy, high injection pressure and nerve stimulation without ultrasound.

Pathophysiology.

Intraneural or intrafascicular injection and mechanical trauma damage roots and trunks. Cord injury follows retroperitoneal or axillary haematoma, and surgical traction or tourniquet causes additional injury.

Persistent arm numbness, paraesthesia, weakness, pain in nerve distribution, hand weakness, and winging or loss of shoulder abduction (long thoracic or axillary involvement). Pain with injection or paraesthesia during block may be recalled.

Red flags.

• Severe pain on injection.
• Hand weakness.
• Rapidly expanding haematoma.
• Horner syndrome with deficit.

Ultrasound for haematoma. MRI of the plexus (or CT) for root avulsion, haematoma and compression. Nerve conduction and electromyography at 3 weeks (and 6 weeks) to show denervation and grade injury. Exclude cervical radiculopathy, rotator cuff injury and stroke.

Differential diagnosis.

• Neuralgic amyotrophy (Parsonage-Turner syndrome).
• Surgical or positional injury.
• Cervical radiculopathy.
• Haematoma.
• Rotator cuff or glenohumeral pathology.

Initial care is documentation, protective splinting, physiotherapy, and surveillance. Treat neuropathic pain.

• Gabapentin: 300 mg orally, titrated every 3 days to 900 to 1,800 mg daily in three divided doses; maximum 3.6 g daily; monitor sedation and renal function; reduce in creatinine clearance under 60 mL/min.
• Amitriptyline: 10 mg orally at night, titrated to 75 mg; maximum 150 mg daily; monitor ECG and anticholinergic effects; avoid in recent myocardial infarction and arrhythmia.

Surgical exploration or nerve grafting or transfer if no recovery at 3 months (earlier for complete lesions, haematoma or avulsion).

Prevention. Ultrasound direction with visualisation of needle tip and injection spread, avoidance of intraneural injection, injection pressure control, and pre-block neurological documentation.

Monitoring. Examination and electrophysiology at 3 weeks and 3 months.

Referral and escalation. Peripheral nerve surgeon and neurology. Disclosure and report.