Brachial Plexus Injury

How the brachial plexus works

The brachial plexus is formed by five nerve roots (C5, C6, C7, C8 and T1) leaving the spinal cord in the neck. They merge and split behind the collarbone and in the armpit, then become the main nerves of the arm: the musculocutaneous, axillary, radial, median and ulnar nerves. Together they control the shoulder, elbow, wrist and hand muscles and carry feeling from the arm.

Because the plexus runs between the neck and shoulder, anything that forcefully pushes the head one way and the shoulder the other way stretches it.

Types and severity

Injuries are also described by which roots are affected:

• Upper plexus (C5 to C6), Erb's palsy: the shoulder and elbow are weak. The arm hangs by the side, turned inward, with the wrist bent ("waiter's tip" posture). Common in birth injury.
• Lower plexus (C8 to T1), Klumpke's palsy: weakness of the hand and finger muscles, sometimes with Horner syndrome (drooping eyelid, small pupil).
• Total plexus injury: the whole arm is limp and numb. Usually from high-speed motorcycle crashes.

Causes

• Motor vehicle and especially motorcycle crashes: the leading cause of severe adult injuries.
• Contact sports: tackling in football or rugby causes stingers and burners.
• Falls onto the shoulder or with the arm wrenched upward.
• Shoulder dislocation or a broken collarbone: can stretch or compress the axillary nerve and plexus.
• Birth injury: a baby's shoulder getting stuck behind the mother's pelvic bone (shoulder dystocia). Higher risk with large babies and maternal diabetes.
• Penetrating wounds, tumors and radiation therapy to the area.

Symptoms

• Weakness or paralysis of the shoulder, arm or hand
• Numbness or loss of feeling in parts of the arm
• A burning or electric shock feeling shooting down the arm (stingers)
• Severe, constant burning or crushing pain in a numb hand, typical of root avulsion
• Muscle wasting over the following weeks
• In a newborn, an arm that hangs limp and does not move when the baby is startled

Different conditions can mimic this. Brachial neuritis causes sudden severe shoulder pain then weakness without trauma. Thoracic outlet syndrome causes intermittent symptoms with overhead arm use.

Diagnosis

1. Examination: a doctor maps which muscles work and where feeling is lost to pinpoint the injured roots.
2. Imaging: X-rays for fractures of the neck, collarbone or ribs. MRI or CT myelography shows root avulsions and the fluid pockets (pseudomeningoceles) they leave.
3. Nerve conduction studies and electromyography (EMG): most informative 3 to 4 weeks after injury. Repeated over time to track recovery.
4. Vascular studies: if the arm's blood supply might be damaged.

Treatment

Non-surgical care

• Stingers: rest from contact until strength and neck movement are fully normal.
• Physical and occupational therapy for all injuries: keeping joints supple stops stiffness while nerves regrow.
• Pain control. Nerve pain responds poorly to standard painkillers and is usually treated with nerve-pain medicines prescribed by a doctor.
• For babies, gentle daily range-of-motion exercises taught by a therapist. Most birth injuries improve within the first few months.

Surgery

Surgery is considered if there is no recovery by about 3 to 6 months, or sooner for clear ruptures or avulsions. Delay matters: after about 12 months, muscles that have lost their nerve supply begin to deteriorate permanently.

• Nerve repair and grafting: a gap in a ruptured nerve is bridged with a piece of a less important nerve, often from the leg.
• Nerve transfers: a working nerve with a less critical job is rerouted to power a key muscle, such as elbow bending.
• Tendon or muscle transfers: for late injuries, to restore specific movements.

Recovery and outlook

Nerves regrow at roughly 1 mm a day, about an inch a month. Recovery of the shoulder and elbow after surgery can take 1 to 2 years, and hand function is the hardest to restore. Most stingers and stretch injuries recover fully. Most babies with birth injuries recover completely or nearly so. Adults with complete avulsions usually regain useful shoulder and elbow function after surgery but may have permanent hand weakness and long-term neuropathic pain.

Frequently asked questions

What are the symptoms of a brachial plexus injury?

Symptoms include weakness or paralysis in the shoulder, arm or hand, numbness, and burning or shock-like pain down the arm. Mild injuries cause a brief stinger. Severe injuries can leave the whole arm limp, sometimes with a droopy eyelid on the same side.

How long does a brachial plexus injury take to heal?

Stingers recover within minutes to days. Stretch injuries usually recover within weeks to 3 months. Torn nerves repaired with surgery regrow slowly, around an inch a month, so improvement continues for 1 to 2 years or more.

Can a brachial plexus injury heal on its own?

Many can. Stretch injuries where the nerve is intact often recover fully without surgery. Ruptured nerves and roots pulled from the spinal cord do not heal on their own and need surgery, ideally within 3 to 6 months of the injury.

What is a stinger or burner?

A stinger is a mild brachial plexus stretch injury, common in football. It causes a sudden burning or electric pain down one arm, sometimes with brief weakness, that usually fades within minutes. Repeated stingers, or symptoms in both arms, need medical review.

What is Erb's palsy?

Erb's palsy is a brachial plexus injury to the upper nerve roots (C5 and C6), usually during a difficult birth. The baby's arm hangs by the side, rotated inward. Most babies recover with physical therapy, but those without improvement by about 3 to 6 months may need surgery.