A sudden, forceful injury, such as from a motorcycle accident, or a difficult childbirth can sometimes result in a devastating injury to the nerves of the arm, leading to weakness, paralysis, and a loss of sensation. In other cases, a person may experience the spontaneous onset of severe shoulder pain followed by a perplexing paralysis. Both of these scenarios can be caused by brachial plexopathy, a disorder affecting the complex network of nerves that controls the entire arm. This is a serious condition that can be life-altering, but it is crucial to understand that a combination of time, intensive rehabilitation, and in some cases, advanced nerve surgery, can help many individuals recover significant function and adapt to their challenges.

Brachial plexopathy is a broad term for any disease or injury that affects the brachial plexus. The brachial plexus is not a single nerve, but an intricate, interwoven network of nerves that sends signals from the spinal cord in the neck to the shoulder, arm, and hand.

To understand this complex structure, it is helpful to use an analogy.

• Think of the nerve supply to your arm as the electrical system for a house.
• The spinal cord in your neck is the main circuit breaker panel, where the power originates.
• The brachial plexus is the incredibly complex junction box located in the tight space between your neck and your shoulder. In this box, the main power lines from the panel (the nerve roots) are bundled, sorted, and re-routed into specific circuits.
• From this junction box, individual “cables” (the peripheral nerves of the arm, like the ulnar, median, and radial nerves) run down the arm to power all the specific appliances (the muscles) and light switches (sensation).
• A brachial plexopathy is what happens when there is catastrophic damage to this main junction box. The circuit breaker panel in the neck may be fine, and the individual cables further down the arm may be fine, but the central sorting and distribution hub has been torn, stretched, or crushed.
• This damage disrupts all the power flowing to the arm, leading to widespread paralysis, weakness, and sensory loss.

In my experience, patients often describe sudden weakness or numbness in one arm after trauma or surgery, prompting an evaluation for brachial plexopathy.

The cause of brachial plexopathy is always damage to the nerves of the plexus. This damage can occur through several different mechanisms and is broadly divided into traumatic and non-traumatic causes.

Traumatic Brachial Plexus Injury (BPI)

This is the most common cause of severe plexopathy. The injury is typically caused by a forceful stretching or tearing of the nerve network.

• Mechanism: The brachial plexus is most vulnerable to a traction (stretching) injury when the head and shoulder are forced violently apart.
• Common Events:
  • High-speed motor vehicle accidents, especially motorcycle accidents where the rider is thrown from the bike.
  • Severe falls, such as from a height.
  • Penetrating injuries, like a gunshot or stab wound.
• Obstetric Brachial Plexus Palsy (Birth Injury): During a difficult childbirth, if the baby’s shoulder gets stuck after the head has been delivered (shoulder dystocia), the stretching of the neck to free the shoulder can injure the brachial plexus. This is the cause of conditions like Erb’s palsy.

Non-Traumatic Brachial Plexopathy

In these cases, the nerve damage is not caused by an external force.

• Parsonage-Turner Syndrome (Neuralgic Amyotrophy): This is an acute, inflammatory condition where the immune system is thought to attack the nerves of the brachial plexus. It is characterized by the sudden onset of severe shoulder and arm pain, followed by the development of patchy muscle weakness and atrophy a few days or weeks later.
• Radiation-Induced Plexopathy: This is a delayed complication that can occur months or years after a person has received radiation therapy to the chest or neck for cancer. The radiation can cause scarring and damage to the blood vessels that supply the nerves, leading to progressive weakness and pain.
• Compression from Tumors: A tumor growing at the top of the lung (a Pancoast tumor) or in the neck can directly compress or invade the brachial plexus.

In my experience, I’ve seen brachial plexopathy in patients after prolonged positioning during surgery or from repetitive overhead activity, such as in athletes.

A person develops brachial plexopathy either as a result of a major traumatic event, a complication of childbirth, or from the onset of a specific medical condition like an inflammatory disorder or cancer. It is not contagious. The risk factors are those associated with high-energy trauma (like riding a motorcycle) or the risk factors for the other underlying medical conditions.

Clinically, trauma like motor vehicle accidents or shoulder dislocations is the most common cause, but inflammation, tumors, or surgical complications can also damage the nerve bundle.

The signs and symptoms of a brachial plexus injury can be devastating and depend entirely on which part of the plexus is damaged and the severity of the injury. The brachial plexus is organized into an upper part (which controls the shoulder and elbow) and a lower part (which controls the hand).

The symptoms can include a combination of the following:

• Motor Symptoms:
  • Weakness (paresis) or complete paralysis (plegia) of the muscles in the shoulder, arm, forearm, or hand.
  • In an upper plexus injury (Erb’s palsy), the person may be unable to lift their arm at the shoulder or bend their elbow, leading to a characteristic “waiter’s tip” posture where the arm hangs at the side and is rotated inward.
  • In a lower plexus injury (Klumpke’s palsy), the person may have paralysis of the small muscles of the hand, leading to a “claw hand” deformity.
  • A complete plexus injury results in a completely flail and paralyzed arm.
• Sensory Symptoms:
  • Numbness, tingling, or a complete loss of sensation in part or all of the arm and hand.
• Pain:
  • Severe neuropathic pain is very common, especially in severe stretching or avulsion injuries (where the nerve roots are torn from the spinal cord). This pain is often described as a constant, severe, crushing or burning sensation.

A droopy eyelid and small pupil (Horner’s syndrome) can be seen if the lowest nerve roots are avulsed.

Clinically, muscle atrophy and absent reflexes help localize the injury within the plexus upper, middle, or lower trunks can present with distinct patterns.

A brachial plexus injury is a complex neurological problem that requires a thorough evaluation by a specialist, such as a neurologist, a neurosurgeon, or a physical medicine and rehabilitation (PM&R) doctor.

1. Clinical Examination: A detailed neurological examination is the most important first step. A doctor will meticulously test the strength of every individual muscle in the shoulder, arm, and hand, and will carefully map out the areas of sensory loss. This detailed exam allows the doctor to pinpoint which specific nerve roots and trunks of the plexus are likely injured.
2. Electrodiagnostic Studies (EMG/NCS): This is the gold standard test for localizing the injury and determining its severity.
   • Nerve Conduction Studies (NCS) measure the speed and strength of electrical signals traveling along the nerves.
   • Electromyography (EMG) uses a small needle electrode to test the electrical activity of the muscles.
   • Together, these tests can tell a doctor if a nerve is merely bruised or if it has been torn. Most importantly, they can help to detect signs of nerve recovery long before any physical movement returns, which is crucial for guiding treatment decisions.
3. Imaging: Advanced imaging is used to directly visualize the nerves and surrounding structures.
   • A Magnetic Resonance Imaging (MRI) scan of the brachial plexus can show swelling, scarring, or a tumor compressing the nerves.
   • A CT Myelogram is often used to look for the most severe type of injury, a nerve root avulsion, where the nerves have been completely ripped out of the spinal cord.

The treatment for a brachial plexus injury is a long and challenging process that requires a multidisciplinary team. The goals are to restore as much function to the arm and hand as possible and to manage pain.

1. Non-Surgical Management and Rehabilitation

Physical and occupational therapy is the most important part of management for all patients with a brachial plexus injury.

• Therapy is started immediately to prevent the joints of the paralyzed arm from becoming stiff, a condition known as a contracture.
• A therapist will perform a passive range of motion exercises on the shoulder, elbow, wrist, and hand every day.
• As nerve recovery occurs, the therapy will shift to active strengthening exercises and retraining the muscles.
• Splinting and bracing are often used to support the limb and keep the hand in a functional position.

2. Neurosurgery for Severe Traumatic Injuries

For severe traumatic injuries where the nerves have been torn or avulsed, surgery may be an option to try to restore some function. The timing of surgery is critical; it is often performed 3 to 6 months after the injury if electrodiagnostic tests show no signs of spontaneous nerve recovery.

These are highly specialized procedures performed by a peripheral nerve neurosurgeon.

• Nerve Repair: If a nerve has been cleanly cut, it can sometimes be stitched directly back together.
• Nerve Graft: If there is a gap in a torn nerve, a surgeon will take a piece of a less important sensory nerve from another part of the body (like the leg) and use it to “graft” or bridge the gap in the important arm nerve.
• Nerve Transfer (Neurotization): This is a modern and highly effective technique. A surgeon will take a healthy, working but less important nearby nerve (or even a branch of a nerve) and will surgically “re-wire” it to connect to the paralyzed muscle’s nerve, bypassing the brachial plexus injury altogether.

3. Treatment for Non-Traumatic Plexopathy

• For Parsonage-Turner Syndrome: Pain management and corticosteroids in the acute phase, followed by therapy.
• For radiation-induced plexopathy: Management is very difficult and focuses on therapy and pain control.

I usually recommend conservative treatment, physical therapy, pain control, and close monitoring for mild cases, which often show gradual improvement.

A brachial plexus injury is a life-altering event that can result in profound weakness and sensory loss in the arm and hand. It is most often caused by high-energy trauma or as a complication of childbirth. The path to recovery is a long and arduous marathon, not a sprint. While not all function may be regained, a deep commitment to a lifelong program of physical and occupational therapy is the key to maximizing recovery and preventing secondary problems like joint stiffness. For those with the most severe injuries, modern advances in nerve surgery, such as nerve grafts and transfers, can offer a remarkable opportunity to restore a significant degree of useful function to a once-paralyzed arm. Clinically, I emphasize patient education, as recovery from brachial plexopathy can take months, and prognosis varies based on severity and cause.

1. The American Association of Neurological Surgeons (AANS). (n.d.). Brachial Plexus Injury. Retrieved from https://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Brachial-Plexus-Injury
2. The American Academy of Orthopaedic Surgeons (AAOS). (n.d.). Brachial Plexus Injuries. Retrieved from https://orthoinfo.aaos.org/en/diseases–conditions/brachial- plexus-injuries/
3. National Institute of Neurological Disorders and Stroke (NINDS). (2023). Brachial Plexus Injuries. Retrieved from https://www.ninds.nih.gov/health-information/disorders/brachial-plexus-injuries