7 Key Symptoms of Brachial Plexus Injury You Should Know

The brachial plexus is a complex network of nerves that runs from the spinal cord in the neck down through the shoulder and into the arm and hand. When these nerves are damaged through trauma, inflammation, or other causes, it results in a brachial plexus injury. This condition can range from mild to severe, affecting the ability to move and feel sensations in the upper extremity. Understanding the symptoms of a brachial plexus injury is crucial for early detection and proper medical intervention.

Brachial plexus injuries can occur in various situations, including birth trauma, sports accidents, motor vehicle collisions, or penetrating wounds. The severity of symptoms depends on the extent and location of the nerve damage. While some injuries may heal on their own with time, others may require extensive medical attention. Recognizing the signs early can make a significant difference in recovery outcomes.

1. Weakness or Inability to Move the Arm

One of the most noticeable symptoms of a brachial plexus injury is weakness in the affected arm or complete inability to move it. This occurs because the damaged nerves can no longer properly transmit signals from the brain to the muscles in the shoulder, arm, or hand.

The degree of weakness varies depending on which nerves are affected and the severity of the injury. Some people may experience:

• Difficulty lifting the arm away from the body
• Trouble rotating the shoulder
• Weakness when bending the elbow
• Inability to grip objects with the hand
• Difficulty with fine motor movements like writing or buttoning clothes

In severe cases, the arm may hang limply at the side with no voluntary movement possible. This paralysis can be temporary or permanent depending on whether the nerves can regenerate or if surgical intervention is needed.

2. Numbness and Loss of Sensation

Numbness or complete loss of feeling in the arm, hand, or fingers is a hallmark symptom of brachial plexus injury. The sensory nerves within the brachial plexus are responsible for transmitting information about touch, temperature, and pain from the skin to the brain.

When these nerves are damaged, patients may experience:

• Complete numbness in specific areas of the arm or hand
• Tingling sensations or “pins and needles”
• Inability to feel hot or cold temperatures
• Reduced ability to sense pain, which can increase risk of injury
• Patchy areas of sensation loss

The pattern of numbness often provides clues about which specific nerves are injured. For example, numbness on the outer side of the upper arm suggests involvement of the axillary nerve, while numbness in the thumb and index finger may indicate median nerve damage.

3. Severe Pain or Burning Sensation

Many people with brachial plexus injuries experience significant pain, which can manifest as sharp, stabbing sensations, burning feelings, or deep aching. This pain results from nerve damage and can be one of the most challenging symptoms to manage.

The pain associated with brachial plexus injury may be characterized by:

• Shooting or electric shock-like sensations down the arm
• Burning pain that persists even at rest
• Sharp stabbing pains triggered by movement
• Constant aching in the shoulder, neck, or arm
• Pain that worsens at night

This neuropathic pain occurs because damaged nerves send abnormal signals to the brain. The intensity can range from mild discomfort to debilitating pain that significantly impacts quality of life. Some patients describe the sensation as feeling like their arm is on fire or being constantly pricked by needles.

4. Muscle Atrophy

Over time, muscles that are not receiving proper nerve signals begin to waste away, a condition known as muscle atrophy. This is a common symptom in brachial plexus injuries, especially when the damage is severe or prolonged.

Muscle atrophy manifests as:

• Visible decrease in muscle size compared to the unaffected arm
• Loose, sagging appearance of the skin over affected muscles
• Progressive weakness even beyond the initial injury
• Changes in arm circumference measurements
• Bony prominences becoming more visible

The muscles of the shoulder, upper arm, forearm, and hand can all be affected depending on which nerves are damaged. Atrophy typically begins within weeks of the injury if the nerve connection is completely severed. Early physical therapy and rehabilitation can help minimize muscle loss, though some degree of atrophy is inevitable with severe nerve damage.

5. Limited Range of Motion

A brachial plexus injury often results in restricted movement in the shoulder, elbow, wrist, or fingers. This limited range of motion stems from both muscle weakness and potential joint stiffness that develops when the arm is not used normally.

Patients may experience:

• Inability to raise the arm above shoulder height
• Difficulty reaching behind the back
• Restricted rotation of the shoulder
• Limited elbow flexion and extension
• Reduced wrist movement
• Finger stiffness and inability to fully open or close the hand

Joint contractures can develop if the arm remains in one position for extended periods. The shoulder may become “frozen,” and the elbow or wrist may develop permanent limitations in movement. Regular gentle movement and stretching, under medical guidance, is important to maintain as much range of motion as possible during recovery.

6. Horner’s Syndrome

In some brachial plexus injuries, particularly those involving the lower nerve roots near the neck, a condition called Horner’s syndrome may develop. This occurs when sympathetic nerve fibers that control certain eye and facial functions are damaged.

Signs of Horner’s syndrome include:

• Drooping of the upper eyelid (ptosis) on the affected side
• Constricted pupil (miosis) that appears smaller than the opposite eye
• Decreased sweating on the affected side of the face (anhidrosis)
• Apparent sunken appearance of the eye
• Slight elevation of the lower eyelid

The presence of Horner’s syndrome typically indicates a more serious injury involving the nerve roots closest to the spinal cord. This finding is particularly important as it suggests the injury may be more extensive and could require different treatment approaches. While Horner’s syndrome itself usually doesn’t cause pain or vision problems, its presence signals significant nerve damage.

7. Altered Reflexes

Changes in normal reflexes represent another important symptom of brachial plexus injury. Reflexes are automatic responses controlled by the nervous system, and damage to the brachial plexus can diminish or eliminate these responses.

Reflex changes may include:

• Absent or reduced biceps reflex (tested by tapping the elbow)
• Diminished triceps reflex
• Altered or absent brachioradialis reflex in the forearm
• Abnormal response to sensory testing
• Lack of normal protective reflexes

Healthcare providers assess reflexes as part of the neurological examination to determine which nerve roots or portions of the brachial plexus are injured. The pattern of reflex loss helps localize the injury and gauge its severity. For instance, loss of the biceps reflex typically indicates damage to the C5-C6 nerve roots, while triceps reflex absence suggests C7-C8 involvement. Return of reflexes during recovery is often a positive sign indicating nerve regeneration.

Common Causes of Brachial Plexus Injury

Understanding what causes brachial plexus injuries can help with prevention and early recognition. The main causes include:

• Birth Trauma: Difficult deliveries, particularly those involving shoulder dystocia where the baby’s shoulder becomes stuck during birth, can stretch or tear the brachial plexus nerves. This is one of the most common causes in newborns.
• Motor Vehicle Accidents: High-impact collisions, especially motorcycle accidents, frequently cause brachial plexus injuries when the head and shoulder are forcefully pulled in opposite directions.
• Sports Injuries: Contact sports like football, wrestling, and hockey can result in brachial plexus damage through forceful impacts or extreme stretching of the neck and shoulder.
• Falls: Falling onto the shoulder or outstretched arm can generate enough force to injure the brachial plexus, particularly if the head is pushed away from the shoulder during impact.
• Penetrating Wounds: Knife wounds, gunshot injuries, or other penetrating trauma can directly sever or damage the nerves of the brachial plexus.
• Tumors: Cancerous or benign tumors growing in or near the brachial plexus can compress and damage the nerves over time.
• Radiation Therapy: Treatment for certain cancers involving radiation to the chest or neck area can sometimes damage the brachial plexus as a side effect.
• Inflammatory Conditions: Rare inflammatory disorders can affect the brachial plexus, causing a condition called Parsonage-Turner syndrome or neuralgic amyotrophy.

Prevention Strategies

While not all brachial plexus injuries can be prevented, certain measures can reduce the risk:

• Safe Driving Practices: Always wear seatbelts, avoid distracted driving, and follow traffic laws to reduce the risk of motor vehicle accidents. Motorcyclists should wear proper protective gear.
• Sports Safety: Use appropriate protective equipment for contact sports, including properly fitted helmets and shoulder pads. Learn and practice proper tackling and falling techniques.
• Workplace Safety: Follow safety protocols in occupations with risk of falls or machinery accidents. Use proper lifting techniques and wear required protective equipment.
• Fall Prevention: Keep walkways clear of obstacles, use handrails on stairs, ensure adequate lighting, and address balance issues, especially in older adults.
• Prenatal Care: Proper prenatal monitoring can identify risk factors for difficult deliveries. Discussion with healthcare providers about delivery options when a large baby or other complications are anticipated may help reduce birth-related injuries.
• Physical Conditioning: Maintaining good neck and shoulder muscle strength and flexibility may provide some protection against injury during impacts.
• Avoid Excessive Strain: Be cautious with activities that put excessive stress on the shoulder and neck, and use proper form when lifting heavy objects.

Frequently Asked Questions

How long does it take for a brachial plexus injury to heal?

Recovery time varies greatly depending on the severity of the injury. Minor injuries may heal within a few weeks to months, while severe injuries can take several years or may result in permanent damage. Nerves regenerate slowly, at approximately one inch per month.

Can a brachial plexus injury heal on its own?

Mild brachial plexus injuries, where nerves are stretched but not torn, often heal on their own with time and physical therapy. However, more severe injuries involving torn nerves may require surgical intervention and may not fully recover without treatment.

What is the difference between brachial plexus injury in adults and newborns?

In newborns, brachial plexus injuries typically occur during birth and often involve stretching of the nerves. Many infant cases improve significantly with time. Adult injuries are usually caused by trauma and may be more severe, involving nerve tears or avulsions that require surgical repair.

Is brachial plexus injury permanent?

Not necessarily. The permanence depends on the type and severity of nerve damage. Neurapraxia (nerve stretching) usually recovers fully. Axonotmesis (more severe damage) may partially recover. Neurotmesis (complete nerve rupture) often results in permanent deficits without surgical intervention.

When should I see a doctor for arm weakness and numbness?

You should seek immediate medical attention if you experience sudden weakness, numbness, or loss of function in your arm following any trauma, accident, or injury. Even without obvious trauma, progressive weakness or persistent numbness lasting more than a few days warrants medical evaluation.

Can brachial plexus injury affect both arms?

While most brachial plexus injuries affect only one side, bilateral injuries affecting both arms can occur, though they are rare. This typically happens only in severe trauma cases such as major motor vehicle accidents or serious falls.

What tests are used to diagnose brachial plexus injury?

Diagnosis typically involves physical examination, medical history, and specialized tests including electromyography (EMG), nerve conduction studies, MRI scans, CT myelography, and sometimes X-rays to assess the extent and location of nerve damage.

Can exercise help with brachial plexus injury recovery?

Yes, physical therapy and targeted exercises are crucial components of recovery. Under professional guidance, exercises help maintain range of motion, prevent muscle atrophy, strengthen unaffected muscles, and retrain movements as nerves regenerate. However, exercises should only be performed as directed by healthcare providers.

References:

• Mayo Clinic – Brachial Plexus Injury
• American Academy of Orthopaedic Surgeons – Brachial Plexus Injuries
• Johns Hopkins Medicine – Brachial Plexus Injuries
• National Institute of Neurological Disorders and Stroke – Brachial Plexus Injuries
• National Center for Biotechnology Information – Brachial Plexus Injury