Brachial Plexopathy

The brachial plexus is a bundle of mixed nerve roots from C5 to T1 that fuse into upper, middle, and lower trunks above the level of the clavicle and redistribute into lateral, posterior, and medial cords below that landmark.

Introduction

  • The brachial plexus is a bundle of mixed nerve roots from C5 to T1 that fuse into upper, middle, and lower trunks above the level of the clavicle and redistribute into lateral, posterior, and medial cords below that landmark.
    • C5 and C6 merge into the upper trunk
    • C7 forms the middle trunk
    • C8 and T1 merge to form the lower trunk
  • These nerves control the motions of your wrists, hands, and arms, allowing you to raise your arm, type on your keyboard, or throw a baseball.
  • The brachial plexus nerves extend to the skin and are sensory, too providing a sense of proprioception as well. For instance, they let you know that the pan you just grabbed with your hand is too hot to hold.

Brachial Plexus Anatomy

  • From the roots, the brachial plexus nerves branch and fuse through the shoulder and down the arm, classified into a few different sections:
    • Trunks
    • Divisions
    • Cords
    • Branches
  • These sections are not functionally different, but help explain the complex anatomy of the brachial plexus.
 
The brachial plexus ends in five major nerve branches that extend down the arm:
  • Musculocutaneous nerve
    • Originates from nerve roots C5-C7 and flexes muscles in the upper arm, at both the shoulder and elbow.
  • Axillary nerve
    • Stems from nerve roots C5 and C6; helps the shoulder rotate and enables the arm to lift away from the body.
  • Median nerve
    • Starts in nerve roots C6-T1 and enables movement in the forearm and parts of the hand.
  • Radial nerve
    • Begins in nerve roots C5-T1 and controls various muscles in the upper arm, elbow, forearm, and hand.
  • Ulnar nerve
    • Rooted in C8-T1, it allows for fine motor control of the fingers.
 

Figure1: Brachial plexus

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Brachial plexus injury

The brachial plexus can be injured in many different ways;
  • From pressure,
  • Stress
  • Being stretched too far.
The nerves may also be cut or damaged by
  • Cancer
  • Radiation treatment.
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Sometimes, brachial plexus injuries happen to babies during birth.
 
  • Brachial plexus injuries cut off all or parts of the communication between the spinal cord and the arm, wrist, and hand. This may mean that you can’t use your arm or hand.
  • Often, brachial plexus injuries also result in total loss of sensation in the area.
  • The severity of a brachial plexus injury varies, depending on the part of the nerve that is injured and the extent of the injury.
  • In some people, function and feeling return to normal, while others may have lifelong disabilities because they can’t use or feel a part of their arm.

Brachial plexopathy

  • It is a form of peripheral neuropathy.
  • Damage to the brachial plexus produces pain, sensory loss, and/or weakness in one arm.
  • Some plexopathies can be bilateral.
  • Causes of brachial plexopathy include:
    • Damage to the brachial plexus from direct injury to the nerve.
    • Stretching injuries (including birth trauma).
    • Pressure from tumors in the area (especially from lung tumors).
    • Damage that results from radiation therapy.

Causes of Brachial Plexus Injuries in Adults

In adults, brachial plexus injuries have a range of causes, including:
  • Blunt trauma
    • Such as falls or motor vehicle accidents.
  • Athletic injuries
    • Especially from contact sports like football.
  • Gunshot wounds
    • A bullet tears through or close to the nerves.
  • Medical trauma
    • A nerve is cut during a surgical procedure or damaged by injection or the positioning of the body during surgery.
  • Cancer:
    • A tumor invades the brachial plexus.
  • Radiation therapy
    • Radiation treatment in the area damages the nerves.

Types of Brachial Plexus Injuries

Brachial plexus injuries are categorised according to how the nerves are damaged and the severity of the injury.

Brachial Plexus Neuropraxia (Stretch)

  • When the nerves are stretched to the point of injury, it is referred to as neuropraxia. There are two main ways this injury occurs;
    • Compression
    • Traction.
  • Compression neuropraxia is the most common injury usually occurring in elderly people.
  • In a compression injury, the brachial plexus nerve root is compressed, usually by the rotation of the head.
  • Traction neuropraxia occurs when the nerve is pulled, usually downward.
  • This injury is usually seen among adolescents and young adults.
  • These types of injuries are often referred to as brachial plexus “burners” or “stingers,” depending on whether the main symptom is a burning or stinging sensation.

Brachial Plexus Rupture

  • In a brachial plexus rupture, a forceful stretch causes the nerve to tear, either partially or completely, refer to figure 2.
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This is a more serious injury than neuropraxia.
  • Ruptures can cause weakness in the shoulder, arm, or hand and can even make certain muscles unusable.
  • These injuries can also be associated with severe pain.
  • Depending on the severity and location of the rupture, these injuries can often be repaired.

Brachial Plexus Avulsion

  • A brachial plexus avulsion occurs when the root of the nerve is completely separated from the spinal cord, refer to figure 2.
  • This injury is usually caused by trauma, such as a car or motorcycle accident.
  • More severe than ruptures, avulsions often cause severe pain. Because it is difficult and usually impossible to reattach the root to the spinal cord.
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Avulsions can lead to permanent weakness, paralysis, and loss of feeling

Brachial Plexus Neuroma

  • Sometimes when nerve tissue is injured, such as from a cut during surgery, scar tissue can form as the nerve attempts to repair itself.
  • This scar tissue is called a neuroma, and it may result in a painful knot on one of the brachial plexus nerves, as shown in figure 2.
  • Treatment for brachial plexus neuromas includes surgical removal of the scarred nerve tissue.
  • The surgeon then either caps the nerve or attaches it to another nerve to prevent another neuroma from forming.

Brachial Neuritis

  • Also called Parsonage Turner syndrome, brachial neuritis is a rare, progressive disorder of the nerves of the brachial plexus of probable inflammatory origin.
  • It presents with an acute onset of severe shoulder and upper arm pain that precedes the appearance of a patchy brachial plexus lesion from pain to weakness, muscle loss, and even loss of sensation.
  • The cause of brachial neuritis is unknown but could be related to an autoimmune response triggered by infections, injury, childbirth, or other factors.
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This syndrome usually affects the shoulder and arm, but it can also affect the diaphragm when the phrenic nerve is involved.
 

Figure 2: Types of brachial plexus injuries (NPkBk Graphic)

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Symptoms

  • Clinical findings depend upon the location and severity of the brachial plexus injuries.
  • Injuries to nerves that root higher up on the spinal cord, in the neck, affect the shoulder.
  • If nerves that originate lower in the brachial plexus are injured, the arm, wrist, and hand are affected.
Common symptoms of brachial plexus injuries are:
  • Numbness of the shoulder, arm, or hand
  • Shoulder pain
  • Tingling, burning, pain, or abnormal sensations (location depends on the area injured)
  • Weakness of the shoulder, arm, hand, or wrist.

How are brachial plexus injuries diagnosed?

  • A health care provider will examine the hand and arm and test for sensation and function to help diagnose a brachial plexus injury.
  • Signs may include:
    • Deformity of the arm or hand
    • Difficulty moving the shoulder, arm, hand, or fingers
    • Diminished arm reflexes
    • Wasting of the muscles
    • Weakness of hand flexing
 
  • A detailed history may help determine the cause of the brachial plexopathy.
  • Age and sex are important because some brachial plexus problems are more common in certain groups.
    • For example, young men more often have inflammatory or post-viral brachial plexus disease called Parsonage-Turner syndrome.
    •  
These are other laboratory diagnostic tests often used:
  • Routine labs and blood work.
  • There are no reliable markers for brachial plexitis, although antinuclear antibodies (ANA) and ESR are checked.
  • An X-ray of the neck and shoulder area
    • to identify fractures or other injuries to the bone and dense tissues around the nerves of the brachial plexus.
  • Ultrasound.
  • Imaging tests, such as MRI or a CT scan, during which contrast dye may be injected to show the injury to the nerves of the brachial plexus and tumors.
  • Tests like nerve conduction study and electromyogram to determine nerve function and electrical activity.
    • EMG can show signs of denervation after 3-4 weeks.
  • Nerve biopsy to examine a piece of nerve under the microscope (rarely needed).
 
These tests may be repeated every few weeks or months to allow your doctor to monitor your progress.

Figure: 6 MRI highlighting brachial plexus

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Su, S., Smith, D. MRI of the brachial plexus. Reference article, Radiopaedia.org. (accessed on 07 Mar 2022)
Clinical significance of cervical MRI in brachial plexus birth injury Petra Grahn,Tiina Pöyhiä,Antti Sommarhem &Yrjänä Nietosvaara

Differential diagnosis

  • Cervical radiculopathy
    • Produces pain in the arm, but the lesion affects only a single nerve root unless there is polyradiculopathy.
  • Mononeuropathy of the upper extremity
    • Can produce pain and weakness, but the deficit is distal to the plexus, which may be evident on exam or EMG.
  • Mononeuritis multiplex
  • Multifocal motor neuropathy with conduction block
  • Amyotrophic lateral sclerosis
  • Cervical cord lesion (e.g transverse myelitis)
  • Orthopedic (shoulder) disorders (e.g. rotator cuff injury, acute calcific tendinitis, adhesive capsulitis)

Treatment

  • Treatment is aimed at correcting the underlying cause and allowing you to use your hand and arm as much as possible.
  • In some cases, no treatment is needed and the problem gets better on its own.

Nonsurgical Treatment for Brachial Plexus Injuries

  • Mild brachial plexus injuries respond well to a combination of nonsurgical treatment options.
 
Your doctor may recommend one or all of the following:
  • Physical therapy
    • To learn exercises that may help restore function in the arms and hands
    • Improve range of motion and flexibility in stiff muscles and joints.
  • Corticosteroid creams or injections
    • To help manage pain during healing.
  • Assistive devices
    • Braces,
    • Splints,
    • Compression sleeves to help use your arm.
  • Medications
    • To control pain.
  • Nerve block
    • Medicine is injected into the area near the nerves to reduce pain.
  • Occupational therapy
    • Work on practical skills like dressing and cooking in cases that involve severe muscle weakness, numbness, and pain.
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Medical conditions such as diabetes and kidney disease can damage nerves. In these cases, treatment is also directed at the underlying medical condition.

Surgical Treatment of Brachial Plexus Injuries

  • Brachial plexus injuries that fail to heal on their own may require surgery to repair the damage.
  • Nerve tissue grows and heals slowly, so it can take months to years to see the results of brachial plexus surgery.
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Brachial plexus surgeries should take place within six months of injury for the best chance at recovery.
  • Nerve repair
    • Reconnects a torn nerve.
  • Neurolysis
    • Removing scar tissue from the injured nerve to improve function.
  • Nerve graft
    • Using a healthy nerve from another part of the body to connect two ends of a separated nerve, guides the healing process.
  • Nerve transfer
    • Attaching a less important but still functional nerve to the damaged nerve, creates a framework for new growth.
  • Tendon and muscle transfers
    • Moving a less important tendon or muscle from one part of the body to the arm to restore function.

Brachial Plexus Birth Injury Treatment

  • In infants, if no improvement is seen after three months of occupational therapy, consulting a pediatric neurologist and pediatric neurosurgeon can help determine if your child can benefit from other interventions or surgery.
  • Up to 1 in 10 babies with brachial plexus injury will require some level of surgery.

Can a brachial plexus injury heal on its own?

  • Brachial plexus injuries don’t always need treatment.
  • Some people, particularly babies with a brachial plexus birth injury or adults with neuropraxia, recover without any treatment, though it can take as long as several weeks or months for the injury to heal.
  • Certain exercises can help with healing and function, but more severe injuries may require surgery.
  • Prompt examination by a health care provider is essential after any suspected brachial plexus injury.

Prognosis

  • Improvement depends on the cause of plexopathy.
  • Idiopathic plexitis commonly improve, with most having a resolution of the pain and eventual improvement in strength.

Possible Complications

  • Deformity of the hand or arm, mild to severe, can lead to contractures.
  • Partial or complete arm paralysis.
  • Partial or complete loss of sensation in the arm, hand, or fingers
  • Recurrent or unnoticed injury to the hand or arm due to diminished sensation

Further Reading

Bibliography

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  • Davidson's Principles and Practice of Medicine 23rd edition page number 1141
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  • Yoshikawa T, Hayashi N, Yamamoto S, Tajiri Y, Yoshioka N, Masumoto T, et al. Brachial plexus injury: Clinical manifestations, conventional imaging findings, and the latest imaging techniques. Radiographics. 2006;26:S133–43.
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