What are the other Names for this Condition? (Also known as/Synonyms)

• HBPN (Hereditary Brachial Plexus Neuropathy)
• Hereditary Neuralgic Amyotrophy (HNA)
• HNA (Hereditary Neuralgic Amyotrophy)

What is Hereditary Brachial Plexus Neuropathy? (Definition/Background Information)

• Hereditary Brachial Plexus Neuropathy (HBPN) is characterized by possible autoimmune inflammation affecting the brachial plexus (part of the neck, shoulders, arms, and hands nerves) of unknown causation
• The exact cause of Hereditary Brachial Plexus Neuropathy is not well-understood. HBPN is considered to be caused by a variety of factors that may be genetic, immunologic, and/or environmental in nature
• HBPN is thought to be triggered by the body’s immune system through triggers such as surgery involving the brachial plexus, autoimmune disorders, childbirth in some women, and infections. It is researched that some individuals are more susceptible than others due an autosomal dominant inheritance patterns
• The signs and symptoms of Hereditary Brachial Plexus Neuropathy include a gradual onset of shoulder pain that may be acute and severe. The pain may spread to the arms or neck and can get worse during night
• Severe cases can result in complications including shortening of muscles, mal-alignment of the upper body, partial vocal cord paralysis, and even breathing difficulties
• A diagnosis of Hereditary Brachial Plexus Neuropathy can be made through physical examinations, muscle and nerve conduction studies, and radiological imaging studies performed on the upper body along with identification of appearance abnormalities that can be associated with HBPN
• A symptomatic treatment for Hereditary Brachial Plexus Neuropathy is offered to address the pain and other symptoms. In some cases, surgery (nerve grafting or tendon transfer procedure) may be necessary
• The prognosis of Hereditary Brachial Plexus Neuropathy is based on the severity of the signs and symptoms. However, in a majority of the individuals, the prognosis is good; although, around 25% of the individuals may have recurring conditions that may affect the quality of life

Who gets Hereditary Brachial Plexus Neuropathy? (Age and Sex Distribution)

• Hereditary Brachial Plexus Neuropathy is an autosomal dominant inherited disorder, with a congenital manifestation. Yet, the signs and symptoms most frequently appear between the ages of 10 and 30 years
• Both males and females can be affected and no specific preference is observed
• All racial and ethnic groups can be affected by HBPN

What are the Risk Factors for Hereditary Brachial Plexus Neuropathy? (Predisposing Factors)

The risk factors for Hereditary Brachial Plexus Neuropathy include several events that can trigger an immune response in the body:

• Recent immunization
• Surgery on the brachial plexus
• Extreme and strenuous exercise
• Trauma to the head and neck region, or to the shoulder region
• Anesthesia
• Bacterial or parasitic infection
• Certain rheumatic diseases such as connective tissue disorders
• Temporal arteritis
• Polyarteritis nodosa
• Childbirth can trigger HBPN in some women

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others. 

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hereditary Brachial Plexus Neuropathy? (Etiology)

The cause of Hereditary Brachial Plexus Neuropathy is not clearly known or understood

• It is inherited in an autosomal dominant pattern
• It is believed to be an inflammatory response in the brachial plexus to various environmental, immunologic, and genetic factors, due to a mutation on the SEPT9 gene
• An individual may be born with a genetic predisposition to the disorder, which may be via a novel mutation or an inherited mutation

The triggers for HBPN may include the following factors:

• Recent immunization
• Surgery on the brachial plexus
• Extreme and strenuous exercise
• Trauma to the head and neck region, or to the shoulder region
• Anesthesia
• Bacterial or parasitic infection
• Certain rheumatic diseases such as connective tissue disorders
• Temporal arteritis
• Polyarteritis nodosa
• Childbirth can trigger Hereditary Brachial Plexus Neuropathy in some women
• Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Hereditary Brachial Plexus Neuropathy?

The signs and symptoms of Hereditary Brachial Plexus Neuropathy often vary from one individual to another, but may include the following:

• Sudden or gradual onset of pain in one or both shoulder(s); the pain is more commonly observed on the right side
• The pain may also radiate to the neck, arm, or hand
• It is often described as sharp, stabbing, burning, or aching pain, especially during specific movements
• Pain is commonly continuous and worse at night or in the evening
• During the acute phase, the pain may be debilitating
• Over time the pain usually lessens, especially when the arm is at rest
• Chronic pain is less severe and may last up to a year or longer
• While a majority of individuals may only have one episode of symptoms, others may have recurrent episodes of pain that may diminish or spread (varying on a case by case basis)
• Sensitivity may persist during movement due to nerve damage: Any movement may trigger an increase in signs and symptoms due to underlying nerve damage (exaggerated response to stimulus or hypersensitivity)
• After days or weeks following the onset of symptoms, pain is replaced by muscle loss:
  • The resulting weakness may be barely noticeable or lead to near paralysis
  • Weakness is relative to the number of nerves affected by the condition
• Reduced reflexes
• Numbness in or around affected areas
• Sensation of tickling, burning, or pricking on the skin
• Light touch may become painful
• Blood vessel damage

Individuals with Hereditary Brachial Plexus Neuropathy may additionally have appearance abnormalities that may include the following:

• Deep-set eyes that are close together
• Skin folds which may cover the corner of the eyes
• Narrow distance between the eyelids
• Long nose bridge and small mouth
• Webbing or fusion of fingers and toes
• Hammer toes
• Fused forearms
• Excessive skin folds in the neck
• Cleft palate
• Split in the tissue that hangs in the back of the throat
• Short stature

How is Hereditary Brachial Plexus Neuropathy Diagnosed?

A diagnosis of Hereditary Brachial Plexus Neuropathy is made by the following observations and tests:

• A careful physical examination and assessment of medical history
• Nerve conduction studies
• Electromyography - to test muscular response to nerve signals
• Magnetic resonance imaging (MRI) studies can help detect inflammation and muscle atrophy
• Muscle conduction studies and nerve conduction studies (assessing the ability of specific peripheral nerves to relay information to the brain) can be helpful in arriving at a diagnosis
• X-ray may be used to rule out other causes of shoulder pain

Note: Hereditary Brachial Plexus Neuropathy may be distinguished from Parsonage-Turner syndrome by the appearance of certain physical abnormalities that are unique to HBPN.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hereditary Brachial Plexus Neuropathy?

The possible complications of Hereditary Brachial Plexus Neuropathy may include:

• Arms, shoulders, or hands may shift in position: Because of the muscle atrophy of the shoulder and other regions, it may result in mal-alignment of the upper body. This can increase the risk of impingement (connective tissue rubbing against the shoulder blade) or subluxation (partial dislocation) in the  affected individuals
• Contractures (shortening of muscles or tendons), which can reduce mobility and cause pain
• Lower back nerves can be affected causing pain, reduced sensation, tingling, or prickling sensation
• Shortness of breath, due to damage to the nerve controlling the diaphragm
• Weakness or partial paralysis of the vocal cords, resulting in hoarseness or a soft voice
• Although it is rare, the cranial or facial nerves may be affected
• Red or purple coloration on the hands which may appear spotted
• Swelling of the affected limbs
• Excessive sweating (unresponsiveness to temperature)

How is Hereditary Brachial Plexus Neuropathy Treated?

The treatment for Hereditary Brachial Plexus Neuropathy is directed towards the symptoms and may include:

• Pain medications (analgesics); opiates
• Non-steroidal anti-inflammatory drugs; oral corticosteroids
• Co-analgesics for the chronic phase (specifically to treat nerve pain)
• Application of heat or cold to the affected shoulder/chest/arm area
• Rest and reduction of activity
• Transcutaneous nerve stimulation to control pain
• Surgery:
  • Nerve grafting: This procedure involves taking part of a nerve from one part of the body to repair a damaged nerve
  • Tendon transfer procedure (following loss of muscle function)
• Physical therapy

How can Hereditary Brachial Plexus Neuropathy be Prevented?

• Currently, there are no specific methods or guidelines to prevent Hereditary Brachial Plexus Neuropathy, since it is a genetic condition
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as Hereditary Brachial Plexus Neuropathy
• Regular medical screening at periodic intervals with tests and physical examinations are recommended
• Avoid trigger factors such as avoiding extremely demanding physical exercise or activities that could lead to trauma

What is the Prognosis of Hereditary Brachial Plexus Neuropathy? (Outcomes/Resolutions)

• The prognosis for Hereditary Brachial Plexus Neuropathy is generally good. Most individuals are known to regain 70-90% of their former strength in the affected areas
• About 25% of individuals will have a recurring bout later on in life
• It has been reported, although rarely, that affected individuals may be left with a severe disability that can impact their quality of life
• As with many disorders, it is important that an early diagnosis be followed by effective treatment, which can help avoid the complications associated with Hereditary Brachial Plexus Neuropathy

Additional and Relevant Useful Information for Hereditary Brachial Plexus Neuropathy:

Hereditary Brachial Plexus Neuropathy is very similar to Parsonage-Turner Syndrome (PTS), but they are 2 distinct conditions. The differences include the following:

• Appearance abnormalities are present in HBPN but not in PTS
• Individuals affected by HBPN have a higher change of the disorder affecting both sides of their body, than do affected individuals with PTS
• HBPN, generally has an equal gender prevalence, whereas PTS is more common in males than in females
• Individuals with HBPN tend to be symptomatic earlier in life than those with PTS