Which are the causes of Parsonage-Turner Syndrome?

TL;DR: Parsonage-Turner Syndrome (PTS), also known as neuralgic amyotrophy, is primarily considered an immune-mediated disorder where the body's immune system mistakenly attacks the nerves of the brachial plexus. While the exact trigger remains unknown in many cases, it is frequently associated with preceding viral infections, vaccinations, or periods of intense physical exertion, suggesting a complex interplay between genetic predisposition and environmental stressors.

What causes Parsonage-Turner Syndrome?

The underlying cause of Parsonage-Turner Syndrome is thought to be an autoimmune reaction. Imagine the brachial plexus—the network of nerves controlling the shoulder and arm—as a series of electrical cables. In this condition, the immune system, perhaps confused by a recent infection or stressor, begins to treat these "cables" as foreign invaders, causing inflammation and damage. This inflammation leads to the sudden, severe pain and subsequent muscle weakness characteristic of Parsonage-Turner Syndrome. Because the body is attacking its own healthy tissue, it is classified as an inflammatory neuropathy.

Are there genetic factors linked to Parsonage-Turner Syndrome?

While most cases of Parsonage-Turner Syndrome occur sporadically (meaning they happen randomly to individuals with no family history), there is a rare hereditary form known as Hereditary Neuralgic Amyotrophy (HNA). In these cases, mutations in the SEPT9 gene have been identified. For the majority of our 160 community members at DiseaseMaps.org, the syndrome is not inherited. However, research suggests that some individuals may have a genetic predisposition that makes their immune system more likely to overreact to environmental triggers.

What are the common triggers and risk factors?

It is important to distinguish between a "cause"—the biological mechanism of nerve damage—and a "trigger," which is an event that sets that mechanism in motion. Parsonage-Turner Syndrome is often preceded by a specific event. Common triggers reported in clinical literature include:

• Viral or Bacterial Infections: Recent respiratory or gastrointestinal illnesses are frequently cited as potential triggers.


• Immunizations: A small percentage of cases have been linked to recent vaccinations, likely due to an immune system "rev-up."


• Physical Exertion: Strenuous exercise, heavy lifting, or surgery can sometimes precede the onset of symptoms.


• Systemic Illness: Autoimmune conditions or recent surgical procedures are recognized risk factors for the development of Parsonage-Turner Syndrome.

Is the etiology fully understood by researchers?

Currently, the exact etiology of Parsonage-Turner Syndrome is still under active investigation. Medical researchers are working to understand why the immune system targets these specific nerves and why the symptoms manifest so suddenly. While we understand the "how" (nerve inflammation), the "why" remains elusive for many patients. Current research is heavily focused on identifying biomarkers that could help predict who is at risk and developing targeted therapies to dampen the immune response before permanent nerve damage occurs.

Next steps

• Consult a neurologist or a specialist in peripheral nerve disorders for a clinical evaluation and electromyography (EMG) testing.


• Keep a detailed health diary of any illnesses, vaccinations, or surgeries that occurred in the 2-4 weeks prior to the onset of your symptoms.


• Join the 160 members on DiseaseMaps.org to share experiences and learn how others manage their recovery and physical therapy.


• Discuss with your physician whether short-term corticosteroid treatment is appropriate for your specific stage of Parsonage-Turner Syndrome.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Neuralgic Amyotrophy.


• Orphanet: Parsonage-Turner Syndrome (ORPHA: 2616).


• OMIM (Online Mendelian Inheritance in Man): Neuralgic Amyotrophy; NA (Entry #162100).


• PubMed/NCBI: Current perspectives on the pathophysiology of neuralgic amyotrophy.