Parsonage-Turner syndrome (PTS) is a rare neuromuscular condition, predominantly involving the upper extremity. Hospital for Special Surgery is one of the few centers in the United States that has a highly specialized interdisciplinary team of radiologists, physiatrists, neurologists and peripheral nerve surgeons dedicated to diagnosis, treatment and research of this condition.
Parsonage-Turner syndrome (PTS), also known as neuralgic amyotrophy or brachial neuritis, is a rare peripheral neuropathy that predominately affects one or more nerves that control movements of the chest wall, shoulder, arm, forearm and hand. PTS can affect one or both sides of the body.
PTS most commonly affects branches arising from the brachial plexus, a complex network of nerves that arise from the cervical spinal cord to control motor function and sensation throughout the upper extremity. PTS can also affect nerves in the forearm. The most commonly affected nerves are the:
Patients typically experience a sudden episode of extreme pain in the shoulder region, frequently during the night or early morning, that then spontaneously resolves after a few days or weeks. This is followed by significant weakness in one or more muscles of the upper extremity. However, PTS can cause signs and symptoms that may overlap with other conditions, such as cervical radiculopathy or calcific tendinosis.
Some people with PTS may also experience Kiloh Nevin syndrome, or the inability to make the "OK" sign by pressing the thumb to the forefinger. This results from neuropathy of the anterior interosseous nerve, which supplies the flexor pollicis longus, pronator quadratus, and partially, the flexor digitorum profundus.
The cause of PTS is largely unknown, although it may be related to inflammation mediated by the immune system and/or changes in blood circulation.
Most people who get PTS have no family history of the condition, but a rare, hereditary form of PTS is recognized. A mutation in the SEPTIN-9 (SEPT9) gene has been identified as one of the contributing causes of hereditary PTS. The SEPT9 gene is active in cells throughout the body, including neurons and immune cells. Mutations in SEPT9 have also been identified in people with other hereditary neuropathies, including:
Parsonage-Turner syndrome is considered a rare disease, with estimated prevalence of 1 to 3 in 100,000 individuals. However, recent studies have estimated that its incidence may be as high as 1 in 1000.
There are some differences in the spectrum of disease between hereditary and non-hereditary forms of PTS. The average age of onset of PTS is 25 years for people with the hereditary form of PTS and 40 for people with non-hereditary PTS. There is a higher incidence of PTS in men than in women.
To help people with PTS, a multidisciplinary team of specialists is often required. This may include neurologists or physiatrists who specialize in neuromuscular medicine, radiologists who specialize in peripheral nerve imaging (MR neurography, ultrasound), peripheral nerve surgeons, and physical or occupational therapists. HSS has a team of specialists who regularly see patients with Parsonage-Turner syndrome and who work collaboratively to ensure that these patients are supported in all aspects of their condition.
The diagnosis of PTS requires, at a minimum, a review of symptoms and a physical exam by a doctor. If PTS is then suspected, electrodiagnostic testing (including electromyography, also known as EMG testing) and advanced radiological imaging such as MR neurography can help doctors confirm the diagnosis and determine which nerves are affected.
PTS commonly presents as severe, acute pain in the shoulder region that lasts for a few days to weeks and is followed by muscle weakness.
Physiatrists and neurologists use electrodiagnostic testing to both confirm the diagnosis of PTS and to monitor recovery by determining the extent of nerve injury.
MRI can be used to rule out other potential causes of PTS-like symptoms, such as cervical radiculopathy. A high-resolution MRI technique, known as magnetic resonance nerography (MR neurography), and ultrasound imaging can also be used to determine which nerves are impacted by PTS and which muscles show denervation (loss of nerve supply). Nerves in the upper extremity affected by PTS are marked by constriction and/or twisting. These are called “hourglass-like constrictions” (also known as "intrinsic constrictions") because the squeezed nerves look like an hourglass on a digital radiological image.
The examples below demonstrate suprascapular neuropathy with weakness in the shoulder's ability for abduction and external rotation.
There is no known cure, but some treatments are available for this rare condition. These include use of oral steroids (particularly in the early stages of the condition) and physical therapy. Surgery may be considered for patients with PTS who do not recover after these measures.
Surgery can be helpful for patients with chronic PTS who do not show improvement with nonsurgical intervention. Microsurgical neurolysis, sometimes referred to as microneurolysis, is used to release the hourglass-like constrictions that form in affected nerves. MRI and/or ultrasound is used to precisely localize these constrictions and thereby provide a surgical roadmap. Physicians at HSS have found that, in people with chronic Parsonage-Turner syndrome, microneurolysis was associated with significantly improved clinical outcomes compared patients who had nonsurgical treatment.
Many patients eventually recover and regain function of their arm without surgery or other interventions. A damaged nerve will generally start to recover in six to nine months, and additional EMG testing can indicate if there are early signs of nerve regeneration.
Surgery may be considered for people who have prolonged symptoms, especially in those who do not show signs of improvement at around 9 to 12 months after symptoms first appear.
"Understanding Parsonage-Turner syndrome" by the HSS Peripheral Nerve Team.
Further research is needed to better understand the cause and possible treatments for PTS. At HSS, our dedicated team of physicians are currently conducting multiple research studies related to Parsonage-Turner syndrome. There are currently two studies open to enrollment:
In addition to conducting the two current PTS studies, HSS physicians organize an international PTS-focused study group. Within the United States, the group comprises researchers from HSS, UCSF, and Beth Israel Deaconess (Boston). Internationally, the group includes members from Ente Ospedaliero Cantonale (Switzerland), Rabdboud University Medical Center & JBZ (Netherlands), and Semmelweis University (Hungary).
To learn more about our research studies, please email us at RadNerve@hss.edu.