Parsonage-Turner Syndrome (PTS), also known as Neuralgic Amyotrophy or brachial neuritis, is an uncommon peripheral nerve disorder. PTS typically presents with an episode of extreme pain in the shoulder region that resolves after a few days to weeks, and is followed with profound weakness and atrophy in one or more muscles of the shoulder and upper arm.
PTS typically involves the upper rather than lower arm, and on rare occasions can affect both arms. It can involve any nerve arising from the brachial plexus—a complex set of nerves above and below the collarbone that provides movement and sensation to the arm. PTS includes a wide spectrum of clinical presentations and overlaps considerably with many alternative diagnoses, which can make diagnosing PTS difficult.
The cause of PTS is largely unknown, though immunologic and vascular mechanisms have been proposed. There may be several subtypes, including a genetic predisposition, an autoimmune disorder, or a mechanical mechanism that, alone or together, lead to development of symptoms.
- Autoimmune or Vascular Triggers
- More than 50% of patients with PTS report an event prior to presentation such as: infection, pregnancy, stress of surgery, or therapeutic events like vaccinations, antibiotic treatments, or immunotherapy
- Many patients report development of symptoms within hours of an unusual amount of upper extremity exertion (e.g. snow shoveling after a blizzard, push-up contest, moving heavy furniture, etc.)
- PTS exists most commonly as a spontaneous form, but a rare hereditary form of PTS does exist
- Nearly 50% of patients cannot identify a proceeding event reflecting that these variables cannot fully explain the entire story of PTS.
- It has been recently hypothesized that in some cases of PTS the inciting event may lead to pathological nerve and/or fascicle swelling that causes impaired nerve gliding and vascular compromise
PTS is a clinical diagnosis. There is no confirmatory diagnostic test; however, there are very typical electrodiagnostic findings that can help make the diagnosis. Electrodiagnostic studies can also help to assess the extent of nerve damage and loss of muscle function to differentiate PTS from other similar presenting diseases. MRI and ultrasound are increasingly helpful diagnostic tests that can reveal changes in the involved nerves and muscles.
It is unknown why some patients with PTS demonstrate absent or incomplete recovery, while most spontaneously recover. Using ultrasound, MRI, and intraoperative findings, recent studies have detected a constriction and/or twisting of nerves in the upper extremity of patients with refractory PTS symptoms. Such constrictions are termed “hour-glass constrictions.” It has been theorized that the immune mediated process leading to PTS causes a series of changes in the architecture of affected nerves. As a result of an inflammatory reaction within one or more nerve bundles, or fascicles, the following sequence of events has been proposed: nerve enlargement, nerve constriction, and in some cases, nerve torsion or twisting. Whether nerve constriction and/or torsion is unique to PTS or a subset of PTS is not known, but the extent of nerve constriction and/or torsion in PTS may play a role in a patient’s ability to recover spontaneously. Preoperative ultrasound and MRI not only help localize the affected nerves, but detect the severity of nerve involvement and also help with a decision for surgical management.
- The acute pain associated with PTS can be treated with anti-inflammatory and pain medication
- Patients are encouraged to use the affected arm as much as possible and perform physical therapy to help manage arm weakness
- Patients should return for periodic evaluations (every 6-8 weeks) to monitor progress using EMG and physical examination
- Surgery may be considered for patients who have prolonged symptoms, especially if MRI or ultrasound suggests focal nerve constriction
- Observation and pain management is traditionally recommended but there are certain pharmacological treatments that are sometimes offered
Further research is required to better understand the cause and treatment.
Dr. Joseph Feinberg is Physiatrist-in-Chief and specializes in brachial plexus and peripheral nerve injuries and disorders. He is Co-Medical Director at Center for Brachial Plexus and Traumatic Nerve Injury.
Dr. Scott Wolfe is the Chief Emeritus of the Hand and Upper Extremity Service and Attending Orthopedic Surgeon at Hospital for Special Surgery. Dr. Scott Wolfe is acknowledged to be one of the most experienced, innovative and authoritative experts in orthopedic upper extremity care. As lead author, he has published well over 100 major papers throughout his 25 year career in the most respected, peer-reviewed, American medical journals. His career goal is to help achieve consistently superior patient outcomes in hand and nerve surgery.
Dr. Darryl Sneag is an assistant attending radiologist at HSS who focuses on peripheral nerve magnetic resonance imaging (MRI). His research interests lie in optimizing current techniques and developing novel MRI pulse sequences, including diffusion tensor imaging (DTI), for the morphologic and biochemical assessment of nerve injury and health. Dr. Sneag is currently the primary investigator of a study evaluating DTI assessment of nerve regeneration on a clinical 3T magnet.
Eliana B. Saltzman, BA is a 4th year medical student from the Icahn School of Medicine currently on a scholarly year at the Hospital for Special Surgery. As part of the research team on the Hand and Upper Extremity, she is involved in various projects that include outcome research following brachial plexus reconstruction, questionnaire development for patients with traumatic brachial plexus injuries, and evaluating optimal nerve reconstruction techniques in an animal model.