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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. It’s often difficult to pinpoint PTS, as it can have a wide spectrum of symptoms and can overlap considerably with many different diagnoses.
The cause of PTS is largely unknown. There may be several subtypes that, alone or together, can lead to development of symptoms:
- Autoimmune or Vascular Triggers
- More than half of patients with PTS report a trigger event such as: infection, pregnancy, surgical stress, vaccinations, antibiotic treatments, or immunotherapy
- Mechanical
- Many patients report symptoms within hours of upper extremity exertion (e.g. snow shoveling after a blizzard, push-up contest, moving heavy furniture, etc.)
- Genetics
- A rare hereditary form of PTS does exist
PTS is a clinical diagnosis with no confirmatory diagnostic test. However, there are very typical electro-diagnostic findings that can help make the diagnosis and assess the extent of nerve damage and loss of muscle function to differentiate PTS from other similar diseases.
It is not known why some patients with PTS demonstrate no recovery or incomplete recovery, while most spontaneously recover. Using ultrasound and MRI, recent studies have detected an “hour-glass constriction” or a twisting of nerves in the upper extremity of patients with refractory PTS symptoms. This constriction 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 help determine a surgical decision.
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 do physical therapy to help manage arm weakness. They should return to their physician for periodic evaluations to monitor progress, using EMG and physical examination. Surgery is an option for patients who have prolonged symptoms, especially if imaging suggests focal nerve constriction.
Dr. Scott Wolfe is an orthopedic surgeon at Hospital for Special Surgery, specializing in orthopedic upper extremity care. He practices at both the HSS Outpatient Center in Stamford, CT and the hospital’s main campus in New York.
