The median nerve innervates or supplies muscles of the forearm with messages needed for sensation and movement. Compression on the nerve can cause this condition known as pronator teres syndrome. The affected individual experiences mild to moderately painful symptoms along with numbness. Hand function may be impaired but disability from this problem is rare.
Pronator syndrome can occur if and when the nerve is compressed in any of several places (e.g., most often between the two heads of the pronator teres muscle, but also at the proximal arch of the flexor digitorum surperficialis, at the ligament of Struthers, at the aponeurosis, or at the head of the flexor pollicis longus). Though you may not be familiar with those specific soft tissues, it gives you an idea of how the nerve comes in contact with many and various structures that could put pressure on it.
This condition is fairly rare. So the diagnosis requires a careful patient history, physical examination, and electrodiagnostic and imaging studies. Specific tests that can be done to make the diagnosis and distinguish this problem from other similar conditions affecting the median nerve. But there are no tests to really confirm the diagnosis.
Electrodiagnostic tests are typically used to confirm other nerve compression problems. The test provides positive proof when there’s a problem. But with pronator syndrome, stimulating the nerve with an electrical impulse shows there’s a problem in nerve conduction for only one out of every 10 patients with symptoms of pronator syndrome.
Women in their 40s are the ones most likely to be seen with this condition. And because there are no objective measures and because surgery to decompress the nerve isn’t always successful, there is a belief that this isn’t a disease, but rather an illness.
Conservative (nonoperative) care is recommended first. Rest, muscle stretching exercises, activity modification, and antiinflammatory medications are tried for at least six months. Studies show that surgery is unsuccessful more often than not.
Surgery is only advised when nonsurgical intervention is unsuccessful after many, many months (up to a year or more). The exact surgical approach to take remains a point of considerable debate and discussion. Although there is no formal evidence-based protocol, most surgeons release the median nerve along its entire course in the forearm for both conditions. Any places of restriction or obstruction are removed.
When surgery does relieve the problem, it could be a placebo effect. So determining disease (true pathologic anatomy or physiology) from illness (physical symptoms caused by emotional or psychologic distress) can’t be cleared up by successful treatment.
Until the concept of pronator syndrome can be fully explored and explained, treatment will likely remain nonsurgical. Antiinflammatory medications and a few sessions with a hand therapist may be all that’s needed.
The therapist will teach the patient how to modify activities to avoid contracting the pronator muscle and thereby keep pressure off the nerve. Exercises to stretch the nerve and manual therapy to release fibrous tissue around the nerve may help. Any postural effects will be addressed. The therapist may conduct a review of the patient’s home and/or office work areas for possible contributing or aggravating factors.