I'd been treating a patient s/p lateral epicondyle ORIF for awhile and noted both a subjective report of loss of biceps strength and visible atrophy of biceps. Initially, I didn't think it was too significant as the patient was not allowed to lift anything with his arm for a couple months. However, as the patient progressed through the later stages of rehab, the atrophy of the biceps remained, even as some strength returned. He had an MRI that revealed no biceps tendon injury, so he was referred to a neurologist. Further testing revealed the patient had the diagnosis of Parsonage-Turner Syndrome.
Parsonage-Turner Syndrome is also known as acute idiopathic brachial neuritis, among other names. The cause is unknown, but is attributed to either viral origin or some form of autoimmune disorder. The neurologist told my patient it can occur after surgery as well. It afflicts 1.64 per 100,000 individuals. Typically the patient presents with pain in the upper quarter, followed up by the onset of muscle weakness and atrophy. What makes it stand out is that the atrophy and weakness remain as the pain subsides. Most of the background information I found associated Parsonage-Turner Syndrome with muscles of the RTC and proximal, however, it can vary as in the case of my patient. For proper diagnosis, be sure to have your patient referred to a neurologist for EMG and NCV. Once diagnosed, there are typically two stages for management. During the acute stage, the patient is instructed to rest and take the appropriate pain medication. Once the pain disappears, the patient should begin physical therapy in order to maintain joint mobility/flexibility and strength in the muscles. Typically, it takes several years to return to prior level of function (longer for elderly patients), and full strength may never return.
As with any case that involves nerve origin, I recommend treating the whole chain as in the case of double crush syndrome. Be sure to address any joint/neural mobility restrictions found. While it is not 100% certain my patient has Parsonage-Turner Syndrome, I thought this would be an interesting pathology to discuss as I was previously unfamiliar with it. For more information, check out this study. Have any of you encountered this pathology before?