Musculoskeletal
Robert S. Allen, MD
Resident Physician
The University of New Mexico
Albuquerque, New Mexico, United States
Emily Olson, MD
Clinical Education Assistant Professor
University of New Mexico
Albuquerque, New Mexico, United States
Robert S. Allen, MD
Resident Physician
The University of New Mexico
Albuquerque, New Mexico, United States
Brachial plexopathy due to post radiation fibrosis
Case Description:
64yo M with PMH p16 positive squamous cell carcinoma of the right tonsil status post chemotherapy and radiation to the right neck in 2017. In 2020, patient developed neuropathic symptoms radiating from right shoulder to the hand. EMG in 2022 showed unobtainable sensory responses on the right without motor findings. With a diagnosis of possible neurogenic thoracic outlet syndrome patient underwent scalene trigger point injections, median perineural injection at the carpal tunnel, and low dose botulinum toxin to the sternocleidomastoid and scalene muscles without benefit. Patient underwent diagnostic ultrasound 3/2025 which demonstrated extensive fibrosis surrounding the brachial plexus at the level of the scalene muscles with enlargement of the nerve roots and trunks proximal to fibrosis. US guided brachial plexus hydrodissection did not provide relief, although providers were unable to fully dissect the nerve. Repeat EMG 5/25 demonstrated new needle EMG findings most severely affecting muscles in a C7 distribution.
Discussions: Radiation induced fibrosis is a common side effect of radiation therapy for treatment of a malignancy that can effect quality of life outcomes in up to 70% of patients. In our case the patient developed severe progressive brachial plexopathy resistant to conservative management, which has not previously been reported. Of note our patient had a relatively late presentation of his TOS due to fibrosis with symptoms not appearing till about 3 years post radiation treatment.
Conclusions:
Radiation induced fibrosis is a late complication of radiation that can entrap nerves. Electromyographers need to be aware of the potential affects of radiation induced fibrosis since, even in the absence of myokymia, radiation could still be the source of otherwise unexplained nerve damage in the location of prior radiation.
