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Radiation-Induced Brachial Plexopathy Workup

  • Author: Ryan O Stephenson, DO; Chief Editor: Robert H Meier, III, MD  more...
Updated: Mar 10, 2015

Laboratory Studies

No laboratory studies help differentiate radiation-induced brachial plexopathy from other disorders involving the brachial plexus.


Imaging Studies

Plain radiography does not have diagnostic value for detecting radiation-induced brachial plexopathy.

Computed tomography (CT) scanning of the involved brachial plexus may reveal a diffuse infiltration of the tissue planes.

Magnetic resonance imaging (MRI) often reveals low signal intensity on T2-weighted images; minimal changes are found with gadolinium.[13, 18, 19]

All of these characteristics are in contrast to neoplastic processes, which would be identified by the presence of a focal mass. In addition, if traditional modalities demonstrate normal findings, positron emission tomography imaging may provide an additional tool for excluding suspected malignant plexopathy. Malignant etiologies of brachial plexopathy are associated with significantly increased uptake of 18-fluoro-2-deoxy-D-glucose, reflecting the increased metabolism associated with neoplastic processes.


Other Tests

Electrodiagnostic testing can be used to help distinguish between radiation-induced and neoplastic disorders of the brachial plexus. Generally, no significant differences between the 2 conditions are noted on sensory and motor conduction studies or late responses. However, nerve conduction studies are important to exclude other causes of paresthesias in the lateral digits, such as carpal tunnel syndrome.

Needle electromyography in radiation-induced brachial plexopathy reveals myokymia more often than in neoplastic-induced brachial plexopathy.[4] Myokymia represents spontaneous discharges accompanied by wavelike muscle quivering. The frequency may be paroxysmal motor unit action potentials or a slow continuous discharge at 1-5 Hz in motor unit action potentials.[13]

Evoked potential studies do not have any particular value for this diagnosis.



In some cases, surgical exploration and biopsy are required to distinguish between radiation-induced and tumor-induced brachial plexopathy. Nerve grafting has been attempted in animals with fair results, but data from human trials are lacking.[20, 21]

Surgical treatment options are aimed at breaking up fibrotic tissue to eliminate mechanical constriction of the plexus and its blood supply. Attempts have been made at exoneurolysis/endoneurolysis, with or without placement of an omental or latissimus dorsi flap as a source of well-perfused tissue. Unfortunately, these approaches have proven ineffective and even harmful. Indeed, dissection alone can lead to a significant worsening of symptoms. Some relief of pain may be achieved in a minority of patients, with little or no impact on other sensory or motor deficits.


Histologic Findings

Findings may include the following:

  • Fibrosis of the neural elements and surrounding soft tissues
  • Chronic perineurial microvascular ischemia
Contributor Information and Disclosures

Ryan O Stephenson, DO Assistant Professor, Department of Physical Medicine and Rehabilitation, University of Colorado Health Science Center; Physiatrist, Medical Director of PM&R Inpatient Consultation Service, Medical Director of Polytrauma and Brain Injury, Medical Director of Regional Amputee Center, Department of Physical Medicine and Rehabilitation, Eastern Colorado Veterans Affairs Medical Center

Ryan O Stephenson, DO is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Patrick M Foye, MD Director of Coccyx Pain Center, Professor and Interim Chair of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School; Co-Director of Musculoskeletal Fellowship, Co-Director of Back Pain Clinic, University Hospital

Patrick M Foye, MD is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, International Spine Intervention Society, American Association of Neuromuscular and Electrodiagnostic Medicine, Association of Academic Physiatrists

Disclosure: Nothing to disclose.

Chief Editor

Robert H Meier, III, MD Director, Amputee Services of America; Active Medical Staff, Presbyterian/St Luke’s Hospital, Spalding Rehabilitation Hospital, Select Specialty Hospital; Consulting Staff, Kindred Hospital

Robert H Meier, III, MD is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, Association of Academic Physiatrists

Disclosure: Nothing to disclose.

Additional Contributors

Rajesh R Yadav, MD Associate Professor, Section of Physical Medicine and Rehabilitation, MD Anderson Cancer Center, University of Texas Medical School at Houston

Rajesh R Yadav, MD is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation

Disclosure: Nothing to disclose.


Robert J Kaplan, MD Staff Physician, Department of Rehabilitation Medicine, James E Van Zandt VA Medical Center

Robert J Kaplan, MD is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation

Disclosure: Nothing to disclose.

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Table. Other Problems to Consider in Radiation-Induced Brachial Plexopathy Diagnosis
Feature Tumor Infiltration Radiation Fibrosis Transient Radiation Injury Acute Ischemic Injury
Incidence of pain 80% 18% 40% Painless
Location of pain Shoulder, upper arm, elbow, fourth and fifth fingers Shoulder, wrist, hand Hand, forearm Hand, forearm
Nature of pain Dull ache in shoulder, lancinating pains in elbow and ulnar aspect of hand; occasional paresthesias and dysesthesias Ache in shoulder; prominent paresthesias in C-5/C-6 distribution of hand and arm Ache in shoulder; prominent paresthesias in C-5/C-6 distribution of hand and arm Paresthesias in C-5/C-6 distribution of hand and arm
Severity Moderate to severe (severe in 98%) Usually mild to moderate

(severe in 20-35%)

Mild Mild
Course Progressive neurologic dysfunction; atrophy and weakness in C-7/T-1 distribution, persistent pain; occasional Horner syndrome Progressive weakness; panplexus or upper plexus distribution; Horner syndrome uncommon Translate weakness with complete resolution Acute nonprogressive weakness and sensory loss
Study findings        
Magnetic resonance imaging High signal intensity on T2-weighted images; may enhance with gadolinium Low signal intensity on T2-weighted images; generally nonenhancing with gadolinium No data Normal
Computed tomography Mass; circumscribed or diffuse tissue infiltration Diffuse tissue infiltration Normal Angiography demonstrates subclavian artery segmental


Electromyography Segmental slowing Diffuse myokymia Segmental slowing Segmental slowing
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