Radiation-induced brachial plexopathy

Case contributed by Dr Shu Su

Presentation

62 year old male with right-sided Pancoast tumour treated with radiotherapy

Patient Data

Age: 62
Gender: Male

Pulmonary scarring/collapse in the posteromedial aspect of the lung apex is associated with oedema and intramuscular enhancement in the adjacent intercostal and scalene musculature and also within serratus posterior, likely to be secondary to radiation change. Similar appearances in the right apex were identified on a CT chest from September 2013. T1 hypointense soft tissue thickening partially surrounds the brachial plexus most pronounced where it crosses the first rib. This appears to draw-in and distort the lower trunk and to a lesser extent the middle trunk of the brachial plexus, and also involves the medial and probably posterior cords. This is associated with mildly asymmetric thickening of the C8 and T1 nerve roots.

Conclusion: 

Distortion of the lower trunk and medial cords and to a lesser extent middle trunk and posterior cord of the right brachial plexus by abnormal soft tissue at the thoracic outlet. The similarity of right apical lung change to a CT from 2013 and the morphology of the brachial plexus abnormality ( drawn in rather than enveloped ) would be more compatible with radiation plexopathy than tumour infiltration.

Report courtesy of Royal Melbourne Hospital Radiology Department

Annotated image

Distortion of brachial plexus trunks. 

Case Discussion

Radiation is the most common cause of non-traumatic brachial plexopathy and much of this is iatrogenic. Symptoms may be delayed for months to years with peak onset being 10-20 months. MRI can be used to distinguish brachial plexopathy due to radiation as opposed to incidence or recurrence of a mass. Unfortunately, both tumours and radiation plexopathy can exhibit hypointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging as well as enhancement following gadolinium contrast; the most reliable sign is the detection of a visible mass in the case of tumour recurrence. The MRI features of acute and chronic brachial plexus changes following radiation are outlined below 1,2:

Acute radiation plexopathy

  • diffuse, uniform, symmetric swelling, hyperintense on T2-weighted imaging
  • slight to moderate hyperintensity on STIR images
  • can have mild contrast enhancement
  • surrounding fat and muscles appear diffusely T2-hyperintense
  • radiogenic pneumonia and pleura thickening possibly present

Chronic radiation fibrosis 

  • usually hypo or iso-intense on T1 and T2
  • does not enhance with gadolinium 
  • architectural distortion and more diffuse thickening of brachial plexus without a focal mass
  • surrounding fibrovascular scar tissue

This case has more features of chronic radiation fibrosis.

Case courtesy of Dr Craig Hacking and A/Prof Pramit Phal.

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Case information

rID: 38776
Case created: 3rd Aug 2015
Last edited: 30th Sep 2015
Inclusion in quiz mode: Included

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