RFS is similar to inflammation, wound healing, and fibrosis of any origin. The mechanisms linking radiation to chronic vascular dysfunction and subsequent tissue sclerosis, fibrosis, and atrophy are complex and not completely understood.
It is assumed that inury tot the vascular endothelium in the radiated area leads to abnormal accumulation of fibrin in the intravascular, perivascular, and extravascular compartments. This may be responsible for the progressive tissue fibrosis and sclerosis that characterizes RFS - a sort of chronic hypoxia to the affected area.
Factors aggravating RFS are recent surgery, chemotherapy, a large radiation treatment (RT) field and high total RT dose, all of which happen often simultaneously in a cancer patient.
Symptoms of RFS include:
- Nerves: (neuropathic) pain, sensory loss, weakness and autonomic dysfunction. Plexopathy is common and results in extensive disability
- Muscles: myopathy; weakness, increased fatigability, painful muscle spasms
- Tendons and ligaments: progressive fibrosis with consequent loss of elasticity, shortening, and contracture
- Bone: osteoradionecrosis, osteopenia in the radiation field
- Skin: progressive fibrosis, sclerosis and intractable adherence to underlying tissues
- Lungs: diffuse alveolar damage; edema, bleding, thrombosis and inflammation
Diagnosis is a challenge because of late onset and non-specific symptoms. The details of the patient's pain, spasm, tightness and the language they use to describe their symptoms are important: pulling, cramping, stabbing, searing, burning.
Physical examination is key, supported by MRI (spine, softe tissue, joints), CT (visceral involvement) and EMG.