SERIOUS damage to the nervous system from radiation therapy or chemotherapy is uncommon, and its pathogenesis is poorly understood. Although there are numerous elaborate descriptions of neuropathological changes, the relevant definition of tolerance to these modes of therapy is based on function. Recently, thresholds for serious neurological damage have begun to be established through clinical observations and experiments with animal models.
The precise targets and mechanisms involved in neurological injury from ionizing radiation are complex. Intrinsic neural tissue seems to be more resistant to radiation injury than the supporting glial tissue and capillary endothelium; in late radiation injury in particular, damage to small and medium vascular arterioles is considered to be the etiology.1-4 When neurological damage occurs, blood vessel abnormalities—including hyalinization, fibrinoid necrosis of the vessel walls, luminal obliteration, and thrombosis—are prominent in both the damaged area of the brain and the surrounding normal tissue. Demyelination is
Goldberg ID, Bloomer WD, Dawson DM. Nervous System Toxic Effects of Cancer Therapy. JAMA. 1982;247(10):1437-1441. doi:10.1001/jama.1982.03320350041026