Radiation Necrosis Clinical Presentation

Updated: Sep 25, 2019
  • Author: Michael J Schneck, MD, MBA; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Radiation necrosis is a focal process that occurs at the initial tumor site.

  • The history generally reflects a subacute or chronic re-emergence of the initial tumor symptoms.

  • Occasional reports exist of patients developing diffuse areas of necrosis away from the initial tumor site.

  • When obtaining a history, include questions to exclude stroke and infection, which can cause a tumorlike appearance on MRI.

Breakthrough or new seizures may occur. These seizures may be partial, complex partial, or partial with secondary generalization (grand mal).

Depending on the tumor location and rate of growth, radiation necrosis can present with signs of mass effect, elevated intracranial pressure, obstructive hydrocephalus, or one of the herniation syndromes.

Hemorrhage in late radiation necrosis is a rare but described phenomenon. [8]

Radiation necrosis involving the frontal or temporal lobes may produce cognitive and personality changes.

  • In nasopharyngeal carcinoma, the anteromedial aspects of the temporal lobes are located in the radiation port.

  • A patient with radiation necrosis in this location may develop symptoms of personality change, memory loss, amnesia, and/or Klüver-Bucy syndrome.

  • Radiation necrosis resulting from radiotherapy for ocular and maxillary cancer can affect the frontal lobes. This can cause hemiparesis, apathy, and/or personality changes.



Evaluate mental status and cortical functioning in patients with radiation necrosis who have a supratentorial lesion or signs of increased intracranial pressure. In cortical testing, examine for aphasia, apraxia, attention, neglect, visuospatial skills, recognition, short-term recall, and calculation.

With the possibility of increased intracranial pressure, examine the fundus for possible papilledema and/or decreased or absent spontaneous venous pulsations.

Since radiation necrosis is a focal lesion, tailor the neurologic exam to look carefully for focality, lateralization, or asymmetry in motor, sensory, or coordination testing.

Since radiation necrosis occurs in the same region as the initial tumor bed, evaluate functions specific to that area of the CNS.



Occurrence generally is related to total radiation doses and fractionation size. The risk increases with increasing doses and larger radiation fraction sizes.

  • Tolerable total radiation dose to the brain is 6500-7000 cGy.

  • Patients who have received a total dose of 5500 cGy have a 3-5% occurrence of radiation necrosis.

  • Fractionation daily dose exceeding 200 cGy also increases risk.

  • Cerebral necrosis is unlikely at doses below 50 Gy in 25 fractions. [9]

Other predisposing factors include the following:

  • Other vasculopathic risk factors (eg, diabetes mellitus, hypercholesterolemia)

  • Chemotherapy: Chemotherapy increases the risks of necrosis even when adjusting for length of follow-up or initial radiation therapy dose.