Review Note
Last Update: 04/01/2024 02:30 AM
Current Deck: Neurology::Neuro-onc
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Radiation Leukoencephalitis
- Occurs {{c1::6 to 9::#}} months after treatment in excess of 40 Gy.
- MRI: {{c2::Confluent high T2}} signal within white matter extending to {{c2::subcortical U fibers}}.
Notes
Radiation leukoencephalitis is a condition characterized by inflammation and damage to the white matter of the brain, which can occur as a complication of radiation therapy. Here's a detailed explanation:
Timing of Occurrence:
- Radiation leukoencephalitis typically develops approximately 6 to 9 months after completion of radiation therapy, particularly when the radiation dose exceeds 40 Gray (Gy). Gray is a unit of measurement for absorbed radiation dose.
Clinical Presentation:
- Patients with radiation leukoencephalitis may present with a variety of neurological symptoms, including cognitive deficits, motor impairments, changes in behavior or personality, headaches, and seizures.
- The severity of symptoms can vary depending on the extent of white matter damage and individual patient factors.
Imaging Findings:
- Magnetic resonance imaging (MRI) is the imaging modality of choice for evaluating radiation leukoencephalitis. On MRI, characteristic findings include:
- Confluent high T2 signal: This refers to areas of increased signal intensity on T2-weighted MRI images, indicating abnormal fluid accumulation within the affected white matter. Confluent high T2 signal suggests widespread involvement of white matter tracts.
- Extension to subcortical U fibers: The abnormal signal intensity extends to involve the subcortical U fibers, which are short association fibers that connect adjacent gyri (convolutions) of the cerebral cortex. In radiation leukoencephalitis, these fibers may exhibit abnormal changes indicative of demyelination or gliosis.
Pathophysiology:
- The exact mechanisms underlying radiation leukoencephalitis are not fully understood, but it is believed to involve damage to the vascular endothelium, resulting in disruption of the blood-brain barrier and subsequent inflammation and demyelination within the white matter. Radiation therapy can induce oxidative stress and DNA damage in glial cells and oligodendrocytes, leading to white matter injury over time.
Management:
- Treatment of radiation leukoencephalitis focuses on managing symptoms and preventing further neurological decline. This may include corticosteroids to reduce inflammation, antiepileptic medications for seizure control, and supportive therapies to address cognitive or motor impairments.
- In some cases, hyperbaric oxygen therapy or other experimental treatments may be considered, although their efficacy is not well-established.
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