Radiation exposure can indeed cause seizures, although this is generally associated with high doses of ionizing radiation affecting the brain rather than low or moderate exposures. The relationship between radiation and seizures is complex and depends on factors such as the dose, duration, and area of exposure, as well as individual susceptibility.
When the brain is exposed to very high doses of radiation—typically in the range of 50 Gy or more—there can be immediate and severe effects on the central nervous system. These effects may include symptoms like stupor, incoherence, and seizures. This level of exposure is usually seen in acute radiation syndrome involving the neurovascular system, where the damage is so extensive that it disrupts normal brain function rapidly. Seizures in this context are a sign of serious neurological injury caused by radiation-induced damage to brain cells and blood vessels, leading to swelling, inflammation, and impaired electrical activity in the brain.
Radiation can damage the brain through several mechanisms. It can injure the endothelial cells lining blood vessels, compromising the blood-brain barrier and causing vasogenic edema (fluid leakage into brain tissue). This swelling can increase pressure inside the skull and disrupt normal neuronal signaling, potentially triggering seizures. Radiation also causes demyelination, which is the loss of the protective sheath around nerve fibers, impairing the speed and coordination of electrical impulses. Additionally, radiation-induced oxidative stress and chronic inflammation can alter brain tissue function over time, increasing the risk of seizures.
Seizures may also occur as a delayed consequence of radiation therapy used to treat brain tumors or metastases. While radiotherapy aims to kill cancer cells, it can inadvertently damage healthy brain tissue, leading to neurotoxicity. This damage may manifest weeks, months, or even years after treatment, sometimes causing seizures as part of a broader syndrome of radiation-induced brain injury. In these cases, seizures are often accompanied by other neurological symptoms such as cognitive decline, memory loss, and motor disturbances.
Even lower doses of radiation, while less likely to cause seizures directly, can accelerate seizure activity in individuals who are genetically predisposed or have pre-existing neurological conditions. Experimental studies in animals have shown that doses as low as a few milligrays can increase seizure susceptibility, although this is not common in humans exposed to typical environmental or medical radiation levels.
Radiation exposure during childhood or early development is particularly concerning because the developing brain is more sensitive to damage. Radiation can increase the risk of brain tumors, which themselves can cause seizures either by direct irritation of brain tissue or by increasing intracranial pressure. The latency period between radiation exposure and tumor development can be long, sometimes spanning decades, making it challenging to link seizures directly to past radiation exposure.
In summary, seizures caused by radiation exposure are primarily associated with high-dose radiation injury to the brain, either from acute radiation syndrome or as a late effect of therapeutic radiation. The underlying causes include vascular injury, edema, demyelination, inflammation, and tumor formation. While seizures are not a common consequence of low-level radiation exposure, they can occur in susceptible individuals or as part of complex neurological damage following significant radiation insult.