How does encephalitis damage brain tissue?

Encephalitis, which is defined as inflammation of the brain, damages brain tissue through several distinct pathological mechanisms depending on the underlying cause.1

• Direct Viral Invasion: Many viruses, such as herpes simplex or rabies, directly invade and injure brain cells (neurons) after reaching the central nervous system via the bloodstream or other pathways.1
• Demyelination: In cases of demyelinating encephalitis—often occurring as a complication of viral infections like measles or following vaccinations—the nerve cell bodies remain intact, but the myelin sheaths that insulate nerve fibers are gradually destroyed.1
• Autoimmune Reactions: Sometimes, the immune system mistakenly attacks healthy brain cells, leading to inflammation. This can also manifest as acute allergic encephalomyelitis, where the immune system causes damage to the myelin sheaths of the central nervous system.12
• Noninfective Agents: Exposure to toxic chemicals such as lead, arsenic, or mercury can also trigger inflammatory damage to brain tissue.1

These processes can lead to irreparable brain damage, with the severity and long-term effects depending on the specific agent involved and the patient's overall health.1