Meningitis & Encephalitis

About Meningitis & Encephalitis

Meningitis is inflammation of the protective membranes (meninges) covering the brain and spinal cord, while encephalitis involves inflammation of the brain tissue itself. Both conditions can be caused by viral, bacterial, fungal, or parasitic infections and represent medical emergencies requiring immediate diagnosis and treatment. These neurological infections can lead to severe complications including brain damage, hearing loss, seizures, and death if not promptly managed.

Pathophysiology

In meningitis, pathogens breach the blood-brain barrier and infect the cerebrospinal fluid, causing inflammatory responses in the subarachnoid space and meninges. Encephalitis occurs when infectious agents directly invade brain parenchyma, triggering localized inflammation, neuronal damage, and potential cerebral edema. The inflammatory cascade in both conditions increases intracranial pressure and disrupts normal cerebrospinal fluid flow, potentially compromising cerebral perfusion and neurological function.

Clinical Reasoning

Early recognition relies on the classic triad of fever, headache, and neck stiffness, though this presentation may be incomplete, especially in immunocompromised patients or young children. Lumbar puncture with cerebrospinal fluid analysis remains the gold standard for diagnosis, revealing elevated white blood cells, protein levels, and decreased glucose in bacterial cases. Empirical antibiotic therapy should be initiated immediately in suspected bacterial meningitis, while antiviral treatment may be considered for encephalitis, as delays in treatment significantly worsen outcomes and increase mortality risk.