Meningitis

About Meningitis

Meningitis is inflammation of the protective membranes (meninges) surrounding the brain and spinal cord, commonly caused by bacterial, viral, or fungal infections. It presents as a medical emergency with symptoms including severe headache, neck stiffness, fever, and altered mental status. Early diagnosis and treatment are critical to prevent serious complications including brain damage, hearing loss, and death.

Pathophysiology

Pathogens breach the blood-brain barrier through hematogenous spread, direct extension from adjacent infections, or traumatic disruption, leading to inflammation of the pia mater, arachnoid mater, and cerebrospinal fluid. The inflammatory response increases intracranial pressure and can cause cerebral edema, reduced cerebral perfusion, and neuronal damage. Bacterial meningitis typically involves more severe inflammation and purulent CSF changes compared to viral forms.

Clinical Reasoning

The classic triad of fever, neck stiffness, and altered mental status is present in only 40-50% of cases, making clinical diagnosis challenging. Lumbar puncture with CSF analysis is the gold standard for diagnosis, revealing elevated white cell count, protein, and decreased glucose in bacterial cases. Empirical antibiotic therapy should be initiated immediately when bacterial meningitis is suspected, as delays in treatment significantly worsen outcomes and increase mortality risk.