Meningitis is an inflammation of the protective membranes covering the brain and spinal cord, usually caused by a bacterial or viral infection. It can be life-threatening and is considered a medical emergency. Symptoms may include fever, headache, stiff neck, sensitivity to light, and confusion. Diagnosis involves physical examination, lumbar puncture, and tests of cerebrospinal fluid. Treatment depends on the cause but may include antibiotics, antivirals, or antifungals. Complications can include hearing loss, brain damage, and death. Vaccines can prevent some types of bacterial meningitis.