-IBIS-1.5.0-
tx
nervous system
meningitis
diagnoses

definition and etiology

definition:
Inflammation and infection of the brain or spinal cord.

etiology:
The cause may be bacterial (Neisseria meningitidis, Hemophilus influenzae, Streptococcus pneumoniae, Group A Streptococcus, E. coli, Pseudomonas, Staphylococcus) or viral (arbo/polio/echo/coxsackie viruses; herpes simplex/zoster).

• Bacterial: There are 4.6-10 cases of bacterial meningitis/100,000 people a year. H. influenzae is usually the associated microorganism in children 2 months to 3 years old, while pneumococcal meningitis occurs mostly in the over-40 population.

• Viral: Most cases of viral meningitis occur after a viral infection and are thought to have an immunologic mechanism.

signs and symptoms

signs and symptoms:

bacterial:
• History recent URI or sore throat.
• Fever, headache, stiff neck/back ((+) Kernig's and Brudzinski's), vomiting.
• Changes in consciousness: irritability; confusion; lethargy; stupor; delirium; coma, in more serious disease.
• 25% of patients become severely ill within 24 hours.
• Skin rash: with meningococcal infections.
• In babies: Fever; vomiting; shrill/metallic/high-pitched cry; bulging fontanelle; seizures.

viral:
The disease appears in one of three ways:
• Asymptomatic: No symptoms, fever or malaise though there would be a (+) CSF analysis.
• Meningitis: Fever, headache, vomiting, malaise, stiff neck/back.
• Encephalitis: Meningitis with cerebral symptoms (change in consciousness, seizures etc.)

lab findings:
• analysis of CSF for cells, protein; culture and gram stain
• CBC: increased WBC with shift to left
• chemscreen for acid-base balance, rule out uremia

course and prognosis

In cases receiving early conventional treatment, antibiotics have reduced the fatality rate of bacterial meningitis to < 10%. However, if diagnosed late, or in neonates, the elderly or debilitated, bacterial meningitis is frequently fatal. In surviving children, 10% will experience neurologic deficits, especially hearing loss. The course of viral meningitis is usually more benign, and even patients that are extremely ill may recover fully.

differential diagnosis

• Subacute meningitis.
• Meningismus.
• Lead encephalopathy.
• Inebriation.
• Delirium tremens.
• Hepatic encephalopathy.
• Behcet's syndrome.


footnotes