Chapter 602 - Central Nervous System Infections from Kliegman: Nelson Textbook of... Page 1 of 20Kliegman: Nelson Textbook of Pediatrics, 18th ed.Copyright 2007 Saunders, An Imprint of ElsevierChapter 602 Central Nervous System InfectionsCharles G. ProberInfection of the central nervous system (CNS) is the most common cause of fever associated with signs and symptoms of CNS disease in children. Many microorganisms can cause infection. Nonetheless, specific pathogens are identifiable and are influenced by the age and immune status of the host and the epidemiology of the pathogen. In general, viral infections of the CNS are much more common than bacterial infections, which, in turn, are more common than fungal and parasitic infections. Infections caused by rickettsiae (Rocky Mountain spotted fever, Ehrlichia) are relatively uncommon but assume important roles under certain epidemiologic circumstances. Mycoplasma spp. can also cause infections of the CNS, although their precise contribution is often difficult to determine.Regardless of etiology, most patients with CNS infection have similar clinical manifestations. Common symptoms include headache, nausea, vomiting, anorexia, restlessness, altered state of consciousness, and irritability; most of these symptoms are nonspecific. Common signs of CNS infection, in addition to fever, include photophobia, neck pain and rigidity, obtundation, stupor, coma, seizures, and focal neurologic deficits. The severity and constellation of signs are determined by the specific pathogen, the host, and the area of the CNS affected.Infection of the CNS may be diffuse or focal. Meningitis and encephalitis are examples of diffuse infection. Meningitis implies primary involvement of the meninges, whereas encephalitis indicates brain parenchymal involvement. Because these anatomic boundaries are often not distinct, many patients have evidence of both meningeal and parenchymal involvement and should be considered to have meningoencephalitis. Brain abscess is the best example of a focal infection of the CNS. The neurologic expression of this infection is determined by the site and extent of the abscess(es) [see Chapter 603 ].The diagnosis of diffuse CNS infections depends on examination of cerebrospinal fluid (CSF) obtained by lumbar puncture (LP). Table 602-1 provides an overview of the expected CSF abnormalities with various CNS disorders.TABLE 602-1 -- Cerebrospinal Fluid Findings in Central Nervous System DisordersPRESSURE LEUKOCYTESPROTEINGLUCOSECONDITION(MM H2O)(MM 3 )(MG/DL)(MG/DL)COMMENTSNormal508050 (or 75%lymphocytesserumglucose)COMMON FORMS OF MENINGITISAcute bacterialUsually10010,000 orUsuallyDecreased,Organismsmeningitiselevatedmore; usually100500usually 50% of secondary family cases occur in the 1st wk after the index patient has been hospitalized.The dose of rifampin is 20 mg/kg/24 hr (maximum dose of 600 mg) given once each day for 4 days. Rifampin colors the urine and perspiration red-orange, stains contact lenses, and reduces the serum concentrations of some drugs, including oral contraceptives. Rifampin is contraindicated during pregnancy.The most striking advance in the prevention of childhood bacterial meningitis followed the development and licensure of conjugated vaccines against H. influenzae type b. Four conjugate vaccines are licensed in the United States. Although each vaccine elicits different profiles of antibody response in infants immunized at 26 mo of age, all result in protective levels of antibody with efficacy rates against invasive infections ranging from 70 to 100%. Efficacy is not as consistent in Native American populations, a group recognized as having an especially high incidence of disease. All children should be immunized with H. influenzae type b conjugate vaccine beginning at 2 mo of age (see Chapter 170 ).Streptococcus Pneumoniae.Routine administration of heptavalent conjugate vaccine against S. pneumoniae is recommended for children younger than 2 yr of age. The initial dose is given at 2 mo of age. Children who are at high risk of invasive pneumococcal infections, including those with functional or anatomic asplenia and those with underlying immunodeficiency (such as infection with HIV, primary immunodeficiency, and those receiving immunosuppressive therapy) should also receive the vaccine.Copyright 2008 Elsevier Inc. All rights reserved. - www.mdconsult.com mk:@MSITStore:C:\New%20folder\KULIAH\Medical%20E-Books\Pediatrics\Nelso... 01/11/2015