In the era of widespread conjugate vaccines, most children have aseptic, not bacterial meningitis. Enteroviruses are the major viral pathogen, with yearly peaks in the summer. In endemic regions, Lyme meningitis has been increasingly common.
Empiric antibiotic coverage while awaiting results of bacterial cultures should cover the most likely pathogens for patients with suspected bacterial meningitis.
Validated clinical decision rules can be used to identify children at low risk for bacterial meningitis, and in endemic regions, Lyme meningitis.
Meningitis refers to an infection of the cerebrospinal fluid (CSF) that bathes the brain, whereas encephalitis is an infection of the brain itself. Most meningitis pathogens enter the CSF space by hematogenous spread. More unusually, pathogens may enter through a mechanical disruption (e.g., a fracture of the base of the skull) or by direct extension from a local infection (e.g., ear, mastoid air cells, sinuses, or orbit). Once the blood–brain barrier has been breached, natural defense mechanisms are less able to stop the multiplication of organisms. Since 1990, the incidence of bacterial meningitis in children under 18 years of age has declined by approximately one-third due to the widespread uptake of the highly effective vaccines against Haemophilus influenzae type B (1990), Streptococcus pneumoniae (7-valent 2000; 12-valent 2010), and Neisseria meningitidis (2005). The predominant bacterial pathogens for children older than 2 months of age remain S. pneumoniae and N. meningitidis, and for the youngest infants Group B streptococcus and Escherichia coli.1
The younger a child with meningitis, the less specific the presenting signs and symptoms will be. Neonates and young infants are likely to present with fever, poor feeding, irritability, inconsolability, or listlessness. Older children with meningitis may present with “classic” signs and symptoms of meningitis which include headache, photophobia, stiff neck, change in mental status, bulging fontanel, nausea, and vomiting. The Brudzinski sign (neck flexion causes the hips and knees to flex involuntarily) and the Kernig sign (hip flexed prevents full extension of the leg) are both late signs of meningeal irritation. However, these clinical signs have poor diagnostic accuracy in identifying cases of bacterial meningitis.2
In the early phases, meningitis may be confused with gastroenteritis or intussusception, respiratory infections (e.g., pneumonia), or deep neck space infections (e.g., retropharyngeal abscess or cervical adenitis). For children with altered mental status, encephalitis, cerebral hemorrhage or abscess, or toxic ingestions must also be considered.
The initial management of an unstable patient with suspected meningitis must focus on assuring airway, breathing, and cardiovascular stability. Supplemental oxygen is always administered. (See Chapter 20 for management of shock.) If signs of increased intracranial pressure develop, clinicians should elevate the head slightly and initiate controlled hyperventilation (target PaCO2 between 30 and 35 mmHg). Children unresponsive to initial therapy may benefit from the use of mannitol ...