Presents in one of two ways: (1) sudden fulminant onset, with rapid progression, seen through shock, purpura, DIC, coma, and/or death within 24 h, or (2) signs of meningitis preceded by several days of fever, URI, or GI illness leading to increasing lethargy and irritability.

Defined as presence of clinical and lab signs of meningitis but with negative cultures. While it is often thought that a more fulminant course of meningitis or encephalitis is suggestive of a bacterial etiology, this is not always the case. Systemic features such as rash, anorexia, arthralgias, and malaise represent viremia and can suggest a viral etiology. Clinical presentation by age: Neonate: In the newborn period, fever may be absent. Common
presentations include apnea, tachypnea, seizure, focal neurologic deficit, depressed state of consciousness, irritability, failure to thrive, emesis, jaundice, sepsis, hypothermia, hyperthermia, opisthotonic posturing. Child and adolescent: Headache (difficult to elicit in child <3 y), fever, nuchal rigidity, photophobia, phonophobia, vomiting, pain with eye movement, petechial rash. Physical exam: Nuchal rigidity: Evidenced by Kernig sign (flexion of the hip 90° with subsequent pain upon extension of the leg) and/or Brudzinski sign (involuntary flexion of the knees and hips after passive neck flexion while supine). Also try chin to chest (more sensitive in early stages) or ask child to kiss his/her knee.⁵ Both considered positive if pain elicited. Note: Lateral neck movement should not produce pain.⁵ Full/bulging anterior fontanelle in neonatal period—only present in ˜1/3 of patients.¹ This is a late sign. Papilledema rare in acute meningitis and suggests more chronic etiology, such as venous sinus thrombosis, idiopathic intracranial hypertension, chronic forms of meningitis. Cranial Neuropathies suggestive of increased ICP include abducens/6th nerve palsy most commonly. Others include trochlear/4th nerve, oculomotor/3rd nerve palsy, or trigeminal/5th nerve palsy less commonly. These are often considered false localizing signs. An oculomotor/3rd nerve palsy indicates uncal herniation. Other physical exam findings such as lymphadenopathy, hepatosplenomegaly, rash, and oral lesions may accompany meningeal signs and when present, speak toward a viral etiology. Etiology: Common bacteria by Age^1,4,6: Neonates: Streptococcus agalactiae, Escherchia coli, Listeria monocytogenes, S. pneumoniae. Children & adolescents: Neisseria meningitidis, S. pneumoniae, Haemophilus influenzae. Common etiologies of viral meningitis: See Tables 22.2 and 22.3. Diagnostic workup: Blood culture: Important—reveals responsible bacteria in 8% to 90% of cases.¹ LP: Timing of LP guided by clinical suspicion for increased ICP. Signs of increased ICP: empiric antibiotics > neuroimaging > consider LP upon results (short course of antibiotics not thought to significantly alter CSF findings). No signs of increased ICP: LP with empiric antibiotics. Contraindications for immediate LP: (1) evidence of increased ICP (Cushing triad, cranial neuropathies [specifically a 6th nerve or 4th nerve palsy] in setting of altered consciousness), (2) severe cardiopulmonary compromise, (3) infection of the overlying skin, (4) underlying bleeding disorder. (thrombocytopenia is a relative contraindication)^1,6 (see Table 22.4) Differential diagnosis: Peritonsillar abscess, brain abscess, retropharyngeal abscess.

Treatment: Do not wait for CSF results before starting treatment!

Steroids: Recommended early in course of suspected pediatric bacterial meningitis. Thought to decrease CNS inflammation and ICP, while decreasing overall mortality, acute complications, and long term sequelae (specifically auditory function). There is likely no benefit if given 1 h after antimicrobials. Dexamethasone 0.6 mg/kg/d in four divided doses for 2 to 4 d should be given before or with the first dose of antibiotics. Use in the neonatal period has not been established.^1,5 Complications of meningitis: Hydrocephalus, subdural effusions, epidural abscess, venous sinus thrombosis, increased ICP, hyponatremia (SIADH), seizures, cerebral
vasculitis. Neurologic sequelae: Deafness is the most frequent neurologic sequelae of bacterial meningitis; frequency up to 15% to 30% (highest risk with S. pneumoniae).¹ Epilepsy in <5%.¹ Intellectual disability, motor impairment, hemiparesis, blindness, learning disability.