9.4 Acute Pediatric Infections: Meningitis, Croup & Febrile Seizures

Acute Pediatric Infections: Meningitis, Croup & Febrile Seizures

Acute pediatric infections presenting with neurological symptoms, altered consciousness, or acute upper airway obstruction represent the most critical emergencies encountered by clinical officers in district hospitals and emergency triage units across Kenya. Rapid clinical differentiation, stabilization of vital airway, breathing, and circulatory parameters, prompt empirical antimicrobial therapy, and judicious abortive anticonvulsant management are life-saving competencies tested rigorously on the Clinical Officers Council examinations.

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1. Acute Bacterial Meningitis (Beyond Neonatal Age)

Acute bacterial meningitis is a life-threatening pyogenic infection of the subarachnoid space and leptomeninges surrounding the brain and spinal cord, associated with high case-fatality rates (20–30%) and permanent neurodevelopmental sequelae (sensorineural deafness, mental handicap, epilepsy, and hydrocephalus).

Etiology Across Age Groups

• Infants and Children (> 3 Months to 5 Years):
  • Streptococcus pneumoniae (pneumococcus): Currently the leading cause of bacterial meningitis in Kenya, associated with the highest morbidity and mortality.
  • Neisseria meningitidis (meningococcus): Serogroups A, C, W-135, and X; responsible for epidemic waves, particularly in the northern arid counties bordering the African Meningitis Belt.
  • Haemophilus influenzae type b (Hib): Historically predominant; incidence has declined significantly following universal Pentavalent vaccination, but remains an important cause in unimmunized children.
• Neonates and Young Infants (< 2 to 3 Months): Group B Streptococcus (Streptococcus agalactiae), Escherichia coli and other enteric Gram-negative bacilli, and Listeria monocytogenes.

Clinical Manifestations

• Young Infants (< 12 Months): Classical signs of meningeal irritation are frequently absent due to open cranial sutures and immature neuromuscular reflexes. Presentation is subtle and non-specific: high-grade fever or hypothermia, irritability, shrill or high-pitched cry, poor feeding/refusal to suck, vomiting, lethargy, vacant stare, hypotonia, and a tense or bulging anterior fontanelle (evaluated when the infant is upright and not crying).
• Older Children (> 12 Months): High fever, severe throbbing headache, photophobia, nausea, projectile vomiting, confusion, delirium, and classic meningeal signs:
  • Nuchal Rigidity (Neck Stiffness): Inability to passively flex the neck to touch the chin to the sternum due to involuntary spasm of extensor spinal muscles.
  • Kernig's Sign: With the patient supine and the hip flexed at 90 degrees, passive extension of the knee causes severe pain and resistance beyond 135 degrees.
  • Brudzinski's Sign: Passive flexion of the neck induces involuntary, reflexive flexion of the hips and knees.

Lumbar Puncture & Cerebrospinal Fluid (CSF) Analysis

Lumbar puncture (LP) between L3/L4 or L4/L5 interspaces is mandatory for any child suspected of having bacterial meningitis, provided absolute contraindications are ruled out.

Absolute LP Contraindications: (1) Signs of elevated intracranial pressure (focal neurological deficits, asymmetric or non-reactive pupils, papilledema, Cushing's triad [bradycardia, hypertension, irregular breathing]); (2) Cardiopulmonary shock or severe respiratory distress; (3) Local infection at the puncture site; (4) Severe bleeding diathesis or severe thrombocytopenia. In the presence of contraindications, do NOT delay antibiotics—administer empirical IV Ceftriaxone immediately.

Pharmacological Management (Kenya Basic Paediatric Protocols)

• Empirical Parenteral Antibiotic:
  • First-Line Regimen: Intravenous Ceftriaxone: 100 mg/kg once daily (or 50 mg/kg every 12 hours, maximum 4.0 g/day) administered by slow IV infusion over 30 minutes for 7 to 10 days (extend to 14 days for S. pneumoniae, 21 days for Gram-negative bacilli).
  • Alternative: IV Ampicillin (50 mg/kg q6h) PLUS IV Chloramphenicol (25 mg/kg q6h) if third-generation cephalosporins are unavailable.
• Adjunctive Corticosteroid Therapy:
  • IV Dexamethasone: 0.15 mg/kg every 6 hours for 2 to 4 days.
  • Must be administered before or concurrently with the first dose of antibiotics to attenuate the massive inflammatory cascade triggered by bacterial lysis. Specifically proven to reduce the incidence of sensorineural hearing loss and long-term neurological disability in Hib and pneumococcal meningitis.
• Supportive Care: Fluid restriction to two-thirds maintenance during the initial 48 hours to prevent fluid overload from SIADH; treat seizures promptly; monitor head circumference daily in infants to detect hydrocephalus or subdural effusion.

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2. Croup (Acute Laryngotracheobronchitis)

Croup is an acute viral inflammatory condition characterized by subglottic airway edema, tracheal narrowing, and vocal cord inflammation, presenting predominantly in children aged 6 months to 3 years (peak incidence in the second year of life).

Etiology & Pathogenesis

• Etiological Agent: Human Parainfluenza viruses (Types 1 and 2 account for >75% of cases). Influenza A and B, Respiratory Syncytial Virus (RSV), and Adenovirus account for the remainder.
• Pathophysiology: Viral proliferation in the upper respiratory tract produces mucosal edema, erythema, and cellular infiltration of the subglottic trachea. Because the subglottic cricoid cartilage forms a non-expandable cartilaginous ring, even 1 mm of mucosal edema dramatically increases airway resistance (Poiseuille's law: resistance is inversely proportional to the radius to the fourth power, R ∝ 1/r⁴), causing critical upper airway obstruction.

Clinical Features & Severity Stratification

Croup classically begins with 1 to 3 days of non-specific coryza, low-grade fever, and mild rhinorrhea, followed by the acute development of the Cardinal Diagnostic Triad:

1. Harsh, barking cough (resembling a seal or barking dog).
2. Hoarseness of voice or muffled, hoarse cry.
3. Inspiratory stridor that characteristically worsens at night or when the child is distressed.

WESTLEY CROUP SEVERITY CLASSIFICATION:

• MILD CROUP:
  - Barking cough and hoarseness present.
  - NO stridor at rest (stridor audible only when agitated, crying, or running).
  - Absent or mild intercostal/subcostal retractions.

• MODERATE CROUP:
  - Audible inspiratory stridor at rest in a calm child.
  - Moderate lower chest wall retractions and suprasternal notch indrawing.
  - Child remains alert, engaged, and consolable.

• SEVERE CROUP:
  - Prominent inspiratory (and occasionally expiratory) stridor at rest.
  - Marked lower chest wall indrawing, tracheal tug, and nasal flaring.
  - Lethargy, restlessness, exhaustion, or agitation indicative of severe hypoxemia.

• IMPENDING RESPIRATORY FAILURE:
  - Softening or disappearance of stridor with diminished breath sounds ("silent chest").
  - Lethargy, pallor, central cyanosis, and bradycardia.

Clinical Management Algorithm

CROUP MANAGEMENT PROTOCOL:

1. Minimize Patient Agitation
   • NEVER separate the child from the mother. Examine the child while sitting comfortably on the mother's lap.
   • Strictly avoid painful procedures, tongue depressors (risk of laryngospasm in epiglottitis), or unnecessary venous cannulation.

2. First-Line Systemic Corticosteroid (ALL Grades of Croup)
   • Oral or IM Dexamethasone: 0.15 mg/kg to 0.6 mg/kg as a single dose (maximum 10–16 mg).
   • Oral administration of the parenteral solution mixed in sweet syrup is highly effective.
   • Reduces subglottic mucosal edema, onset of clinical action within 1 to 2 hours, duration of action 36–72 hours.
   • Dramatically reduces the need for hospitalization, intubation, and repeat clinic visits.

3. Nebulized Adrenaline (Moderate to Severe Croup with Stridor at Rest)
   • Nebulize 0.5 mL/kg of 1:1,000 Adrenaline (epinephrine) solution (maximum 5 mL) with high-flow oxygen.
   • Alpha-1 adrenergic stimulation induces rapid subglottic arteriolar vasoconstriction, shrinking mucosal edema within 10–30 minutes.
   • Rebound mucosal edema can occur after 2 hours; observe child in the health facility for at least 3 to 4 hours post-nebulization.

4. Oxygen Therapy
   • Humidified blow-by oxygen held near the face by the caregiver if SpO2 < 90%.

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3. Febrile Seizures

A febrile seizure is defined as a seizure occurring in an infant or child aged 6 months to 5 years (peak incidence 12 to 18 months), associated with an acute fever (> 38.0°C), in the absence of central nervous system infection (meningitis, encephalitis), systemic metabolic derangement (hypoglycemia, electrolyte disturbance), or a prior history of afebrile unprovoked seizures.

Clinical Classification

Acute Emergency Seizure Abortive Protocol

Most febrile seizures are brief and terminate spontaneously before the child reaches a healthcare facility. If a seizure is actively ongoing for more than 5 minutes, emergency abortive anticonvulsant therapy must be administered without delay:

ACUTE SEIZURE ABORTIVE PROTOCOL (Seizure Duration > 5 Minutes):

Step 1: Airway, Breathing, Circulation & Positioning
  • Position the child in the left lateral recovery position to prevent aspiration of saliva or vomitus.
  • Clear oral secretions with gentle suction; administer high-flow oxygen via face mask.
  • Do NOT insert any objects, spoons, or fingers into the child's mouth.
  • Check bedside blood glucose immediately (treat < 2.2 mmol/L with 5 mL/kg 10% dextrose IV).

Step 2: First-Line Anticonvulsant Administration
  • IF IV ACCESS AVAILABLE: Administer slow IV Diazepam 0.2 to 0.3 mg/kg over 2 minutes.
  • IF NO IV ACCESS (Most common): Administer Rectal Diazepam 0.5 mg/kg (using a small syringe or rectal tube)
    OR Buccal Midazolam 0.2 to 0.5 mg/kg (drip solution against the inner buccal mucosa).

Step 3: Repeat Dosing (If Seizure Persists at 10 Minutes [5 min after 1st dose])
  • Repeat a second dose of Rectal Diazepam (0.5 mg/kg) or slow IV Diazepam (0.2–0.3 mg/kg).
  • Be prepared to support ventilation with bag-valve-mask if respiratory depression occurs.

Step 4: Status Epilepticus (Seizure Persisting > 15 to 20 Minutes)
  • Establish secure intravenous access.
  • Administer IV Phenobarbital (loading dose: 20 mg/kg infused over 20 minutes)
    OR IV Phenytoin (loading dose: 20 mg/kg infused in normal saline over 20 minutes with cardiac monitoring).
  • Transfer urgently to the pediatric intensive care unit (PICU).

Diagnostic Workup & Role of Lumbar Puncture

The paramount clinical task is ruling out acute bacterial meningitis:

• In infants under 12 months presenting with fever and a first seizure, a lumbar puncture is strongly recommended because neck stiffness and classical meningeal signs are notoriously unreliable in this age group.
• In children who have received prior oral antibiotics, clinical signs of meningitis may be masked ("partially treated meningitis"), lowering the threshold for LP.
• In children with complex febrile seizures or persistent drowsiness, perform a full septic screen and lumbar puncture.

Parental Counseling & Prognosis

• Reassurance: Parents are invariably terrified, often believing the child is dying. Clearly explain that simple febrile seizures do not cause brain damage, cognitive delay, or death.
• Recurrence Risk: Approximately 30% of children will experience a recurrent febrile seizure with future fever episodes (risk rises to 50% if the first seizure occurred under 12 months of age).
• Fever Management: Antipyretics (oral Paracetamol 10–15 mg/kg or Ibuprofen 10 mg/kg every 6 to 8 hours) relieve discomfort and reduce fever, but clinical trials demonstrate they do NOT prevent febrile seizure recurrence.
• Long-term Anticonvulsants: Daily prophylactic anticonvulsant therapy (such as daily phenobarbital or sodium valproate) is strictly not indicated for simple febrile seizures due to adverse behavioral and cognitive side effects that far outweigh the benign natural course of the condition.