MCQ: Meningitis with Shock

Correct answer: E. Waterhouse–Friderichsen syndrome

The most important clues are the purpuric rash, meningitis, shock refractory to fluids and inotropes, hyponatremia, and hyperkalemia. Together, these findings strongly suggest acute adrenal insufficiency due to bilateral adrenal hemorrhage, classically associated with fulminant meningococcal sepsis.

Explanation: Waterhouse–Friderichsen syndrome

Waterhouse–Friderichsen syndrome is a life-threatening complication of severe infection, classically caused by Neisseria meningitidis. It is characterized by bilateral adrenal hemorrhage, acute adrenal insufficiency, and circulatory collapse.

Meningococcal infection can cause widespread endothelial injury, disseminated intravascular coagulation (DIC), and hemorrhage into both adrenal glands. Destruction or dysfunction of the adrenal cortex results in deficient cortisol and, in primary adrenal failure, aldosterone production. The resulting hormonal deficiency contributes to profound hypotension that may remain refractory despite fluid resuscitation and vasopressor support.

The CDC’s clinical guidance for meningococcal disease describes meningococcal infection as a potentially rapidly progressive illness that can cause septicemia, shock, and death without prompt treatment.

Interpreting the laboratory findings

• Serum sodium: 128 mmol/L — hyponatremia. Aldosterone deficiency promotes renal sodium loss. Cortisol deficiency can also increase antidiuretic hormone activity, contributing to hyponatremia.

• Serum potassium: 6.5 mmol/L — significant hyperkalemia. Aldosterone deficiency reduces renal potassium excretion. This is an important clue to primary adrenal insufficiency.

• Refractory shock: Cortisol deficiency impairs vascular responsiveness to catecholamines, worsening hypotension despite fluids and inotropes.

• Purpuric rash and meningitis: These findings raise strong suspicion for invasive meningococcal disease, which can be complicated by DIC and bilateral adrenal hemorrhage.

The combination of refractory shock and the characteristic electrolyte pattern makes Waterhouse–Friderichsen syndrome the best answer. However, the electrolyte findings are supportive rather than diagnostic on their own.

Why are the other options incorrect?

A. Septic shock

Septic shock is already present in this child, but it does not explain the additional clue of hyponatremia with marked hyperkalemia as specifically as acute primary adrenal insufficiency does. Waterhouse–Friderichsen syndrome is a possible complication of fulminant septicemia and explains the refractory shock in this setting.

B. Neurogenic shock

Neurogenic shock is usually associated with spinal cord injury or significant disruption of sympathetic pathways. It commonly produces hypotension with relative bradycardia and does not explain the purpuric rash and electrolyte abnormalities in this case.

C. Intracranial hemorrhage

Intracranial hemorrhage may cause seizures and altered consciousness, particularly in severe infection with coagulopathy. However, it does not adequately explain the combination of refractory shock, hyponatremia, and hyperkalemia.

D. Hyponatremic dehydration

Hyponatremia may contribute to seizures and altered consciousness when severe, but a sodium concentration of 128 mmol/L would not usually explain this entire presentation. Simple dehydration also does not account for marked hyperkalemia and refractory shock as coherently as adrenal failure.

Immediate clinical management

Waterhouse–Friderichsen syndrome is a medical emergency. Management includes:

• Immediate treatment of suspected invasive bacterial infection with appropriate intravenous antibiotics; do not delay antibiotics while awaiting confirmation.

• Haemodynamic resuscitation and intensive-care support.

• Prompt administration of intravenous hydrocortisone when adrenal crisis is strongly suspected; do not delay treatment while waiting for cortisol or ACTH results.

• Urgent treatment and monitoring of hyperkalemia, including ECG monitoring.

• Measurement of cortisol and ACTH, if this can be done without delaying treatment, and investigation for coagulopathy and adrenal hemorrhage as clinically indicated.

The Merck Manual’s guidance on primary adrenal insufficiency discusses the characteristic combination of hypotension, hyponatremia, and hyperkalemia, as well as emergency treatment of adrenal crisis.

Clinical pearl

Meningitis + purpuric rash + refractory shock + hyponatremia + hyperkalemia = suspect Waterhouse–Friderichsen syndrome.

Remember that septic shock and Waterhouse–Friderichsen syndrome are not mutually exclusive: the syndrome is a complication of severe sepsis associated with adrenal hemorrhage and acute adrenal insufficiency.

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References

1. Bush LM, Vazquez-Pertejo MT. Meningococcal diseases [Internet]. Merck Manual Professional Edition. Available from: https://www.merckmanuals.com/professional/infectious-diseases/gram-negative-cocci-and-coccobacilli/meningococcal-diseases

2. Centers for Disease Control and Prevention. Clinical guidance for meningococcal disease [Internet]. Atlanta (GA): CDC. Available from: https://www.cdc.gov/meningococcal/hcp/clinical-guidance/index.html

3. Waterhouse-Friderichsen Syndrome [Internet]. StatPearls. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK551510/