Can myxedema coma cause convulsions?

Can Myxedema Coma Cause Convulsions?

Seizures are very rarely reported in myxedema coma, and when altered consciousness occurs in hypothyroid patients presenting with seizure-like activity, other causes should be strongly considered first. 1

Clinical Presentation of Myxedema Coma

Myxedema coma presents with a characteristic constellation of findings that typically do not include seizures:

• Classic features include: hypothermia, bradycardia, altered mental status progressing to coma, respiratory failure, hyponatremia, and hypoglycemia 2, 3, 4
• Cardiovascular manifestations: hypotension, circulatory collapse, pericardial effusion, and heart failure 5, 4
• Metabolic derangements: elevated creatinine phosphokinase (indicating rhabdomyolysis), metabolic acidosis, and renal failure 5, 6
• Neurological findings: progressive lethargy, stupor, coma, hyporeflexia, and tetraparesis 4, 6

Why Seizures Are Not Typical

The evidence strongly suggests seizures are not a characteristic feature of myxedema coma:

• Hepatic encephalopathy guidelines explicitly state that "seizures are very rarely reported in HE" when discussing metabolic encephalopathies 1, and this principle extends to other metabolic comas including myxedema
• Recent pediatric case series of 8 myxedema coma patients reported no seizures among presenting symptoms, with patients instead showing edema, lethargy, and altered consciousness 7
• Multiple case reports describing severe myxedema coma presentations consistently describe hypothermia, bradycardia, hyporeflexia, and coma—but not seizures 3, 5, 4

Critical Differential Diagnosis

When a hypothyroid patient presents with seizure activity, you must aggressively pursue alternative diagnoses:

• Hypoglycemia: Can precipitate both coma and seizures; must be corrected immediately 2
• Hyponatremia: Severe hyponatremia (common in myxedema coma) can independently cause seizures 3, 4
• Concurrent infections: Sepsis or CNS infections may precipitate both myxedema coma and seizures 3, 6
• Other metabolic derangements: Renal failure, metabolic acidosis 5, 6

Management Implications

If seizure-like movements occur in suspected myxedema coma:

• Immediately check glucose and correct hypoglycemia, as this can precipitate both coma and seizures 2
• Assess for myoclonus rather than true seizures—myoclonic jerks can occur in severe metabolic encephalopathies and may be mistaken for seizures 1
• Rule out concurrent pathology including CNS infection, stroke, or other causes of altered mental status 4
• Initiate standard myxedema coma treatment with ICU admission, airway management (intubation if Glasgow Coma Score ≤8), thyroid hormone replacement, and hydrocortisone 100 mg IV every 8 hours until adrenal insufficiency is ruled out 2

The absence of seizures as a typical feature helps distinguish myxedema coma from other causes of metabolic encephalopathy and should prompt thorough investigation for alternative or concurrent diagnoses when seizures are observed.