Life-threatening hyperthermic syndromes associated with medication use
Drug-related hyperthermia encompasses several life-threatening conditions characterized by elevated body temperature, autonomic dysfunction, and altered mental status. Prompt recognition and appropriate management are crucial for patient survival.
Key Point: All three syndromes represent medical emergencies requiring immediate intervention and intensive care support.
Malignant hyperthermia is a life-threatening disorder of skeletal muscle homeostasis. Its inheritance is autosomal dominant with an incidence of around 1 in 30,000.
Diagnosis can be difficult and it may present insidiously over hours, or as an acute life-threatening event at induction. Hyperthermia itself may be a late feature.
A potentially life-threatening complication of treatment with antipsychotic drugs, or abrupt withdrawal of dopamine agonists.
Diagnosis of exclusion: A careful assessment, including physical examination and comprehensive tests, is required to exclude other potential causes.
Follow-up: A delay of at least 2 weeks in restarting antipsychotic treatment is advised following full resolution of an NMS episode.
Clinical manifestation of excess serotonin in the central nervous system, resulting from the therapeutic use or overdose of serotonergic drugs.
Diagnosis: Clinical diagnosis based on Hunter Serotonin Toxicity Criteria (HSTC), of which clonus is a key diagnostic feature.
Severe serotonin toxicity is a medical emergency that often requires emergency treatment.
| Feature | Neuroleptic Malignant Syndrome | Serotonin Syndrome |
|---|---|---|
| Causative agents | Dopamine antagonists | Serotonergic agents |
| Onset | Gradual (days) | Rapid (hours) |
| Similar Features | ||
| Cardiovascular | Hypertension, tachycardia | Hypertension, tachycardia |
| Respiratory | Tachypnea | Tachypnea |
| Thermoregulation | Hyperthermia (> 40°C) | Hyperthermia (> 40°C) |
| Autonomic | Hypersalivation, diaphoresis | Hypersalivation, diaphoresis |
| Mental status | Encephalopathy, stupor, coma | Agitation, hypervigilance, delirium |
| Distinct Features | ||
| Reflexes | Hyporeflexia | Hyperreflexia |
| Muscle tone | 'Lead-pipe' rigidity | Rigidity with clonus |
| Pupils | Normal pupils | Dilated pupils |
| Bowel sounds | Reduced, sluggish | Hyperactive |
| Laboratory Findings | ||
| Increased CK, leucocytosis, low serum iron, acidosis | More commonly no specific lab findings | |
| Management | ||
| Dantrolene, amantadine, bromocriptine | Benzodiazepines, cyproheptadine | |