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KembaraXtra -Medicine- Neuroleptic Malignant Syndrome
Neuroleptic malignant syndrome (NMS) is a rare, life-threatening neurologic emergency most commonly caused by an adverse reaction to dopamine-blocking antipsychotic medications. Mortality may reach 20%. NMS can occur at any time during neuroleptic therapy, though it most often develops within the first month. The syndrome results from central dopamine receptor blockade, leading to severe skeletal muscle rigidity via the nigrostriatal pathway and hyperthermia from hypothalamic dysfunction. Most cases resolve within two weeks after discontinuation of the offending agent.
NMS is associated with typical and atypical antipsychotics, including high-potency agents such as haloperidol, as well as metoclopramide and promethazine. It may also follow abrupt withdrawal of dopaminergic agents in Parkinson disease. Risk factors include rapid dose escalation, high doses, intravenous administration, dehydration, prior history of NMS, catatonia or agitation, infection, and surgery. Concomitant use of lithium or SSRIs may increase risk.
Clinically, NMS is characterized by hyperthermia, severe “lead-pipe” muscle rigidity, altered mental status ranging from confusion to coma, and autonomic instability. Common findings include tachycardia, labile blood pressure, diaphoresis, tachypnea, dysrhythmias, tremor, dysphagia, incontinence, mutism, and leukocytosis. Temperatures may exceed 41°C (106°F). Complications include rhabdomyolysis, acute renal failure, respiratory failure, and disseminated intravascular coagulation.
Diagnosis is clinical and relies on a careful medication history and physical examination. Laboratory findings typically show markedly elevated creatine kinase, leukocytosis, electrolyte abnormalities, acute kidney injury, elevated liver enzymes, and myoglobinuria. Ancillary testing such as CT, EEG, or lumbar puncture may be required to exclude alternative causes of fever and altered mental status.
The differential diagnosis includes malignant hyperthermia, serotonin syndrome, anticholinergic toxicity, sympathomimetic poisoning, heat stroke, CNS infections, alcohol withdrawal, tetanus, thyrotoxicosis, and withdrawal from intrathecal baclofen. Differentiation is critical, as management strategies differ.
Management centers on immediate discontinuation of all neuroleptic agents and aggressive supportive care. Airway protection, oxygen, cardiac monitoring, rapid cooling measures, and aggressive IV fluid resuscitation are essential. Benzodiazepines are first-line therapy to reduce agitation and muscle rigidity. If rigidity or hyperthermia is uncontrolled, rapid sequence intubation with nondepolarizing neuromuscular blockers is preferred. Bromocriptine and amantadine may be used as dopaminergic agents for ongoing management, while dantrolene may be considered for refractory rigidity, though none have shown definitive mortality benefit.
All patients with suspected NMS require hospital admission, frequently to an intensive care unit. Early recognition, withdrawal of the offending agent, and meticulous supportive management are the most important determinants of outcome. Patients and families must be counseled regarding future avoidance of causative medications, as recurrence risk is significant.
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