Special Topics
Neuroleptic Malignant Syndrome: A Case Study and Treatment Timeline
A day-by-day account of how neuroleptic malignant syndrome develops, how it is recognized, how it is treated, and how an antipsychotic is safely restarted afterward.
About this case. This is a teaching case: a de-identified composite assembled from the published literature and from patterns seen in consultation practice. It does not describe any single identifiable patient, and no protected health information is used. It is educational material, not medical advice. See the legal disclaimer.
Treatment timeline
Day 0
Dose escalation
A 34-year-old man with schizoaffective disorder is admitted for an acute psychotic relapse after several weeks off medication. Haloperidol is restarted and titrated rapidly to 15 mg daily, with intramuscular doses for agitation and scheduled promethazine at night. He is dehydrated on arrival and physically restrained twice in the first 24 hours.
Temp 37.1 C, HR 96, BP 128/78, CK 210 U/L
Day 2
First warning signs
Nursing notes describe him as quieter and slower rather than calmer. He is diaphoretic, has difficulty rising from a chair, and drinks little. The change is attributed to sedation from the antipsychotic. This is the moment where the diagnosis is most often missed: the earliest sign of NMS is usually a hypokinetic, rigid state that looks like an over-medicated patient improving.
Temp 37.9 C, HR 112, BP 148/92, CK 1,050 U/L
Day 3, morning
Lead-pipe rigidity and fever
He is mute, tremulous, and incontinent. Passive movement of both elbows meets uniform resistance through the full range of motion (lead-pipe rigidity), without clonus and with reduced rather than brisk reflexes, the motor picture that separates NMS from serotonin syndrome. Blood pressure swings widely across the shift.
Temp 39.6 C, HR 130, BP labile 96/60 to 170/100, CK 8,400 U/L, WBC 15.6, Na 149
Day 3, hour 0 of treatment
All dopamine antagonists stopped
Haloperidol and promethazine are discontinued immediately, including the antiemetic, which is a commonly overlooked culprit. He is transferred to the intensive care unit for cooling, aggressive intravenous crystalloid to protect the kidneys from myoglobinuria, telemetry, and deep vein thrombosis prophylaxis. Supportive care, not a specific drug, is the intervention with the strongest evidence.
Day 3, hours 1 to 6
Benzodiazepine and specific pharmacotherapy
Lorazepam 2 mg intravenously every 6 hours is started for rigidity and the substantial overlap with malignant catatonia. Because temperature exceeds 39 C with severe rigidity and a CK above 8,000, dantrolene 1 mg/kg intravenously is added and repeated, with bromocriptine 2.5 mg every 8 hours by nasogastric tube to replace lost dopaminergic tone. Liver enzymes are monitored on dantrolene.
Day 4 to 5
Turning the corner
Temperature falls below 38 C and autonomic swings narrow. Creatine kinase peaks at 19,200 U/L on day 4 and then declines; creatinine rises modestly to 1.5 mg/dL and normalizes with continued hydration, so renal replacement therapy is avoided. Rigidity softens and he begins to follow simple commands.
Temp 37.8 C, HR 98, BP 132/80, CK 19,200 then falling
Day 7 to 10
Resolution
Dantrolene is stopped after 72 hours of stability, bromocriptine is tapered over a week to avoid rebound, and lorazepam is continued while catatonic features resolve. He remains psychotic but medically stable. Total episode duration from first fever to resolution is 8 days, consistent with the typical 7 to 10 day course after an oral agent is withdrawn.
Day 12
Antipsychotic-free window
A minimum two-week antipsychotic-free interval is observed after full resolution, the single most important variable in reducing recurrence on rechallenge. Psychiatric symptoms are managed with lorazepam and, if agitation had escalated, electroconvulsive therapy would have been the preferred bridge, since it treats both NMS and the underlying psychosis.
Week 4
Rechallenge
He is rechallenged with a low-potency, lower-D2-affinity agent, quetiapine 25 mg at night, titrated slowly with daily temperature, pulse, and weekly CK monitoring, and with strict avoidance of dehydration, restraint, and intramuscular loading. He tolerates titration to a therapeutic dose without recurrence. Long-acting injectable formulations are avoided permanently.
What this case teaches
- The earliest change is usually motor and behavioral slowing, not fever. A patient who looks 'over-sedated' after a rapid titration deserves a rigidity examination and a CK.
- Rigidity in NMS is lead-pipe, hypokinetic, and hyporeflexic and evolves over days. Serotonin syndrome is hyperkinetic, with clonus and hyperreflexia, and evolves over hours.
- Antiemetics such as promethazine, metoclopramide, and prochlorperazine are dopamine antagonists and can both cause NMS and prolong it if they are not stopped.
- Aggressive fluid resuscitation preventing myoglobinuric renal failure has better evidence behind it than any specific pharmacotherapy.
- Abrupt withdrawal of levodopa or amantadine produces a clinically identical parkinsonism-hyperpyrexia syndrome; treatment is to restore the dopaminergic agent.
- Recurrence on rechallenge is uncommon when at least two weeks have elapsed, a lower-potency agent is chosen, and titration is slow.