Agitation in dementia with Lewy bodies after a single dose of haloperidol
A 76-year-old retired head teacher is brought by his wife with a 2-year history of fluctuating alertness, vivid hallucinations of children playing in the garden, and dream-enactment behaviour in which he has punched and kicked her at night. He has mild symmetrical bradykinesia and rigidity, recurrent falls, and his blood pressure falls from 138/80 to 92/60 on standing. His MMSE is 22/30 with prominent visuospatial errors. He takes donepezil 5 mg, amlodipine and occasional co-codamol. Admitted with a urinary tract infection, he became agitated on the ward and was given haloperidol 2 mg intramuscularly. Twenty-four hours later he is drowsy, rigid and febrile at 38.5°C, with fluctuating blood pressure; CK is 1,150 U/L and creatinine has risen from 95 to 150 µmol/L. The medical team asks whether this is sepsis or a drug reaction and whether an antipsychotic can be used for his agitation.
1. What is the underlying diagnosis and what is the acute syndrome? Give your reasoning and immediate management, including how you would distinguish sepsis from a drug reaction.
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The underlying illness is probable dementia with Lewy bodies: fluctuating cognition, recurrent well-formed visual hallucinations, REM sleep behaviour disorder and parkinsonism, with visuospatial impairment and autonomic dysfunction (orthostatic drop, falls). If parkinsonism had preceded dementia by more than a year, the label would be Parkinson's disease dementia (the 1-year rule).
Twenty-four hours after a single dose of haloperidol he has drowsiness, rigidity, fever, labile blood pressure, a CK of 1,150 U/L and acute kidney injury. This is a severe neuroleptic sensitivity reaction on the NMS spectrum, not simply sepsis. In dementia with Lewy bodies, D2 blockade can cause profound rigidity, immobility, fever and rhabdomyolysis, and typical antipsychotics roughly double mortality.
Immediate management: stop haloperidol; treat as an emergency with IV fluids, cooling, close monitoring of CK, renal function and urine output; consider dantrolene or bromocriptine if NMS criteria are met; involve critical care and neurology. Sepsis still needs treatment - the urinary tract infection requires cultures and antibiotics - but antibiotics alone will not explain the rigidity and fever after a dopamine blocker. Look for other causes of delirium (pain, constipation, dehydration, urinary retention) and stop the amlodipine temporarily if he is hypotensive.
2. How would you manage his agitation and psychosis in the longer term without typical antipsychotics?
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Avoid antipsychotics wherever possible: agitation is usually driven by pain, constipation, infection, dehydration, sleep disturbance and sensory deprivation, so treat those first and use reorientation, bright light, familiar staff and family presence, and a regular routine.
Cholinesterase inhibitors have the best evidence for cognitive and psychotic symptoms in dementia with Lewy bodies - optimise donepezil to 10 mg and consider switching to a rivastigmine patch, monitoring for bradycardia, syncope and GI effects. If an antipsychotic is unavoidable for dangerous agitation, use quetiapine 12.5–25 mg or clozapine 12.5–25 mg with FBC monitoring, starting at a fraction of the usual elderly dose and observing closely. Never use haloperidol, risperidone or other typical antipsychotics.
Avoid anticholinergics and physical restraint. Treat orthostatic hypotension with non-drug measures first (fludrocortisone or midodrine if needed), and manage REM sleep behaviour disorder with melatonin or low-dose clonazepam at night. Document the neuroleptic sensitivity as an allergy in every record and give the family a letter to show other clinicians. Reassess renal function and CK until they normalise.
3. Address driving, decision-making capacity and what the family should be told.
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Driving: with visual hallucinations, fluctuating attention and visuospatial impairment, driving is unsafe. Advise him to stop now, inform the licensing authority as local rules require, and arrange a formal driving assessment and occupational therapy review. Do not leave the decision to the family alone, and document the advice.
Capacity: it fluctuates, so assess in a lucid period and use a structured approach - can he understand, retain, communicate and weigh the relevant information for the specific decision (medication, finances, discharge, future care)? Assume capacity unless it is demonstrated otherwise, and use a best-interests process with family involvement if a decision must be made when he lacks capacity.
Family: explain the diagnosis and its expected course, the antipsychotic sensitivity, and that the hallucinations may be less distressing to him than they appear to others. Refer to a dementia support service, arrange a carer's assessment for his wife - who is also being injured at night - and discuss advance care planning, future placement and safety at home. Give written advice about falls, driving, medication and when to seek emergency help, and arrange memory-clinic follow-up with a full medication review.