Differentials
Neuroleptic malignant syndrome (NMS)
SIGNS / SYMPTOMS
History of exposure to antipsychotics, unless patient is on multiple drugs including serotonergic agents.
Slow onset of symptoms, usually over days.
Bradykinesia, extrapyramidal effects, lead-pipe rigidity, and autonomic lability differentiate.[2]
Absence of neuromuscular excitation.
INVESTIGATIONS
Diagnosis is clinical. There are no differentiating tests.
Sympathomimetic toxicity
SIGNS / SYMPTOMS
History of exposure to sympathomimetics.
Absence of neuromuscular excitation.
INVESTIGATIONS
Diagnosis is clinical. Urine drug screen for amfetamines may aid in the diagnosis.
Anticholinergic delirium
SIGNS / SYMPTOMS
History of exposure to anticholinergics.
Bowel sounds absent.
Dry skin.
Absence of neuromuscular excitation.
INVESTIGATIONS
Diagnosis is clinical. There are no differentiating tests.
Malignant hyperthermia
SIGNS / SYMPTOMS
History of exposure to anaesthetics.
Occurs perioperatively.
Absence of neuromuscular excitation.
INVESTIGATIONS
Diagnosis is clinical. There are no differentiating tests.
Meningitis
SIGNS / SYMPTOMS
Non-specific symptoms including neck stiffness and nausea/vomiting, photophobia, and rash.
Kernig's or Brudzinski's signs may be present.
Absence of neuromuscular excitation.
INVESTIGATIONS
Investigations include CT/MRI head; cerebrospinal fluid microscopy, Gram stain, cultures, and protein/glucose; and blood cultures.
Encephalitis
SIGNS / SYMPTOMS
Focal neurological deficit, rash, and altered mental state.
Absence of neuromuscular excitation.
INVESTIGATIONS
Investigations include CT/MRI brain, blood cultures, throat swab (for viruses), and cerebrospinal fluid analysis.
Non-convulsive status epilepticus
SIGNS / SYMPTOMS
Absence of neuromuscular excitation.
INVESTIGATIONS
An EEG should be done in consultation with a neurologist.
Baclofen withdrawal
SIGNS / SYMPTOMS
History of exposure to intrathecal baclofen.
INVESTIGATIONS
Positive response to reintroduction of baclofen.
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