Differential Diagnosis

The patient's symptoms of extreme confusion, anxiety, high fever, stiff neck and extremities, high heart rate, high blood pressure, and profuse sweating, especially after starting haloperidol (a typical antipsychotic), suggest a range of potential diagnoses. Here is the differential diagnosis organized into the requested categories:

• Single Most Likely Diagnosis

  • Neuroleptic Malignant Syndrome (NMS): This is a life-threatening, neurological disorder most often caused by an adverse reaction to neuroleptic or antipsychotic medication. The patient's recent initiation of haloperidol, along with symptoms of high fever, muscle rigidity, altered mental status, and autonomic dysfunction (high blood pressure, tachycardia, sweating), makes NMS the most likely diagnosis.

• Other Likely Diagnoses

  • Serotonin Syndrome: Although less likely given the specific context of haloperidol use, serotonin syndrome is a possibility if the patient was also taking serotonergic medications. It presents with similar symptoms of altered mental status, autonomic instability, and neuromuscular abnormalities.
  • Malignant Hyperthermia: This is a rare but life-threatening medical emergency triggered by certain medications used for general anesthesia, not typically by antipsychotics like haloperidol. However, the presentation of high fever, muscle rigidity, and autonomic instability could initially suggest this diagnosis.

• Do Not Miss Diagnoses

  • Infection (e.g., Meningitis, Sepsis): Infections can present with fever, confusion, and autonomic instability. It's crucial to rule out an infectious cause, especially given the patient's altered mental status and high fever.
  • Heat Stroke: This condition involves high body temperature and can present with altered mental status and autonomic dysfunction. It's essential to consider environmental factors and the patient's ability to regulate body temperature.

• Rare Diagnoses

  • Dystonic Reaction: Although dystonic reactions can occur with antipsychotic use, they typically present with involuntary muscle contractions and spasms without the systemic symptoms of fever and autonomic instability seen in this patient.
  • Parkinsonian Hyperpyrexia: A rare condition associated with Parkinson's disease treatment, characterized by fever and rigidity, but it's less likely in this context given the patient's recent diagnosis and treatment with haloperidol for schizophrenia.