Differential Diagnosis for 24-year-old Male with Acute Onset of Confusion, Muscle Rigidity, and Fever

• Single most likely diagnosis
  • Neuroleptic Malignant Syndrome (NMS): This condition is a life-threatening side effect of neuroleptic medications, which are commonly used to treat schizophrenia. The symptoms of confusion, muscle rigidity, and fever are classic for NMS, especially given the patient's history of schizophrenia treatment.
• Other Likely diagnoses
  • Meningitis: Although less likely than NMS given the context, meningitis can cause confusion, fever, and sometimes muscle rigidity. It's a consideration, especially if there's a suspicion of infection.
  • Encephalitis: Similar to meningitis, encephalitis (inflammation of the brain tissue) can present with confusion, fever, and sometimes rigidity, making it a plausible differential diagnosis.
  • Sepsis: Sepsis, particularly when caused by certain infections, can lead to confusion (septic encephalopathy), fever, and sometimes muscle rigidity due to the systemic inflammatory response.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Status Epilepticus: Although less common, status epilepticus can present with confusion and altered mental status. The muscle rigidity could be post-ictal or part of a seizure manifestation. Missing this diagnosis could be fatal.
  • Intracranial Hemorrhage: A hemorrhagic stroke could present with sudden onset of confusion and fever if there's associated infection or inflammation. Muscle rigidity might be seen in the form of decerebrate posturing.
  • Heat Stroke: Given the high fever, heat stroke is a possibility, especially if the patient was exposed to high temperatures or engaged in strenuous physical activity. It can cause confusion, muscle rigidity, and high fever.
• Rare diagnoses
  • Serotonin Syndrome: This is a rare but potentially life-threatening condition caused by an excess of serotonin in the body, often due to medication interactions. It can present with confusion, muscle rigidity, and fever, among other symptoms.
  • Wilson's Disease: A rare genetic disorder that leads to copper accumulation in the body, Wilson's disease can cause neurological symptoms including confusion and rigidity, but it would be unusual for it to present acutely with fever.
  • Autoimmune Encephalitis: This is a group of conditions that occur when the body's immune system mistakenly attacks healthy brain cells, leading to inflammation of the brain. It can present with a wide range of neurological and psychiatric symptoms, including confusion and fever, but is relatively rare.