Differential Diagnosis for Acute Onset of Altered Mental Status

The patient's presentation with acute onset of altered mental status, preceded by chills, shivering, and diffuse body aches, necessitates a broad differential diagnosis. The history of diabetes, prior brain tumor resection, open heart surgery, and lymphedema adds complexity to the case.

• Single Most Likely Diagnosis

  • Sepsis: Given the patient's history of lymphedema, which can predispose to infections, and the acute onset of symptoms such as chills, shivering, and diffuse body aches followed by altered mental status, sepsis is a highly plausible diagnosis. The patient's age and comorbid conditions increase the risk of sepsis.

• Other Likely Diagnoses

  • Urinary Tract Infection (UTI): UTIs are common in older adults and can present with altered mental status, especially in the context of fever and systemic symptoms.
  • Pneumonia: Community-acquired pneumonia can present with similar symptoms, including fever, chills, and altered mental status, particularly in elderly patients with comorbid conditions.
  • Stroke or Transient Ischemic Attack (TIA): Given the patient's history of open heart surgery and the acute onset of neurological symptoms, a vascular event is possible.
  • Metabolic Encephalopathy: Diabetes can lead to metabolic derangements (e.g., diabetic ketoacidosis or hyperosmolar hyperglycemic state) that cause altered mental status.

• Do Not Miss Diagnoses

  • Meningitis: Although less common, meningitis is a critical diagnosis that must be considered, especially given the patient's history of brain tumor resection, which might increase the risk of CNS infections.
  • Brain Abscess: As a complication of the residual brain tumor or a new infection, a brain abscess could explain the patient's symptoms.
  • Endocarditis: Given the patient's history of open heart surgery, endocarditis is a possibility, especially if there are signs of infection and embolic phenomena.
  • Status Epilepticus: Non-convulsive status epilepticus can present with altered mental status and is a medical emergency.

• Rare Diagnoses

  • CNS Vasculitis: This is an inflammatory condition affecting the blood vessels in the brain and could explain the patient's neurological symptoms, although it is less common.
  • Paraneoplastic Syndromes: Given the history of brain tumor, paraneoplastic syndromes, which are rare disorders triggered by the immune system's response to a cancer, could be considered.
  • Creutzfeldt-Jakob Disease: A rare, degenerative, fatal brain disorder that could present with rapidly progressive dementia and altered mental status, although the acute onset of systemic symptoms like chills and shivering would be unusual.