What is the most likely diagnosis for a 42-year-old man with altered mental status, somnolence, and impaired attention, who has a history of generalized anxiety disorder and major depressive disorder, and was recently treated for a dental abscess with unknown medications, presenting with hypoxemia, dry mouth, and mild edema, and laboratory results showing hypernatremia, hypokalemia, metabolic acidosis, impaired renal function, and elevated liver enzymes?

Differential Diagnosis

• Single most likely diagnosis
  • A) Benzodiazepine overdose: The patient's somnolence, dry mouth, and altered mental status are consistent with benzodiazepine overdose, especially given the recent treatment for a dental abscess, which may have involved prescription of benzodiazepines or other sedatives.
• Other Likely diagnoses
  • E) Thiamine deficiency: Although less likely, thiamine deficiency (Wernicke's encephalopathy) could present with altered mental status and should be considered, especially if the patient has a history of poor nutrition or alcohol abuse, which is not explicitly mentioned but could be a factor in patients with generalized anxiety disorder and major depressive disorder.
  • C) Nonconvulsive status epilepticus: This condition can present with altered mental status and should be considered, especially if there are any subtle motor signs or a history suggestive of seizure activity, though the provided information does not strongly support this diagnosis.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Infections (e.g., meningitis, encephalitis): Although the patient's temperature is normal, infections can sometimes present without fever, especially in immunocompromised patients or those on certain medications. The recent dental abscess increases the risk of bacterial spread.
  • Stroke or intracranial hemorrhage: These conditions require immediate diagnosis and treatment. The patient's altered mental status and somnolence could be indicative of a neurological emergency.
• Rare diagnoses
  • B) Major depressive disorder with catatonia: While the patient has a history of major depressive disorder, catatonia is a rare condition and less likely given the acute onset and the presence of other potential explanations for the patient's condition.
  • D) Normal pressure hydrocephalus: This condition typically presents with a triad of gait disturbance, dementia, and urinary incontinence, which does not match the patient's presentation. It is less likely and would not explain the acute onset of symptoms.