Differential Diagnosis for the 7-year-old Girl's Condition

The patient's symptoms, including blurred vision, seeing spiders on the wall (likely hallucinations), fever, tachycardia, agitation, and disorientation, suggest an anticholinergic or sympathomimetic toxidrome, or possibly serotonin syndrome, depending on the medication ingested. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • Anticholinergic toxicity (e.g., from medications like benztropine): The symptoms of blurred vision, agitation, disorientation, and fever are classic for anticholinergic toxicity. Benztropine, an anticholinergic agent used in the treatment of Parkinson's disease and drug-induced parkinsonism, is a likely culprit given the symptom profile.

• Other Likely diagnoses

  • Bupropion overdose: Bupropion can cause seizures, agitation, and hallucinations in overdose, fitting some of the patient's symptoms. However, it's less likely to cause the specific combination of anticholinergic effects seen here.
  • Serotonin syndrome (e.g., from medications like fluoxetine): While serotonin syndrome can cause agitation, altered mental status, and autonomic instability, the presence of hallucinations and the specific anticholinergic symptoms (like blurred vision) make it less likely compared to anticholinergic toxicity.

• Do Not Miss diagnoses

  • Lithium toxicity: Although less likely given the symptom profile, lithium toxicity can cause altered mental status, agitation, and visual disturbances. It's crucial not to miss this diagnosis due to its potential severity and the need for specific treatment.
  • Neuroleptic malignant syndrome (NMS): NMS is a rare but life-threatening condition that can be caused by various medications, including antipsychotics. While the symptoms don't perfectly align with NMS, the presence of fever, altered mental status, and autonomic instability necessitates consideration of this diagnosis to avoid missing it.

• Rare diagnoses

  • Lorazepam overdose: Lorazepam, a benzodiazepine, is less likely to cause the patient's symptoms, especially the hallucinations and anticholinergic effects. Benzodiazepine overdose typically presents with sedation, respiratory depression, and possibly altered mental status but not usually with the specific symptoms described.
  • Other medication overdoses: Depending on what medications the mother has access to, other overdoses could potentially cause similar symptoms. However, given the information provided, these would be less likely and more specific to the medication in question.