Differential Diagnosis

The patient's presentation includes crawling around on the floor, unresponsiveness to requests, fear, perspiration, and rapid vertical nystagmus. These symptoms suggest a significant alteration in mental status and possible hallucinogenic or stimulant intoxication. Here's a categorized differential diagnosis:

• Single most likely diagnosis

  • LSD intoxication: The patient's behavior, such as crawling around and being frightened, along with the presence of rapid vertical nystagmus, is highly suggestive of LSD (lysergic acid diethylamide) intoxication. LSD is known to cause significant alterations in perception, hallucinations, and can lead to extreme anxiety or fear.

• Other Likely diagnoses

  • Cocaine intoxication: Cocaine can cause agitation, paranoia, and hallucinations, which might explain the patient's frightened state and erratic behavior. However, the presence of rapid vertical nystagmus is more commonly associated with hallucinogens like LSD.
  • PCP intoxication: Phencyclidine (PCP) can cause a dissociative state, hallucinations, and erratic behavior. While it's a possibility, the specific combination of symptoms, especially the rapid vertical nystagmus, is less typical for PCP intoxication compared to LSD.

• Do Not Miss diagnoses

  • Acute psychotic episode: Although less likely given the specific symptoms, an acute psychotic episode could present with hallucinations and disorganized behavior. It's crucial to consider psychiatric causes, especially if substance use cannot be confirmed.
  • Medical emergency (e.g., neurological or infectious cause): Conditions like meningitis, encephalitis, or a seizure disorder could potentially cause altered mental status and nystagmus. These are less likely given the context but would be critical to rule out due to their severity.

• Rare diagnoses

  • Other hallucinogen intoxications: While LSD is a common hallucinogen, other substances like psilocybin (mushrooms) or DMT could potentially cause similar symptoms. However, the specific presentation and the presence of rapid vertical nystagmus make LSD more likely.
  • Panic disorder: This diagnosis seems less likely given the patient's overall presentation, including the physical symptoms and the specific behavior of crawling around on the floor, which is not typical for panic disorder.