Usmle Step 1 MCQ's # 24

Title: Usmle Step 1 MCQ's # 24
Subject: Behavioral Science

Q NO 24: A 70-year-old woman with a history of diabetes and alcoholism is sent to the emergency department by her chronic care facility. Stewards at her home report she has had “mental status changes.” These changes have evolved acutely but fluctuate widely. On mental status examination, the woman has deficiencies of recent memory, and a diminished level of awareness. During the inter view, her speech becomes nonsensical and she begins to describe visual hallucinations. Physical examination reveals fever and tachycardia. Which of the following best characterizes this patient’s condition?

A. Amnesia
B. Delirium
C. Dementia
D. Normal aging
E. Psychosis secondary to schizophrenia

Explanation:
The correct answer is B. Delirium is characterized by acute onset of mental status changes that wax and wane. It may present as impaired awareness easy distraction, confusion, and disturbances of perception such as illusions misinterpretations, and visual hallucinations. Recent memory is usually impaired, and speech may be rambling, perseverating, nonsensical pressured or incoherent. Patients may also be agitated or obtunded. The degree of awareness of their condition may fluctuate with time. Physical examination or laboratory studies usually reveal some organic cause for the delirium. Common causes of delirium include intoxication occult infection, head trauma seizure, mania, thyrotoxicosis, renal failure, hepatic failure, neoplasm, stroke, and shock.
Amnesia (choice A) may be due to head trauma, Korsakoff syndrome, transient global amnesia, or various other cerebral events. Head trauma produces retrograde as well as anterograde amnesia while post concussive syndrome is associated with mental dullness, poor memory, depressed mood, and headaches. This patient’s fever, isolated memory deficits, and lack of causal pathology makes the diagnosis of amnesia unlikely.
Dementia (choice C) in contrast to delirium, is a chronically progressive condition that produces a steady and lasting decline in short- and long-term memory. It is associated with a decline in social and occupational functioning. The patient’s sensorium remains intact in dementia. This patient has no long-term memory deficits and the course of the disease is fluctuating and acute. In addition, the patient has sensory disturbances (visual hallucinations). Thus, the diagnosis of dementia is incorrect.
Normal aging (choice D) does not produce the profound memory deficits and sensory deficits outlined here. Characterizing the patient’s constellation of symptoms as normal aging is incorrect.
Psychosis secondary to schizophrenia (choice E) does not characterize this patient’s findings. The altered sensorium of delirium tends to affect the visual modalities while the psychosis of schizophrenia typically affects the auditory’ system (auditory’ hallucinations).