Patient with pneumonia ceases to recognize doctor and staff, thinks he is in jail and complains of scorpions attacking him.

A patient with pneumonia for 5 days is admitted to the hospital. He suddenly ceases to recognize the doctor and staff. He thinks that he is in jail and complains of scorpions attacking him. He is in an altered sensorium. This condition is most likely:

A. Acute delirium
B. Acute schizophrenia
C. Acute dementia
D. Acute paranoia

Answer is A. Acute delirium.
The patient has an acute confusional disorder with:

• altered sensorium, which connotes disturbed consciousness
• disorientation to place and person
• disturbance in perception, complaining of scorpions attacking him

All these features are consistent with the diagnosis of delirium, secondary to a clinical disease condition.

In contrast, dementia has an insidious onset, with a normal consciousness, and disorientation only in later stages. Immediate memory is intact while recent and remote memory disturbed.Hallucinations may occur and diurnal variation is usually absent. There is usually normal attention and concentration.