What is the characteristic EEG finding in delirium that helps distinguish it from most dementias?

• A Focal epileptiform discharges in the temporal lobe
• B Generalised background slowing with disorganised theta and delta activity ✓
• C Periodic sharp wave complexes every 0.5 to 1 second
• D Intermittent rhythmic delta activity confined to sleep recordings

Explanation

Delirium produces generalised slowing of the posterior dominant rhythm with increased theta and delta activity proportional to the degree of encephalopathy; the changes typically reverse as the patient recovers. Periodic sharp wave complexes are the hallmark of sporadic Creutzfeldt-Jakob disease, not ordinary delirium, which eliminates option C. Most patients with mild Alzheimer's disease have a normal or only mildly slowed EEG, making this a useful discriminator.

Reference: Kaplan and Sadock's Synopsis of Psychiatry, 12th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.