Ganser syndrome is a rare and somewhat poorly understood condition, currently categorized in DSM-5 and ICD-10 as a dissociative disorder, although it’s classification has changed over time. It was first presented by German neurologist Sigbert Ganser in 1897, where he described symptoms such as “approximate answers to simple questions, perceptual abnormalities such as visual and auditory hallucinations, clouding of consciousness, and symptoms of somatic conversion”. Approximate answers to simple questions refers to patients providing obviously incorrect answers to simple questions, such as “how many legs does a dog have?”, where a typical answer might be “Three”. The syndrome is often seen in patients with head injury and stroke.

Source: Ganser’s syndrome. Dwyer J, Reid S. (2004). Lancet. 2004 Jul 31-Aug 6;364(9432):471-3.