Abstract

Recent studies indicate that patients who are diagnosed with vegetative states may retain more awareness than their clinical assessments suggest. Disorders of consciousness traditionally have been diagnosed on the basis of outwardly observable behaviors alone, but new functional imaging studies have shown surprising levels of brain activity in some patients, indicating that even higher-level cognitive functions like language processing and visual imagery may be preserved. For example, one recently developed method purports to detect voluntary mental imagery solely on the basis of neural response patterns observed with functional magnetic resonance imaging. This line of research has already led to some widely reported cases of patients who were discovered to have more brain activity than expected. In November 2009, Rom Houben, a Belgian man who was thought to be in a coma for 23 years, was diagnosed with locked-in syndrome through the use of neuroimaging; however, that assessment was later overturned by further testing.