Spared and impaired cognitive abilities after bilateral frontal damage

We report on a patient (PG) with a severe behavioural disorder following massive bilateral prefrontal damage due to herpetic encephalitis. The lesion involves also the mesial and polar regions of the temporal lobes; the frontal dorso-lateral cortices were relatively spared. The patient's inattentiveness and alternating impulsive and apathetic behaviour led to her social alienation. The only self-motivated activities we observed were those initiated to satisfy her enhanced urge to eat and play games. She did not react to surprise stimuli that consistently elicit a reaction of surprise in healthy people. She also presented "adynamic aphasia" associated with anomia and episodic amnesia. A striking feature of the syndrome was the patient's consistent "utilization behaviour". Her motor behaviour was marked by constant akathisia. She performed surprisingly well on intelligence, "frontal", and visuo-spatial tests. This non-demented patient exhibited a clear dissociation between her relatively spared cognitive abilities and grossly impaired behaviour. In the discussion we explore the extent to which a defect of the supervisory control may be held responsible for the inconsistencies in the patient's coping skill performances.