Double Disassociation of Anosognosia for Alexia and Simultanagnosia but Quantitative Awareness of Optic Ataxia.

Abstract

A 66-yr-old man with a history of atrial fibrillation and a pacemaker developed sudden onset confusion, disorientation, and visual disturbance without motor weakness. Clinically, significant deficits were found in reading (alexia) and simultaneous multiobject perception (simultanagnosia), both of which the patient denied limitation in, and in vision-right hemianopsia-which he readily acknowledged. Visual acuity in the left visual field was normal. The patient also demonstrated a symptom of optic ataxia-a lack of coordination between visual inputs and hand movements-a deficit he also acknowledged. Work-up with computed topography revealed a left posterior cerebral artery infarct affecting the occipital lobe and extending to involve the parietal lobe and the splenium of the corpus callosum. The authors describe and discuss this fascinating case-the first case to their knowledge of a double disassociation of anosognosia for alexia and simultanagnosia but full, indeed quantitative, awareness of hemianopsia and optic ataxia. This case may be informative on the mechanism of anosognosia in general and supports intentional feed-forward and exemplar reafference models. With regard to the rehabilitation process, appreciation that a patient has anosognosia for various deficits is crucial in recovery and health maintenance.