Orientation agnosia in pentagon copying

Abstract

Ala et al 1 have recently claimed that patients with Alzheimer's disease (AD) were less likely to make errors on the pentagon copying component of the mini mental state examination (MMSE) than patients affected by Lewy body (LB) dementia. Using (standard and modified) MMSE scoring criteria they found normal copies in 16 of 27 patients with AD but in only two of 13 patients with LB. Although this difference was non-significant,1 they concluded that this feature might be useful in differential diagnosis. It is of some interest that the MMSE scoring criteria employed by Ala et al 1 did not regard errors of rotation as abnormal. In the light of recently identified visuospatial deficits which affect the domain of orientation, it may well be that the criteria of Ala et al for a “normal” copy are inappropriate. This has implications for the claimed diagnostic power of their measure.Patients with orientation agnosia are able to recognise objects, but have a selective visuospatial impairment, in that they have lost knowledge of object orientation.2 The most striking feature of this disorder is shown in the patients' drawing of objects, where they rotate their copy by 90 or 180 degrees relative to the original. This previously underinvestigated deficit is far from rare. In one study, seven of 63 (11%) patients with stroke grossly rotated their copy of the …