Egocentric disorientation and heading disorientation: evaluation by a new test named card placing test.

ABSTRACT

We recently developed a new clinical test named card placing test (CPT) which can assess a subject's ability to deal with visuospatial information. The CPT requires a subject to recreate an array of three cards, each of which was randomly placed on eight grids around the subject, before (CPT-A) and after the subject's rotation (CPT-B). With this design, the CPT can assess a subject's ability to represent visuospatial information either egocentrically (CPT-A) or allocentrically (CPT-B). We administered the test on two patients with topographical disorientation; one with egocentric disorientation and another with heading disorientation. The patient with egocentric disorientation demonstrated poor performances on both CPT-A and CPT-B. The patient with heading disorientation, on the other hand, showed good record results for CPT-A but poor ones for CPT-B. An implication is that the patient with egocentric disorientation had disorder in an egocentric reference frame per se, while the patient with heading disorientation could not integrate information on the spatial locations derived from an egocentric reference frame with that on changes of the body directions. We suggest that the CPT is a simple and useful clinical test to evaluate patients with topographical disorientation.