Rehabilitation in a complex case of topographical disorientation.

This paper describes the rehabilitation process of a patient with severe topographical disorientation. The study demonstrates the sustained effects of a tailor-made, meticulous rehabilitation programme based on the gradual development of compensatory strategies. The patient (RB) had a memory impairment specific to environmental landmarks. He was able to recognise objects in his environment, but was unable to identify any salient object as a landmark and was also unable to derive any directional information from a chosen landmark. As such, his topographical disorientation syndrome was complex in that he had elements of both landmark agnosia and a heading disorientation, as described by Aguirre and D'Esposito (1999). Because of this dual damage to the exocentric framework, the tools and methods used in RB's rehabilitation programme were all based on his intact egocentric frame of reference. Remarkable training effects were found for routes he used frequently. After years of training he could walk these routes without the aid of the written information he had used previously, which can be interpreted as a form of implicit learning. In the 12 years we followed this patient some transfer occurred, as the patient was ultimately able to identify his own landmarks. However, RB remains dependent on other people to construct new routes for him on the basis of these landmarks.