Neglect and prism adaptation: A new therapeutic tool for spatial cognition disorders

Issue title: Plasticity in Spatial Neglect – Recovery and Rehabilitation

Article type: Research Article

Authors: Rode, Gilles^{; ;} | Klos, Thomas | Courtois-Jacquin, Sophie^{; ;} | Rossetti, Yves^{; ;} | Pisella, Laure^;

Affiliations: Service de rééducation neurologique, Hospices Civils de Lyon, Hôpital Henry Gabrielle, 20 route de Vourles, 69230 St Genis Laval, France | INSERM U534, Espace et Action, UMR-S 534, Institut National de la Santé Et de la Recherche Médicale, 16 avenue Lépine, Case 13, F-69676 Bron, France | Université Claude Bernard LYON 1, IFNL, Institut Fédératif des Neurosciences de Lyon, Hôpital Neurologique, Bât B13, 59 Bd Pinel, 69394 LYON cedex, France | Zentrum für Neurologie und neurologische Rehabilitation (ZNR), Klinikum am Europakanal, Am Europakanal 71, 91056 Erlangen, Germany | Mouvement et Handicap, Rééducation Neurologique, Hôpital Henry Gabrielle, Hospices Civils de Lyon – IFNL, Route de Vourles, St Genis Laval, France

Note: [] Corresponding author: Pr. Gilles Rode, Hôpital Henry Gabrielle, Hospices Civils de Lyon, 20 route de Vourles, 69230Saint-Genis-Laval, France. Tel.: +33 04 78 86 50 24; Fax: +33 04 78 86 50 30; E-mail: gilles.rode@chu-lyon.fr

Abstract: Purpose: A large proportion of right-hemisphere stroke patients show unilateral neglect, a neurological deficit of perception, attention, representation, and/or performing actions within their left-sided space, inducing many functional debilitating effects on everyday life, and responsible for poor functional recovery and ability to benefit from treatment. This spatial cognition disorder affects the orientation of behaviour with a shift of proprioceptive representations toward the lesion side. Methods: This shift can be reduced after a prism adaptation period to a right lateral displacement of visual field (induced by a simple target-pointing task with base-left wedge prisms). The modification of visuo-motor or sensory-motor correspondences induced by prism adaptation involves improvement of different symptoms of neglect. Results: Classical visuo-motor tests could be improved for at least 2h after adaptation, but also non-motor and non-visual tasks. In addition, cross-modal effects have been described (tactile extinction and dichotic listening), mental imagery tasks (geographic map, number bisection) and even visuo-constructive disorders. These cognitive effects are shown to result from indirect bottom-up effects of the deeper, adaptive realignment component of the reaction to prisms. Lesion studies and functional imaging data evoke a cerebello-cortical network in which each structure plays a specific role and not all structures are crucial for adaptation ability. Conclusions: These cognitive effects of prism adaptation suggest that prism adaptation does not act specifically on the ipsilesional bias characteristic of unilateral neglect but rehabilitates more generally the visuo-spatial functions attributed to the right cortical hemisphere. These results reinforce the idea that the process of prism adaptation may activate brain functions related to multisensory integration and higher spatial representations and show a generalization at a functional level. Prism adaptation therefore appears as a new powerful therapeutic tool for spatial cognition disorders.

Keywords: Neglect, prism adaptation, rehabilitation, after-effect, right hemisphere

Journal: Restorative Neurology and Neuroscience, vol. 24, no. 4-6, pp. 347-356, 2006