Tilted 3D visual scenes influence lateropulsion: A single case study of pusher syndrome

ABSTRACT

Introduction

Hemiparetic stroke patients with so-called “pusher syndrome” (synonyms: contraversive lateropulsion, contraversive pushing) use their non-paretic extremities to push toward their paralyzed side and actively resist external posture correction. The disorder is associated with a distorted perception of postural vertical combined with a maintained, or little deviating perception of visual upright. With the aim of reducing this mismatch, and thus reducing contraversive lateropulsion, we manipulated the orientation of visual input in a virtual reality setup.

Method

We presented healthy subjects and an acute stroke patient with severe pusher syndrome a 3D visual scene that was either upright or tilted in roll plane by 20°. By moving the sitting participants in roll plane to the left and right, we assessed the occurrence of contraversive lateropulsion, namely the active resistance to external posture manipulation.

Results

With the 3D visual scene oriented upright, the patient with pusher syndrome showed the typical active resistance against tilts toward the ipsilesional side. He used his non-paretic arm to block the examiner’s attempt to move the body axis toward that side. With the visual scene tilted to the ipsiversive left, his pathological resistance was significantly reduced. Statistically, the tolerated body tilt angles no longer differed from those of healthy subjects.

Conclusions

We conclude that even short presentations of tilted 3D visual input can reduce symptoms of severe contraversive lateropulsion. The technique provides potential for a new treatment method of pusher syndrome and offers a simple, straightforward approach that can be effortlessly integrated in clinical practice.

Trial Registration

German Clinical Trials Register (DRKS00026700).

KEYWORDS:

• Visual vertical
• postural vertical
• virtual reality
• pusher syndrome
• contraversive pushing
• stroke

Acknowledgments

We thank patient AS for his willingness to participate in our experiment. We also thank Tobias Schumacher, Marion Himmelbach, and Franziska Oesterle for their support during patient recruitment, as well as Endi Epifanio and Felix Müller for physiotherapeutic assistance during the experiment and for translating when communicating with the patient.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Deutsche Forschungsgemeinschaft [KA 1258/23-1].