Understanding the pusher behavior of some stroke patients with spatial deficits: a pilot study.
OBJECTIVE
To investigate whether pusher behavior (ie, a tendency among stroke patients with spatial deficits to actively push away from the nonparalyzed side and to resist any attempt to hold a more upright posture) affects only the trunk, for which gravitational feedback is given by somesthetic information, or the head as well, whose gravitational information is mainly given by the vestibular system (without vision).


METHODS
Description and measurement of clinical features.


METHODS
Rehabilitation center research laboratory.


METHODS
Eight healthy subjects age matched to 14 patients with left hemiplegia resulting from right-hemisphere stroke (3 pushers showing a severe spatial neglect, 11 without pusher behavior).


METHODS
All participants were asked to actively maintain an erect posture while sitting for 8 seconds on a rocking, laterally unstable platform. The task was performed with (in light) and without (in darkness) vision.


METHODS
The number of trials needed to succeed in the task was monitored. In successful trials, head, shoulders, thoracolumbar spine, and pelvis orientation in roll were measured by means of an automated, optical television image processor.


RESULTS
Compared with other patients and healthy subjects, the 3 pushers missed many more trials and displayed a contralesional tilt of the pelvis but kept a correct head orientation. This tilt was especially pronounced without vision. Spatial neglect was a key factor, explaining 56% of patients' misorientation behavior with vision and 61% without vision.


CONCLUSIONS
This pilot kinematic analysis shows that pusher behavior does not result from disrupted processing of vestibular information (eg, caused by a lesion involving the vestibular cortex); rather, it results from a high-order disruption in the processing of somesthetic information originating in the left hemibody, which could be graviceptive neglect (extinction). This disruption leads pushers to actively adjust their body posture to a subjective vertical biased to the side opposite the cerebral lesion.
Pérennou
Dominic Alain
DA
Unité de Rééducation Neurologique, Département de Médecine Physique et Réadaptation du CHU de Nimes, Université Montpellier 1 Centre Médical, 30240 Le Grau du Roi, France. dominic.perennou@chu.nimes.fr
Amblard
Bernard
B
Laassel
El Mostafa
el M
Benaim
Charles
C
Hérisson
Christian
C
Pélissier
Jacques
J
D000328:Adult; D000368:Aged; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D006429:Hemiplegia / Q000503:physiopathology / Q000534:rehabilitation*; D006801:Humans; D007699:Kinesthesis / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009949:Orientation / Q000502:physiology*; D010468:Perceptual Disorders / Q000503:physiopathology / Q000534:rehabilitation*; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology; D011434:Proprioception / Q000502:physiology*; D020521:Stroke / Q000503:physiopathology; D000071939:Stroke Rehabilitation