Subjective visual vertical in pitch and roll in right hemispheric stroke

Patients with right hemispheric stroke usually present an anticlockwise deviation of the subjective visual vertical (SVV) in the frontal (roll) plane. However, the occurrence of a similar disorder in the sagittal (pitch) plane has never been assessed. We investigated the subjective visual vertical in both planes in those patients.

Eight patients, 4 with spatial neglect (N+) and 4 without neglect (N-), were compared with 4 healthy participants (C). They sat facing a luminous bar adjustable in rotation, either in the roll or in the pitch plane, and had to orient it in a vertical position, in the dark.

Compared with N- (-0.1 degrees) and C (+1.1 degrees) groups, N+ patients presented with a significant backward deviation (-4.5 degrees) of the SVV in pitch. In accordance with other studies, they also showed a significant anticlockwise deviation (-8.8 degrees) of the SVV in roll, as compared with N- (-1.9 degrees) and C (+0.4 degrees) subjects. This was associated with an opposite trunk deviation in both planes.

While confirming the anticlockwise deviation already reported in the frontal plane, we showed for the first time to our knowledge a backward deviation of the SVV in neglect patients, which has to be put in relation with their balance disorders.