Gaze control and foot kinematics during stair climbing: characteristics leading to fall risk in progressive supranuclear palsy.
OBJECTIVE
Does gaze control influence lower-extremity motor coordination in people with neurological deficits? The purpose of this study was to determine whether foot kinematics during stair climbing are influenced by gaze shifts prior to stair step initiation.


METHODS
Twelve subjects with gaze palsy (mild versus severe) secondary to progressive supranuclear palsy were evaluated during a stair-climbing task in a cross-sectional study of mechanisms influencing eye-foot coordination. Infrared oculography and electromagnetic tracking sensors measured eye and foot kinematics, respectively. The primary outcome measures were vertical gaze fixation scores, foot lift asymmetries, and sagittal-plane foot trajectories.


RESULTS
The subjects with severe gaze palsy had significantly lower lag foot lift relative to lead foot lift than those with a mild form of gaze palsy. The lag foot trajectory for the subjects with severe gaze palsy tended to be low, with a heading toward contact with the edge of the stair.


METHODS
with severe gaze palsy were 28 times more likely to experience "fixation intrusion" (high vertical gaze fixation score) during an attempted shift of gaze downward than those with mild ocular motor deficits (odds ratio [OR]=28.3, 95% confidence interval [CI]=6.4-124.8). Subjects with severe gaze shift deficits also were 4 times more likely to have lower lag foot lift with respect to lead foot lift than those with mild ocular motor dysfunction (OR=4.0, 95% CI=1.7-9.7).


CONCLUSIONS
The small number of subjects and the variation in symptom profiles make the generalization of findings preliminary. Deficits in gaze control may influence stepping behaviors and increase the risk of trips or falls during stair climbing. Neural and kinematic hypotheses are discussed as possible contributing mechanisms.
Di Fabio
Richard P
RP
Department of Physical Medicine and Rehabilitation, University of Minnesota, Minneapolis, MN 55455, USA. difab001@umn.edu
Zampieri
Cris
C
Tuite
Paul
P
D000058:Accidental Falls; D000222:Adaptation, Physiological / Q000502:physiology*; D000368:Aged; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology; D001696:Biomechanical Phenomena; D001921:Brain / Q000503:physiopathology*; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D005528:Foot / Q000503:physiopathology*; D006801:Humans; D016015:Logistic Models; D008297:Male; D009434:Neural Pathways / Q000503:physiopathology; D009474:Neurons / Q000502:physiology; D015835:Ocular Motility Disorders / Q000209:etiology / Q000503:physiopathology*; D009949:Orientation / Q000502:physiology; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D013028:Space Perception / Q000502:physiology; D013494:Supranuclear Palsy, Progressive / Q000150:complications / Q000503:physiopathology*