In order to maintain balance, the brain receives and processes input from multiple sensory systems including the visual, vestibular, and somatosensory systems. The information from these systems is sent to the brain where the information is then combined, organized and interpreted. This results in the output of reflexes (vestibulo-ocular reflex [VOR] and vestibulospinal reflex [VSR]). The VOR and the VSR work together with other motor systems to control gaze stability and control whole body equilibrium. Impairment in any of these sensory systems can result in dizziness, loss of balance, and visual instability. While the contributions of the visual, vestibular, and somatosensory systems on visual stability have been well described in the literature, contribution of cervical spine somatosensation on visual stability is not fully understood. The overall aim of the present work was to investigate whether impaired somatosensory information from the cervical spine, caused by neck muscle fatigue, directly influences dynamic visual stability in healthy young and healthy older participants. Results indicated that healthy young and healthy older participants who were fatigued had significantly poorer Dynamic Visual Acuity (DVA) than those who were not fatigued (P<.05). In Conclusion, our research suggests that when assessing vestibular function in patients complaining of dizziness and/or visual disturbance with a history of neck trauma, one may speculate that VOR dysfunction could have a cervical origin due to somatosenory disturbance, which may lead to visual disturbances and dizziness.

LLU Discipline

Rehabilitation Sciences


Rehabilitation Sciences


School of Allied Health Professions

First Advisor

Petrofsky, Jerrold S.

Second Advisor

Berk, Lee S.

Third Advisor

Hubbard Richard

Fourth Advisor

Laymon, Michael S.

Fifth Advisor

Zimmerman, Grenith

Degree Name

Doctor of Philosophy (PhD)

Degree Level


Year Degree Awarded

January 2011

Date (Title Page)




Library of Congress/MESH Subject Headings

Fatigue; Fatigue - Physiopathology;

Subject - Local

Vestibular Systems; Somatosensory Systems; Visual Systems; Brain; Vestibulo-ocular Reflex; Fatigue; Neck Muscle Fatigue



Page Count

114 p.

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses & Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives