The relationship between eye stabilization reflexes, smooth pursuit eye movements and the range of motion of the cervical spine in healthy individuals.
B.K Ischebeck1,2, J de Vries1, M Janssen1, G.J. Kleinrensink1, M.A. Frens1, .J.N. van der Geest1
1 Dept Neuroscience, Erasmus MC, Rotterdam, the Netherlands.
2 Spine and Joint Centre, Rotterdam, the Netherlands.
Physicians currently do not have methods to objectively determine the severity of the complaints of chronic neck pain patients. Earlier research has suggested that ocular stabilization reflexes, used to stabilize the visual image on the retina, may have been altered in patients with chronic neck pain.
Although straightforward measurement of (spinal) proprioception is still impossible, neurophysiological research has revealed an alternative sensorimotor measurement via the cervico-ocular reflex (COR), which receives sensory input from neck proprioception. Changes in COR are therefore likely to reflect changes in neck proprioception-, and recording of eye reflexes might help to objectively assess the severity of the complaints of neck pain patients.
Our hypothesis is that reflexive eye movement measurements can assist into making the connection between functional impairments and symptoms for chronic neck pain patients.
As a start in determining the symptom-profile we measured healthy controls. Subjects were restrained in a chair using seatbelts, and their head was fixed with a bite bar. Rotations of the chair and/or head were controlled via computer. Eye movements were recorded with an infrared eye-tracking device (EyeLink 2.04, SensoMotoric Instruments, Germany), and range of motion were measured using a CROM-device. We correlated the characteristics of three eye stabilization reflexes-, [the COR, vestibular-ocular reflex (VOR) and the optokinetic reflex (OKR)], to the subject’s ability to track a moving target [Smooth Pursuit (SP) eye movements] at different head positions over the (ROM) of the cervical spine. Preliminary results suggest that the relationship between eye stabilization reflexes, SP and ROM and that this relation depends on the orientation of the head, and we hypothesize that this relationship will vary for patients with chronic neck pain.