Document Detail


The linear vestibulo-ocular reflex, locomotion and falls in neurological disorders.
MedLine Citation:
PMID:  20086286     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: During locomotion, head perturbations, consisting of rotations and translations (linear movements), occur with predominant frequencies of 0.5-5.0 Hz. The vestibular reflexes act at short latency to safeguard clear vision and stable posture during locomotion. Much is known about the angular vestibulo-ocular reflex (aVOR) in response to head rotations, which depend on the semicircular canals of the vestibular labyrinth. However, the means to test reliably the linear or translational vestibulo-ocular reflex (tVOR), which depends on the otolithic organs, has only become available more recently.
METHODS: We used a moving platform to translate normal human subjects vertically at frequencies similar to those occurring during locomotion, under ambient illumination.
RESULTS: Our findings suggested that, whereas aVOR is concerned with stabilizing images of visual targets on the retina to optimize visual acuity, tVOR seems best suited to minimize retinal image motion between objects lying in different depth planes, in order to optimize motion parallax information. We then asked whether the tVOR functioned abnormally in patients with two neurological disorders that often cause falls: progressive supranuclear palsy (PSP) and cerebellar ataxia. We found that patients with PSP cannot adjust tVOR responses appropriately during viewing of near objects, nor converge their eyes. Vestibular-evoked myogenic potentials (VEMPs), an otolith-spinal reflex, are also impaired in PSP patients. Patients with cerebellar ataxia also lack the ability to adjust tVOR for near viewing, even though they may be able to converge.
CONCLUSIONS: Taken together, our studies suggest that abnormal otolithic vestibular reflexes contribute to postural instability in PSP and cerebellar ataxia, and deserve further investigation.
Authors:
Ke Liao; Mark F Walker; Anand C Joshi; Millard Reschke; Michael Strupp; Judith Wagner; R John Leigh
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Review    
Journal Detail:
Title:  Restorative neurology and neuroscience     Volume:  28     ISSN:  1878-3627     ISO Abbreviation:  Restor. Neurol. Neurosci.     Publication Date:  2010  
Date Detail:
Created Date:  2010-01-20     Completed Date:  2010-04-06     Revised Date:  2013-04-10    
Medline Journal Info:
Nlm Unique ID:  9005499     Medline TA:  Restor Neurol Neurosci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  91-103     Citation Subset:  IM    
Affiliation:
Biomedical Engineering, Daroff-Dell'Osso Laboratory, Veterans Affairs Medical Center and University Hospitals, Case Western Reserve University, Cleveland, OH, USA.
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MeSH Terms
Descriptor/Qualifier:
Accidental Falls*
Cerebellar Ataxia / complications,  physiopathology
Gait Disorders, Neurologic / etiology,  physiopathology*
Humans
Postural Balance / physiology*
Psychomotor Performance / physiology
Reflex, Abnormal / physiology
Reflex, Vestibulo-Ocular / physiology*
Supranuclear Palsy, Progressive / complications,  physiopathology
Vestibular Diseases / complications,  physiopathology*
Vestibular Function Tests
Grant Support
ID/Acronym/Agency:
EY06717/EY/NEI NIH HHS; R01 EY006717-24/EY/NEI NIH HHS

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