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From the Divisions of Neurology (Dr. Salman), Population Health Sciences (Dr. To), Ophthalmology and Vision Sciences (Dr. Westall), and Psychology (Dr. Dennis), Hospital for Sick Children, Division of Neurology (Drs. Salman and Sharpe) and Vision Science Research Program (Drs. Salman, Sharpe, and Steinbach, L. Lillakas), University Health Network, and Institute of Biomedical Engineering (Dr. Eizenman), University of Toronto, Ontario, Canada.
Address correspondence and reprint requests to Dr Salman, Division of Pediatric Neurology, Children’s Hospital, 820 Sherbrook St., AE 108, Harry Medovy House, Winnipeg, MB, Canada R3A 1R9; e-mail: msalman{at}hsc.mb.ca
Background: Saccades are essential for optimal visual function. Chiari type II malformation (CII) is a congenital anomaly of the cerebellum and brainstem, associated with spina bifida.
Objective: To investigate the effects of CII on saccades and correlate saccadic parameters with brain MRI measurements.
Methods: Saccades were recorded in 21 participants with CII, aged 8 to 19, using an infrared eye tracker. Thirty-nine typically developing children served as controls. Participants made saccades to horizontal and vertical target steps. Nineteen participants with CII had MRI. Regression analyses were used to investigate the effects of spinal lesion level, number of shunt revisions, presence of nystagmus, and midsagittal MRI measurements on saccades.
Results: Saccadic amplitude gains, asymptotic peak velocities, and latencies did not differ between the control and CII groups (p > 0.01). No significant differences were found between saccadic gains, asymptotic peak velocities or latencies, and spinal lesion level, number of shunt revisions, presence of nystagmus, or MRI measurements.
Conclusions: Saccades were normal in most participants with Chiari II malformation (CII). Neural coding of saccades is robust and is typically not affected by the anatomic deformity of CII.
Additional material related to this article can be found on the Neurology Web site. Go to www.neurology.org and scroll down the Table of Contents for the June 28 issue to find the title link for this article.
Supported by a Research Training Competition Award, Hospital for Sick Children (HSC); KidsAction; Spina Bifida and Hydrocephalus Association of Canada; Clinician Scientist Training Program Awards at HSC and Vision Sciences Program at Toronto Western Hospital; Bloorview MacMillan Hospital Foundation Grants (M.S.S.); NIH grant "Spina Bifida: Cognitive and Neurobiological Variability" (Dr. J. Fletch); CIHR of Canada Grants MT5404 and ME 5909 (J.A.S.); NSERC of Canada A7664, Sir Jules Thorn Charitable Trust, and Krembil Family Foundation Grants (M.J.S.); and CIHR and the Ontario Ministry of Health and Long-Term Care Investigator Award (T.T.).
Dr. Eizenman is the developer of the tracker. He has shares and interest in El Mar Inc., the manufacturer of the eye tracker.
Received February 2, 2005. Accepted in final form March 10, 2005.
This article has been cited by other articles:
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  M. S. Salman, J. A. Sharpe, L. Lillakas, M. Dennis, and M. J. Steinbach Visual Fixation in Chiari Type II Malformation J Child Neurol, February 1, 2009; 24(2): 161 - 165. [Abstract] [PDF]
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