Saccades in children with spina bifida and Chiari type II malformation.
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.
Division of Neurology, Hospital for Sick Children, Ontario, Canada. msalman@hsc.mb.ca
M S
MS
Salman
J A
JA
Sharpe
M
M
Eizenman
L
L
Lillakas
T
T
To
C
C
Westall
M J
MJ
Steinbach
M
M
Dennis
D000293:Adolescent; D000328:Adult; D001139:Arnold-Chiari Malformation / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D001933:Brain Stem / Q000473:pathology / Q000503:physiopathology; D002526:Cerebellar Diseases / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D002531:Cerebellum / Q000473:pathology / Q000503:physiopathology; D002557:Cerebrospinal Fluid Shunts / Q000706:statistics & numerical data; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000503:physiopathology; D009460:Neurologic Examination; D015835:Ocular Motility Disorders / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology*; D009801:Oculomotor Muscles / Q000294:innervation / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology; D012438:Saccades / Q000502:physiology*; D016135:Spinal Dysraphism / Q000150:complications* / Q000473:pathology / Q000503:physiopathology