RT Journal Article
SR Electronic
T1 ABNORMALITIES OF FIXATION, SACCADE AND PURSUIT IN POSTERIOR CORTICAL ATROPHY
JF Journal of Neurology, Neurosurgery & Psychiatry
JO J Neurol Neurosurg Psychiatry
FD BMJ Publishing Group Ltd
SP e4
OP e4
DO 10.1136/jnnp-2015-312379.18
VO 86
IS 11
A1 Shakespeare, Timothy
A1 Kaski, Diego
A1 Yong, Keir
A1 Patterson, Ross
A1 Slattery, Catherine
A1 Ryan, Natalie
A1 Schott, Jonathan
A1 Crutch, Sebastian
YR 2015
UL http://jnnp.bmj.com/content/86/11/e4.90.abstract
AB Background and aims The clinico-neuroradiological syndrome posterior cortical atrophy (PCA) is the cardinal ‘visual dementia’. We evaluated oculomotor function in patients with PCA.Methods 20 PCA patients, 17 typical Alzheimer's disease (tAD) patients and 22 healthy controls completed tests of fixation, saccade and smooth pursuit eye movements using an infrared pupil tracking system.Results Eye movement abnormalities occur in 80% of PCA patients (compared to 17% tAD, 5% controls). PCA saccades were significantly hypometric, especially for distant targets. PCA patients were slower to reach saccadic targets whose onset overlapped with fixation, consistent with ‘sticky fixation’. Time to reach saccadic targets was also significantly associated with parietal and occipital cortical thickness measures. On fixation stability tasks, tAD patients showed more square wave jerks whose frequency was associated with lower cerebellar grey matter volume, whilst PCA patients showed characteristically large saccadic intrusions whose frequency correlated significantly with generalised reductions in cortical thickness. Smooth pursuit was also impaired, with lower gain in both PCA and tAD patient groups compared to controls.Conclusions Eye movement abnormalities are near-ubiquitous in PCA, and may help distinguish PCA from tAD. We suggest the PCA oculomotor profile reflects weak input from degraded occipito-parietal spatial representations of stimulus location into a superior collicular spatial map for eye movement regulation. The results have implications for other patients with dementia-related visual impairment.