PT  - JOURNAL ARTICLE
AU  - Shakespeare, Timothy
AU  - Kaski, Diego
AU  - Yong, Keir
AU  - Patterson, Ross
AU  - Slattery, Catherine
AU  - Ryan, Natalie
AU  - Schott, Jonathan
AU  - Crutch, Sebastian
TI  - ABNORMALITIES OF FIXATION, SACCADE AND PURSUIT IN POSTERIOR CORTICAL ATROPHY
AID  - 10.1136/jnnp-2015-312379.18
DP  - 2015 Nov 01
TA  - Journal of Neurology, Neurosurgery & Psychiatry
PG  - e4--e4
VI  - 86
IP  - 11
4099  - http://jnnp.bmj.com/content/86/11/e4.90.short
4100  - http://jnnp.bmj.com/content/86/11/e4.90.full
SO  - J Neurol Neurosurg Psychiatry2015 Nov 01; 86
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.