Objective assessment of the hemisphere-specific neurological outcome of carotid endarterectomy: a quantitative saccadometric analysis.
BACKGROUND
Carotid endarterectomy (CEA) improves the cerebrovascular prognosis of patients with carotid stenosis but carries a risk of causing postoperative neurological deterioration.


OBJECTIVE
We assessed hemisphere-specific changes in saccadic eye movements to determine the utility of saccadometry as a quantitative neurosurgical outcome measure.


METHODS
Visually evoked saccades were recorded at the bedside before and 2 days after surgery from 30 patients undergoing CEA for symptomatic carotid stenosis. Hemisphere-specific latency distributions were compared using Kolmogorov-Smirnov statistics. Latency distributions were fitted using the Linear Approach to Threshold with Ergodic Rate model and compared with binomial logistic regression.


RESULTS
There were 21 males and mean age at surgery was 71±7 years. Following CEA, the distribution of saccades initiated by the cerebral hemisphere distal to the operated artery significantly changed in 25 patients. By contrast, there were 14 significant contralateral-hemisphere saccadic changes (P<.001). Significant contralateral saccadic changes always co-occurred with significant ipsilateral changes and 10 of 14 patients with contralateral saccadic change had contralateral carotid stenosis. There was a significantly greater postoperative reduction in early saccades generated by the ipsilateral hemisphere than by the contralateral hemisphere (P<.02)


CONCLUSIONS
CEA leads to significant hemisphere-specific subclinical changes in saccadic performance and, in particular, differentially affects the proportion of early saccades, a measure of the ability of the frontal cortex to successfully inhibit lower centers, generated by the 2 hemispheres. Saccadometry, a bedside test, provides data that can be statistically compared for individual and groups of patients. It could allow the neurological outcome of carotid surgery to be objectively quantified.
Department of Physiology, Neuroscience & Development, University of Cambridge, and Cambridge Vascular Research Unit, Department of Vascular Surgery, Addenbrooke's Hospital, Cambridge, United Kingdom. RN@cantab.net
S A Reza
SA
Nouraei
Jonathan C P
JC
Roos
Stewart R
SR
Walsh
Jan K
JK
Ober
Michael E
ME
Gaunt
Roger H S
RH
Carpenter
D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000503:physiopathology* / Q000601:surgery; D017023:Coronary Angiography / Q000379:methods; D016894:Endarterectomy, Carotid / Q000379:methods*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time / Q000502:physiology; D012438:Saccades / Q000502:physiology*