Saccadic latency in hepatic encephalopathy: a pilot study

Abstract

Hepatic encephalopathy is a common complication of cirrhosis. The degree of neuro-psychiatric impairment is highly variable and its clinical staging subjective. We investigated whether eye movement response times—saccadic latencies—could serve as an indicator of encephalopathy. We studied the association between saccadic latency, liver function and paper- and pencil tests in 70 patients with cirrhosis and 31 patients after liver transplantation. The tests included the porto-systemic encephalopathy (PSE-) test, critical flicker frequency, MELD score and ammonia concentration. A normal range for saccades was established in 31 control subjects. Clinical and biochemical parameters of liver, blood, and kidney function were also determined. Median saccadic latencies were significantly longer in patients with liver cirrhosis when compared to patients after liver transplantation (244 ms vs. 278 ms p < 0.001). Both patient groups had prolonged saccadic latency when compared to an age matched control group (175 ms). The reciprocal of median saccadic latency (μ) correlated with PSE tests, MELD score and critical flicker frequency. A significant correlation between the saccadic latency parameter early slope (σE) that represents the prevalence of early saccades and partial pressure of ammonia was also noted. Psychometric test performance, but not saccadic latency, correlated with blood urea and sodium concentrations. Saccadic latency represents an objective and quantitative parameter of hepatic encephalopathy. Unlike psychometric test performance, these ocular responses were unaffected by renal function and can be obtained clinically within a matter of minutes by non-trained personnel.Electronic supplementary materialThe online version of this article (doi:10.1007/s11011-010-9210-1) contains supplementary material, which is available to authorized users.

Using saccades to diagnose covert hepatic encephalopathy

“…Moreover, it is comparatively rapid, taking only 7 min to gain a data set, and requires no specialist training or personnel to administer. We have shown that an assessment of a patient's saccades correlates strongly with psychometric performance, an observation in line with those made by Krismer et al (Krismer et al 2010).…”

“…Finally, previous studies have demonstrated that HE affects eye movements. Smooth pursuit eye movements are disrupted in conjunction with the degree of encephalopathy (Montagnese 2005), and a recent pilot study using saccadometry has shown increased saccadic latency in HE, correlating both with psychometric tests and flicker fusion performance (Krismer et al 2010). We therefore investigated whether the measurement of saccades might provide a novel quantitative neurological assessment for the diagnosis of CHE.…”

Variability in the decision process leading to saccades: A specific marker for schizophrenia?

“…The LATER model is a robust and simple way to model the RT distribution of saccades, and it was successfully applied to provide a quantitative measure of the RT distribution differences in patients with a variety of neurological disorders (Antoniades et al, 2010(Antoniades et al, , 2012Chandna, Chandrasekharan, Ramesh, & Carpenter, 2012;Krismer et al, 2010;Perneczky et al, 2011).…”

Measurement of Saccade Parameters in Relation to Adaptation to Homonymous Hemianopia

“…Prior to any data analysis, incorrect trials were filtered out and removed. Saccades with a latency less than 50 ms were excluded, in line with other saccade research (Krismer et al 2010;Knox, Wolohan & Helmy 2017;Amatya, Gong & Knox 2011). Saccades with latencies this low are generated too fast to be a response to the visual stimulus and are classed as anticipatory.…”