Saccadic latency in hepatic encephalopathy: a pilot study

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

The Study of CSC Strip Readout Electronics Operation at High Background Rates

The influence of the background rate on the operation of cathode strip chamber ( CSC) readout electronics has been studied. The investigation has been performed with two different cathode readout electronics: 16-channels preamplifier-shapers based on GASPLEX and Minsk ASIC "Katod-1". The first one have been tested with 4-layer 0.5´0.5 m2 CSC. One layer has been irradiated by X-ray tube ( Eg=8KeV) while the others - used for cosmic muon track coordinate reconstruction. Electronics based on Minsk ASIC have been tested with P3 prototype of ME1/1 CSC in pion beam at H2 experimental area. For both electronics the background contribution to the registered events as a function of the background rate are presented