Critical flicker frequency for quantification of low-grade hepatic encephalopathy

Abstract

Subclinical hepatic encephalopathy (SHE) is currently diagnosed by psychometric tests or neurophysiologic techniques. In view of its sociomedical relevance, simple and reproducible tests for routine diagnosis are required. This study evaluates critical flicker-frequency thresholds for quantification of low-grade hepatic encephalopathy. A total of 115 patients (92 with cirrhosis, 23 controls) were analyzed for HE severity (mental state, computerized psychometric tests), and the threshold frequencies at which light pulses are perceived as fused (fusion frequency) or flickering light (critical flicker frequency [CFF]). CFF was a highly reproducible parameter with little age, day-time, and training dependency. CFFs in cirrhotic patients without HE (HE 0) were not different from those found in noncirrhotic controls. Significantly lower CFFs were found in cirrhotic patients with subclinical or manifest HE, and the various HE groups separated from each other at a high level of significance (P < .01). By using a CFF cut-off value of 39 Hz, a 100% separation of patients with manifest HE from noncirrhotic controls and HE 0 cirrhotic patients was obtained. SHE patients separated from HE 0 cirrhotic patients with high sensitivity (55%) and specificity (100%). The HE severity-dependent differences were found in both, alcoholic and posthepatitic cirrhosis. Statistically significant correlations (P < .01) were found between CFFs and individual psychometric tests. Aggravation of preexisting HE after transjugular intrahepatic portosystemic stent shunt (TIPS) implantation was accompanied by a corresponding decrease of CFF, whereas improvement of HE increased CFF. In conclusion, CFF is a sensitive, simple, and reliable parameter for quantification of low-grade HE severity in cirrhotic patients and may be useful for the detection and monitoring of SHE. H epatic encephalopathy (HE) is a frequent complication of cirrhosis and its appearance indicates poor prognosis. 1-4 HE is usually classified into 4 stages according to the presence and severity of neuropsychiatric symptoms on clinical evaluation. 5 However, a significant proportion of cirrhotic patients, who appear normal on clinical examination, exhibit various quantifiable neuropsychologic deficits and this condition has been termed subclinical hepatic encephalopathy (SHE). 6-10 Whereas detection of overt HE (grade I-IV) is made clinically and does not provide a major diagnostic challenge, diagnosis of SHE is problematic. Psychometric and electrophysiologic tests are currently used for detection of SHE. In addition, proton-magnetic resonance spectroscopy of the brain may bear a not yet fully elaborated diagnostic potential, 11 but is unsuitable for clinical routine. Electrophysiologic tests such as visual-evoked, somatosensory-evoked, or brain stem auditory-evoked potentials suffer from methodologic problems, require sophisticated equipment and analysis, and exhibit a lower sensitivity than psychometric tests. 7,12-14 Psychometric bedside tests, such as the number-connection test...

Minimal Hepatic Encephalopathy is an under Recognized Entity in Clinical Practice of Bangladeshi Physician

“…In different study it was shown that prevalence of minimal hepatic encephalopathy is less than 15% in Child Pugh A class and it is more than 50% in Child Pugh B//C class 11 . In our study prevalence MHE in Child Pugh A class is 27% and it was about 72% in Child Pugh B & C which is concordant with other studies.…”

Validity of Inhibitory Control Test and Critical Flicker Frequency to Diagnose Minimal Hepatic Encephalopathy

“…The critical flicker frequency (CFF) measures function at the level of the cortex and has a direct correlation with psychometric tests [11] . This test applies the theory that the pathogenesis of HE comprises Figure 1 Reciever operating characteristic curve for sensitivity and specificity of ICT in diagnosis of MHE.…”

“…In the study by Kircheis et al [11] , by using a threshold of 39 Hz when comparing healthy subjects to patients with cirrhosis, SHE (Subclinical Hepatic Encephalopathy) patients separated from cirrhotic patients without hepatic encephalopathy with high sensitivity (55%) and specificity (100%). CFFs in cirrhotic patients without HE were not different from those found in noncirrhotic controls.…”

Heart rate variability and critical flicker fusion frequency changes during and after parachute jumping in experienced skydivers

“…We thus also investigated how jumps could hamper cortical arousal using Critical Flicker Fusion Frequency (CFFF). The CFFF is non invasive and reliable in measuring cortical arousal (Hou et al 2007;Rota-Bartelink 1999) and has been demonstrated a good marker of cortical changes due to physical workload (Luczak and Sobolewski 2005;Luczak et al 1995;Davranche and Pichon 2005), drug administration (Hunter et al 1994;Hindmarch 1982), alcohol intoxication (Leigh 1982;Liu and Ho 2010;Schillaci and Fazio 1967), anaesthesia (Salib et al 1992;Sharma et al 2011;Wernberg et al 1980), encephalopathy (Ali et al 1994;Chang 1 3 et al 2007;Kircheis et al 2002;Lauridsen et al 2011) as well as hyperoxia (Balestra et al 2012;Hemelryck et al 2013). CFFF variations happen in parallel to EEG changes and are thus better than merely relying on subjective reports for neuropsychological defects (Seki and Hugon 1976).…”