EYE-Mobile TRACKer IN the Diagnosis of Minimal Hepatic Encephalopathy
EYE-Mobile TRACKer IN the Diagnosis of Minimal Hepatic Encephalopathy
Hepatic encephalopathy (HE) corresponds to the neurological or the neuropsychological
 symptoms caused by an acute or chronic liver disease and/or porto-systemic shunt. Many
 patients present neurological symptoms even if their liver disease is stabilized.
 Furthermore, HE is associated with an altered quality of life and an increased mortality. Its
 incidence is high with 30 to 80% of cirrhotic patients that will display according to
 retained diagnostic criteria. HE symptoms are going from subtle neuropsychological
 abnormalities detected only on neuropsychological testing, minimal HE, to altered
 consciousness, overt HE. Recently, the therapeutic armamentarium has increased with now
 several drugs (rifaximin, ammonia lowering agents) that are able to prevent new bouts of HE.
 Unfortunately, the diagnosis of minimal HE is difficult and no gold-standard is available.
 None of the proposed test is rapid and easily performed at bedside.

 Recently, different studies suggest the potential interest of the study of the ocular
 movements in HE. Abnormalities in ocular saccades could be an early predictor of cortical
 impairment. In a pilot feasibility study using an eye-tracker, we could show that cirrhotic
 patients with minimal HE had, compared to healthy controls, increased latencies, decreased
 speed of voluntary and reflex saccades, more errors in anti-saccades, more anticipations
 saccades and more difficulties to fix the target.

 Our hypothesis was that the use of the eye-tracker will enable the diagnosis of minimal HE by
 studying the characteristics of saccades and anti-saccades.

 Since no gold-standard is available for the diagnosis of minimal HE, we will use the
 conclusion of an adjudication committee formed by 2 experts. Their clinical judgment will
 take into account the results of medical history, clinical examination, neuropsychological
 testing, PHES, Critical Flicker Frequency test (CFF), ammonemia levels, EEG and brain MRI
 with spectroscopy.
Hepatic encephalopathy (HE) corresponds to the neurological or the neuropsychological
 symptoms caused by an acute or chronic liver disease and/or porto-systemic shunt. Many
 patients present neurological symptoms even if their liver disease is stabilized.
 Furthermore, HE is associated with an altered quality of life and an increased mortality. Its
 incidence is high with 30 to 80% of cirrhotic patients that will display according to
 retained diagnostic criteria. HE symptoms are going from subtle neuropsychological
 abnormalities detected only on neuropsychological testing, minimal HE, to altered
 consciousness, overt HE. Recently, the therapeutic armamentarium has increased with now
 several drugs (rifaximine, ammonia lowering agents) that are able to prevent new bouts of HE.
 Unfortunately, the diagnosis of minimal HE is difficult and no gold-standard is available.
 None of the proposed test is rapid and easily performed at bedside.

 Recently, different studies suggest the potential interest of the study of the ocular
 movements in HE. Abnormalities in ocular saccads could be an early predictor of cortical
 impairment. In a pilot feasibility study using an eye-tracker, we could show that cirrhotic
 patients with minimal HE had, compared to healthy controls, increased latencies, decreased
 speed of voluntary and reflex saccads, more errors in anti-saccads, more anticipations
 saccads and more difficulties to fix the target.

 Our hypothesis was that the use of the eye-tracker will enable the diagnosis of minimal HE by
 studying the characteristics of saccads and anti-saccads.

 Since no gold-standard is available for the diagnosis of minimal HE, we will use the
 conclusion of an adjudication committee formed by 2 experts. Their clinical judgment will
 take into account the results of medical history, clinical examination, neuropsychological
 testing, PHES, Critical Flicker Frequency test (CFF), ammonemia levels, EEG and brain MRI
 with spectroscopy.

 Gold standard definition: diagnostic of minimal HE as stated by adjudication committee
 composed of 2 experts. Each patient will be classified as : patient without EH (neither
 clinical or minimal) and patient with EHM. The results of medical history, clinical
 examination, EEG results (triphasic waves, decreased frequency), ammonia level (above
 50mcmol/L or not), neuropsychological testing encompassing PHES (below -4 or not) and CFF
 (below 39Hz or not), brain MRI with MR-spectroscopy (HE profile on MRS) will be aggregated to
 obtain their adjudication. All the tests will be performed by trained personal aware of the
 evaluation of cirrhotic patients with possible HE. The eye-tracking evaluation will be
 blinded to the conclusion of the adjudication committee (presence or absence of HE).

 Since the data from the eye-tracker are quantitative, a ROC curve will be used to evaluate
 the diagnostic performance of each parameters measured by the study device (mainly, saccads
 latencies, voluntary and reflexes ones, and the percentage of errors in saccads, anti-saccads
 and voluntary anticipations).

 The ability of each measure to diagnose minimal HE will be evaluated by the area under the
 ROC and its 95% confidence interval. Sensibility, specificity, positive and negative
 predictive values will be given for each possible cut-off with their 95% confidence interval.
 In order to optimize the diagnostic performance, the most discriminating values will be used
 to build a multivariate diagnostic model. To prevent overfitting frequently associated with
 "standard" logistic regression, the selection of variables of interest will be performed with
 the LASSO method. This method is valuable when the number of subjects are limited.
Inclusion Criteria:

 Eligibility criteria for EHM+ subjects:

 -  Age between 18 and 70 (inclusive)

 -  Cirrhosis

 -  Minimal hepatic encephalopathy

 -  Expression of non opposition

 Eligibility criteria for EHM- subjects:

 -  Age between 18 and 70 (inclusive)

 -  Cirrhosis

 -  No hepatic encephalopathy (minimal or clinical)

 -  Paired with EHM+ subjects about age, gender, MELD score and cirrhosis etiology

 -  Expression of non opposition

 Exclusion Criteria for all subjects:

 -  Age older than 70

 -  MMS score < 24

 -  Clinical hepatic encephalopathy

 -  Cirrhosis etiology different from alcoholic, viral or metabolic one

 -  Intake of psychotropic drugs within 48h

 -  Alcohol intake > 30 g/j

 -  Heart, renal or respiratory failure

 -  Evolutive neurological diseases

 -  History of neurological diseases causing consequences

 -  Non corrected visuals disorders

 -  Oculomotor disorders from any etiology

 -  Highly-resistant bacteria carrier subjects

 -  Inability to put on the eye-tracker device