Grades of Hepatic Encephalopathy
Hepatic encephalopathy (HE) should be classified according to four key factors: underlying disease type, severity of manifestations, time course, and presence of precipitating factors, with severity graded from minimal to coma using the West Haven criteria. 1
Classification System
1. According to Underlying Disease
- Type A: HE resulting from acute liver failure (ALF)
- Type B: HE resulting from portosystemic bypass or shunting without liver disease
- Type C: HE resulting from cirrhosis
Type A has distinct features including risk of increased intracranial pressure and cerebral herniation, while Types B and C have similar clinical manifestations. 1
2. According to Severity of Manifestations (West Haven Criteria)
The severity of HE is categorized along a continuum that has been subdivided for clinical and research purposes:
Covert HE 1
- Minimal HE: No clinically evident cognitive abnormalities but abnormal performance on psychometric or neuropsychological tests
- Grade 1: Trivial lack of awareness, shortened attention span, impaired addition/subtraction, altered sleep rhythm
Overt HE 1
- Grade 2: Lethargy, disorientation for time, obvious personality change, inappropriate behavior
- Grade 3: Somnolence to semi-stupor, responsive to stimuli, confusion, gross disorientation
- Grade 4: Coma, unresponsive to verbal or painful stimuli
3. According to Time Course
- Episodic HE: Isolated episodes with return to baseline
- Recurrent HE: Episodes occurring with a time interval of 6 months or less
- Persistent HE: Behavioral alterations that are always present and interspersed with relapses of overt HE 1
4. According to Precipitating Factors
- Nonprecipitated
- Precipitated: Factors should be specified (e.g., infection, bleeding, constipation) 1
Diagnostic Approach
The diagnosis of HE requires:
- Detection of signs suggestive of HE in patients with liver insufficiency or portosystemic shunting
- Exclusion of other causes of brain dysfunction
- Recognition of precipitating factors 1
Clinical Evaluation Tools
- For Overt HE: Clinical examination using West Haven criteria or Glasgow Coma Scale 1
- For Covert HE: Neuropsychological tests such as:
- Paper-pencil tests (PHES - Psychometric Hepatic Encephalopathy Score)
- Computerized tests (CRT, ICT, SCAN, or Stroop)
- Neurophysiological tests (CFF or EEG) 1
Important Clinical Considerations
- HE should be treated as a continuum ranging from unimpaired cognitive function to coma 1
- Brain imaging (CT or MRI) does not contribute to diagnosis or grading but may be needed to exclude other pathologies, especially given the 5-fold increased risk of intracerebral hemorrhage in these patients 1
- Blood ammonia levels alone do not add diagnostic, staging, or prognostic value, though a normal value should prompt diagnostic reevaluation 1
Differential Diagnosis
Several conditions can mimic HE and must be excluded:
- Metabolic disorders: Diabetic complications, electrolyte disorders
- Substance-related: Alcohol intoxication/withdrawal, drug effects
- Neurological: Neuroinfections, nonconvulsive epilepsy, stroke
- Psychiatric disorders
- Other: Dementia, brain lesions, obstructive sleep apnea 1
The accurate classification and grading of HE is essential for appropriate management decisions and prognostication, as different grades require different treatment approaches and have varying implications for mortality and quality of life.