## Pathophysiology

Click the dropdown below if you would like some information on the pathophysiology
 InlineDropdown label="Pathophysiology" variant="block" tone="info" 
* **Primary process:** Astrocyte dysfunction (Alzheimer type II astrocytosis)
* **Central mechanism: Hyperammonemia**
  * Gut bacteria produce ammonia from dietary protein.
  * Liver failure and portosystemic shunting → impaired ammonia clearance.
  * Ammonia crosses the blood–brain barrier.
  * Astrocytes convert ammonia + glutamate → glutamine (via glutamine synthetase).
  * Intracellular glutamine accumulation → osmotic astrocyte swelling → low-grade cerebral edema.

* **Key amplifying mechanisms:**
  * **Neuroinflammation:** Cytokines (TNF-α, IL-6, IL-17) potentiate ammonia toxicity.
  * **Increased GABAergic tone:** Neurosteroids (e.g., allopregnanolone) enhance GABA-A receptor activity → neuronal inhibition.
  * **Manganese deposition:** Basal ganglia accumulation → T2 MRI hyperintensity, parkinsonism.
  * **Oxidative/nitrosative stress:** Reactive species impair neuronal signaling.

* **Acute liver failure:**
  * Rapid ammonia elevation ( 200 μmol/L) → high risk of severe cerebral edema and herniation.
 /InlineDropdown 

## Classification and Clinical Spectrum

HE is classified by underlying etiology:
- **Type A**: Acute liver failure.
- **Type B**: Portosystemic bypass with intact liver.
- **Type C**: Cirrhosis.

Severity is graded using the West Haven Criteria:
| **Severity** | **Description**                                                                        | **Category** |
|----------------------------------|----------------------------------------------------------------------------------------|--------------|
| Grade 0                          | Minimal HE; not outwardly detectable; deficits only on specialized testing.           | Covert       |
| Grade 1                          | Behavioral changes, impaired attention, no disorientation; minimal to no change in consciousness. | Covert       |
| Grade 2                          | Lethargy, disorientation, possibly asterixis, inappropriate behavior.                 | Overt        |
| Grade 3                          | Marked confusion, incoherent speech, sleeping most of the time but arousable to voice. | Overt        |
| Grade 4                          | Comatose, unresponsive to pain; may have decorticate or decerebrate posturing.        | Overt        |

Covert HE (grades 0–1) is clinically significant, affecting quality of life and increasing risks of falls, motor vehicle accidents, and hospitalizations despite preserved consciousness.

## Diagnosis

HE remains a **_diagnosis of exclusion_**. Clinical assessment is based on West Haven Criteria, with grades 2–4 considered overt HE. Disorientation and asterixis are reliable clinical markers for overt HE. For severely altered consciousness, the Glasgow Coma Scale can be utilized.

Covert HE is diagnosed using:
- Psychometric Hepatic Encephalopathy Score: ≥4 SDs below healthy controls on a 5-test battery.  InlinePopup label="More Info" title="PHES" tone="emerald" 
Psychometric Hepatic Encephalopathy Score (PHES) is a standardized paper-and-pencil neuropsychological test battery used to detect minimal (covert) hepatic encephalopathy in patients with cirrhosis who do not have obvious clinical signs.

Key Features
- Purpose: Identify subtle cognitive impairment (attention, psychomotor speed, visuospatial ability) not detectable on routine clinical exam.

Components (5 subtests):
- Number Connection Test A (NCT-A)
- Number Connection Test B (NCT-B)
- Digit Symbol Test
- Serial Dotting Test
- Line Tracing Test (time + errors)


 /InlinePopup 
- Animal Naming Test: 15 animals/minute (70% sensitivity, 63% specificity); 10 animals/minute (15% sensitivity, 92% specificity).
- EncephalApp Stroop Test:  198 seconds (80% sensitivity, 61% specificity). [ u Link to Test /u ](https://encephalapp.com/)

Clinical presentations of covert HE include increased falls, poor sleep, irritability, anorexia, and gait disturbance.

## Initial Workup

A broad workup is recommended to evaluate for precipitants or alternative causes. Investigations include: 
-  InlinePopup label="CBC" title="CBC" 
New anemia to suggest GI bleed?
Leukocytosis to suggest infection?
 /InlinePopup 
-  InlinePopup label="BMP/CMP" 
Hypo-/hyper-natremia? 
Calcium disorders? 
New acute kidney injury? 
Uremia?
 /InlinePopup 
-  InlinePopup label="Liver enzymes" title="Liver enzymes" 
Worsening AST/ALT?
Worsening ALK Phos?
Worsening bilirubin to suggest new obstruction or worsening function?
 /InlinePopup 
-  InlinePopup label="Coagulation studies" title="Coagulation studies" Worsening INR to suggest worsening liver function? /InlinePopup 
-  InlinePopup label="Urinalysis/Urine Culture" title="Urinalysis/Urine Culture" Ketones to suggest malnutrition? Signs of infection? /InlinePopup 
- Blood cultures (if concern for infection)
-  InlinePopup label="Medication Review and Urine drug screen/GCMS" title="Medication Review and Urine drug screen/GCMS" Benzos? Opioids? Anticholinergics? Illicit drugs such as cocaine, meth, marijuana, etc? /InlinePopup 
-  InlinePopup label="Diagnostic Paracentesis (if ascites)" title="Diagnostic Paracentesis (if ascites)" Key Studies 
- Cell count with differential 
- Albumin 
- Total protein 
- Gram stain 
- Culture (inoculate into blood culture bottles at bedside) 

SBP Dx 
- Ascitic fluid PMN ≥ 250 cells/mm³ /InlinePopup 
- *Ammonia level*: Not routinely recommended; variable and may be elevated in non-HE conditions. However, a low ammonia in a confused/comatose patient strongly suggests an alternative diagnosis.

## Chronic Management and Prevention

- Long-term lactulose therapy: titrate to maintain 2–3 soft stools daily.
- Add rifaximin: 550 mg twice daily for recurrent HE (reduces hospitalization rate and time to recurrence). 
 InlinePopup label="EBM - Lactulose Alone" title="Evidence Based Medicine" tone="amber" 

[** u Nonabsorbable disaccharides for hepatic encephalopathy: A systematic review and meta-analysis /u **](https://pubmed.ncbi.nlm.nih.gov/27081787/)

## **P — Population**
The population consists of adult patients with **cirrhosis**, enrolled in 38 randomized controlled trials (n = 1,828 total participants). These trials included two major clinical contexts:

* **Treatment trials (31 RCTs):** Patients with existing hepatic encephalopathy (HE), including both **overt HE** and **minimal HE**.
* **Prevention trials (7 RCTs):** Patients with cirrhosis at risk for developing HE, including primary and secondary prevention populations.
Subgroup analyses distinguished between:
* Patients with **overt HE**
* Patients with **minimal HE**
* Patients without HE undergoing preventive therapy
---

## **I — Intervention**
The intervention consisted of **nonabsorbable disaccharides (NADs)**:
* **Lactulose**
* **Lactitol**
These agents were used either for:
* **Treatment of established HE**
* **Primary or secondary prevention of HE**
---

## **C — Comparison**
The comparator group consisted of:
* **Placebo**
* **No intervention**
---

## **O — Outcomes**
### **Primary Treatment Outcomes**
In patients with established HE (treatment RCTs):
* **Improvement/resolution of HE**
  * RR = **0.63**
  * 95% CI **0.53–0.74**
  * NNT = **4**

* **Serious liver-related adverse events**
  (liver failure, variceal bleeding, serious infections, spontaneous bacterial peritonitis, hepatorenal syndrome)
  * RR = **0.42**
  * 95% CI **0.26–0.69**
  * NNT = **50**

* **Mortality (overt HE subgroup)**
  * RR = **0.36**
  * 95% CI **0.14–0.94**
  * NNT = **20**

* **Mortality (minimal HE subgroup)**
  * No statistically significant reduction reported

### **Prevention Outcomes**

In primary/secondary prevention trials:
* **Prevention of HE development**
  * RR = **0.47**
  * 95% CI **0.33–0.68**
  * NNT = **6**

* **Reduction in serious liver-related adverse events**
  * RR = **0.48**
  * 95% CI **0.33–0.70**
  * NNT = **6**

* **Mortality reduction**
  * RR = **0.63**
  * 95% CI **0.40–0.98**
  * NNT = **20**
 /InlinePopup   
 InlinePopup label="EBM - Rifaximin with or without Lactulose" title="Evidence Based Medicine" tone="amber" 

[** u Rifaximin for prevention and treatment of hepatic encephalopathy in people with cirrhosis /u **](https://pubmed.ncbi.nlm.nih.gov/37467180/)

## **P — Population**
Adults (n = 4,545) with **hepatic encephalopathy (HE)**—acute (13 trials), chronic (7), minimal (8)—or at risk for HE (13 prevention trials), across 41 RCTs.

---

## **I — Intervention**
* **Rifaximin alone**
* **Rifaximin + nonabsorbable disaccharide (NAD)** (e.g., lactulose/lactitol)

---

## **C — Comparison**
* **Placebo / no intervention**
* **NAD alone**

---

## **O — Outcomes**

### **Mortality**
* Rifaximin vs placebo: RR 0.83 (95% CI 0.50–1.38), I²=0% → no effect
* Rifaximin vs NAD: RR 0.99 (0.49–1.97), I²=0% → no effect
* **Rifaximin + NAD vs NAD:** RR 0.69 (0.55–0.86), NNTB=22, I²=0% → reduced mortality

---

### **Hepatic Encephalopathy (clinical improvement/prevention)**
* Rifaximin vs placebo: RR 0.56 (0.42–0.77), NNTB=5, I²=68%
  * Minimal HE: RR 0.40 (0.31–0.52), NNTB=3
  * Prevention: RR 0.71 (0.56–0.91), NNTB=10
* Rifaximin vs NAD: RR 0.85 (0.69–1.05), I²=0% → little/no effect
* **Rifaximin + NAD vs NAD:** RR 0.58 (0.48–0.71), NNTB=5, I²=62%
 /InlinePopup 
- Address reversible precipitants: Proactive constipation management, avoid hepatotoxic medications and sedatives, prompt infection management, maintain euvolemia and electrolyte balance. 
- Nutrition: Maintain protein intake (1.2–1.5 g/kg/day); avoid restriction.  InlinePopup label="EBM" title="EBM" tone="amber" [** u Efficacy of Nutritional Therapy for Patients With Cirrhosis and Minimal Hepatic Encephalopathy in a Randomized Trial /u **](https://pubmed.ncbi.nlm.nih.gov/26453952/) 
Population (P): 
- Adults with cirrhosis and minimal hepatic encephalopathy (MHE) diagnosed by PHES 
- Tertiary care center, New Delhi, India 
- n = 120 (60 intervention, 60 control) 

Intervention (I): 
- Nutritional therapy for 6 months - 30–35 kcal/kg/day 
- 1.0–1.5 g vegetable protein/kg/day 

Comparison (C): 
- Usual diet (no additional nutritional therapy) 

Outcomes (O) 
– Results: 
     - Reversal of Minimal Hepatic Encephalopathy: 71.1% (intervention) vs 22.8% (control), P = .001 
     - Improvement in PHES score: +3.86 ± 3.58 vs +0.52 ± 4.09, P = .001 
     - Improvement in HRQOL (SIP score): 3.24 ± 3.63 vs 0.54 ± 3.58 improvement, P = .001 
     - Development of overt HE: 10% vs 21.7%, P = .04 No significant baseline differences in PHES or SIP scores 

Study Design: 
     - Randomized controlled trial - 6-month follow-up /InlinePopup 
- Screen for covert HE: In all cirrhosis patients due to impact on quality of life, falls, and driving safety.
- Gastroenterology consultation
- Liver transplant evaluation: HE does not preclude transplantation but signals advanced disease.

## Prognosis

HE marks a transition to decompensated cirrhosis with poor survival outcomes:
- Transplant-free survival of 0.95 years in patients ≥65 vs 2.5 years in patients  65. InlinePopup label="EBM" title="Evidence Based Medicine" tone="amber" 
[Outcomes after hepatic encephalopathy in population-based cohorts of patients with cirrhosis](https://pubmed.ncbi.nlm.nih.gov/32363684/)

## **P — Population**
U.S. adults with **cirrhosis and hepatic encephalopathy (HE)** enrolled in Medicare (20% random sample, 2008–2014), n = 49,164, with Part D coverage. External validation cohort: 2,184 privately insured patients with complete laboratory data.

Key clinical subgroups:
* Age ≥65 vs  65 years
* Presence vs absence of ascites
* Cirrhosis etiologies (including NAFLD)

---

## **I — Exposure / Interventions**
* **Rifaximin use**
* **Lactulose use**
* **Combination lactulose + rifaximin**
* **Gastroenterology consultation**

(Time-varying covariates analyzed using Cox proportional hazards models)

---

## **C — Comparison**
* No rifaximin vs rifaximin
* No lactulose vs lactulose
* Monotherapy vs combination therapy
* No gastroenterology consultation vs consultation

---

## **O — Outcomes**

### **Transplant-Free Survival (Mortality)**
* Median survival:
  * ≥65 vs  65 years: 0.95 vs 2.5 years
  * With vs without ascites: 1.1 vs 3.9 years
* NAFLD (vs other etiologies): HR 1.07 (95% CI 1.02–1.12)
* Gastroenterology consultation: HR 0.73 (95% CI 0.67–0.80)
* Rifaximin use: HR 0.40 (95% CI 0.39–0.42)

---

### **Healthcare Utilization**
**30-day readmissions (per person-year):**
* Gastroenterology consultation: IRR 0.71 (95% CI 0.57–0.88)
* Rifaximin use: IRR 0.18 (95% CI 0.08–0.40)

**Hospital-days:**
* Lactulose alone: IRR 0.31 (95% CI 0.30–0.32)
* Rifaximin alone: IRR 0.49 (95% CI 0.45–0.53)
* Lactulose + rifaximin: IRR 0.28 (95% CI 0.27–0.30) → lowest utilization

---

**Bottom line:** In observational Medicare data, rifaximin and gastroenterology consultation were associated with improved transplant-free survival and fewer readmissions; combination lactulose + rifaximin was associated with the lowest hospital utilization.
 /InlinePopup 
- Survival probability at 28 days: Grade 2 HE 79.8%, Grade 3 74.3%, Grade 4 60.2%. [** u Link /u **](https://pubmed.ncbi.nlm.nih.gov/40971056/)
- Complete reversal of HE --  Associated with better survival (HR 0.271). [** u Link /u **](https://pubmed.ncbi.nlm.nih.gov/40971056/)
- Covert HE --  Associated with increased hospitalization (47% vs 15%), death (18% vs 3%), motor vehicle crashes (17% vs 3%). [** u Link /u **](https://jamanetwork.com/journals/jama/fullarticle/2804599?utm_source=openevidence utm_medium=referral)