Hepatic Encephalopathy

Hepatic Encephalopathy 

Hepatic encephalopathy (HE) is a brain dysfunction caused by liver insufficiency and/or portosystemic shunting, producing a spectrum ranging from subtle cognitive impairment to coma.

HE is a clinical syndrome, not a diagnosis made by ammonia alone.HE is a diagnosis of exclusion.

DEFINITION

HE is a syndrome of neurological and psychiatric abnormalities occurring in patients with liver dysfunction and/or portosystemic shunting.

Three major clinical settings

CLASSIFICATION OF HEPATIC ENCEPHALOPATHY

• Type A — due to Acute liver failure
• Type B — due to Portosystemic shunting without any liver disease (rare).
• Type C — CirrhosisThe most common clinical setting.Type C HE may be:covert,episodic,recurrent,persistent.

West Haven grade 

PATHOPHYSIOLOGY

The old concept:”Ammonia causes hepatic encephalopathy.”

is incomplete.

The modern understanding is:

Ammonia + astrocyte dysfunction + neuroinflammation + altered neurotransmission + gut microbiome + portosystemic shunting + systemic inflammation + impaired cerebral energy metabolism.

AMMONIA — CENTRAL PLAYER

The liver normally removes ammonia through:Urea cycle

Ammonia → urea → urinary excretion.

And:

Glutamine synthesis

NH₃ + glutamate → glutamine

primarily in:

• liver
• skeletal muscle
• brain

WHY AMMONIA RISES IN CIRRHOSIS

Several mechanisms contribute.

1. Reduced hepatic detoxification

Damaged hepatocytes have reduced capacity for ammonia metabolism.

2. Portosystemic shunting

Blood bypasses the liver.

Therefore: Portal ammonia → systemic circulation → brain

3. Increased intestinal ammonia production

Sources include:

• bacterial urease activity
• intestinal glutamine metabolism
• GI bleeding

4. Reduced skeletal muscle buffering

Skeletal muscle converts:

NH₃ → glutamine

Sarcopenia therefore worsens HE.

This is clinically important:

Muscle is an important extrahepatic ammonia-detoxifying organ.

Hence severe sarcopenia increases susceptibility to HE.

AMMONIA AND THE BRAIN

Ammonia crosses the blood-brain barrier.

Astrocytes are particularly important because they express glutamine synthetase.

Inside astrocytes:

Glutamate + NH₃ → glutamine

Excess ammonia therefore causes:

↑ glutamine accumulation inside astrocytes

which contributes to:

• osmotic swelling,astrocyte dysfunction,altered neurotransmission

which contributes to:

• cerebral edema
• intracranial hypertension
• brain herniation

In chronic cirrhosis, the brain adapts more gradually, so massive cerebral edema is less typical.

MANGANESE

Chronic liver disease may cause:

manganese accumulation in the basal ganglia

MRI :Bilateral, symmetric T1 hyperintensity of the globus pallidus and substantiae nigrae.

This can be associated with:

• extrapyramidal symptoms
• parkinsonism
• cognitive abnormalities

PRECIPITANTS OF HE

When a cirrhotic patient develops acute confusion:Do not simply label it “hepatic encephalopathy.” Search for the precipitant.

CLINICAL FEATURES

HE can affect almost every aspect of neurological function.

Cognitive

• impaired attention
• poor concentration
• memory impairment
• slowed thinking
• impaired executive function
• disorientation

Behavioral

• irritability
• apathy
• inappropriate behavior
• personality change
• aggression
• euphoria
• anxiety

Sleep

Common:

• daytime sleepiness
• nighttime insomnia
• reversal of sleep–wake cycle

NEUROMUSCULAR FEATURES

Asterixis

Classic feature.

It is actually:negative myoclonus rather than a true tremor.

The patient cannot maintain a sustained posture, causing brief lapses of muscle contraction.

How to elicit

Ask patient to:

1. extend arms
2. dorsiflex wrists
3. spread fingers

Observe for:

brief irregular flapping movements.

Asterixis can also occur in:

• hypercapnia
• uremia
• drug toxicity

Therefore:

Asterixis is not pathognomonic for HE.

OTHER NEUROLOGICAL FEATURES

• dysarthria
• hyperreflexia
• increased muscle tone
• hyporeflexia in severe disease
• extrapyramidal signs
• parkinsonism
• ataxia
• impaired coordination
• rarely seizures

DIAGNOSIS

There is no single diagnostic test for HE.

Diagnosis is essentially:

Clinical diagnosis + liver disease/portosystemic shunting + exclusion of alternative causes + identification of precipitant.

AMMONIA

Serum ammonia should NOT be used as a stand-alone diagnostic test for HE Because:

High ammonia does not prove HE.

Many patients with cirrhosis have elevated ammonia without clinical encephalopathy.

And:Normal ammonia does not completely exclude HE.

However:A normal ammonia level should prompt reconsideration of the diagnosis, particularly if the clinical picture is atypical.

• Ideally, obtain an ammonia level in a fasted patient.Ammonia levels may fluctuate considerably over time (e.g., increasing after a meal).
• Avoid venous stasis (tourniquet, fist clenching).
• Sample can either be venous or arterial 

DIAGNOSTIC PARACENTESIS

In a patient with:cirrhosis + ascites + new HE

you should have a low threshold for diagnostic paracentesis.

Why?

Because:SBP may present with HE without prominent abdominal symptoms.

Ascitic fluid should generally include:

• cell count
• PMN count
• culture

SBP is diagnosed when:ascitic PMN ≥250 cells/mm³

even if culture is negative.

WHEN TO IMAGE THE BRAIN(to exclude alternative pathology)

Routine CT brain is not mandatory for every classic episode of HE.

But neuroimaging should be strongly considered when there is:

• focal neurological deficit
• Head trauma
• Seizure(they are uncommon due to hepatic encephalopathy, seizures should prompt to find other cause)
• severe unexplained deterioration
• atypical presentation
• first episode without clear explanation
• Concern for intracranial hemorrhage
• Anticoagulant use
• failure to improve with treatment

EEG

EEG is useful when considering:

• nonconvulsive status epilepticus
• unexplained persistent coma
• atypical neurological presentation
• Hepatic encephalopathy typically produces a triphasic wave pattern but EEG findings are not specific.

DIFFERENTIAL DIAGNOSIS OF ALTERED SENSORIUM IN CIRRHOSIS

Management

Step 1 — ABC

Assess:

• airway
• oxygenation
• ventilation
• circulation

Grade III–IV HE

Consider early airway protection if:

• inability to protect airway
• recurrent aspiration
• severe hypoxemia
• hypercapnia
• inability to handle secretions
• deep coma

STEP 2 — CHECK GLUCOSE IMMEDIATELY

Hypoglycemia can mimic HE.Always perform:bedside glucose.

STEP 3 — SEARCH FOR PRECIPITANTS

Infection

• CBC
• cultures when indicated
• urine analysis/culture
• chest imaging
• diagnostic paracentesis if ascites

GI bleeding

Look for:melena,hematemesis,hematochezia,falling Hb,BUN rise

Electrolytes

Check:Na,K,Mg,Ca,bicarbonate.

Renal-urea,creatinine,urine output.

Medication review

Specifically ask:

• benzodiazepines?
• opioids?
• sedatives?
• diuretics?
• recent medication changes?

LACTULOSE

First-line therapy for overt HE

Lactulose is a nonabsorbable disaccharide.

It reaches the colon and is metabolized by bacteria.

Its effects include:

• acidification of colonic contents
• conversion of NH₃ → NH₄⁺
• reduced ammonia absorption
• cathartic effect
• altered gut microbiota

LACTULOSE DOSING

For acute overt HE:

Oral/NG—25 mL approximately every 2 hours

until the patient has bowel movements and clinical improvement.

Then titrate downwards 30 ml Q6hr .

Maintenance target : approximately 2–3 bowel movements daily.

LACTULOSE ENEMA

Useful when the patient:

• cannot receive enteral medication
• ileus

Lactulose 300 mL + water 700 mL→ Total volume = 1,000 mL

• Administer as a retention enema
• Ideally retain for 30–60 minutes
• Can be repeated every 4–6 hours initially if needed, depending on clinical response and bowel movements.

IMPORTANT LACTULOSE PRINCIPLE

• Too little lactulose:→ persistent HE.
• Too much lactulose:→ diarrhea→ dehydration→ hypokalemia→ hypernatremia→ worsened HE.
• Therefore:Lactulose should be titrated to clinical response, not given indefinitely at maximal doses.

PEG in acute hepatic encephalopathy

Typical regimen studied:

• PEG 3350–electrolyte solution 4 L PO/NG as a single dose, usually over ~30–120 min.
• A meta-analysis of 4 trials (229 patients) also found faster HE resolution with PEG than lactulose.
• AASLD/EASL guidelines designate lactulose as first choice for episodic overt HE and note that PEG evidence needed further validation; more recent evidence supports PEG as an effective option for rapid catharsis, but it has not replaced lactulose as the conventional first-line therapy.

RIFAXIMIN

Rifaximin is a minimally absorbed oral antibiotic.

It modifies intestinal bacterial flora and reduces production of gut-derived neurotoxins.

Dose—550 mg orally twice daily

The strongest evidence is for:Secondary prevention of recurrent HE.

It is particularly useful in patients who have:

• recurrent overt HE
• persistent/recurrent episodes despite lactulose

Sedation

Use-Dexmedetominie>>Propofol

Wernicke Encephalopathy in Cirrhosis

• Patients with cirrhosis are at risk of thiamine deficiency due to alcohol use, malnutrition, or poor oral intake.
• Wernicke encephalopathy (WE) may coexist with hepatic encephalopathy (HE), and clinical differentiation can be difficult, particularly in an obtunded patient.
• There is no rapid diagnostic laboratory test that reliably excludes WE; thiamine levels are not useful for acute decision-making.
• Classic features of WE are altered mental status, ocular abnormalities (nystagmus/ophthalmoplegia), and ataxia, but the classic triad is often incomplete and may be difficult to assess in critically ill patients.
• Therefore, when WE is suspected, empiric IV thiamine should be given without waiting for laboratory confirmation.
• Treatment: Thiamine 500 mg IV every 8 hours, typically for 2–3 days, followed by lower-dose IV/oral thiamine depending on clinical response and nutritional status.
• Give thiamine before or with glucose when feasible, but do not delay necessary glucose administration in hypoglycemia.

PROBIOTICS

Probiotics/synbiotics may influence:

• gut microbiota
• bacterial urease activity
• intestinal inflammation

Some studies show improvement in minimal/covert HE.

However:They are not substitutes for lactulose/rifaximin in standard management of overt HE.

L-ORNITHINE L-ASPARTATE — LOLA

LOLA provides substrates for ammonia detoxification through:

• urea cycle
• glutamine synthesis

It may reduce ammonia levels and improve HE in some studies.

However, practice varies by region and evidence quality.

It is not the central first-line treatment in major Western guidelines.

BRANCHED-CHAIN AMINO ACIDS

BCAA supplementation may be considered in selected patients, particularly when:

• protein intake is inadequate
• oral/enteral protein is poorly tolerated
• malnutrition/sarcopenia is present

Important:Protein restriction should generally be avoided.

PROTEIN RESTRICTION

Do NOT routinely restrict protein.

Protein restriction causes:

• muscle catabolism
• sarcopenia
• reduced skeletal muscle ammonia detoxification

This can actually worsen the tendency to HE.

A commonly recommended target in cirrhosis is approximately:

1.2–1.5 g/kg/day

with emphasis on:

• vegetable protein
• dairy protein
• adequate total calories
• frequent meals
• late-evening snack

WHY VEGETABLE/DAIRY PROTEIN MAY HELP

Compared with large amounts of red meat, vegetable/dairy protein may be associated with:

• better tolerance
• favorable gut microbiome effects
• increased fiber
• lower ammonia generation in some contexts

But the most important principle remains:Adequate protein intake.

TIPS AND HEPATIC ENCEPHALOPATHY

TIPS decreases portal pressure by creating a portosystemic shunt.

But:portal blood bypasses hepatic detoxification.

Therefore TIPS can increase:systemic ammonia exposure → HE

POST-TIPS HE Management:

First—Treat conventional precipitants.

Then—Optimize:

• lactulose
• rifaximin
• nutrition

Refractory severe HE

Consider evaluation for:

TIPS reduction/occlusion in selected patients

with careful assessment of portal hypertension consequences.

LARGE SPONTANEOUS PORTOSYSTEMIC SHUNTS

Some patients have large spontaneous shunts such as:

• splenorenal shunts
• gastrorenal shunts
• other mesocaval shunts

These can cause:

recurrent/refractory HE despite apparently reasonable liver function.

In selected patients, interventional shunt embolization can be considered.

REFRACTORY HE

Think of refractory HE when there are:

• repeated episodes
• persistent HE despite appropriate therapy
• no correctable precipitant
• adherence to lactulose/rifaximin
• large portosystemic shunt
• TIPS-associated HE

Evaluation should include:

1. medication review
2. infection
3. GI bleeding
4. renal dysfunction
5. electrolytes
6. constipation
7. nutritional status
8. TIPS evaluation
9. spontaneous portosystemic shunts
10. transplant candidacy

LIVER TRANSPLANTATION

For patients with:

• recurrent overt HE
• decompensated cirrhosis
• other complications of portal hypertension
• worsening liver function

HE is an important marker of decompensated liver disease.

Liver transplantation can definitively correct the underlying hepatic failure in appropriate candidates.

HEPATIC ENCEPHALOPATHY IN ACUTE LIVER FAILURE

This deserves a separate section.Acute liver failure is:Acute severe hepatic injury + coagulopathy + encephalopathy in a patient without pre-existing cirrhosis.

HE in ALF is a neurological emergency.

WHY ALF HE IS DIFFERENT

The major danger is:Cerebral edema

Mechanism:

massive ammonia accumulation → astrocyte glutamine accumulation → astrocyte swelling → cerebral edema → intracranial hypertension

This can progress to:

• reduced cerebral perfusion
• brain herniation
• death

CIRRHOTIC HE vs ALF HE

MANAGEMENT OF CEREBRAL EDEMA IN ALF

• Head elevation 30° with neutral head position.
• Avoid hypoxemia
• Avoid hypercapnia(causes cerebral vasodilation)
• Avoid fever
• Control severe agitation
• Hyperosmolar therapy May include:mannitol,hypertonic saline

depending on clinical circumstances and ICU protocol.

MANNITOL

For established intracranial hypertension in ALF:

mannitol may be used when appropriate.

Renal function and serum osmolality must be considered.

HYPERTONIC SALINE

Hypertonic saline can be used to raise serum sodium in selected ALF patients at high risk of cerebral edema.

The objective is not to produce extreme hypernatremia.

It is a carefully controlled neurocritical-care intervention.

MEAL PATTERN

Prefer:

• frequent meals
• small meals
• late evening carbohydrate/protein snack

This helps reduce:

overnight fasting → muscle catabolism → amino acid breakdown → ammonia production.

WHAT NOT TO DO

❌ Don’t diagnose HE solely from ammonia.

❌ Don’t chase a normal ammonia level as the treatment target.

❌ Don’t routinely restrict protein.

❌ Don’t give excessive lactulose causing diarrhea.

❌ Don’t ignore infection.

❌ Don’t assume every altered cirrhotic patient has HE.

❌ Don’t forget SBP evaluation in an appropriate patient with ascites.

❌ Don’t miss GI bleeding.

❌ Don’t forget intracranial pathology.

❌ Don’t continue unnecessary benzodiazepines/opioids.