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Wernicke’s Encephalopathy
- Acutely reversible neurologic syndrome due to thiamine (B1) deficiency.
- Commonly seen in alcoholics, malnourished patients, and those with a history of bariatric surgery.
Clinical Presentation
- Classic triad:
- Ataxia – impaired coordination and gait instability.
- Ophthalmoplegia – weakness or paralysis of the eye muscles.
- Confusion – disorientation and cognitive impairment.
- May progress to Korsakoff syndrome (irreversible amnesia, confabulation).
Labs, Studies & Imaging
- MRI: Mammillary body atrophy (late finding).
- Clinical diagnosis; thiamine levels may be low but are not required for diagnosis.
Treatment & Management
- IV thiamine BEFORE glucose
- Prevents lactic acidosis due to poor glucose metabolism without thiamine.
- Nutritional rehabilitation.
High-Yield Facts
- Always suspect in altered mental status in alcoholics or malnourished patients.
- Giving glucose before thiamine can worsen symptoms.
Hepatic Encephalopathy
- Brain dysfunction due to accumulated ammonia and neurotoxins in liver failure.
- Triggers: GI bleeding, infection, dehydration, sedatives.
Clinical Presentation
- Altered mental status
- Asterixis – flapping tremor of the hands.
- Hyperreflexia – exaggerated deep tendon reflexes.
Labs, Studies & Imaging
- Serum ammonia: Often elevated but does not correlate with severity.
- Liver function tests (LFTs): May show elevated AST/ALT, bilirubin, and INR.
- Electrolytes: Hypokalemia and metabolic alkalosis can worsen symptoms.
- CT/MRI brain: Used to rule out structural causes if diagnosis is unclear.
Treatment & Management
- Lactulose (first-line, reduces ammonia absorption).
- Rifaximin (second-line, reduces ammonia-producing gut bacteria).
- Correct underlying cause (e.g., treat infection, stop sedatives).
High-Yield Facts
- Asterixis is a hallmark finding and strongly suggests hepatic encephalopathy.
- Ammonia level alone does not diagnose hepatic encephalopathy—clinical correlation is key.
Toxic & Metabolic Encephalopathy
- Encephalopathy secondary to systemic illness, metabolic derangements, or toxins.
- Common causes: Hypoglycemia, hyperglycemia, hypoxia, uremia, drug overdose (opioids, benzodiazepines), sepsis.
Clinical Presentation
- Fluctuating altered mental status
- Hyperreflexia – exaggerated deep tendon reflexes.
- Myoclonus – sudden, brief involuntary muscle jerks.
Labs, Studies & Imaging
- EEG: Generalized background slowing is the classic finding for metabolic encephalopathy. Triphasic waves may be seen in hepatic or uremic encephalopathy.
- CMP: Check for glucose, sodium, potassium, calcium, and renal/liver function abnormalities.
- ABG: May show acidosis, hypoxia, or hypercapnia depending on etiology.
- Toxicology screen: Identify potential drug or toxin exposure.
- Blood cultures: Consider if sepsis is suspected as a cause.
- CT/MRI brain: Rule out structural pathology if presentation is unclear.
Treatment & Management
- Address underlying cause (e.g., correct glucose, oxygen, electrolytes).
- Supportive care.
High-Yield Facts
- EEG background slowing is the classic finding in metabolic encephalopathy.
- Always correct reversible causes first (oxygen, glucose, electrolytes).
Uremic Encephalopathy
- Occurs in advanced renal failure due to accumulation of uremic toxins.
- Common in patients with end-stage renal disease (ESRD) who are not receiving adequate dialysis.
Clinical Presentation
- Altered mental status
- Asterixis – flapping tremor of the hands.
- Myoclonus – sudden, brief involuntary muscle jerks.
- Seizures – may occur in severe cases.
Labs, Studies & Imaging
- Elevated BUN and creatinine – hallmark of renal failure (typically BUN > 100 mg/dL, creatinine > 10 mg/dL in severe cases).
- Electrolyte abnormalities – hyperkalemia, metabolic acidosis, hypocalcemia.
- EEG – May show generalized slowing or triphasic waves.
Treatment & Management
- Urgent dialysis – definitive treatment.
- Electrolyte correction – address hyperkalemia, acidosis, and calcium imbalance.
- Seizure management – if present, treat with antiepileptic drugs.
High-Yield Facts
- Uremic encephalopathy resolves with dialysis.
- Triphasic waves on EEG may be seen but are not specific.
Hypertensive Encephalopathy
- Severe hypertension leading to cerebral edema and dysfunction.
- Part of hypertensive emergency spectrum.
Clinical Presentation
- Severe headache
- Altered mental status
- Vomiting
- Seizures
- Papilledema – optic disc swelling due to increased intracranial pressure.
Labs, Studies & Imaging
- CT head: Rule out stroke, hemorrhage.
Treatment & Management
- Lower BP gradually with IV medications (nicardipine, labetalol, clevidipine). Nitroprusside is generally avoided due to risk of rapid BP drop and cyanide toxicity.
- Avoid rapid BP drops to prevent ischemia.
High-Yield Facts
- BP must be severely elevated (typically >180/120 mmHg) to cause symptoms.
