encephalopathy

Encephalopathy is a broad medical term used to describe diffuse brain dysfunction that alters mental status, cognition, or level of consciousness. It is not caused by a focal structural lesion, though symptoms can be mixed with focal signs. Encephalopathy reflects injury or dysfunction of brain function from metabolic, toxic, infectious, inflammatory, or hypoxic mechanisms and is often a secondary manifestation of another underlying condition.

Common categories include metabolic and toxin-induced encephalopathies (such as liver failure with hyperammonemia, severe electrolyte disturbances, hypoglycemia, uremia, or drug/toxin exposure), hypoxic-ischemic encephalopathy after insufficient cerebral perfusion or oxygen delivery, septic or inflammatory encephalopathy associated with severe infection or systemic inflammation, and autoimmune encephalopathies. In some cases the exact cause remains unidentified after initial evaluation.

Specific forms frequently discussed include hepatic encephalopathy, septic encephalopathy, hypoxic-ischemic encephalopathy, uremic encephalopathy, and neonatal encephalopathy related to perinatal asphyxia. The term may be used more broadly when clinical evaluation cannot immediately pinpoint a single cause.

Diagnosis relies on clinical assessment of altered consciousness and cognitive function, followed by laboratory tests to identify precipitants (liver and kidney function, electrolytes, glucose, toxins, infectious markers). Imaging, typically CT or MRI, is used to exclude focal structural lesions. EEG can reveal diffuse slowing consistent with encephalopathy, particularly when the cause is unclear. Specific tests, such as serum ammonia measurement, can help diagnose hepatic encephalopathy.

Management emphasizes treating the underlying cause and providing supportive care. This includes airway and hemodynamic support, correction of metabolic derangements, and appropriate antimicrobial or detoxification therapies as indicated. In hepatic encephalopathy, lactulose and rifaximin are used to reduce intestinal ammonia production. Prognosis varies with the etiology, severity, and timeliness of treatment.