From the Guidelines
The workup for asterixis should focus on identifying the underlying cause, as it is a neurological sign rather than a diagnosis itself, and should include a clinical and paraclinical work-up to exclude a differential or associated diagnosis, as suggested by the experts in the 2023 French recommendations for the diagnosis and management of hepatic encephalopathy 1.
Key Components of the Workup
The workup should begin with a thorough history and physical examination, paying particular attention to:
- Liver disease
- Kidney failure
- Respiratory disorders
- Medication use
Laboratory Tests and Imaging Studies
Laboratory tests should include:
- A comprehensive metabolic panel to assess liver function (ALT, AST, bilirubin, albumin)
- Kidney function (BUN, creatinine, GFR)
- Electrolytes (particularly sodium, potassium, calcium, and magnesium)
- Arterial blood gases to evaluate for respiratory failure or acid-base disturbances
- Ammonia levels if hepatic encephalopathy is suspected Imaging studies such as brain CT or MRI may be warranted if structural neurological causes are suspected.
Additional Testing and Management
Additional testing may include:
- Toxicology screening
- Thyroid function tests
- Vitamin B1 levels depending on clinical suspicion
- Electroencephalography (EEG) can be helpful in cases where metabolic encephalopathy is present Management should target the underlying cause, such as lactulose and rifaximin for hepatic encephalopathy, dialysis for uremic encephalopathy, or correction of electrolyte abnormalities, as recommended by the 2014 practice guideline by the American Association for the Study of Liver Diseases and the European Association for the Study of the Liver 1.
Asterixis and Its Significance
Asterixis occurs due to impaired function of the cerebral cortex, diencephalon, or upper brainstem, resulting in lapses of sustained muscle contraction, typically manifesting as brief, irregular lapses of posture, most commonly observed in the outstretched hands, and is a key sign to investigate in the workup for hepatic encephalopathy, as suggested by the experts in the 2023 French recommendations 1.
From the Research
Workup for Asterixis
The workup for asterixis involves a thorough evaluation to determine the underlying cause of this clinical sign.
- Asterixis can result from varied causes, including medications, renal disorder, hepatic dysfunction, pulmonary insufficiency, stroke, and other brain lesions 2.
- A careful search for predisposing factors, such as underlying infection, gastrointestinal bleeding, electrolyte disturbances, hepatocellular carcinoma, dehydration, hypotension, and excessive use of benzodiazepines, psychoactive drugs, or alcohol, is essential in patients presenting with overt hepatic encephalopathy 3.
- The evaluation should also include a review of the patient's medical history, physical examination, and laboratory tests to identify potential causes of asterixis.
Clinical Significance
Asterixis is an important clinical sign that can indicate a range of underlying conditions, including hepatic encephalopathy, renal disorder, and structural brain lesions.
- The presence of asterixis can be associated with a poor prognosis, particularly in patients with hepatic encephalopathy, where 1-year mortality rates are almost 60% 3.
- The clinical significance of asterixis lies in its ability to indicate the presence of an underlying condition that requires prompt medical attention.
Patterns and Presentations
Asterixis can occur in various patterns and presentations, including: