Also known as “flapping hand tremor,” asterixis is a neurologic condition in which a person loses motor control typically in the fingers and wrists. It is a clinical sign that describes a patient’s inability to maintain a sustained posture marked by brief, irregular, involuntary jerking movements (Rasiz & Savio, 2021).
How to Assess for Asterixis
The most common way to assess for asterixis is by asking the patient to hold out both arms like they are going to “stop traffic,” wrists dorsiflexed, fingers spread, and their eyes closed. Observe for 30 seconds and watch for an abnormal “flapping” tremor at the wrist. Another way to assess for asterixis is by placing the patient in the dorsal recumbent position (supine with their knees bent up in an outward position with the feet flat) and then allowing the knees to fall to the sides. The presence of “flapping” at the hip joint indicates asterixis (Rasiz & Savio, 2021).
Causes of Asterixis
Asterixis is caused by an abnormaility of the diencephalic motor centers that regulate agonist and antagonist mucle tone, posture and muscle movement (Bickley et al., 2021). Exactly how or why it happens is still unknown. It can occur unilaterally or bilaterally and can be irregular in frequency and severity. Bilateral asterixis is associated with metabolic encephalopathy, particularly related to liver disease, and may be present in patients with cardiac and respiratory failure (hypercapnia), uremia, electrolyte abnormalities (i.e., hypoglycemia, hypokalemia, and hypomagnesemia), and drug toxicity. High blood levels of phenytoin, benzodiazepines, barbiturates, valproate, gabapentin, carbazemine, lithium, deftazidime, and metoclopramide can also cause asterixis (Rasiz & Savio, 2021). Unilateral asterixis is typically caused by a brain lesion in the thalamus, midbrain, parietal cortex, or frontal cortex.
Treatment for Asterixis
Asterixis is a condition for which there is no specific treatment. Instead, treatment focuses on managing the underlying cause, such as correcting electrolyte imbalance, hypercapnia or drug toxicity.
Bickley, L. S., Szilagyi, P. G., Hoffman, R. M., & Soriano, R. P. (2021). Bate’s Guide to Physical Examination and History Taking (13th ed.). Wolters Kluwer Health: Philadelphia.
Rasiz, Z. & Savio, J. (2021, July 31). Asterixis. StatPearls [Internet].