From the Research
Asterixis in the lower limb is most commonly caused by metabolic encephalopathy, with liver failure, uremia, respiratory failure, and electrolyte disturbances being the primary underlying causes, as supported by the most recent and highest quality study 1. The cause of asterixis in the lower limb can be attributed to various factors, including:
- Metabolic encephalopathy, which is the most common cause, resulting from liver failure, uremia, respiratory failure, or electrolyte disturbances
- Focal brain lesions, which can cause unilateral asterixis, as seen in studies 2, 3, 4
- Other structural brain lesions, such as ischemic or hemorrhagic disorders, which can also lead to asterixis 4 However, it is essential to note that the most recent and highest quality study 1 suggests that metabolic encephalopathy is the primary cause of asterixis in the lower limb. The pathophysiology of asterixis involves the disruption of normal motor control pathways, particularly the reticular activating system in the brainstem, due to the accumulation of toxins in the bloodstream 5. To assess for lower limb asterixis, the patient should be positioned supine with hips and knees flexed and feet dorsiflexed, and the examiner should observe for brief, irregular downward movements of the feet. Treatment of asterixis in the lower limb focuses on addressing the underlying cause, such as:
- Lactulose for hepatic encephalopathy
- Dialysis for uremia
- Correction of electrolyte abnormalities
- Improving ventilation for respiratory failure It is crucial to investigate metabolic causes, particularly in patients with known liver or kidney disease, as asterixis in the lower limbs carries the same clinical significance as hand asterixis.