Which physical examination maneuver is used to assess metabolic encephalopathy?

• A. Asterixis
• B. Romberg
• C. Pronator drift
• D. Heel-to-shin

Answer: (A)

When assessing metabolic encephalopathy, look for asterixis, the characteristic flapping tremor of the hands. This sign appears when the patient extends the arms and keeps the wrists dorsiflexed; shortly after, there are brief, irregular lapses in muscle tone that cause the hands to flap. It reflects fluctuating cortical motor control due to diffuse brain dysfunction from toxins (such as ammonia in hepatic encephalopathy) and is a classic bedside marker of metabolic encephalopathy.

The other maneuvers probe different systems: Romberg tests proprioception and vestibular/cerebellar function by having the patient stand with feet together and eyes closed; pronator drift screens for subtle upper motor neuron weakness; heel-to-shin assesses cerebellar coordination. These are not specifically diagnostic of metabolic encephalopathy, which is why asterixis is the best choice here.