Which sign is defined by an inability to perform rapid alternating movements?

• A. Inability to perform rapid alternating movements
• B. Inability to judge distance or range of movement
• C. Rhythmic, quick oscillatory eye movements
• D. Decreased muscle tone

Answer: (A)

Rapid alternating movements require precise timing and coordination between opposing muscles, a function mainly governed by the cerebellum. When this system is impaired, the sign that emerges is dysdiadochokinesia—the inability to perform rapid, alternating movements smoothly and quickly (for example, trouble with rapid pronation-supination of the forearm). This is why the described symptom—an inability to perform rapid alternating movements—best fits the sign being tested. The other signs point to different cerebellar or neuromuscular issues (dysmetria reflects impaired distance judgment; nystagmus involves rhythmic eye movements; hypotonia is decreased muscle tone) and do not specifically describe the RAM problem.