Sustained or repetitive muscle contractions result in repetitive movements, twisting or abnormal fixed postures describes which condition?

• A. Myoclonus
• B. Dystonia
• C. Tremor
• D. Rigidity

Answer: (B)

Dystonia is defined by involuntary muscle contractions that are often sustained or occur in brief bursts, producing twisting or repetitive movements and abnormal postures. These contractions can be long-lasting, leading to a fixed or distorted position, or they can come on in bursts that interfere with normal movement. That pattern—twisting or abnormal postures from muscle contractions—is the hallmark of dystonia.

The other options don’t fit as well. Myoclonus involves sudden, brief jerks rather than sustained twisting postures. Tremor is a rhythmic, oscillating movement, not usually associated with persistent abnormal postures. Rigidity refers to a uniform increase in muscle tone with stiffness, typically seen as a constant resistance to movement, without the characteristic twisting postures caused by dystonia.