Which term best describes a syndrome of involuntary muscle contractions that cause twisting or abnormal postures?

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

Answer: (A)

Dystonia is the term that fits this description because it involves involuntary muscle contractions that produce abnormal, often twisting postures or repetitive movements. These contractions can be sustained or occur in bursts, leading to the characteristic twisting and abnormal positions seen in dystonia. This pattern is what distinguishes dystonia from other motor phenomena: tremor is mainly rhythmic, oscillatory movement; rigidity is a general increase in muscle tone causing stiffness; and a spasm is a sudden, brief cramp-like contraction. Dystonia can affect one area or multiple areas and may be task-specific, such as writer’s cramp or cervical dystonia, illustrating how the abnormal, patterned muscle activation creates the distinctive postures.