Which phenomenon involves irregular, shocklike contractions that may be generalized or focal, not arising from the basal ganglia, and can persist during sleep or coma?

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

Answer: (D)

Myoclonus is characterized by sudden, brief, shocklike contractions of muscles. These jerks can be generalized or focal and arise from generators in the cortex, brainstem, or spinal cord rather than the basal ganglia, which is why they can persist during sleep or even in coma. This capacity to continue across sleep-wake states reflects the multiple levels at which myoclonus can originate.

Dystonia involves sustained or repetitive muscle contractions that produce abnormal postures or twisting movements, not brief shocks. Tremor is rhythmic, oscillatory movement, lacking the abrupt, irregular jerks typical of myoclonus. Akathisia presents as subjective restlessness with a compulsion to be in motion, not sudden muscle jerks.