Which statement about myokymia is NOT true?

• A. It is characterized by unilateral eyelid twitching
• B. It commonly affects the orbicularis oculi only
• C. It is commonly caused by stress
• D. It is characterized by unilateral eyelid forced closure

Answer: (D)

The key idea is the nature of myokymia: it is a benign, intermittent flutter or twitch of the eyelid muscles, usually confined to one eye and most often involving the orbicularis oculi, driven by transient irritants like fatigue or stress. This twitching is typically mild and does not cause the eye to be forcibly closed. The statement describing unilateral eyelid forced closure describes a pattern more like blepharospasm, where there are repeated, involuntary contractions strong enough to tightly close the eyelids. The other statements fit myokymia well: it commonly presents as unilateral eyelid twitching; the orbicularis oculi is the primary muscle involved; and stress is a common precipitating factor.