What is a common sign found in patients with myotonic muscular dystrophy involving the face?

In myotonic muscular dystrophy, a prominent sign is the loss of facial expression, which results from the weakness of the facial muscles. This muscular impairment leads to a characteristic appearance where individuals may have difficulty smiling, frowning, or exhibiting other facial movements, making their face appear less animated or "mask-like."

The absence or reduction of facial expression is indicative of the muscle weakness associated with the disease, which impacts not only voluntary movements but also involuntary muscle actions over time. This can significantly affect social interactions and emotional expression, contributing to the challenges faced by patients.

Other options, such as facial edema, facial drooping, or facial hyperactivity, do not accurately capture the typical presentation seen in myotonic muscular dystrophy and are not consistent with the expected symptoms associated with this condition.