Which condition presents with grip myotonia, facial weakness, and cardiac conduction anomalies?

Myotonic dystrophy is characterized by distinctive clinical features including grip myotonia, which is the inability to relax muscle grip after contraction, and facial weakness, which can lead to a characteristic appearance involving ptosis (drooping eyelids) and difficulty with facial expressions. In addition to these muscle-related symptoms, myotonic dystrophy is also associated with cardiac conduction anomalies, which can lead to arrhythmias and other heart-related issues.

The presence of all three symptoms—grip myotonia, facial weakness, and cardiac conduction problems—strongly indicates myotonic dystrophy as the diagnosis, making it crucial to consider this condition in clinical evaluations when these symptoms are observed.

Other conditions listed present differently. Becker muscular dystrophy primarily affects proximal muscle strength with delayed onset and does not typically feature myotonia or significant facial weakness early in the disease. Duchenne muscular dystrophy predominantly affects the lower limbs and leads to significant muscle wasting and weakness but does not typically present with myotonia or cardiac arrhythmias as primary features. Spinal muscular atrophy type 1 involves severe weakness and atrophy of skeletal muscles but lacks the characteristic grip myotonia and facial weakness associated with myotonic dystrophy.