Which symptom is typically associated with myasthenia gravis as evidenced by reduced arm muscle strength with repetitive movement?

Myasthenia gravis is characterized by weakness and rapid fatigue of voluntary muscles, particularly when these muscles are used repeatedly. This weakness is due to an autoimmune response that targets the acetylcholine receptors at the neuromuscular junction, leading to impaired communication between nerves and muscles.

In this context, preserved deep tendon reflexes are significant because, while the voluntary muscle strength diminishes with repetitive use, the reflex arcs remain intact. This means that although a patient may exhibit weakness in their arms after performing repetitive tasks, the reflex actions elicited by tapping the tendon are still functional and demonstrate that the underlying nervous system pathways are operational.

The presence of preserved deep tendon reflexes contrasts with the other choices. Hyperreflexia would indicate an upper motor neuron issue, which is not typically observed in myasthenia gravis. Loss of sensation suggests a sensory nerve issue rather than a neuromuscular one, and increased muscle mass is not a hallmark feature of myasthenia gravis; in fact, muscle atrophy may occur due to disuse as a result of weakness.

Thus, preserved deep tendon reflexes highlight that while there is diminished strength in voluntary muscle activities, the basic reflex mechanisms remain functional, supporting the diagnosis of myas