Easy fatigability of muscles seen in:
**Core Concept**
Easy fatigability of muscles is a clinical manifestation associated with various neuromuscular disorders. It is characterized by the rapid onset of muscle weakness and fatigue, often after minimal physical exertion. This symptom is typically seen in conditions that affect the neuromuscular junction, muscle membrane, or muscle fibers themselves.
**Why the Correct Answer is Right**
The correct answer is associated with myasthenia gravis, a chronic autoimmune disorder that affects the neuromuscular junction. In myasthenia gravis, antibodies target and destroy the nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction, leading to impaired muscle contraction and easy fatigability. The lack of functional nAChRs results in reduced acetylcholine binding and subsequent muscle weakness.
**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as no information was provided.
**Option B:** Not correct, as this option does not directly relate to easy fatigability of muscles.
**Option C:** Incorrect, as this option does not accurately describe a condition associated with easy fatigability of muscles.
**Clinical Pearl / High-Yield Fact**
Myasthenia gravis is often triggered by medications that block acetylcholine receptors, such as aminoglycoside antibiotics and certain anesthetics. Patients with myasthenia gravis may also experience ptosis, diplopia, and difficulty swallowing.
**Correct Answer: D. Myasthenia gravis**