myasthenia

1. Abnormal muscular weakness or fatigue.
2. Myasthenia gravis.

1. Abnormal muscular weakness or fatigue.
2. Myasthenia gravis.

Primary skeletal muscle weakness in the absence of nervous system lesions or myositis or myodystrophy. For the most part the weakness is reversible or temporary. Examples amongst animal diseases are myasthenia gravis, hypocalcemia, hypopotassemia, hypoglycemia, and many plant toxins that cause the so-called staggers syndromes in food animals.

• angiosclerotic m. — excessive muscular fatigue due to vascular changes; intermittent claudication.
• m. gastrica — weakness and loss of tone in the muscular coats of the stomach; atony of the stomach.
• m. gravis — a syndrome of muscular weakness that is aggravated by activity and relieved by rest. There is no muscular atrophy or loss of sensation. Affected dogs and cats show predominantly episodic weakness, but various other manifestations, such as laryngeal paralysis, dysphagia and megaesophagus, may also be seen. Clinical signs are rapidly reversed by anticholinesterase drugs and this is used as a diagnostic test for the disease. It may be congenital or acquired as an autoimmune disease, inherited in some breeds.
• paraneoplastic m. gravis — seen in association with neoplasms and other lesions of the thymus.

The noun has 2 meanings:

Meaning #1: a chronic progressive disease characterized by chronic fatigue and muscular weakness (especially in the face and neck); caused by a deficiency of acetylcholine at the neuromuscular junctions
  Synonym: myasthenia gravis

Meaning #2: any muscular weakness