Myasthenia gravis

Question 1

Definition

Answer 1

characterised by weakness and rapid fatigue of any muscles under voluntary control.

Question 2

Aetiology

Answer 2

Aetiology:
– caused by a breakdown in the normal communication between nerves and muscles
- Antibodies:
— your nerves communicate with muscles by releasing neurotransmitters, in myasthenia gravis, your immune system produces acetylcholine that block and destroy many of the muscles receptor sites that the neurotransmitters usually fit into
— can also block a protein called muscle-specific receptor tyrosine kinase (MuSK)

• Thymus gland:
  — Researchers believe that the thymus gland triggers or maintains the production of the antibodies that block acetylcholine.
  – large in infancy and small in healthy adults, some adults may have large, or have tumours (cancerous or non-cancerous) that can affect the way that the thymus gland functions
• neonatal myasthenia gravis:
  — rarely, mothers who have MG can give it to their child if they are pregnant
  — if treated promptly, children generally recover within 2 months after birth
• congenital myasthenia syndrome (where children are born with it)

Question 3

Symptoms:

Answer 3

Muscle weakness that’s caused by myasthenia gravis worsens as the affected muscle is used.

Because the symptoms usually improve with rest, muscle weakness can come and go.
– however the symptoms tend to progress over time, usually reaching their worst within a few years after the onset of the disease.

Eye muscles:
– more than half of people with MG, the 1st signs and symptoms involve the eye:
—- ptosis
—- diplopia (may be horizontal or vertical), improves or resolves when one eye is closed

Face and throat muscles:
– 15% of cases, 1st symptoms involve the face and throat muscles:

—- impaired speaking- speech may sound soft or nasal
—- cause dysphagia
—- affect chewing
—- change facial expressions

Neck and limn muscles:
– can weaken the muscles in your neck, arms and legs. Weakness in your legs can affect how you walk. Weak muscles make it hard to hold up your head.