Myasthenia gravis

 

Three Types of Myasthenia gravis

1. Ocular Myasthenia gravis

• higher prevalence in males

• muscle weakness confined to the eye

1. Generalized Myasthenia gravis

• affects the proximal musculature throughout the body with four different disease progressions

1. a course with periodic remission

2. a slow progression course

3. a rapidly progressive course

4. a fulminating course

1. Bulbar myasthenia Myasthenia gravis

• involves the muscles innervated by the cranial nerves IX, X, XI and XII

• disease progression is typically rapid or fulminating

Manifestations

• may present during pregnancy, post-partum or linked to the administration of some anesthetics

• Fatigue after exercise

• Hx of upper respiratory tract infections

• muscles of eyes, face, mouth, throat and neck are affected first

Affected extraoccular muscles of the eye and levator muscles result in (Primarily):

• diplopia

• ptosis

• ocular palsies

Affected muscles controlling facial expression, mastication, swallowing and speech result in (Secondary):

• facial droop

• no expressive ability

• dysphagia

• dysphasia

• episodes of choking and aspiration

Muscles of neck, shoulder girdle, and hip girdle are less frequently affected resulting in:

• pt experiences fatigue

• periods of rest required

• pt may have difficulty maintaining head position

• muscles of diaphragm and chest wall become weakened

• ventilation may be impaired

• impairment of deep breathing and cough muscles predispose pt to atelectasis and congestion