Myastenia Gravis

Question 0

General in myasthenia

Answer 0

Neuro muscular disease

It presents with weakness and fatigue

The prevalence is one in 10,000 to one in 50,000 and it affects twice as many women as men

Thymectomy results in remission of 35% of patients and improvement in 50% of patients

Question 1

Signs and symptoms of myasthenia

Answer 1

Ocular muscle weakness resulting in Diplopia and ptosis

Difficulty in chewing or talking

Respiratory muscle weakness

Question 2

Effects of pregnancy on MG

Answer 2

1/3 women get better

1/3 get worse

1/3 stay the same

Risk of deterioration highest if diagnosed within the last 12 months

30% women have exarcerbation post partum

Question 3

Disease can be precipitated by (in myasthenia)

Answer 3

Emotional stress or anxiety

Intercurrent infections

Increased temperature

Sub therapeutic levels of medication caused by pregnancy changes

Question 4

Effects of MG on pregnancy and labour

Answer 4

No change to pregnancy

It affects striated muscles so Ist stage I labour ok ; 2nd stage of labour may become a problem

Question 5

Neonatal MG

Answer 5

Transient 9-20% babies

Poor sucking

Feeble cry

Generalised hypotonia

Swallowing difficulties

Facial paresis

Respiratory depression

Complete recovery within 2 months

Question 6

Arthrogryposis multiplex congenital

Answer 6

Congenital joints contractures

Reduced fetal movements in utero

Some infants survive, some die in utero or in the neonatal period for pulmonary hypoplasia

High risk of recurrence

Question 7

Antepartum care for myasthenia

Answer 7

MDT

continue anticholinesterase meds - increased doses or reduction of dose interval may be appropriate

Treat any infection aggressively

Anaesthetic assessment - more resistant to suxamethonium; more sensitive to non depolarising muscle relaxants. Narcosis can cause muscle fatigue

Magnesium sulphate can precipitate a crisis

Corticosteroids, immunosuppressants and plasmapheresis may be necessary in pregnancy

Question 8

Intrapartum care for myasthenia

Answer 8

Administer anticholinesterase parentally to ensure adequate absorption

Aim for vaginal delivery but may require instrumental to avoid exhaustion

C/s for obstetric reasons only

Question 9

Breastfeeding and myasthenia

Answer 9

Receptor antibodies pass in breast milk and may potentiate neonatal MG

drugs pass in milk and may cause gastrointestinal upset in the newborn