MYOTONIC DYSTROPHY in pregnancy - management .pptx

DEALS WITH MYOTONIC DYSTROPHY IN PREGNANCY

1. MYOTONIC DYSTROPHY

2. Incidence Myotonic dystrophy is a rare degenerative neuromuscular and neuroendocrine disease. Pregnancy in severely affected women is rare. In some milder cases, the disease may only be recognized in pregnancy .

3. Pathogenesis Myotonic dystrophy type 1 is the commonest muscular dystrophy encountered in adulthood. This is an autosomal dominant inherited disorder. It is a trinucleotide repeat disorder, with the affected gene located on chromosome 19. The number of repeats affects the phenotype so that individuals with more repeats have an earlier onset and more severe form of the disease. Since the number of repeats increases with cell division and gametogenesis, successive generations show anticipation.

4. Clinical features ■ Progressive muscular dystrophy ■ Muscle weakness ■ Myotonia (failure to relax after forceful contraction) ■ Myopathic facies (due to weakness of facial muscles) ■ Cataracts ■ Frontal alopecia ■ Cognitive problems ■ Heart conduction defects ■ Hypersomnia, dysphagia ■ Pneumonia and hypoventilation

5. Effect of pregnancy on myotonic dystrophy ■ Pregnancy may be associated with marked exacerbations of myotonia and muscle weakness, or symptoms may be unchanged. ■ Deterioration may occur early in pregnancy, but is most severe in the third trimester. ■ Improvement after delivery is rapid.

6. Effect of myotonic dystrophy on pregnancy ■ There is an increased risk of: ––First and second trimester miscarriage ––Stillbirth ––Polyhydramnios (indicative of an affected fetus) ––Preterm delivery (also more common with an affected fetus) ––Placenta praevia .

7. ■ The second trimester losses and preterm delivery may be related to abnormal myotonic involvement of the uterus. ■ Abnormalities of all three stages of labour have been described. Both prolonged and rapid first and second stages are reported. Uterine inertia responds to oxytocin ■ Postpartum haemorrhage is common due to failure of uterine contractions in the third stage. ■ The baby may be affected with congenital myotonic dystrophy, which is distinct from the adult form and probably arises from a combination of the autosomal dominant gene and an intrauterine environmental factor.

8. ■ The congenital syndrome includes: – Severe generalized hypotonia and weakness. – Difficulties in breathing, sucking and swallowing. – Talipes. – Arthrogryposis. – Learning difficulties. – Myotonia and cataracts are usually absent.

9. Management ■ Prenatal diagnosis is possible by direct DNA analysis or chorionic villus biopsy. ■ General anaesthesia should be avoided and great care is needed with respiratory depressants such as opiates that may exacerbate pulmonary hypoventilation. ■ Referral to an obstetric anaesthetist is recommended.