myotonic dystrophy

myotonic dystrophy

type 1: congenital/childhood/adult/late

type 2: prox myotonic dys/myo/myopathy syndrome

type 1: unstable trinucleotide expansion

adult onset= autosomal dominant

premature balding, muscle degeneration, cataracts, diabetes mellitus, gonadal atrophy, cardiac abnormalities, adrenal insufficiency, cardiac abnormalities

cardiac- AV delay, atrial tachydysrhythmias, diastolic dysfunction, MVP, cardiomyopathy, sudden death

restrictive lung disease, mild hypoxemia

may have respiratory muscle myotonia-- dyspnea-treat w procainamide

alteration of smooth musc function-gastric atony, intestinal hypomotility

aspiration risk from pharyngeal muscle weakness

pregnancy: may ppt CCF, may need CS for uterine atony

infants of mothers with myotonia-- may develop congenital myotonic dystrophy

Rx: supportive / preventive

sodium channel blockers: less conclusive results

Anaes:

sux : exaggerated contracture-- avoid

chronic myopathy: response to ND NMBA may be exaggerated

muscle stimulation with nerve stimulator: may trigger myotonia

neostigmine: may trigger myotonia

sensitive to respiratory depressant effects