Quick Hit: Myotonic Dystrophy

Myotonic Dystrophy
Quick hit notes from QBanks and Obstetric Anesthesia and Uncommon Disorders

-autosomal dominant CTG-trinucleotide repeat
-impaired muslce relaxation
-Succinycholine –> excessive fasciulations, difficult intubation
-restrictive lung disease -> P/O resp failure
-poor cough/pharyngeal muscle dysynch. -> aspiration/PNA
-imparied response to hypoxia and hypercarbia (senstive to opioids, benzos, barbs, inh)
-comorbidities include: cardiomypathy/dysrhythmias/av block, DM, adreneal insufficiency, thyroid dysfx
-OB pt with MD: increased heart failure risk and myotonic crisis, also increased is placenta accreta, failed labor
-Monitoring: Myotnoia can appear as sustainaed tetanus (even if there is actually sig blockade) -> too early extubations
-MYOTONIC CRISIS: marked contracture of skeletal muscles, 2-3+minutes, ventilation compromised, NOT relieved by nerve block/nmbd/GA
-Prevent Crisis: Warm patient, handle muscles gently, avoid succ and shivering
-Treat Crisis: Procainamide (100mg/min to 1g caution with conduction defects), dantrolene, phenytoin (if localized only, some suggest direct injection of local anesth into muscle)
Plan: avoid succ, easy on resp depressant meds, no superior regional vs. GA