Myasthenia gravis in a parturient: postpartum cholinergic crisis followed by myasthenic crisis
Abstract Number: SU-82
Abstract Type: Case Report/Case Series
Myasthenia gravis (MG) is an autoimmune disorder occurring frequently in women in second and third decades of life. MG has not been shown to adversely affect course of pregnancy. Assisted second stage of vaginal delivery is recommended with epidural analgesia. The neonate should be monitored for muscle weakness. We report an interesting case of suspected cholinergic crisis followed by myasthenic crisis in a parturient with preeclampsia.
18 y/o G1P0 at 36.1 wga, BMI of 37 with history of MG for past 7 years was scheduled for induction of labor for pre-eclampsia with severe features. She had mild range blood pressures, normal lab values and persistent headache. Relevant history included a thymectomy 5 years ago and compliance with pyridostigmine ER 180mg TID and IR 60mg TID. Induction of labor proceeded with cervical ripening and oxytocin. Lumbar epidural catheter provided analgesia with 0.1% ropivacaine with fentanyl 2mcg/ml. After 36 hours of labor, the obstetricians decided to perform a cesarean delivery due to arrest of cervical dilation and fetal intolerance to labor. Cesarean delivery proceeded without complications under epidural anesthesia with lidocaine 2% and epinephrine. Epidural PF morphine was given for analgesia. IV azithromycin was given per institutional protocol to prevent postcesarean endometritis. One hour into recovery and shortly after receiving 2 mg IV morphine, patient became tachypneic, tachycardic, aggressive, with altered mental status and excessive oral secretions. Severe respiratory acidosis was noted. After administration of IV propofol and succinylcholine, she was intubated. SBP of 230 was treated with labetalol and furosemide. Magnesium sulfate was avoided. Pyridostigmine was held as cholinergic crisis was suspected and glycopyrolate was scheduled. CTPE protocol was negative for embolus, but showed opacities consistent with aspiration/ pneumonia. She was treated with antibiotics and extubated after 2 days. Post extubation, she failed a swallow test and had to be reintubated 24 hours later due to desaturations and respiratory failure. EMG revealed myasthenic crisis. She was started on IVIG, prednisone and restarted on pyridostigmine. She was successfully extubated a few hours later. Elevated BP was treated with hydralazine, clonidine and enalapril. She was discharged on POD 11, neonate was discharged from NICU on day 15.
The course of myasthenia gravis in pregnancy is unpredictable. It may be hard to differentiate between muscle weakness caused by cholinergic crisis and myasthenic crisis without edrophonium test. Our patient presumably had a cholinergic crisis initially and then developed a myasthenic crisis after the pyridostigmine was held. Beta blockers, calcium channel blockers, certain antibiotics, magnesium sulfate, phenytoin, non-depolarizing muscle relaxants, opioids and/or respiratory infections can trigger myasthenic crisis.
Berlit et al, Case reports in obstetrics and gynecology, vol.2012, 736024