The Effect of Midazolam, Fentanyl and a Small Dose of Etomidate for Prevention of Myoclonus during Induction of Anesthesia with Etomidate / 대한마취과학회지

BACKGROUND: The hypothesis that subcortical disinhibition is the reason for etomidate-induced myoclonus suggest that drugs acting on the subcortical area may reduce myoclonus. To verify the hypothesis, premedication with placebo, etomidate of a small dosage, midazolam and fentanyl were compared. METHODS: Sixty ASA physical status I or II patients undergoing elective surgery were allocated into four groups. All groups were induced with etomidate 0.3 mg/kg and vercuronium 0.1 mg/kg and maintained with 50% N2O and 1.5-2% enflurane. Group I (n = 15) received normal saline 3 ml 5 minutes before the etomidate 0.3 mg/kg administration, group II (n = 15) received 0.05 mg/kg etomidate 50 seconds before the etomidate 0.3 mg/kg administration, group III received midazolam 0.05 mg/kg 5 minutes before the etomidate 0.3 mg/kg and group IV received 2 microgram/kg fentanyl 5 minutes before the etomidate 0.3 mg/kg. In all patients, the grade, starting time, maintenance time of myoclonus and vital signs were checked and compared between the four groups. RESULTS: In group IV, myoclonus did not develope except in one patient and there were no differences in the incidence of myoclonus between the others. All premedicating drugs do not affect vital signs. CONCLUSIONS: We find that fentanyl reduces the incidence of etomidate-induced myoclonus but midazolam and a small dose of etomidate are not effective.

Spinal Myoclonus on Lower Extremities Following Spinal Anesthesia or Subdural Administration of Intended Epidural Steroid Injection: Three cases reports / 대한마취과학회지

Clonic movement is an extremely rare complication that occurs after neuroaxial blockade. We have experienced three patients showing intermittent clonic movement on both lower extremities following spinal anesthesia or subdural administration of intended epidural steroid injection.The first and the second patients, 13-year-old boy and 51-year-old man, experienced clonic movement following standard spinal anesthesia with hyperbaric tetracaine with epinephrine for operation on lower extremities. The third one, 24-year-old man, was an outpatient for the treatment of intractable radiculopathy, previously had an L4 laminectomy. His clonic movement may have resulted from the accidental subdural administration of an intended epidural injection of 0.5% lidocaine 6 ml containing triamcinolone 40 mg. Clonic movement has appeared as the occurrence of intermittent, short-timed (about 2~5 seconds), severe annoying, bilateral involuntary muscle contraction on lower extremities at the stage of recovery. It sustained for about 4~19 hours. The treatment was mainly sedation with sedatives and inhalation anesthetics, and partially muscle relaxants or anticholinesterase. They recovered without any sequelae.