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Maternal convulsion during high-dose sevoflurane anaesthesia for open foetal surgery

2017; Elsevier BV; Volume: 118; Issue: 4 Linguagem: Inglês

10.1093/bja/aex067

1471-6771

Candace W. Shavit, Mark D. Rollins, Marla B. Ferschl,

Cerebrospinal fluid and hydrocephalus

Editor—Open in utero repair of foetal myelomeningocele improves postnatal neurological outcome1Adzick NS Thom EA Spong CY et al.A randomized trial of prenatal versus postnatal repair of myelomeningocele.N Engl J Med. 2011; 364: 993-1004Crossref PubMed Scopus (1340) Google Scholar and is being performed with increased frequency worldwide. We present the case of an otherwise healthy pregnant patient at 25-weeks gestation undergoing open foetal myelomeningocele repair who experienced three tonic-clonic convulsions while anaesthetized. We hypothesize that high-dose sevoflurane [2.5 minimum alveolar concentration (MAC)], used to ensure uterine relaxation during the surgery,2Ferschl M Ball R Lee H Rollins MD. Anesthesia for in utero repair of myelomeningocele.Anesthesiology. 2013; 118: 1211-1223Crossref PubMed Scopus (33) Google Scholar was responsible for the convulsive activity. An otherwise healthy, 70-kg, 22-year-old gravida 1, para 0 patient at 25-weeks gestation presented for open repair of a foetal L3-S1 myelomeningocele. Her pregnancy was otherwise uncomplicated and without preeclampsia. The patient was anaesthetized per our standard protocol.2Ferschl M Ball R Lee H Rollins MD. Anesthesia for in utero repair of myelomeningocele.Anesthesiology. 2013; 118: 1211-1223Crossref PubMed Scopus (33) Google Scholar Sevoflurane was administered as the maintenance anaesthetic and incrementally increased over the first 45 min following induction to an end-tidal concentration of 5.5% (2.5 MAC) for uterine relaxation. A phenylephrine infusion (30–50 μg min−1) was administered to maintain arterial blood pressure within 10% of preoperative values during the surgery. The patient remained haemodynamically stable throughout the procedure with minimal blood loss. Approximately 1 h after induction (sevoflurane at 2.5 MAC for 15 min), the patient was noted to have tongue protrusion and facial spasms, which quickly spread to involve significant clonic movements of her head and arms. We concluded possible seizure activity and 2 mg i.v. midazolam was administered without delay. The tonic-clonic activity subsided. Laboratory values (chemistry panel and arterial blood gas) sent immediately after the seizure were unremarkable. A second episode with more significant tonic-clonic movements of the upper extremities and abdominal contractions occurred approximately 1 h after the first, and lasted 2 min, ceasing only after administration of 60 mg of propofol. A third and final occurrence of clonic movement, primarily involving head shaking, happened 20 min later. Propofol (30 mg) was administered and the movement stopped. Once the foetal repair was complete, we loaded the patient with 4 g magnesium sulphate to prevent premature labour and decreased the sevoflurane concentration to 1.0 MAC. The foetal repair was successfully completed without complication despite the seizure activity. Postoperatively, the patient had no neurologic deficits. She denied any previous neurologic insults or seizure history. The consulting neurologist did not recommend further EEG or brain imaging and attributed the events to the high concentration of inhaled sevoflurane. Multiple studies demonstrate that sevoflurane can cause epileptiform EEG changes in both adults and children, usually without clinical manifestation. Seizure-like activity occurring after induction with sevoflurane is more common than convulsions occurring during emergence from sevoflurane.3Constant I Seeman R Murat I. Sevoflurane and epileptiform EEG changes.Paediatr Anaesth. 2005; 15: 266-274Crossref PubMed Scopus (183) Google Scholar The mechanism responsible for convulsive activity due to sevoflurane remains unknown, but may be dose dependent and due to γ-aminobutyric acid (GABA)ergic inhibition and thereby sensitization of neuroexcitatory channels.4Voss LJ Sleigh JW Barnard JPM Kirsch HE. The howling cortex: seizures and general anesthetic drugs.Anesth Analg. 2008; 107: 1689-1703Crossref PubMed Scopus (147) Google Scholar5Pilge S Jordan D Kochs EF Schneider G. Sevoflurane-induced epileptiform electroencephalographic activity and generalized tonic-clonic seizures in a volunteer study.Anesthesiology. 2013; 119: 447Crossref PubMed Scopus (20) Google Scholar Female sex, rapid anaesthesia onset, and high alveolar concentration are all risk factors for the development of epileptiform EEG activity during induction with sevoflurane.6Julliac B Guehl D Chopin F et al.Risk factors for the occurrence of electroencephalogram abnormalities during induction of anesthesia with sevoflurane in nonepileptic patients.Anesthesiology. 2007; 106: 243-251Crossref PubMed Scopus (33) Google Scholar Additional factors that might increase the epileptogenic potential of sevoflurane include a history of epilepsy,7Iijima T Nakamura Z Iwao Y Sankawa H. The epileptogenic properties of the volatile anesthetics sevoflurane and isoflurane in patients with epilepsy.Anesth Analg. 2000; 91: 989-995Crossref PubMed Scopus (114) Google Scholar8Watts AD Herrick IA McLachlan RS Craen RA Gelb AW. The effect of sevoflurane and isoflurane anesthesia on interictal spike activity among patients with refractory epilepsy.Anesth Analg. 1999; 89: 1275-1281Crossref PubMed Scopus (70) Google Scholar intracranial pathology,9Hilty CA Drummond JC. Seizure-like activity on emergence from sevoflurane anesthesia.Anesthesiology. 2000; 93: 1357-1359Crossref PubMed Scopus (37) Google Scholar and hyperventilation.10Vakkuri A Jantti V Särkelä M Lindgren L Korttila K Yli-Hankala A. Epileptiform EEG during sevoflurane mask induction: effect of delaying the onset of hyperventilation.Acta Anaesthesiol Scand. 2000; 44: 713-719Crossref PubMed Scopus (47) Google Scholar Our case is the first to describe seizure-like activity at a steady-state dose of sevoflurane. Although data are limited, convulsive activity is not described with the use of other volatile anaesthetic agents.11Vakkuri AP Seitsonen ER Jäntti VH et al.A rapid increase in the inspired concentration of desflurane is not associated with epileptiform encephalogram.Anesth Analg. 2005; 101: 396-400Crossref PubMed Scopus (17) Google Scholar12Voss LJ Ludbrook G Grant C Sleigh JW Barnard JPM. Cerebral cortical effects of desflurane in sheep: comparison with isoflurane, sevoflurane and enflurane.Acta Anaesthesiol Scand. 2006; 50: 313-319Crossref PubMed Scopus (25) Google Scholar For cases where the use of high-dose halogenated agents is desired, it might be reasonable to consider desflurane or isoflurane. Alternatively, utilizing adjunct medications such as supplemental intravenous anaesthetic (SIVA) with propofol and remifentanil combined with a lower dose (1 MAC) of inhaled agent has been described to maintain uterine relaxation for open foetal surgery13Boat A Mahmoud M Michelfelder EC et al.Supplementing desflurane with intravenous anesthesia reduces fetal cardiac dysfunction during open fetal surgery.Paediatr Anaesth. 2010; 20: 748-756Crossref PubMed Scopus (74) Google Scholar14Ngamprasertwong P Michelfelder EC Arbabi S et al.Anesthetic techniques for fetal surgery: effects of maternal anesthesia on intraoperative fetal outcomes in a sheep model.Anesthesiology. 2013; 118: 796-808Crossref PubMed Scopus (23) Google Scholar and might reduce the risk of seizure. Additionally, intraoperative EEG monitoring should be considered, especially if non-depolarizing muscle relaxants are used that could mask clonic activity.