A0036 Intraoperative Motor Evoked Potentials in a Pregnant Patient

Background: Intraoperative neurophysiological monitoring (IONM) is used to monitor the integrity of neuronal pathways and is necessary in neurosurgical procedures to prevent postoperative deficits. But its use and safety in pregnant cases is sparsely reported and remains to be established.

Case Description: We describe case of a lady with 26 weeks of gestation with right intraventricular tumor extending up to thalamus posted for craniotomy and excision under IONM. Motor evoked potentials (MEPs) were chosen since tumor was close to thalamus and internal capsule. Patient was induced and intubated, and anesthesia was maintained with bi-spectral index (BIS)–guided total intravenous anesthesia (TIVA). We monitored fetal rate with USG and also monitored uterine tone with fetal cardiotocography (CTG). We limited the number of MEP stimulations to minimum and used lowest currents (150–175 V) to get responses. No significant changes in MEP amplitude were observed intra-operatively, and patient was extubated without any motor or sensory deficits. Normal fetal heart rate was also confirmed with CTG and fetal ECHO.

Conclusions: A multidisciplinary team approach involving neuroanesthesiologists, neurosurgeons, and obstetricians with continuous monitoring of the fetal well-being by fetal heart rate, uterine contractions by CTG, and intraoperative neurophysiological monitoring by MEP were useful in our case. In our case, no deleterious intraoperative or postoperative complications were seen in mother and fetus with the use of MEP monitoring. Keeping the voltage minimum for MEP, reducing number of MEP stimulation trains, monitoring of fetal heart rate, and uterine tone are some of the strategies which can be considered in such cases.