Intraoperative neurophysiological monitoring in paediatric neurosurgery

Abstract

Intraoperative neurophysiological monitoring (IONM) in paediatric neurosurgeries is emerging over the past few years, and it is being widely used to decrease the risk of postoperative deficits. The same techniques of IONM used in adults can be used in paediatric patients with some modifications keeping in consideration their immature developing nervous system. Neurophysiology in children differs from that in adults. In paediatric patients, the IONM signals and responses differ according to the age of the child. The type of surgery and the neuronal pathways expected to be at risk, determine the type of IONM modality used. 1,2 Various factors like age, type and location of the lesion, preoperative neurological functional status should be considered while using IONM in paediatric patients. There are also immense challenges with anaesthesia maintenance in children undergoing IONM. Also, the IONM signals and responses are not as easily obtained as in adults due to many factors related to the immature nervous system. 3,4

The challenge of epilepsy surgery and intraoperative neurophysiological monitoring in an underweight young infant

“…The IONM allows for safe removal of the epileptogenic zone close to eloquent areas, decreases postoperative deficits, and improves outcomes [5,9]. Although some believe IONM has limited use in younger children, we show that it is feasible, however, signals and responses differ according to the child's age [10]. Moreover, in children, an ECoGbased surgical plan is less successful when ECoGbased change of the surgical procedure is indicated but not achievable [5].…”

Anesthesia management of neonates and infants requiring intraoperative neurophysiological monitoring: A concise review

“…14 A recent report suggests avoiding inhalational anesthetics while using IONM. 4 In a previous report of IONM in 15 infants undergoing spinal cord surgery, inhalational anesthesia allowed MEP measurement; however, high stimulating voltages (maximum voltages >500 V) were required. 15 Another study reported that isoflurane or sevoflurane used below 0.5 MAC, supplemented with fentanyl (1 mcg/kg if necessary for immobility maintenance) and dexmedetomidine (bolus dose of 1 mcg/kg over 10 min, followed by an infusion of 0.5-0.7 mcg/kg/h, expected Ce 1 mcg/L) allowed monitoring of TcMEPs including motor and anal MEPs in 97.3% and 90.7% of infants under 12 months of age undergoing tethered cord surgery, respectively.…”

“…The same nerve stimulation procedure is performed repeatedly at several points during surgery to evaluate any signal attenuation or disappearance following surgical manipulation. Younger children, especially under 3 years of age, require a greater stimulating voltage and a higher pulse train frequency to induce MEPs and SSEPs because of their immature central nervous system's (CNS) (i.e., incomplete myelination, reduced conduction velocities, and fewer monosynaptic connections between the corticospinal tract and alpha‐motor neurons) 4 . Previous reports suggested that the stimulating voltage for transcranial MEPs (TcMEPs) was less in infants aged <6 months (200–400 V) than those aged >6 months (300–500 V) 5 .…”

“…The previous report suggests that at a BIS value of 50 for sedation in adults, the amplitude of MEPs under propofol anesthesia can be twice as large as the amplitude of MEPs under sevoflurane anesthesia 14 . A recent report suggests avoiding inhalational anesthetics while using IONM 4 . In a previous report of IONM in 15 infants undergoing spinal cord surgery, inhalational anesthesia allowed MEP measurement; however, high stimulating voltages (maximum voltages >500 V) were required 15 .…”

“…Younger children, especially under 3 years of age, require a greater stimulating voltage and a higher pulse train frequency to induce MEPs and SSEPs because of their immature central nervous system's (CNS) (i.e., incomplete myelination, reduced conduction velocities, and fewer monosynaptic connections between the corticospinal tract and alpha-motor neurons). 4 Previous reports suggested that the stimulating voltage for transcranial MEPs (TcMEPs) was less in infants aged <6 months (200-400 V) than those aged >6 months (300-500 V). 5 Improved technology nowadays allows neurophysiological signals to be more reliably recorded in neonates and infants.…”