The integrity of the spinal cord is potentially at risk during spine surgeries. Intraoperative neurophysiological monitoring has been the standard of care and is considered mandatory in order to reduce the risk of damage to the neural pathways during such procedures. (1) Continuous use of evoked potentials in the intraoperative period helps to prevent and reduce the incidence of neural injury.

The main goal has been to improve the assessment of different components of the motor system and to enhance both the sensitivity and specificity of MEP findings. Reliable interpretation of myogenic potentials elicited by transcranial electric or magnetoelectric stimulation of the motor cortex and recorded from extremity muscles is compromised, however, by a number of factors, mainly by the influence of general anesthesia.

Fentanyl is a synthetic opioid of the phenylpiperidine family and is structurally related to meperidine. It is highly potent with a rapid onset and a shorter duration of action. The intraoperative requirement of propofol for hypnosis is also reduced by the use of fentanyl.

Dexmedetomidine is an alpha 2 agonist with beneficial actions such as sedation, analgesia, and anxiolysis exerting an opioid-sparing effect which in turn reduces the minimum alveolar concentration (MAC) of inhaled anesthetics. It elicits a strong sedative effect without any evident respiratory depression and is administered as an anesthetic adjuvant. (2)It is a potentially useful drug in the TIVA regimen, facilitating neurophysiological monitoring as it does not interfere with SSEP recordings. Dexmedetomidine as an adjuvant in propofol-based TIVA has been suggested to alleviate postoperative pain also. (3)

 In our study we used propofol-based total intravenous anesthesia (TIVA) with either dexmedetomidine or fentanyl as adjuvants to minimize the use of inhalational agents which are known to interfere with neurophysiological monitoring.