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| Year : 2018 | Volume
: 66
| Issue : 1 | Page : 279-280 |
Anesthetic considerations for intraoperative neurophysiological monitoring in patients undergoing scoliosis surgery
Naveen Naik, Tanvir Samra
Department of Anaesthesia, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| Date of Web Publication | 11-Jan-2018 |
Correspondence Address:
Dr. Tanvir Samra
H no 262/Sector 33 A, Chandigarh - 160 020
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0028-3886.222863
How to cite this article:
Naik N, Samra T. Anesthetic considerations for intraoperative neurophysiological monitoring in patients undergoing scoliosis surgery. Neurol India 2018;66:279-80 |
Sir,
We read the article published by Krishnakumar et al.,[1] regarding the multimodal intraoperative neuromonitoring (IONM) in scoliosis. We would like to discuss our anesthetic protocol that ensures minimum interference with neurophysiological monitoring and enables a rapid recovery postoperatively. The authors have not elaborated on the anesthetic drugs administered, which may have been responsible for the “false positives” mentioned in their article.
The cohort in our center consisted of 3 children, 14 adolescents, and 1 adult with a female:male ratio of 2:1. Congenital scoliosis (n = 10), adolescent idiopathic scoliosis (n = 6), and neuromuscular disorders (n = 2) were the chief diagnoses, and the Cobb's angle ranged from 50–90 degrees. In the operation theatre, the patients were administered glycopyrollate (5 ug/kg), morphine (0.2 mg/kg), fentanyl (1 ug/kg), and propofol (2–3 mg/kg). A single dose of atracurium (0.5 mg/kg) was used for intubation of the trachea. Baseline values for intraoperative neuromonitoring (IONM) were taken after regression of the neuromuscular blockade (monitored using 'Train of Four'). Propofol (125–150 ug/kg/min titrated to bispectral index [BIS] of 45–55), fentanyl (1 ug/kg/h), and dexmedetomidine (bolus of 1ug/kg over 10 min followed by an infusion of 0.5–0.7 ug/kg) were used for maintenance of anesthesia. The IONM equipment was attached to the patient [NIM ECLIPSE E4, Medtronic neurophysiological monitor was used which has the ability to perform a 32-channel electroencephalogram (EEG) recording as well as motor evoked potential (MEP), somatosensory evoked potential (SSEP), and electromyography (EMG) monitoring].
The anesthetic goals included maintaining a mean arterial pressure of 65–70 mmHg; transfusion of blood if the hematocrit value was less than 21%; avoidance of neuromuscular blockers with relaxants being used only once to facilitate intubation; and, avoidance of inhalational anesthetics and nitrous oxide.
Patients were extubated in the supine position on return of spontaneous breathing efforts and consciousness. Satisfactory combined SSEPs and MEPs were obtained in all patients. We also reported a false positive result in one case in which the Cobb's angle was 90 degrees and the curvature was stiff. We presume the false positive result to be due to a vascular compression secondary to instrumentation.
We also incorporated the use of a checklist in our cases, which has been developed by Vitale et al.,[2] after a literature review and four surveys with 21 spine surgeons and a neurologist. Krishnakumar et al.,[1] made no mention of this checklist which has 5 headings and 26 items, namely, control of the room, monitoring of the anesthetic system, monitoring of the technical issues relating to the neurophysiological monitoring, and instructions for the surgeons. Consensus-based best practice guidelines for IONM focuses on a team approach, defines significant warning criteria, and advices a wake-up test for all cases with persistent signal degradation.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| » References | |  |
| 1. | Krishnakumar R, Srivatsa N. Multimodal intraoperative neuromonitoring in scoliosis surgery: A two-year prospective analysis in a single centre. Neurol India 2017;65:75-9.  [ PUBMED] [Full text] |
| 2. | Vitale MG, Skaggs DL, Pace GI, Wright ML, Matsumoto H, Anderson RC, et al. Best practices in intraoperative neuromonitoring in spine deformity surgery: Development of an intraoperative checklist to optimize response. Spine Deform 2014;2:333-9. |
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