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|Year : 2021 | Volume
| Issue : 1 | Page : 187-189
KetaDex: A Saviour for Intraoperative Multimodal Neurophysiological Monitoring in Complex Neurosurgeries
RP Sangeetha, Suparna Bharadwaj
Department of Neuroanesthesiology and Neurocritical Care, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
|Date of Submission||22-Feb-2019|
|Date of Decision||16-May-2019|
|Date of Acceptance||30-Sep-2019|
|Date of Web Publication||24-Feb-2021|
Associate Professor, Department of Neuroanesthesia and Neurocritical Care, National Institute of Mental Health and Neurosciences, Bengaluru - 560 029, Karnataka
Source of Support: None, Conflict of Interest: None
Background: The anaesthetic mandate for a combination of electrocorticography (ECoG) and subcortical motor evoked potential mapping (SCMEPM) substantially differs from that required for each of these monitors in isolation. There is no current consensus defining the anaesthetic management for intraoperative multimodal monitoring combining these two modalities. Case description: We report our experience of anaesthetising a drug resistant epileptic patient for craniotomy and resection of his frontal gliotic lesion. We propose a novel anaesthetic technique to cater to the multiple goals of this surgery like optimal neuromonitoring under adequate depth of anaesthesia. We used balanced anaesthesia technique. Continuous intravenous (IV) infusions of Inj. Dexmedetomidine of 1.5 mcg/kg/hour and Inj. Ketamine at 0.5mg/kg/hour were used to supplement inhalational anaesthetic titrated to a MAC up to 0.5. Neuromuscular blockade was avoided after the initial tracheal intubation dose. Conclusion: To the best of our knowledge, this is the first case reporting the safety and efficacy of balanced anaesthetic technique for concurrent ECoG and SCMEPM. Successful intraoperative ECoG and SCMEPM monitoring with absent intraoperative awareness confirmed the safety of our anaesthetic technique. Through this, a composite of patient safety, surgeon satisfaction and adequate intraoperative monitoring could be achieved.
Keywords: Electrocorticography, epilepsy surgery, KetaDex, subcortical motor evoked potential mapping
Key Message: A combination of ketamine and dexmedetomidine is a safe and effective anesthetic choice for the conduct of multimodal intraoperative neurophysiological monitoring in complex neurosurgeries.
|How to cite this article:|
Sangeetha R P, Bharadwaj S. KetaDex: A Saviour for Intraoperative Multimodal Neurophysiological Monitoring in Complex Neurosurgeries. Neurol India 2021;69:187-9
The role of intraoperative neurophysiological monitoring for resection of neurosurgical lesions cannot be over emphasized. A combination of cortical/subcortical-motor evoked potential (SCMEP) and electrocorticography (ECoG) allows safe and maximal resection of epileptogenic lesions of the eloquent cortex. Anesthetic techniques have to be tailored to suit the specific requirements of each monitoring modality, ensuring adequate anesthetic depth and hemodynamic stability. We report our experience of anesthetising a patient with intractable epilepsy for lesion resection, permitting successful monitoring of both ECoG and SCMEPM.
| » Case Report|| |
A 23-year-old gentleman weighing 70 kg presented to our hospital with a history of focal partial motor seizures of left upper and lower limbs since 6 years of age. His seizures were drug resistant despite compliance to levetiracetam and lacosamide. Cerebral magnetic resonance imaging revealed a right frontal gliotic lesion [Figure 1]a. Surgery for resection of epileptic focus through right frontal craniotomy was planned under general anesthesia with ECoG and SCMEP monitoring. The right-handed patient had no other comorbidities. Neurological and other systemic examinations and hematological and cardiac work up were unremarkable. Risks of general anesthesia and possible intraoperative awareness were discussed. Antiepileptic medications were continued perioperatively. Following intravenous (IV) anesthetic induction, trachea was intubated and bite block was inserted. Balanced anesthesia was maintained using air: oxygen mixture with FiO2 of 0.5 and Isoflurane titrated to a MAC not exceeding 0.5, IV Fentanyl infusion at 2 microgram/kg/hour, IV dexmedetomidine infusion of 1.5 microgram/kg/hour, and IV ketamine infusion of 0.5 milligram/kg/hour. Dexmedetomidine has its proven suitability for both SCMEP and ECoG due to its noninterference with both background EEG and epileptic spikes. This, supplemented with Ketamine infusion, helps maintain adequate depth of anesthesia. Further neuromuscular blocking agents were avoided. As the brain lesion was abutting the corticospinal tracts, transcutaneous MEP as well as SCMEP were planned. Scalp electrodes for MEP stimulation were applied according to the International 10-20 system. Compound muscle action potentials (CMAP) for MEP and SCMEP were recorded from left mentalis, left hyoglossus, and left upper and lower limb muscles. Right limb muscles were monitored as control. There were no changes in the periodic MEP and SCMEP responses as compared to baseline. Perioperative course was uneventful [Figure 1]b.
|Figure 1: Intraoperative neurophysiological monitoring; (a) T2-weighted MRI image showing loss of right frontal neuronal mass with expansion of right frontal horn of lateral ventricle suggestive of right frontal gliosis; (b) Stable hemodynamic parameters maintained throughout the surgery; (c) Electroencephalographic (EEG) monitoring of anesthetic depth.; (d) Motor-evoked responses (MEP) at baseline with Inj. Ketamine and Inj. Dexmedetomidine infusions on flow in the background of 0.5 MAC of Isoflurane; (e) MEP recorded after total resection of lesion; (f) Subcortical motor-evoked potential mapping (SCMEPM) of the left-hand muscle|
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| » Discussion|| |
This is the first report discussing the combination of dexmedetomidine and ketamine (KetaDex) for concurrent monitoring of MEP/SCMEPM and ECoG [Figure 1]c,[Figure 1]d,[Figure 1]e,[Figure 1]f. Careful selection of anesthetic agents allows hassle-free cortical and subcortical motor mapping facilitating safe and optimal surgical resection. Total intravenous anesthesia with propofol without neuromuscular blocking agents is preferred for MEP monitoring. However, simultaneous ECoG monitoring precludes its use due to suppression of the frequency of epileptic spikes. The quest for an alternative agent persuaded us to explore the utility of KetaDex which proved to be suitable for MEP/SCMEP/ECoG monitoring with adequate anesthetic depth. Use of KetaDex has been reported for safe adult procedural sedation and anesthetic management of noncardiac surgeries in patients with cyanotic congenital cardiac disease. Dexmedetomidine offsets ketamine-induced cardiostimulatory effects, delirium, and agitation and maintains hemodynamic stability. Interference of ketamine with EEG required its cautious interpretation to titrate anesthetic depth. Intraoperative awareness with explicit recall was ruled out using the Modified Brice questionnaire after surgery.
| » Conclusion|| |
To the best of our knowledge, this is the first report affirming the safety and efficacy of a novel anesthetic combination of ketamine and dexmedetomidine for the conduct of multimodal intraoperative neurophysiological monitoring in complex neurosurgeries.
Consent for publication
Written informed consent was obtained from the patient for publication of this case report and accompanying images.
Institute Ethics committee waiver was sought for the publication of this case report.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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