Monitoring of motor evoked potentials in C-spinal surgery 報告人：R1康庭瑞 Case Chart No: 4213769 Brief history: 1. The 19 y/o man had suffered from TA in May,2002 and multiple trauma, including right F-T-P EDH with depressed skull fracture, left F-T-P SDH and ICH, and type II odontoid fracture was noted. 2. Emergency craniotomy and hematoma evacuation were done at that time. Case 3. Cranioplasty in June,2002; odontoid screw fixation in July; screw removal due to mal-alignment of odontoid process on August 6th; posterior bone fusion and Halifax fixation of C1-2 on August 12th; and right Kocher VP shunt on August 23th,2002 at 光田 hospital 4. After operation, GCS:E4M6V2 5. He received cranioplasty with mini-plate fixation on November at NTUH 6. This time, he was admitted for removal of C1-2 Halifax, C1 laminectomy and lugue fixation C0-3 with bone fusion Spinal surgery Induction: Fentanyl 100ug, Pentothol 300mg, Atracurium 40mg Intubation: lightwand stylet Monitors: pulse oximetry, ECG, capnography, invasive blood pressure, CVP, MEP Position: prone positionendotracheal tube position and fixation, free of pressure Maintain: total intravenous anesthesiaPropofol, Ketamine+Rapifan, Esmeron Intraoperative spinal cord and nerve root monitoring Somatodensory evoked potentials Standard test of spinal cord function during various surgical proceduresdorsal and lateral columns; good correlation between SSEP and motor function The upper extremity SSEP monitor the brachial plexus, essential during procedures of the cervical spine, indirectly monitor peripheral nerve function The lower extremity SSEP assess overall spinal cord function Criteria for significant changes in waveform:10% latency increase, 50% decrease in signal amplitude, and/or complete loss of potential Motor evoked potentials (1) Stimulation techniques: (1) transcranial magnetic or electrical stimulation of the cerebral cortex (2) direct(epidural) or indirect(percutaneous) stimulation of the spinal cord Recorded: (1) from spinal cord using epidural electrodes (2) from mixed peripheral nerves using surface or subdermal electrodes neurogenic action potentials (3) from muscle compound muscle action potentials Motor evoked potentials (2) Vascular injury to the anterior spinal cord can occur motor deficit without a change in the sensory potential Intramedullary spinal cord tumor resection, vascular abnormalities, and correction of spinal deformity Absence of the MEPs remedy and if no recovery of EPs wake-up test Drawbacks of transcranial MEP Technically more demanding than SSEP Transcranial stimulation remains a controversial topic Lack of significant criteria for warning except neurogenic action potentials Confounding factors Anesthetics: volatile anesthetics reducing amplitude, prolonging latency of EPs Temperature: hypothermia Hypotension Hypoxia cerebral ischemia Anemia Preexisting neurologic lesions Inhalation agents Greatest depressive effect on evoked potentials Dose-dependent prolong the latency and decrease the amplitude of EP N2O decrease the amplitude of EP but have minimal effect on the latency of EP Intravenous anesthetics Less effects on evoked potentials Thiopental, opioid and propofol depress MEP to a greater extent than do etomidate or methohexital A 2-mg/kg dose of thiopental decreased the MEP amplitude 42.8 percent, and subsequent doses caused a further dose-dependent decrease Ketamine does not follow the basic anesthesia-related EEG pattern, and was desirable for MEP monitoring Our anesthetic formula for MEP monitoring Ketamine 200mg + Rapifen 2mg in 20ml N/S run 10~12 ml/hr Propofol 70mg//hr Esmeron 6mg/hr Conclusion Selection of adequate neuromonitoring during spinal surgery is important Totally intravenous anesthesia and short acting agents is better Maintain anesthesia depth: TOF for controlling muscle relaxant dosage; BIS or EEG for monitoring hypnosis Reference Combined monitoring of motor and somatosensory evoked potentials in orthopaedic spinal surgery. [Clinical Trial. Journal Article] Clinical Neurophysiology. 2002 Jul. Transcranial electrical motor evoked potential monitoring for brain tumor resection. [Journal Article] Neurosurgery. 2001 May. Spinal cord and nerve root monitoring during surgical treatment of lumbar stenosis. [Review] Clinical Orthopaedics & Related Research. 2001 Mar. Total intravenous anesthesia for intraoperative monitoring of motor pathways : an integral view combining clinical and experimental data Journal of Neurosurgery 2002 Mar Effects of four intravenous anesthetic agents on motor evoked potentials elicited by magnetic transcranial stimulation. Neurosurgery 1993 Thank You !!