Threshold-level multipulse transcranial electrical stimulation of motor cortex for intraoperative monitoring of spinal motor tracts: description of method and … (original) (raw)
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Journal of Neurosurgery, 1998
Numerous methods have been pursued to evaluate function in central motor pathways during surgery in the anesthetized patient. At this time, no standard has emerged, possibly because each of the methods described to date requires some degree of compromise and/or lacks sensitivity. Object. The goal of this study was to develop and evaluate a protocol for intraoperative monitoring of spinal motor conduction that: 1) is safe; 2) is sensitive and specific to motor pathways; 3) provides immediate feedback; 4) is compatible with anesthesia requirements; 5) allows monitoring of spontaneous and/or nerve root stimulus—evoked electromyography; 6) requires little or no involvement of the surgical team; and 7) requires limited equipment beyond that routinely used for somatosensory evoked potential (SSEP) monitoring. Using a multipulse electrical stimulator designed for transcranial applications, the authors have developed a protocol that they term “threshold-level” multipulse transcranial electr...
Somatosensory- and motor-evoked potential monitoring during spine and spinal cord surgery
Spinal Cord, 2007
Objectives: Complex spinal surgery carries a significant risk of neurological damage. The aim of this study is to determine the reliability and applicability of multimodality motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SEPs) monitoring during spine and spinal cord surgery in our institute. Methods: Recordings of MEPs to multipulse transcranial electrical stimulation (TES) and cortical SEPs were made on 52 patients during spine and spinal cord surgery under propofol/ fentanyl anaesthesia, without neuromuscular blockade. Results: Combined MEPs and SEPs monitoring was successful in 38/52 patients (73.1%), whereas only MEPs from at least one of the target muscles were obtained in 12 patients (23.1%); both MEPs and SEPs were absent in two (3.8%). Significant intraoperative-evoked potential changes occurred in one or both modalities in five (10%) patients. Transitory changes were noted in two patients, whereas three had persistent changes, associated with new deficits or a worsening of the pre-existing neurological disabilities. When no postoperative changes in MEP or MEP/SEP modalities occurred, it was predictive of the absence of new motor deficits in all cases. Conclusion: Intraoperative combined SEP and MEP monitoring is a safe, reliable and sensitive method to detect and reduce intraoperative injury to the spinal cord. Therefore, the authors suggest that a combination of SEP/MEP techniques could be used routinely during complex spine and/or spinal cord surgery.
Medical & Biological Engineering & Computing, 2004
Motor evoked potentials (MEPs) evoked by transcranial electrical stimulation (TES) have become an important technique for monitoring spinal cord function intra-operatively, but can fail in some patients. A new technique of double-train stimulation is described. A multipulse transcranial electrical stimulus is preceded by a preconditioning pulse train that leads to larger MEP responses. An MEP monitoring system was adapted for double-train transcranial stimulation (DTS). MEP responses from 160 anterior tibial muscles obtained by double-train stimulation were analysed. All patients received propofol/remifentanil/ O2/N20 anaesthesia. Fifty-two (83%) out of 63 single-train tibial MEPs with response amplitudes below 100/~V were magnified to over 100/~V, with an inter-train (inter-stimulus) interval ITI-10-35ms. These 63 amplitudes were magnified by an overall logarithmic mean factor of 15.5. For 97 MEPs with amplitudes above 100/~V, the logarithmic mean facilitation factor was 2.4. It was concluded that double-train TES stimulation can markedly facilitate responses to a single stimulus train (STS). The facilitation appears to be most effective when the responses to STS would otherwise be small or absent. This preconditioning stimulation technique is therefore useful when an STS leads to responses that are too small for effective monitoring.
The Journal of bone and joint surgery. American volume, 2004
There has been little enthusiasm for somatosensory evoked potential monitoring in cervical spine surgery as a result, in part, of the increased risk of motor tract injury at this level, to which somatosensory monitoring may be insensitive. Transcranial electric motor evoked potential monitoring allows assessment of the motor tracts; therefore, we compared transcranial electric motor evoked potential and somatosensory evoked potential monitoring during cervical spine surgery to determine the temporal relationship between the changes in the potentials demonstrated by each type of monitoring and neurological sequelae and to identify patient-related and surgical factors associated with intraoperative neurophysiological changes. Somatosensory evoked potential and transcranial electric motor evoked potential data recorded for 427 patients undergoing anterior or posterior cervical spine surgery between January 1999 and March 2001 were analyzed. All patients who showed substantial (at least...
Neurology, 2012
Objective: To evaluate whether spinal cord intraoperative monitoring (IOM) with somatosensory and transcranial electrical motor evoked potentials (EPs) predicts adverse surgical outcomes. Methods: A panel of experts reviewed the results of a comprehensive literature search and identified published studies relevant to the clinical question. These studies were classified according to the evidence-based methodology of the American Academy of Neurology. Objective outcomes of postoperative onset of paraparesis, paraplegia, and quadriplegia were used because no randomized or masked studies were available. Results and Recommendations: Four Class I and 8 Class II studies met inclusion criteria for analysis. The 4 Class I studies and 7 of the 8 Class II studies reached significance in showing that paraparesis, paraplegia, and quadriplegia occurred in the IOM patients with EP changes compared with the IOM group without EP changes. All studies were consistent in showing all occurrences of paraparesis, paraplegia, and quadriplegia in the IOM patients with EP changes, with no occurrences of paraparesis, paraplegia, and quadriplegia in patients without EP changes. In the Class I studies, 16%-40% of the IOM patients with EP changes developed postoperative-onset paraparesis, paraplegia, or quadriplegia. IOM is established as effective to predict an increased risk of the adverse outcomes of paraparesis, paraplegia, and quadriplegia in spinal surgery (4 Class I and 7 Class II studies). Surgeons and other members of the operating team should be alerted to the increased risk of severe adverse neurologic outcomes in patients with important IOM changes (Level A). Neurology ® 2012;78:585-589 GLOSSARY AAN ϭ American Academy of Neurology; ACNS ϭ American Clinical Neurophysiology Society; EP ϭ evoked potential; IOM ϭ intraoperative monitoring; MEP ϭ motor evoked potential; SEP ϭ somatosensory evoked potential; tce ϭ transcranial electrical.
Conducted somatosensory evoked potentials during spinal surgery
Journal of …, 1982
V t In 27 patients undergoing laminectomy, spinal cord function was monitored by epidural bipolar recordings of conducted spinal somatosensory evoked potentials (SEP's) across the laminectomy site, with calculation of spinal conduction velocity (CV). In control cases without myelopathy, the CV remained relatively constant (+ 3%) even during prolonged operations, despite markedly changing levels of anesthesia. Acute CV changes were detected intraoperatively in three cases: these patients displayed improvement after extramedullary (Case 1) and intramedullary decompression (Case 2), and deterioration after direct unilateral dorsal column injury (Case 3). These intraoperative CV alterations correlated postoperatively with changes in the neurological examination. Although a unilateral lesion confined to the dorsal column abolished the ipsilateral SEP in Case 3, complete anterior quadrant lesions did not consistently change the CV (Case 4). This further suggests that the SEP is generated entirely by ipsilateral dorsal column activation. Accurate measurement of this dorsal column conduction velocity across the operative field provides a very sensitive means of monitoring spinal cord function during operations for neurosurgical spinal lesions.