Temporal summation--the key to motor evoked potential spinal cord monitoring in humans.

“…As a result of general anaesthesia, recording of peripheral muscle activation is harder, but has become possible after introduction of a short train of transcranial electrical stimulation [20]. Intraoperative motor evoked potentials can also be elicited by trains of transcranial magnetic stimulation [21], but electrical stimulation with scalp needle electrodes leads to more reliable and reproducible potentials and is easier to perform.…”

Section: Motor Evoked Potentialsmentioning

confidence: 99%

Multimodal intraoperative monitoring: an overview and proposal of methodology based on 1,017 cases

et al. 2007

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To describe different currently available tests of multimodal intraoperative monitoring (MIOM) used in spine and spinal cord surgery indicating the technical parameters, application and interpretation as an easy understanding systematic overview to help implementation of MIOM and improve communication between neurophysiologists and spine surgeons. This article aims to give an overview and proposal of the different MIOM-techniques as used daily in spine and spinal cord surgery at our institution. Intensive research in neurophysiology over the past decades has lead to a profound understanding of the spinal cord, nerve functions and their intraoperative functional evaluation in anaesthetised patients. At present, spine surgeons and neurophysiologist are faced with 1,883 publications in PubMed on spinal cord monitoring. The value and the limitations of single monitoring methods are well documented. The diagnostic power of the multimodal approach in a larger study population in spine surgery, as measured with sensitivity and specificity, is dealt with elsewhere in this supplement (Sutter et al. in Eur Spine J Suppl, 2007). This paper aims to give a detailed description of the different modalities used in this study. Description of monitoring techniques of the descending and ascending spinal cord and nerve root pathways by motor evoked potentials of the spinal cord and muscles elicited after transcranial electrical motor cortex, spinal cord, cauda equina and nerve root stimulation, continuous EMG, sensory cortical and spinal evoked potentials, as well as direct spinal cord evoked potentials applied on 1,017 patients.The method of MIOM, continuously adapted according to the site, stage of surgery and potential danger to nerve tissues, proved to be applicable with online results, reliable and furthermore teachable.

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“…Previous reports of animal and human studies using cortical and spinal stimulation have described that double or repetitive stimuli at an ISI of 2 ms are suitable for enhancing motor responses (Bannister and Porter 1967;Calancie et al 1998;Muir and Porter 1973;Taniguchi et al 1993;Taylor BA et al 1993;Taylor JL et al 2002;Yamada et al 1995). In animal experiments during anesthetization, movements in the limbs, excitatory postsynaptic potentials (EPSPs) at the spinal motoneurons (MNs), and MEP size have been analyzed and 2 ms is the optimal ISI in every research (Bannister and Porter 1967;Muir and Porter 1973;Yamada et al 1995).…”

Section: Mechanism Of Mep Enlargementmentioning

confidence: 99%

“…In animal experiments during anesthetization, movements in the limbs, excitatory postsynaptic potentials (EPSPs) at the spinal motoneurons (MNs), and MEP size have been analyzed and 2 ms is the optimal ISI in every research (Bannister and Porter 1967;Muir and Porter 1973;Yamada et al 1995). In human studies during anesthetization, the optimal ISI was 2 ms to obtain maximal MEPs (Calancie et al 1998;Taniguchi et al 1993;Taylor BA et al 1993). The studies of animals and humans described earlier revealed that the temporal summation of EPSP at the spinal cord level might be maximal at an interval of 2 ms because facilitation within the cortex does not contribute in the anesthetized condition.…”

Section: Mechanism Of Mep Enlargementmentioning

confidence: 99%

Double-Pulse Magnetic Brain Stem Stimulation: Mimicking Successive Descending Volleys

Matsumoto¹,

Hanajima²,

Hamada³

et al. 2008

Journal of Neurophysiology

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Matsumoto H, Hanajima R, Hamada M, Terao Y, Yugeta A, Inomata-Terada S, Nakatani-Enomoto S, Tsuji S, Ugawa Y. Double-pulse magnetic brain stem stimulation: mimicking successive descending volleys. J Neurophysiol 100: 3437-3444, 2008. First published October 15, 2008 doi:10.1152/jn.90751.2008. Magnetic stimulation with a double-cone-coil over the back of the head activates the motor tracts at the level of pyramidal decussation (brain stem stimulation [BST]). However, single-pulse BST (single BST) sometimes cannot elicit motor-evoked potentials (MEPs) in patients with corticospinal tract involvement. We developed a technique using double-pulse BST (double BST) to elicit MEPs even in patients whose threshold is abnormally elevated. Subjects were 11 healthy volunteers and 12 patients with corticospinal tract involvement in whom single BST evoked no discernible MEP. Double BST was performed at the intensities of resting and active motor threshold for single BST; MEPs were recorded from the first dorsal interosseous muscle. Interstimulus intervals (ISIs) between two pulses were 1.5, 2, 3, 5, and 10 ms in healthy subjects. Double BST enlarged MEPs at ISIs of 1.5-5 ms with a peak at 2 ms in the relaxed condition, but not in the active condition. At an ISI of 2 ms in the relaxed condition, the MEP amplitude was 15 times as large as that to single BST in relaxed muscles. The onset latency of the enlarged MEP from the second pulse in relaxed muscles was the same as that by single BST in active muscles. Double BST at a 2-ms interval elicited MEPs in eight patients. Double BST can enhance MEPs probably by temporal summations of excitatory postsynaptic potentials at the spinal motoneurons. Using this new technique, we can obtain more information about the central motor conduction even when single BST fails to elicit any MEP.

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Temporal summation--the key to motor evoked potential spinal cord monitoring in humans.

Cited by 96 publications

References 9 publications

Intraoperative nerve monitoring during total shoulder arthroplasty surgery

Intraoperative nerve monitoring during total shoulder arthroplasty surgery

Multimodal intraoperative monitoring: an overview and proposal of methodology based on 1,017 cases

Double-Pulse Magnetic Brain Stem Stimulation: Mimicking Successive Descending Volleys

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