Transcranial High-frequency Repetitive Electrical Stimulation for Recording Myogenic Motor Evoked Potentials with the Patient under General Anesthesia

✓ The feasibility of high-frequency transcranial electrical stimulation (TES) through screw electrodes placed in the skull was investigated for use in intraoperative monitoring of the motor pathways in patients who are in a state of general anesthesia during cerebral and spinal operations. Motor evoked potentials (MEPs) were elicited by TES with a train of five square-wave pulses (duration 400 µsec, intensity ≤ 200 mA, frequency 500 Hz) delivered through metal screw electrodes placed in the outer table of the skull over the primary motor cortex in 42 patients. Myogenic MEPs to anodal stimulation were recorded from the abductor pollicis brevis (APB) and tibialis anterior (TA) muscles. The mean threshold stimulation intensity was 48 ± 17 mA for the APB muscles, and 112 ± 35 mA for the TA muscles. The electrodes were firmly fixed at the site and were not dislodged by surgical manipulation throughout the operation. No adverse reactions attributable to the TES were observed. Passing current through the screw electrodes stimulates the motor cortex more effectively than conventional methods of TES. The method is safe and inexpensive, and it is convenient for intraoperative monitoring of motor pathways.

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Comparison of motor-evoked potentials monitoring in response to transcranial electrical stimulation in subjects undergoing neurosurgery with partial vs no neuromuscular block

Journal of Neuroanaesthesiology and Critical Care ◽

10.4103/2348-0548.124864 ◽

2014 ◽

Vol 01 (01) ◽

pp. 077-078

Author(s):

Nitasha Mishra

Keyword(s):

Electrical Stimulation ◽

Evoked Potentials ◽

Motor Evoked Potentials ◽

Neuromuscular Block ◽

Transcranial Electrical Stimulation

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Methodology for intraoperatively eliciting motor evoked potentials in the vocal muscles by electrical stimulation of the corticobulbar tract

Clinical Neurophysiology ◽

10.1016/j.clinph.2008.11.013 ◽

2009 ◽

Vol 120 (2) ◽

pp. 336-341 ◽

Cited By ~ 40

Author(s):

Vedran Deletis ◽

Isabel Fernandez-Conejero ◽

Sedat Ulkatan ◽

Peter Costantino

Keyword(s):

Electrical Stimulation ◽

Evoked Potentials ◽

Motor Evoked Potentials ◽

Corticobulbar Tract ◽

Stimulation Of

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Neuromodulation of motor-evoked potentials during stepping in spinal rats

Journal of Neurophysiology ◽

10.1152/jn.00169.2013 ◽

2013 ◽

Vol 110 (6) ◽

pp. 1311-1322 ◽

Cited By ~ 22

Author(s):

Parag Gad ◽

Igor Lavrov ◽

Prithvi Shah ◽

Hui Zhong ◽

Roland R. Roy ◽

...

Keyword(s):

Spinal Cord ◽

Electrical Stimulation ◽

Evoked Potentials ◽

Motor Evoked Potentials ◽

Motor Task ◽

Hindlimb Muscles ◽

Epidural Spinal Cord Stimulation ◽

Highly Correlated ◽

Muscle Responses

The rat spinal cord isolated from supraspinal control via a complete low- to midthoracic spinal cord transection produces locomotor-like patterns in the hindlimbs when facilitated pharmacologically and/or by epidural electrical stimulation. To evaluate the role of epidural electrical stimulation in enabling motor control (eEmc) for locomotion and posture, we recorded potentials evoked by epidural spinal cord stimulation in selected hindlimb muscles during stepping and standing in adult spinal rats. We hypothesized that the temporal details of the phase-dependent modulation of these evoked potentials in selected hindlimb muscles while performing a motor task in the unanesthetized state would be predictive of the potential of the spinal circuitries to generate stepping. To test this hypothesis, we characterized soleus and tibialis anterior (TA) muscle responses as middle response (MR; 4–6 ms) or late responses (LRs; >7 ms) during stepping with eEmc. We then compared these responses to the stepping parameters with and without a serotoninergic agonist (quipazine) or a glycinergic blocker (strychnine). Quipazine inhibited the MRs induced by eEmc during nonweight-bearing standing but facilitated locomotion and increased the amplitude and number of LRs induced by eEmc during stepping. Strychnine facilitated stepping and reorganized the LRs pattern in the soleus. The LRs in the TA remained relatively stable at varying loads and speeds during locomotion, whereas the LRs in the soleus were strongly modulated by both of these variables. These data suggest that LRs facilitated electrically and/or pharmacologically are not time-locked to the stimulation pulse but are highly correlated to the stepping patterns of spinal rats.

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