Low frequency depression of the H wave in normal and spinal man

Ishikawa, Koichi; Ott, Kenneth; Porter, R.; Stuart, Douglas G.

doi:10.1016/0014-4886(66)90039-2

Cited by 85 publications

(54 citation statements)

References 23 publications

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“…21 In spinally intact individuals, the H-reflex demonstrates depressed amplitude, due to marked frequency-dependent depression, once stimulus frequencies reach or exceed 1 Hz. 22,23 However, frequency-dependent depression of the Hreflex is less evident in patients or animals with chronic SCI. 12,13,22,24,25 Previously, we reported the ability of long-term passive exercise therapy to restore frequencydependent depression of the H-reflex in adult rats with complete spinal cord transections.…”

Section: Introductionmentioning

confidence: 99%

“…22,23 However, frequency-dependent depression of the Hreflex is less evident in patients or animals with chronic SCI. 12,13,22,24,25 Previously, we reported the ability of long-term passive exercise therapy to restore frequencydependent depression of the H-reflex in adult rats with complete spinal cord transections. 24,25 Specifically, we found that a period of 3 months of motorized bicycle exercise training (MBET), performed in episodes of 1 h/ day, 5 days/week, was capable of restoring frequencydependent depression of the H-reflex to the level of intact animals.…”

Section: Introductionmentioning

confidence: 99%

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Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats

et al. 2005

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats

et al. 2005

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“…When the tibial nerve is repetitively stimulated, there is a progressive fall in the amplitudes of the H reflexes (Ishikawa et al 1966;SchindlerIvens and Shields 2000). Conditioning inputs through stimulation of other peripheral nerves activate spinal circuits that are otherwise not engaged and lead to different patterns of H-reflex modulation (Mao et al 1984;Meunier et al 1993;PierrotDeseilligny and Burke 2012).…”

mentioning

confidence: 99%

Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord

Hofstoetter

Danner

Freundl

et al. 2015

Journal of Neurophysiology

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Hofstoetter US, Danner SM, Freundl B, Binder H, Mayr W, Rattay F, Minassian K. Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord. J Neurophysiol 114: 400 -410, 2015. First published April 22, 2015 doi:10.1152/jn.00136.2015.-In individuals with motor-complete spinal cord injury, epidural stimulation of the lumbosacral spinal cord at 2 Hz evokes unmodulated reflexes in the lower limbs, while stimulation at 22-60 Hz can generate rhythmic burstlike activity. Here we elaborated on an output pattern emerging at transitional stimulation frequencies with consecutively elicited reflexes alternating between large and small. We analyzed responses concomitantly elicited in thigh and leg muscle groups bilaterally by epidural stimulation in eight motor-complete spinal cord-injured individuals. Periodic amplitude modulation of at least 20 successive responses occurred in 31.4% of all available data sets with stimulation frequency set at 5-26 Hz, with highest prevalence at 16 Hz. It could be evoked in a single muscle group only but was more strongly expressed and consistent when occurring in pairs of antagonists or in the same muscle group bilaterally. Latencies and waveforms of the modulated reflexes corresponded to those of the unmodulated, monosynaptic responses to 2-Hz stimulation. We suggest that the cyclical changes of reflex excitability resulted from the interaction of facilitatory and inhibitory mechanisms emerging after specific delays and with distinct durations, including postactivation depression, recurrent inhibition and facilitation, as well as reafferent feedback activation. The emergence of large responses within the patterns at a rate of 5.5/s or 8/s may further suggest the entrainment of spinal mechanisms as involved in clonus. The study demonstrates that the human lumbosacral spinal cord can organize a simple form of rhythmicity through the repetitive activation of spinal reflex circuits.

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“…Secondly, H-reflexes are subject to low-frequency depression, whereby with repeated stimulation the amplitude of later H-reflexes is attenuated compared with the first H-reflex by an amount dependent upon the rate of nerve stimulation. 12,14,30 For the rates of stimulation we used in this study (3 Hz), low-frequency depression would be expected to cause a drop in H-reflex amplitude to approximately 60% of the first reflex in a test series. 6 We saw no attenuation whatsoever of evoked responses to repeated pedicle track-or screw-based stimulation at 3 Hz, provided that the stimulating probe was held in the same position and the stimulus intensity was kept constant.…”

mentioning

confidence: 99%

Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 1. Methods and alarm criteria

Calancie¹,

Donohue

Harris

et al. 2014

SPI

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Object Reports of the accuracy of existing neuromonitoring methods for detecting or preventing medial malpositioning of thoracic pedicle screws have varied widely in their claimed effectiveness. The object of this study was to develop, test, and validate a novel neuromonitoring method for preventing medial malpositioning of pedicle screws in the thoracic spine during surgery. Methods This is a prospective, blinded and randomized study using a novel combination of input (4-pulse stimulus trains delivered within the pedicle track) and output (evoked electromyography from leg muscles) to detect pedicle track trajectories that—once implanted with a screw—would cause that screw to breach the pedicle's medial wall and encroach upon the spinal canal. For comparison, the authors also used screw stimulation as an input and evoked electromyogram from intercostal and abdominal muscles as output measures. Intraoperative electrophysiological findings were compared with postoperative CT scans by multiple reviewers blinded to patient identity or intraoperative findings. Results Data were collected from 71 patients, in whom 802 screws were implanted between the T-1 and L-1 vertebral levels. A total of 32 screws ended up with screw threads encroaching on the spinal canal by at least 2 mm. Pulse-train stimulation within the pedicle track using a ball-tipped probe and electromyography from lower limb muscles correctly predicted all 32 (100%) of these medially malpositioned screws. The combination of pedicle track stimulation and electromyogram response from leg muscles proved to be far more effective in predicting these medially malpositioned screws than was direct screw stimulation and any of the target muscles (intercostal, abdominal, or lower limb muscles) we monitored. Based on receiver operating characteristic analysis, the combination of 10-mA (lower alarm) and 15-mA stimulation intensities proved most effective for detection of pedicle tracks that ultimately gave rise to medially malpositioned screws. Additional results pertaining to the impact of feedback of these test results on surgical decision making are provided in the companion report. Conclusions This novel neuromonitoring approach accurately predicts medially malpositioned thoracic screws. The approach could be readily implemented within any surgical program that is already using contemporary neuromonitoring methods that include transcranial stimulation for monitoring motor evoked potentials.

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Low frequency depression of the H wave in normal and spinal man

Cited by 85 publications

References 23 publications

Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats

Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats

Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord

Neuromonitoring with pulse-train stimulation for implantation of thoracic pedicle screws: a blinded and randomized clinical study. Part 1. Methods and alarm criteria

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