A new method using neuromagnetic stimulation to measure conduction time within the cauda equina

Maccabee, Paul J.; Lipitz, M.E.; Desudchit, Tayard; Golub, R.W.; Nitti, V.W.; Bania, J.P.; Willer, J.A.; Cracco, Roger Q.; Cadwell, John; Hotson, Guy; Eberle, L.; Amassian, Vahé E.

doi:10.1016/0924-980x(95)00264-l

Cited by 56 publications

(43 citation statements)

References 18 publications

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“…Table 3 The sensory fiber and motor nerve fiber conduction velocity in the S1 nerve root within the spinal canal Length of S1 nerve root (cm) 17.5 a (SD = 0. reflexes to tibial nerve stimulation lengthened out-of-proportion to the M wave changes during the ischemia. These findings complement earlier studies of the possible clinical feasibility of S1 nerve root stimulation for H-reflexes using magnetic (Zhu et al, 1992;Maccabee et al, 1996) and electrical stimulation (Ertekin et al, 1996). The application of S1 nerve root stimulation methods for eliciting H-reflexes provides a method for distinguishing between proximal and distal lesion sites of the S1 nerve root and its peripheral pathway subserving soleus H-reflexes.…”

Section: Discussionsupporting

confidence: 81%

“…Recent studies have documented that soleus H-reflex can be elicited by magnetic or electrical stimulation of the S1 nerve root and proximal portions of the sciatic nerve (Zhu et al, 1992;Ertekin et al, 1996;Maccabee et al, 1996). The ability to elicit the soleus H-reflex from stimulation of several different sites (S1 nerve root, sciatic nerve, tibial nerve) will be of help in distinguishing between proximal and distal involvement of the reflex pathway.…”

Section: Introductionmentioning

confidence: 99%

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Soleus H-reflex to S1 nerve root stimulation

Zhu

Starr

Haldeman

et al. 1998

Electroencephalography and Clinical Neurophysiology/Electromyog

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Section: Discussionsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Soleus H-reflex to S1 nerve root stimulation

Zhu

Starr

Haldeman

et al. 1998

Electroencephalography and Clinical Neurophysiology/Electromyog

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“…Geometric and electric factors result in lowthreshold sites for electrical stimulation where posterior root fibers enter the spinal cord. 18,[31][32][33][34][35] At these sites, posterior root fibers entering the cord caudal to the cathode can have lower thresholds than longitudinal fibers passing the level of the cathode. The high electric conductivity of the cerebrospinal fluid and the longitudinal orientation of the white matter allow the current to spread in a rostrocaudal direction.…”

mentioning

confidence: 99%

Stepping-like movements in humans with complete spinal cord injury induced by epidural stimulation of the lumbar cord: electromyographic study of compound muscle action potentials

et al. 2004

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Study design: It has been previously demonstrated that sustained nonpatterned electric stimulation of the posterior lumbar spinal cord from the epidural space can induce stepping-like movements in subjects with chronic, complete spinal cord injury. In the present paper, we explore physiologically related components of electromyographic (EMG) recordings during the induced stepping-like activity. Objectives: To examine mechanisms underlying the stepping-like movements activated by electrical epidural stimulation of posterior lumbar cord structures. Materials and methods: The study is based on the assessment of epidural stimulation to control spasticity by simultaneous recordings of the electromyographic activity of quadriceps, hamstrings, tibialis anterior, and triceps surae. We examined induced muscle responses to stimulation frequencies of 2.2-50 Hz in 10 subjects classified as having a motor complete spinal cord injury (ASIA A and B). We evaluated stimulus-triggered time windows 50 ms in length from the original EMG traces. Stimulus-evoked compound muscle action potentials (CMAPs) were analyzed with reference to latency, amplitude, and shape. Results: Epidural stimulation of the posterior lumbosacral cord recruited lower limb muscles in a segmental-selective way, which was characteristic for posterior root stimulation. A 2.2 Hz stimulation elicited stimulus-coupled CMAPs of short latency which were approximately half that of phasic stretch reflex latencies for the respective muscle groups. EMG amplitudes were stimulus-strength dependent. Stimulation at 5-15 and 25-50 Hz elicited sustained tonic and rhythmic activity, respectively, and initiated lower limb extension or stepping-like movements representing different levels of muscle synergies. All EMG responses, even during burst-style phases were composed of separate stimulus-triggered CMAPs with characteristic amplitude modulations. During burst-style phases, a significant increase of CMAP latencies by about 10 ms was observed. Conclusion: The muscle activity evoked by epidural lumbar cord stimulation as described in the present study was initiated within the posterior roots. These posterior roots muscle reflex responses (PRMRRs) to 2.2 Hz stimulation were routed through monosynaptic pathways. Sustained stimulation at 5-50 Hz engaged central spinal PRMRR components. We propose that repeated volleys delivered to the lumbar cord via the posterior roots can effectively modify the central state of spinal circuits by temporarily combining them into functional units generating integrated motor behavior of sustained extension and rhythmic flexion/extension movements. This study opens the possibility for developing neuroprostheses for activation of inherent spinal networks involved in generating functional synergistic movements using a single electrode implanted in a localized and stable region.

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“…Some centers have reported problems with stimulus artifacts from high-output sacral stimulation [Eardley et al, 1990;Jost and Schimrigk, 1994a;Maccabee et al, 1996]. Ghezzi et al [1991] found that MEP waveforms were barely perceptible when TMS was applied over the upper lumbar area.…”

Section: Pelvic Floor Mepsmentioning

confidence: 98%

“…In a careful study of cauda equina conduction, Maccabee et al [1996] found two ¢xed low-threshold sites or 'hot-spots' along the lumbosacral spine. Possible anatomical correlates for these 'hot-spots' are: proximally the exit of cauda equina rootlets from the spinal cord; and distally the transit of nerve rootlets through the osseous foramina [Ugawa et al, 1989;Maccabee et al, 1996]. However, they also observed responses with intermediate latency on stimulation between the proximal and distal 'hotspots, ' showing that excitation is not restricted to these sites.…”

Section: Sources Of Variabilitymentioning

confidence: 99%