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- Axelson, Hans W, et al.
(författare)
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Trigeminal Nerve Stimulation Does Not Acutely Affect Cortical Excitability in Healthy Subjects
- 2014
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 7:4, s. 613-617
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Trigeminal nerve stimulation (TNS) has recently emerged as a new therapeutic option for patients with drug-resistant epilepsy but its potential mechanisms of action are not known. Since other antiepileptic treatments have been shown to alter cortical excitability, thereby reducing the liability to seizures, it has been suggested that cranial nerve stimulation such as TNS may act in the same way.OBJECTIVE: To study whether TNS has the potential to alter cortical excitability in healthy subjects.METHODS: An adaptive paired-pulse transcranial magnetic stimulation protocol stimulating the dominant hand motor area was used to measure resting motor threshold (rMT), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and long-interval intracortical inhibition (LICI) before, during, and after 40 min of 120 Hz bilateral external continuous trigeminal nerve stimulation. Neuronavigation was used for guidance.RESULTS: TNS was well tolerated by all subjects. No significant changes were seen in the parameters studied.CONCLUSION: Unlike for example anti-epileptic drugs and the ketogenic diet, trigeminal nerve stimulation does not seem to alter cortical excitability in healthy subjects. This is the first study on cortical excitability in relation to continuous trigeminal nerve stimulation. It still remains to be proven that TNS has the prerequisites to effectively counteract epileptic events in humans.
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- Caliandro, Pietro, et al.
(författare)
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Jitter of Corticospinal Neurons During Repetitive Transcranial Magnetic Stimulation : Method and Possible Clinical Implications
- 2014
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 7:4, s. 580-586
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Tidskriftsartikel (refereegranskat)abstract
- Background: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex activates corticospinal neurons mainly through the depolarization of cortico-cortical axons belonging to interneurons of superficial layers. Objective: We used single-fiber electromyography (SFEMG) to estimate the "central jitter" of activation latency of interneural pools from one pulse of TMS to another. Methods: We evaluated 10 healthy subjects and one patient with multiple sclerosis. By recording SFEMG evoked activity from the left first dorsal interosseous (FDI), we first used a standard repetitive electrical 3 Hz stimulation of the ulnar nerve at the wrist to calculate the mean consecutive difference from at least 10 different potentials. The same procedure was applied during 3 Hz repetitive TMS of the contralateral motor cortex. The corticospinal monosynaptic connection of the FDI and the selectivity of SFEMG recording physiologically justified the subtraction of the "peripheral jitter" from the whole cortico-muscular jitter, obtaining an estimation of the actual "central jitter." Results: All subjects completed the study. The peripheral jitter was 28 mu s +/- 6 and the cortico-muscular jitter was 344 mu s +/- 97. The estimated central jitter was 343 +/- 97 mu s. In the patient the central jitter was 846 mu s, a value more than twice the central jitter in healthy subjects. Conclusion: Current results demonstrate that the evaluation of the central component of the cumulative cortico-muscular latency variability in healthy subjects is feasible with a minimally invasive approach. We present and discuss this methodology and provide a "proof of concept" of its potential clinical applicability in a patient with multiple sclerosis.
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