Quadripulse transcranial magnetic stimulation inducing long-term depression in healthy subjects may increase seizure risk in some patients with intractable epilepsy

Setsu Nakatani-Enomoto; Ritstuko Hanajima; Masashi Hamada; Hideyuki Matsumoto; Yasuo Terao; Stefan Jun Groiss; Takenobu Murakami; Mitsunari Abe; Hiroyuki Enomoto; Kensuke Kawai; Rumiko Kan; Shin-Ichi Niwa; Hirooki Yabe; Yoshikazu Ugawa

doi:10.1016/j.cnp.2023.07.001

Quadripulse transcranial magnetic stimulation inducing long-term depression in healthy subjects may increase seizure risk in some patients with intractable epilepsy

Clin Neurophysiol Pract. 2023 Jul 7:8:137-142. doi: 10.1016/j.cnp.2023.07.001. eCollection 2023.

Authors

Setsu Nakatani-Enomoto^{1

2

3}, Ritstuko Hanajima^{2

4}, Masashi Hamada², Hideyuki Matsumoto², Yasuo Terao^{2

5}, Stefan Jun Groiss^{1

6}, Takenobu Murakami^{1

4}, Mitsunari Abe¹, Hiroyuki Enomoto¹, Kensuke Kawai^{7

8}, Rumiko Kan⁹, Shin-Ichi Niwa⁹, Hirooki Yabe⁹, Yoshikazu Ugawa^{1

2

10}

Affiliations

¹ Department of Neurology, School of Medicine, Fukushima Medical University, Fukushima, Japan.
² Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
³ Department of Rehabilitation, Faculty of Health Care and Medical Sports, Teikyo Heisei University, Chiba, Japan.
⁴ Division of Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Tottori, Japan.
⁵ Department of Cell Physiology, Kyorin University School of Medicine, Tokyo, Japan.
⁶ Department of Neurology-Center for Movement Disorders and Neuromodulation-and Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany.
⁷ Department of Neurosurgery, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
⁸ Department of Neurosurgery, Jichi Medical University, Tochigi, Japan.
⁹ Department of Neuropsychiatry, School of Medicine, Fukushima Medical University, Fukushima, Japan.
¹⁰ Department of Human Neurophysiology, School of Medicine, Fukushima Medical University, Fukushima, Japan.

Abstract

Objective: This study aimed to assess the efficacy and safety of quadripulse transcranial magnetic stimulation-50 (QPS-50) in patients with intractable epilepsy.

Methods: Four patients were included in the study. QPS-50, which induces long-term depression in healthy subjects, was administered for 30 min on a weekly basis for 12 weeks. Patients' clinical symptoms and physiological parameters were evaluated before, during, and after the repeated QPS-50 period. We performed two control experiments: the effect in MEP (Motor evoked potential) size after a single QPS-50 session with a round coil in nine healthy volunteers, and a follow-up study of physiological parameters by repeated QPS-50 sessions in four other healthy participants.

Results: Motor threshold (MT) decreased during the repeated QPS-50 sessions in all patients. Epileptic symptoms worsened in two patients, whereas no clinical worsening was observed in the other two patients. In contrast, MT remained unaffected for 12 weeks in all healthy volunteers.

Conclusions: QPS-50 may not be effective as a treatment for intractable epilepsy.

Significance: In intractable epilepsy patients, administering repeated QPS-50 may paradoxically render the motor cortex more excitable, probably because of abnormal inhibitory control within the epileptic cortex. The possibility of clinical aggravation should be seriously considered when treating intractable epilepsy patients with non-invasive stimulation methods.

Keywords: Intractable epilepsy; Motor threshold; Quadripulse transcranial magnetic stimulation; Seizure.