• Makoto Kadowaki, Kenji Sugiyama, Takao Nozaki, Tomohiro Yamasaki, Hiroki Namba, Mikihiro Shimizu, and Kazuhiko Kurozumi.
• Department of Neurosurgery, Hamamatsu University School of Medicine, Hamamatsu , Shizuoka , Japan.
• Neurosurgery. 2024 Aug 1; 95 (2): 447455447-455.

Background And ObjectivesIn magnetic resonance-guided focused ultrasound (MRgFUS) procedures, headache is a frequent symptom and cause of treatment discontinuation. Herein, we assessed the efficacy of scalp nerve block (SNB) for alleviating headache during MRgFUS procedures.MethodsThe effect of SNB on intraprocedural headache was examined by retrospectively comparing 2 patient cohorts at a single institution. During the study period from April 2020 to February 2022, an SNB protocol for all patients with a skull density ratio ≤0.55 was instituted on October 6, 2021. The number of patients with a skull density ratio ≤0.55 was 34 before the protocol and 36 afterward. Headache intensity was evaluated using a numerical rating scale (NRS) after each sonication. To evaluate the effect of SNB on headache intensity, multiple regression analysis was performed per patient and per sonication. In the per-patient analysis, the effect of SNB was evaluated using the maximum NRS, mean NRS, and NRS at the first ultrasound exposure that reached 52.5°C. In the per-sonication analysis, the effect of SNB was evaluated not only for the entire sonication but also for sonications classified into ≤9999 J, 10 000 to 29 999 J, and ≥30 000 J energy doses.ResultsWith SNB, headache alleviation was observed in the NRS after the first sonication that reached 52.5°C in each patient (β = -2.40, 95% CI -4.05 to -0.758, P = .00499), in the NRS when all sonications were evaluated (β = -0.647, 95% CI -1.19 to -0.106, P = .0201), and in the NRS when all sonications were classified into 10 000 to 29 999 J (β = -1.83, 95% CI -3.17 to -0.485, P = .00889).ConclusionSNB significantly reduced headache intensity during MRgFUS, especially that caused by sonication with a moderate-energy dose. These findings suggest that scalp nerves play a role in headache mechanisms during MRgFUS.Copyright © Congress of Neurological Surgeons 2024. All rights reserved.

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