Yoo YJ, et al. Brain Neurorehabil. 2022 Jul;15(2):e17. https://doi.org/10.12786/bn.2022.15.e17

So JI, et al. Ann Rehabil Med. 2017 Feb;41(1):51-57. https://doi.org/10.5535/arm.2017.41.1.51

Kim DY, et al. Brain Neurorehabil. 2023 Jul;16(2):e18. https://doi.org/10.12786/bn.2023.16.e18

To determine a diagnostic cut-off value for the cross-sectional area (CSA) of the radial nerve using ultrasonography for radial neuropathy located at the spiral groove (SG). Seventeen patients with electrodiagnostic evidence of radial neuropathy at the SG and 30 healthy controls underwent ultrasonography of the radial nerve at the SG . The CSAs at the SG were compared in the patient and control groups. The CSA at the SG between the symptomatic and asymptomatic sides (ΔSx-Asx and Sx/Asx, respectively) were analyzed to obtain the optimal cut-off value. The relationship between the electrophysiological severity of radial neuropathy and CSA was also evaluated. Among the variables examined, there were statistically significant differences in the CSA between the patient and control groups, ΔSx-Asx, and Sx/Asx at the SG. In a receiver operating characteristics analysis, the cut-off CSA was 5.75 mm2 at the SG (sensitivity 52.9%, specificity 90%), 1.75 mm2 for ΔSx-Asx (sensitivity 58.8%, specificity 100%), and 1.22 mm2 for Sx/Asx (sensitivity 70.6%, specificity 93.3%) in diagnosing radial neuropathy at the SG. There was no significant correlation between CSA and electrophysiological severity score for either patient group. The reference value obtained for CSA of the radial nerve at the SG may facilitate investigation of radial nerve pathologies at the SG.

Lee SH, et al. Brain Neurorehabil. 2024 Nov;17(3):e24. https://doi.org/10.12786/bn.2024.17.e24

Transcranial direct current stimulation (tDCS) has emerged as a promising tool for stroke rehabilitation, supported by evidence demonstrating its beneficial effects on post-stroke recovery. However, patients with skull defects, such as burr holes, have been excluded from tDCS due to limited knowledge regarding the effect of skull defects on the electric field. We investigated the effect of burr holes on the electric field induced by tDCS and identified the electrode location that modulates the electric field. We generated mesh models of the heads of five patients with burr holes and five age-matched control patients who had never undergone brain surgery, based on magnetic resonance imaging. Then we conducted tDCS simulations, with the cathode fixed in one position and the anode in various positions. Regression analysis was employed to investigate the relationship between the electric field at the burr hole and the distance from the burr hole to the anode. In patients with burr holes, the electric field intensity increased as the anode approached the burr hole, reaching a maximum electric field when the anode covered it, with this pattern remaining consistent across all patient models. Assuming the holes were filled with cerebrospinal fluid, the maximum electric field was 1.20 ± 0.20 V/m (mean ± standard deviation, SD). When the anode was positioned more than 60 mm away from the burr hole, the electric field at the burr hole remained low and constant, with an average value of 0.29 ± 0.04V/m (mean ± SD). In contrast, for all patients without burr holes, the electric field intensity stayed constant regardless of the anode's position, with a maximum amplitude of 0.36 ± 0.04 V/m (mean ± SD). Furthermore, when the burr hole was assumed to be filled with scar tissue, the mean peak electric field was 0.93 ± 0.16 V/m, indicating that the electric field strength varies depending on the conductivity of the tissue filling the burr hole. Based on the simulations, the minimum recommended distance from the burr hole to the anode is 60 mm to prevent unintended stimulation of the brain cortex during tDCS. These findings will contribute to the development of safe and effective tDCS treatments for patients with burr holes.