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Letter to the editor
Successful Treatment of a Patient With Tremors and Extensive Brain Lesions Using Posterior Subthalamic Area–Deep Brain Stimulation -
Taku Nonaka1,2
, Takashi Asahi1
, Shiro Horisawa2, Kiyonobu Ikeda1, Nobutaka Yamamoto1, Takaomi Taira2 -
Journal of Movement Disorders 2025;18(4):372-374.
DOI: https://doi.org/10.14802/jmd.25096
Published online: July 16, 2025
1Department of Neurosurgery, Kanazawa Neurosurgical Hospital, Ishikawa, Japan
2Department of Neurosurgery, Tokyo women’s Hospital, Tokyo, Japan
- Corresponding author: Takashi Asahi, MD, PhD Department of Neurosurgery, Kanazawa Neurosurgical Hospital, 262-2 Go-machi, Nonoichi-shi, Ishikawa 921-8841, Japan / Tel: +81-76-246-5600 / Fax: +81-76-246-3914 / E-mail: takashi.asahi@gmail.com
• Received: April 14, 2025 • Revised: June 8, 2025 • Accepted: July 16, 2025
Copyright © 2025 The Korean Movement Disorder Society
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Dear Editor,
Essential tremor (ET) is a neurological disorder characterized by tremors of unknown etiology. When pharmacological treatments are insufficient, surgical interventions targeting the ventromedial thalamic (Vim) nucleus, such as deep brain stimulation (DBS), radiofrequency thalamotomy, and focused ultrasound, have proven effective [1]. The posterior subthalamic area (PSA), located between the red and subthalamic nuclei, has also been identified as an effective target for tremor control [2]. Here, we present a case of successful PSA-DBS in a patient with ET and severe brain atrophy in whom identification of the Vim nucleus was challenging due to marked hemispheric atrophy and ventricular enlargement. This patient underwent PSA-DBS, which proved to be effective.
A 62-year-old woman developed left upper limb tremors at the age of 54 years. Her medical history included three craniotomies for subcortical hemorrhage at age 2 years, resulting in right hemiparesis, epilepsy, and mild intellectual disability. The patient primarily used her left hand for daily activities. When she was diagnosed with ET by her previous neurologist, she was initially prescribed propranolol, which gradually lost efficacy as her symptoms progressed and significantly impacted her daily life. She was seen at another hospital for focused ultrasound surgery, but this was deemed inappropriate because of the strong brain deformity, and she was referred to our hospital.
Neurological examination revealed action tremors in the left upper limb and residual right hemiparesis, although the patient retained independent walking ability (Supplementary Video 1 in the online-only Data Supplement). The tremor was mild at rest but became more pronounced with posture and voluntary movement. Daily activities such as drinking from a cup and using chopsticks exacerbated the tremor and interfered with daily life. There was no evidence of ataxia or dystonia in the unaffected (left) arm. Because of hemiparesis, the patient’s right upper limb could not be reliably evaluated for tremor. No stiffness or rigidity was observed in the extremities. Medication-induced tremor, hyperthyroidism, and other metabolic disorders were appropriately excluded. The tremor characteristics closely resembled those typically observed in patients with ET without brain deformity and were considered consistent with a diagnosis of ET. The Fahn–Tolosa–Marin tremor rating scale (FTMTRS) score was 30. Despite mild intellectual disability, she was able to communicate effectively in daily situations. Imaging revealed marked atrophy of the left cerebral hemisphere and ventricular enlargement, complicating identification of the right Vim nucleus (Figure 1A and B). However, the red nucleus on the right was visible on magnetic resonance imaging (MRI), indicating PSA localization (Figure 1C).
On the basis of these findings, we performed PSA-DBS. Surgical planning was conducted using Elements® (Brain Lab), with direct targeting via the red nucleus due to difficulties with the conventional anterior‒posterior commissure (AC‒PC) line method. Attempts were made to delineate the thalamic Vim by tractography, but this was not possible because of severe brain deformation. The target was set in the lateral white matter of the red nucleus at its maximum diameter on axial images (Figure 1D). The GenusR16TM and D-leadTM (Boston Scientific) DBS systems were used.
Surgery was initiated under propofol sedation, with the patient awake for intraoperative stimulation. After tremor suppression was confirmed, the lead was placed. Postoperative computed tomography combined with preoperative MRI confirmed lead placement in the lateral white matter of the red nucleus (PSA) (Figure 1D, E, and F). The final stimulation parameters were set at 1-C+, 30 μs, 130 Hz, and 9 mA, resulting in tremor elimination without side effects, which persisted over 2 years of follow-up (FTMTRS was 0).
This case demonstrates the successful application of PSA-DBS in a patient with ET in whom Vim nucleus identification was challenging due to brain atrophy and structural changes resulting from childhood cerebral hemorrhage. Although automatic anatomical structure detection in the planning software was ineffective, the visible red nuclear structure facilitated targeting (Figure 1C and D).
Both the Vim and the PSA are part of the dentate–rubrothalamic tract, which accounts for their efficacy in alleviating tremors when stimulated [3]. However, Vim-DBS typically relies on identifying the AC‒PC line and the thalamic border on preoperative MR images. Methods for targeting the PSA have been described, including anatomical landmark-based techniques [2] and tractography [3]. In this case, tractography was not feasible because of significant brain deformation. The PSA has been reported to lie in the white matter between the subthalamic nucleus and the red nucleus on axial imaging [2]. Because the PSA is located lateral to the red nucleus, we estimated the target position on the basis of the identifiable position of the red nucleus. Tremor suppression was confirmed with intraoperative stimulation, validating the accuracy of lead placement.
In this case, we used a 30 μs pulse width for stimulation. Several studies comparing 30 μs and 60 μs stimulation in Parkinson’s disease patients have reported an expanded therapeutic window and improved fine-tuning of stimulation parameters [4]. Furthermore, a recent systematic review including PSA-DBS indicated that shorter pulse widths are more effective in alleviating ET [5]. Therefore, we routinely use 30 μs stimulation to achieve more precise parameter adjustments and minimize energy-related tissue effects.
When comparing Vim and PSA effectiveness, although Vim has more reported cases, PSA-DBS is also well documented. Dembek et al. [6] reported that PSA-DBS achieved symptom improvement at lower current values and significantly lower TRS hemiscores than Vim-DBS did. Fan et al. [7] reviewed 23 studies and reported that PSA-DBS resulted in significantly greater TRS improvement than Vim-DBS.
Although this is a single case report, this case suggests that PSA-DBS using the red nucleus as a reference may improve symptoms in patients with ET with structural brain abnormalities, precluding Vim nucleus identification.
Supplementary Materials
The online-only Data Supplement is available with this article at https://doi.org/10.14802/jmd.25096.
Video 1.
Preoperative condition of the patient (first half): Action tremor in the left upper limb, particularly noticeable during the use of chopsticks, cups, and writing, significantly impacted daily life. Postoperative condition (second half): Complete resolution of action tremor.
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Ethics Statement
This study was approved by the ethics committee of Kanazawa Neurosurgical Hospital (approval number ID [R05-19], Ishikawa, Japan). The written informed consent was obtained from the patient.
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Conflicts of Interest
The authors have no financial conflicts of interest.
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Funding Statement
None
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Acknowledgments
None
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Author Contributions
Conceptualization: Takashi Asahi, Shiro Horisawa, Takaomi Taira. Data curation: Taku Nonaka. Methodology: Shiro Horisawa. Project administration: Takaomi Taira. Supervision: Kiyonobu Ikeda, Takaomi Taira. Validation: Takashi Asahi. Visualization: Takashi Asahi. Writing—original draft: Taku Nonaka. Writing—review & editing: Takashi Asahi, Nobutaka Yamamoto.
Notes
Figure 1.
Neuroimaging and lead trajectory targeting the posterior subthalamic area. A, B: Axial computed tomography images demonstrating marked ventricular enlargement and brain asymmetry. C-F: Fast gray matter acquisition T1 inversion recovery 3 T magnetic resonance images. C: Slight delineation of the right red nucleus and surrounding white matter. D: The red nucleus is marked with a red circle using planning software; the actual lead trajectory is indicated by a yellow line. E (coronal) and F (axial): Volume of tissue activated under final stimulation parameters (30 μs, 130 Hz, 9 mA), confirming effective stimulation of the posterior subthalamic area lateral to the red nucleus.
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- 2. Nowacki A, Debove I, Rossi F, Schlaeppi JA, Petermann K, Wiest R, et al. Targeting the posterior subthalamic area for essential tremor: proposal for MRI-based anatomical landmarks. J Neurosurg 2019;131:820–827.ArticlePubMed
- 3. Nowacki A, Schlaier J, Debove I, Pollo C. Validation of diffusion tensor imaging tractography to visualize the dentatorubrothalamic tract for surgical planning. J Neurosurg 2019;130:99–108.ArticlePubMed
- 4. Dayal V, Grover T, Tripoliti E, Milabo C, Salazar M, Candelario-McKeown J, et al. Short versus conventional pulse-width deep brain stimulation in Parkinson’s disease: a randomized crossover comparison. Mov Disord 2020;35:101–108.ArticlePubMedPDF
- 5. Smeets S, Boogers A, Van Bogaert T, Peeters J, McLaughlin M, Nuttin B, et al. Deep brain stimulation with short versus conventional pulse width in Parkinson’s disease and essential tremor: a systematic review and meta-analysis. Brain Stimul 2024;17:71–82.ArticlePubMed
- 6. Dembek TA, Petry-Schmelzer JN, Reker P, Wirths J, Hamacher S, Steffen J, et al. PSA and VIM DBS efficiency in essential tremor depends on distance to the dentatorubrothalamic tract. Neuroimage Clin 2020;26:102235.ArticlePubMedPMC
- 7. Fan H, Bai Y, Yin Z, An Q, Xu Y, Gao Y, et al. Which one is the superior target? A comparison and pooled analysis between posterior subthalamic area and ventral intermediate nucleus deep brain stimulation for essential tremor. CNS Neurosci Ther 2022;28:1380–1392.ArticlePubMedPMCPDF
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Figure 1. Neuroimaging and lead trajectory targeting the posterior subthalamic area. A, B: Axial computed tomography images demonstrating marked ventricular enlargement and brain asymmetry. C-F: Fast gray matter acquisition T1 inversion recovery 3 T magnetic resonance images. C: Slight delineation of the right red nucleus and surrounding white matter. D: The red nucleus is marked with a red circle using planning software; the actual lead trajectory is indicated by a yellow line. E (coronal) and F (axial): Volume of tissue activated under final stimulation parameters (30 μs, 130 Hz, 9 mA), confirming effective stimulation of the posterior subthalamic area lateral to the red nucleus.
Figure 1.
Successful Treatment of a Patient With Tremors and Extensive Brain Lesions Using Posterior Subthalamic Area–Deep Brain Stimulation
