Habenula as a Marker of Thalamic Asymmetrical Skew and a Landmark for the Vim-Vc Boundary in MRgFUS Thalamotomy.

Authors

Namiko Nishida, Yoshito Sugita, Masahiro Sawada, Kayoko Obora, Yosuke Taruno, Satoshi Kaneko, Takayoshi Ishimori, Hiroki Toda

Published in

Stereotactic and functional neurosurgery. Pages 1. Sep 10, 2026. Epub Sep 10, 2026.

Abstract

Traditional targeting based on the anterior commissure-posterior commissure (AC-PC) line in MR-guided focused ultrasound (MRgFUS) thalamotomy does not account for individual thalamic asymmetry, potentially leading to suboptimal outcomes or adverse effects.
To investigate whether habenular torsion, an anatomical marker of thalamic asymmetry, predicts clinical outcomes and sensory side effects following ventral intermediate nucleus (Vim) thalamotomy.
We retrospectively analyzed 157 patients (essential tremor: 121; Parkinson's disease: 36) who underwent unilateral MRgFUS thalamotomy. Angular metrics, including the Torsion Index (inter-hemispheric habenular angular difference) and the Lesion-Habenula difference (based on a lesion axis originating from the midline-habenula intersection), were measured on axial MRI 2.0 mm dorsal to the AC-PC line. Tremor improvement (CRST) and ventralis caudalis (Vc)-related sensory symptoms were evaluated immediately and at the 1-year follow-up.
Tremor improved by over 70% immediately after treatment, with no significant difference between torsion groups (p = 0.490), indicating that torsion did not compromise efficacy. However, Anterior Torsion (Torsion Index < 0) was significantly associated with a higher incidence of both immediate (43.2% vs. 14.5%, p < 0.001) and persistent (25.0% vs. 5.1%, p = 0.001) Vc symptoms. ROC analysis identified the Torsion Index (AUC 0.72-0.75) and Lesion-Habenula difference (AUC 0.76-0.84) as robust predictors for sensory side effects, significantly outperforming the standard AP ratio (AUC 0.47-0.50).
Habenular torsion is a critical anatomical biomarker for predicting post-operative sensory complications. Incorporating the Torsion Index into preoperative planning allows for a personalized, anatomy-driven targeting approach, potentially enhancing the safety and efficacy of stereotactic thalamotomy.

PMID:
42721101
Bibliographic data and abstract were imported from PubMed on 11 Sep 2026.

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