Prelemniscal Radiations: A New Reliable Landmark of the Thalamic Nucleus Ventralis Intermedius Location?

Lefranc, Michel; Carron, Romain; Régis, Jean

doi:10.1159/000441393

Cited by 17 publications

(10 citation statements)

References 35 publications

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“…Lefranc et al importing fraction anisotropy colored maps into GP-TPS suggests allowing 15 Gy to reach the center of what is represented as IC in their maps. 22 That constraint is more audacious than the one presented in this study, in which we accepted 15 Gy reaching the medial border of IC. Unfortunately, Lefranc et al did not present clinical results in their technical paper describing targeting; however, in a recent publication, the same group reported that in 50 patients treated with their usual protocol and followed by a multiinstitutional prospective evaluation, only 1 patient experienced side effects.…”

Section: Discussionmentioning

confidence: 64%

“…plan have used a more aggressive approach, allowing 15 Gy to reach the center of the IC. 22 This study shows that by using the conventional indirect target to reach the VIM and obeying our defined constraints, only 5 (12.5%) of 40 plans delivered a < 15 Gy maximum dose to the medial border of the IC when an indirect target with the conventional coordinates was used. Therefore, taking advantage of all the strategies available in the GP-TPS, as well as the changes in the target, without compromising the effectiveness of the treatment is important.…”

Section: Discussionmentioning

confidence: 81%

“…Subtle changes in the VIM when GK-T is performed were already suggested by the pioneering authors of the technique, 8,30,45 who had to progressively decrease the dose used to achieve acceptable results. 30 Plugging techniques, 22,40 before a laborious strategy, have become automatic since the Gamma Knife Perfexion (Elekta, Inc.) was introduced. This study used the Grade 1 DSF of the GP-TPS to improve dose distribution according to the location of the IC.…”

Section: Discussionmentioning

confidence: 99%

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The role of diffusion tensor imaging tractography for Gamma Knife thalamotomy planning

Gomes

Gorgulho

López

et al. 2016

JNS

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OBJECTIVEThe role of tractography in Gamma Knife thalamotomy (GK-T) planning is still unclear. Pyramidal tractography might reduce the risk of radiation injury to the pyramidal tract and reduce motor complications.METHODSIn this study, the ventralis intermedius nucleus (VIM) targets of 20 patients were bilaterally defined using Iplannet Stereotaxy Software, according to the anterior commissure–posterior commissure (AC-PC) line and considering the localization of the pyramidal tract. The 40 targets and tractography were transferred as objects to the GammaPlan Treatment Planning System (GP-TPS). New targets were defined, according to the AC-PC line in the functional targets section of the GP-TPS. The target offsets required to maintain the internal capsule (IC) constraint of < 15 Gy were evaluated. In addition, the strategies available in GP-TPS to maintain the minimum conventional VIM target dose at > 100 Gy were determined.RESULTSA difference was observed between the positions of both targets and the doses to the IC. The lateral (x) and the vertical (z) coordinates were adjusted 1.9 mm medially and 1.3 mm cranially, respectively. The targets defined considering the position of the pyramidal tract were more medial and superior, based on the constraint of 15 Gy touching the object representing the IC in the GP-TPS. The best strategy to meet the set constraints was 90° Gamma angle (GA) with automatic shaping of dose distribution; this was followed by 110° GA. The worst GA was 70°. Treatment time was substantially increased by the shaping strategy, approximately doubling delivery time.CONCLUSIONSRoutine use of DTI pyramidal tractography might be important to fine-tune GK-T planning. DTI tractography, as well as anisotropy showing the VIM, promises to improve Gamma Knife functional procedures. They allow for a more objective definition of dose constraints to the IC and targeting. DTI pyramidal tractography introduced into the treatment planning may reduce the incidence of motor complications and improve efficacy. This needs to be validated in a large clinical series.

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

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The role of diffusion tensor imaging tractography for Gamma Knife thalamotomy planning

Gomes

Gorgulho

López

et al. 2016

JNS

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“…Lefranc et al [94] retrospectively examined DTI in 20 patients who had undergone radiosurgical Vim thalamotomy and were selected for good response (>80% tremor reduction). The prelemniscal radiations (Raprl), which are known to abut the inferior – posterior aspect of the Vim, were found to be reliably visible on color fractional anisotropy maps and consistently related to the lesion as well as to expected location based on the Schaltenbrand-Wahren atlas, suggesting that the Raprl may serve as an internal fiducial landmark in Vim localization.…”

Section: Resultsmentioning

confidence: 99%

Advanced Imaging and Direct Targeting of the Motor Thalamus and Dentato-Rubro-Thalamic Tract for Tremor: A Systematic Review

Gravbrot

Saranathan

Pouratian

et al. 2020

Stereotact Funct Neurosurg

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Direct targeting methods for stereotactic neurosurgery in the treatment of essential tremor have been the subject of active research over the past decade but have not yet been systematically reviewed. We present a clinically oriented topic review based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses Group guidelines. Our focus is studies using advanced magnetic resonance imaging (MRI) techniques (ultrahigh-field structural MRI, diffusionweighted imaging, diffusion-tensor tractography, and functional MRI) for patient specific, in vivo identification of the ventral intermediate nucleus and the dentato-rubro-thalamic tract.

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“…We additionally used beam channel blocking to optimize the dose gradient toward the internal capsule. 23,35,37,38,40…”

Section: Srs-t Proceduresmentioning

confidence: 99%

Pretherapeutic resting-state fMRI profiles are associated with MR signature volumes after stereotactic radiosurgical thalamotomy for essential tremor

Tuleasca

Régis

Najdenovska

et al. 2018

Journal of Neurosurgery

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ABBREVIATIONS AC = anterior commissure; ADL = activities of daily living; BOLD = blood oxygenation level-dependent; DBS = deep brain stimulation; DMN = defaultmode network; DTI = diffusion tensor imaging; ET = essential tremor; FEW = family-wise error; IC = interconnectivity; ICA = independent component analysis; MNI = Montreal Neurological Institute; PC = posterior commissure; rs-fMRI = resting-state functional MRI; SMA = supplementary motor area; SRS = stereotactic radiosurgery; SRS-T = SRS thalamotomy; TSTH = tremor score on the treated hand; Vim = ventral intermediate nucleus.OBJECTIVE Essential tremor (ET) is the most common movement disorder. Drug-resistant ET can benefit from standard stereotactic deep brain stimulation or radiofrequency thalamotomy or, alternatively, minimally invasive techniques, including stereotactic radiosurgery (SRS) and high-intensity focused ultrasound, at the level of the ventral intermediate nucleus (Vim). The aim of the present study was to evaluate potential correlations between pretherapeutic interconnectivity (IC), as depicted on resting-state functional MRI (rs-fMRI), and MR signature volume at 1 year after Vim SRS for tremor, to be able to potentially identify hypo-and hyperresponders based only on pretherapeutic neuroimaging data. METHODS Seventeen consecutive patients with ET were included, who benefitted from left unilateral SRS thalamotomy (SRS-T) between September 2014 and August 2015. Standard tremor assessment and rs-fMRI were acquired pretherapeutically and 1 year after SRS-T. A healthy control group was also included (n = 12). Group-level independent component analysis (ICA; only n = 17 for pretherapeutic rs-fMRI) was applied. The mean MR signature volume was 0.125 ml (median 0.063 ml, range 0.002-0.600 ml). The authors correlated baseline IC with 1-year MR signatures within all networks. A 2-sample t-test at the level of each component was first performed in two groups: group 1 (n = 8, volume < 0.063 ml) and group 2 (n = 9, volume ≥ 0.063 ml). These groups did not statistically differ by age, duration of symptoms, baseline ADL score, ADL point decrease at 1 year, time to tremor arrest, or baseline tremor score on the treated hand (TSTH; p > 0.05). An ANOVA was then performed on each component, using individual subject-level maps and continuous values of 1-year MR signatures, correlated with pretherapeutic IC. RESULTS Using 2-sample t-tests, two networks were found to be statistically significant: network 3, including the brainstem, motor cerebellum, bilateral thalamus, and left supplementary motor area (SMA) (p FWE = 0.004, cluster size = 94), interconnected with the red nucleus (MNI -2, -22, -32); and network 9, including the brainstem, posterior insula, bilateral thalamus, and left SMA (p FWE = 0.002, cluster size = 106), interconnected with the left SMA (MNI 24, -28, 44). Higher pretherapeutic IC was associated with higher MR volumes, in a network including the anterior default-mode network and bilateral thalamus (ANOVA, p FWE = 0.004, cluster size = 73), inter...

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Prelemniscal Radiations: A New Reliable Landmark of the Thalamic Nucleus Ventralis Intermedius Location?

Cited by 17 publications

References 35 publications

The role of diffusion tensor imaging tractography for Gamma Knife thalamotomy planning

The role of diffusion tensor imaging tractography for Gamma Knife thalamotomy planning

Advanced Imaging and Direct Targeting of the Motor Thalamus and Dentato-Rubro-Thalamic Tract for Tremor: A Systematic Review

Pretherapeutic resting-state fMRI profiles are associated with MR signature volumes after stereotactic radiosurgical thalamotomy for essential tremor

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