Electrode Implantation for Deep Brain Stimulation in Dystonia: A Fast Spin-Echo Inversion-Recovery Sequence Technique for Direct Stereotactic Targeting of the Gpi
Bibliographic record
Abstract
Objective: Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is an effective treatment for medically refractory primary dystonia. We present our technique for direct preoperative visualization of the target using a fast spin-echo inversion-recovery (FSE-IR) sequence. Methods: Twenty-three consecutive patients (mean age 41 years, range 9-68 years, male to female ratio 11:12) with severe dystonia were operated using a combination of FSE-IR imaging for direct visualization of the globus pallidus internus with stereotactic, gadolinium-enhanced T1-MPRage images. The complete procedure, including stereotactic MRI, was performed under general anesthesia with propofol and remifentanyl. We used multichannel microdrive systems (Medtronic; Alpha-Omega) to introduce up to five parallel microelectrodes for microelectrode recordings (MER) and test stimulation with the central trajectory directed at the anatomically predefined target. The initial standard coordinates in relation to the mid-commissural point (mid-AC-PC) were as follows: lateral 21 mm, anterior 3 mm, and inferior 2 mm, which were then adapted to the individual case based on direct visualization of the target area and further refined by the intraoperative neurophysiology. Results: In ten patients (43%) atlas-based standard coordinates were modified based on the direct visualization of the GPi in the FSE-IR images (bilaterally in seven patients, unilaterally in three). The modified targets ranged from 18.5 to 23.5 mm (mean 20.76 mm) laterally, 1-7 mm (mean 2.75 mm) anteriorly and 1-2 mm (mean 1.95 mm) inferiorly to the mid-AC-PC. We implanted the permanent electrode based on the results of MER and intraoperative stimulation performed to determine the threshold for pyramidal tract responses on the central trajectory in 67%, medially in 16%, anteriorly in 11%, laterally in 4%, dorsally in 2%. The procedure resulted in excellent clinical benefits (average reduction of the Burke-Fahn-Marsden Dystonia Rating Score (BFMDRS) or the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) were respectively 65.9%, range 20.9-91.4%) within the first year after surgery. Safety was demonstrated by the absence of intracranial bleeding or other surgical complications causing neurological morbidity. Conclusion: Inversion recovery sequences are an excellent tool for direct visualization of the GPi. These images can be fused to stereotactic MRI or CCT and may help to improve anatomical targeting of the GPi for the implantation of DBS electrodes. Zusammenfassung Hintergrund: Die tiefe Hirnstimulation des Globus pallidus internus (Gpi) ist eine wirksame Therapie bei medikamentös therapie-refraktärer primärer Dystonie. Wir präsentieren unsere Technik der direkten präoperativen Darstellung des Zielpunktes mit einer fast-spin-echo inversion-recovery MR-Sequenz. Methoden: Dreiundzwanzig Patienten (mittleres Alter 41 Jahre, Range 9-68 Jahre) mit einer schweren Dystonie wurden operiert. Die Planung der Zielpunkte und Trajektorien erfolgte anhand von stereotaktischen MRT Bildern (Gadolinium-verstärkte T1-MPRage und fast-spin-echo inversion-recovery Sequenzen). Die gesamte Prozedur, einschließlich stereotaktischem MR und Implantation des Impulsgebers, wurde in Vollnarkose (Propofol, Remifentanyl) an einem Tag durchgeführt. Die initial verwendeten Standardkoordinaten in Relation zur Mitte der AC-PC-Linie waren: 21 mm lateral, 3 mm anterior, 2 mm inferior. Der Zielpunkt wurde, falls erforderlich, präoperativ anhand der direkten Darstellung des Gpi in der FSE-IR Sequenz geändert. Ergebnisse: In zehn der 23 Patienten (43%) wurde von den Standardkoordinaten aufgrund der Bildgebung abgewichen (bilateral in 7 Patienten, unilateral in 3 Patienten). Die neuen Zielpunktkoordinaten variierten von 18,5 mm bis 23,5 mm lateral (Mittelwert (MW) 20,76 mm), 1-7 mm (MW 2,75 mm) anterior und 1-2 mm (MW 1,95 mm) inferior zu Mid-AC-PC. Die endgültige Elektrode wurde aufgrund der intraoperativen MER und der Teststimulationen auf dem zentralen Trajekt in 67% implantiert, medial in 16%, anterior in 14%, lateral in 4%, und dorsal in 2%. Postoperativ kam es zu einer Verbesserung des Burke-Fahn-Marsden Dystonie Scores (BFMDRS) bzw. der Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) um im Mittel 65,9% (Range 20,9% bis 91,4%) innerhalb des ersten Jahres nach der Operation. Intrazerebrale Blutungen oder sonstige postoperative Komplikationen traten nicht auf. Zusammenfassung: Die inversion-recovery Sequenzen bieten eine exzellente Darstellung des Gpi. Diese Bilder können mit stereotaktischen MRT oder CCT fusioniert werden und helfen bei der anatomischen Darstellung des Gpi für die Zielpunktplanung bei der tiefen Hirnstimulation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".