Localisation des électrodes de stimulation corticale dans le traitement des douleurs neuropathiques chroniques réfractaires : une large étude multicentrique
Bibliographic record
Abstract
Motor cortex stimulation has been used for over 30 years to treat refractory chronic neuropathic pain. However, its efficacy remains controversial, its mechanisms of action unclear and the optimal electrode placement is debated. Our aim was to analyze a large series of patients to identify optimal lead placement.We analyzed retrospectively 100 patients (mean age 54 ± 13 years, 56 males and 44 females) treated with motor cortex stimulation for chronic neuropathic refractory pain across eight French, German and Brazilian centers. Postoperative computed tomographies (CTs) were normalized in the Montreal Neurological Institute (MNI) template using advanced normalization tools to calculate the coordinates of active contacts. These coordinates were mapped onto several registered to the MNI space. The width of the subarachnoid space was computed. Patients were grouped in non-responders (all stimulation settings failed to relieve the pain) and responders. The latter were labelled certain responders (the analgesic effect stopped when the implantable pulse generator was turned off) and probable responders. Logistic regression was used to compare patient characteristics, stimulation parameters, contact coordinates and atlas values.With Motor Cortex Stimulation (MCS), the mean numerical pain decrease was 2.62 in 78 responders (53 probable and 25 certain) and 0.88 in 22 non-responders. In responders, the stimulation voltage was lower (3.46 V vs. 4.71 V, p < 0.0001), frequency higher (39 vs. 37 Hz, p= 0.026) and the subarachnoid space was smaller (4.95 mm vs 5.73 mm, p = 0.023). The location of contacts on the cortex was similar between groups. We didn’t observe a cortical “sweet spot” for MCS analgesia and effective contacts were distributed over the sensitive, motor and premotor regions. Active contacts were effective regardless of motor cortex somatotopy. When the MCS activated cortical areas that were rich in long projection fibers, the pain relief improved.These results challenge traditional motor cortex stimulation assumptions. Precise targeting of somatotopic motor regions may not be critical for pain relief. Instead, the width of the subarachnoid space could predict analgesic response. Our observations suggest that MCS modulates non-specific pain control centers, such as descending inhibitory pathways originating in the brain stem or the insula, through long projection fibers. This study highlights the need for a more nuanced approach to this technique, moving away from motor somatotopy and integrating connectivity analyses to refine electrode placement and optimize clinical outcomes.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 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".