Considering Pedicle Screw Resistance in Electromyography of the Spine
Bibliographic record
Abstract
BACKGROUND: Evoked electromyographic (EMG) monitoring of pedicle screws has been shown to be an effective adjuvant to image guidance or direct visualization of pedicle screw placement. Electrical stimulation is delivered to the head of the screw at various intensities until a muscle potential is evoked. This practice is based on the fact that an intact pedicle effectively shields nerve roots from electrical stimulus. Several factors have been debated that may affect the interpretation of results; however, to the best of our knowledge, the electrical resistance of modern manufactured pedicle screws and stimulation devices has not been studied. OBJECTIVE: To determine if pedicle screw resistances affect triggered EMG. METHODS: Samples of the most commonly implanted pedicle screws in Canada were obtained, with diameters ranging from 4.5 to 7 mm. The resistance between the screw head and thread and core at the midpoint and tip of the screw was recorded using a Multimeter in accordance with IEEE standards. For screws with variable threads, the midpoint was considered the point at which the thread pitch changed. RESULTS: All screws had low impedances when tested at the point of the screw, but much higher when the cup is tested. The resistance of different manufactures' screws was significantly different, ranging from 0.514 to 2156 Ohms. CONCLUSION: Despite differences in resistance, most screws had resistances in ranges that allow for triggered EMG pedicle integrity testing. Resistance from pedicle screws is an important consideration in EMG monitoring of the spine.
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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 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".