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Published on: February 6, 2018
Concentric Versus Delta Bipolar Probes for Intraneural Fascicle Selection: A Rabbit Model Study
Lucas Marina Ono1, Elisa Sanz2,3, Mario Arenillas4
1From the Department of Plastic Surgery, Hospital Universitario de Getafe, Madrid, Spain.
Plastic and Reconstructive Surgery. Global Open
|June 19, 2026
Summary
Delta probes offer superior reproducibility and consistent high responses for peripheral nerve surgery monitoring compared to concentric probes, which show variable results with increasing stimulus intensity.
Area of Science:
- Neurosurgery
- Neuromonitoring
- Peripheral Nerve Surgery
Background:
- Bipolar stimulating probes are essential for intraoperative monitoring in nerve surgery.
- No prior studies have compared different bipolar probe types.
- This study evaluates concentric versus Delta probes in a rabbit brachial plexus injury model.
Purpose of the Study:
- To compare the performance of concentric and Delta bipolar probes.
- To assess probe applicability for intraoperative neuromonitoring in peripheral nerve surgery.
Main Methods:
- Compound muscle action potentials (CMAPs) were recorded from the biceps brachii in rabbits.
- Stimulation of brachial plexus trunks was performed using concentric and Delta probes at varying intensities (0.2-3 mV).
- Correlation between stimulus intensity and CMAP amplitude, and interstimulus amplitude variability were analyzed.
Main Results:
- Delta probes demonstrated no significant correlation between stimulus intensity and CMAP amplitude (Spearman R=0.181, P=0.264).
- Concentric probes showed a strong correlation between stimulus intensity and CMAP amplitude (Spearman R=0.74, P=0.001).
- Delta probes exhibited significantly less variability (CV=0.01) compared to concentric probes (CV=0.1).
Conclusions:
- Delta probes provide highly reproducible, high-amplitude CMAP responses even with low stimulus intensities.
- Concentric probes yield less reproducible responses with gradually increasing CMAP amplitudes as stimulus intensity rises.
- Delta probes are recommended for consistent intraoperative neuromonitoring in peripheral nerve surgery.
