INSTRUMENTATION AND TECHNIQUE

Electromagnetic Navigation Systems and Intraoperative Neuromonitoring: Reliability and Feasibility Study

Keeble, Hannah MSc^{^,}
Lavrador, José Pedro MD
Pereira, Noémia MSc
Lente, Kornelius MSc
Brogna, Christian MD
Gullan, Richard MD
Bhangoo, Ranjeev MD
Vergani, Francesco MD, PhD
Ashkan, Keyoumars MD, FRCS

Correspondence: Hannah Keeble, MSc, inomed Neurocare Limited, One Lyric Square, 3.11, Floor 3, London W6 0NB, United Kingdom. Email: [email protected]

Hannah Keeble and José Pedro Lavrador contributed equally to this work.

Operative Neurosurgery 20(4):p 373-382, February 2021. | DOI: 10.1093/ons/opaa407

BACKGROUND

A recent influx of intraoperative technology is being used in neurosurgery, but few reports investigate the accuracy and safety of these technologies when used simultaneously.

OBJECTIVE

To assess the ability to use an electromagnetic navigation system alongside multimodal intraoperative neurophysiological monitoring (IONM).

METHODS

Single-institution prospective cohort study of patients requiring craniotomy for brain tumor resection operated using an electromagnetic navigation system (AxiEM, Medtronic®). motor evoked potentials, somatosensory evoked potentials (SSEPs), electroencephalography, and electromyography were recorded and analyzed with AxiEM on (with/without filters) and off. The neurological outcomes of the patients were recorded.

RESULTS

A total of 15 patients were included (8 males/7 females, mean age 52.13 yr). Even though the raw acquisition is affected by the electromagnetic field (particularly SSEPs), no significant difference was detected in the morphology, amplitude, and latency of the different monitoring modalities (AxiEM off vs on) after the appropriate software filter application. Adjustments to the frequency of SSEP stimulation and number of averages, and reductions to the low-pass filters were applied. Notch filters were used appropriately and changes to the physical setup of the IONM and electromagnetic navigation system equipment reduced noise. Postoperatively, none of the patients developed new focal deficits; 7 patients showed improvement in their motor deficit (4 recovered fully).

CONCLUSION

The information provided by the IONM in intracranial neurosurgery patients whilst also using electromagnetic navigation systems is reliable for monitoring, mapping, and detecting intraoperative complications, provided that the appropriate software filters and tools are applied.