The Role of Intraoperative Neuromonitoring in Cardiac Surgical Procedures – Part 3

As we continue discussing the vital role Intraoperative Neurophysiological Monitoring (IONM) plays in Cardiac Surgery procedures in this third and final part of our vascular series, it is imperative to explore a specific type of surgery to have a more in-depth understanding of the whole IONM-surgical panorama. One example of a relatively common vascular surgery is Carotid Endarterectomy.

Carotid Endarterectomy is a surgical procedure that removes build-up or fat accumulations along carotid arteries (1). It is commonly performed for treating carotid artery disease, which usually involves atherosclerosis or the accumulation of fat plaques that limit blood flow to the brain (1). Some of the risks regarding this procedure are, for instance, seizures, stroke, heart attack, infections, intracerebral hemorrhage, nerve problems, etc. (2). Moreover, according to the article Carotid Endarterectomy: A Ten-year Analysis of Outcome and Cost of Treatment by Maini et al., approximately more than 100,00 carotid endarterectomy (CEA) surgical procedures are performed every year in the United States, and more than 1 million CEAs have been performed worldwide since the early 1950s (3).

Furthermore, the article, Predictors of Cross-Clamp Induced Intraoperative Monitoring Changes During Carotid Endarterectomy Using Both EEG and SSEP Monitoring by Sridharan et al. explains how selective shunting during CEA could be guided using intraoperative monitoring modalities such as electroencephalography (EEG) and somatosensory evoked potentials (SSEPs) which have become vital tools for the detection of cerebral ischemia due to its high sensitivity (4). Additionally, in another article, Somatosensory Evoked Potentials and Electroencephalography During Carotid Endarterectomy Predict Late Stroke but Not Death by N Domenick et al. also discusses the predictive role that those same IONM modalities, EEG and SSEPs, play in the detection of perioperative strokes (5). Moreover, the same article also discusses how multimodality neuromonitoring by these two IONM modalities can also offer a predictive value regarding long-term strokes since they presented data in which patients who did not experience iatrogenic IONM changes had a higher stroke-free survival rate (for up to five years) compared to other patients that did (5).

Also, in the article Comparison of Single and Dual Monitoring during Carotid Endarterectomy by Masaaki Uno et al., the authors explain how the use of dual monitoring, in this case, the use of SSEPs and MEPs (motor evoked potentials) could be crucial for the assessment of ischemic changes during CEAs due to a “complementary relationship” between the two modalities which could lead to better results and reduce the potential of false-negative alarms (6).

Additionally, the article Carotid Endarterectomy Surgeries: A Multimodality Intraoperative Neurophysiological Monitoring Approach by Jahangiri et al. explains how some patients suffering carotid artery stenosis who could also be experiencing poor collateral blood flow are at risk of suffering cerebral ischemia during CEA which could lead to several surgical complications (7). Thus, the authors emphasize the importance of applying a multimodality monitoring approach involving SSEPs and EEG in patients undergoing these surgical procedures to assess cerebral perfusion and the need for selective shunting after cross-clamping (7). Also, it provides a higher sensitivity and specificity for detecting iatrogenic anomalies, thus preventing possible post-operative deficits (7). Furthermore, the same article discusses the benefits of using a Transcranial Doppler (TCD) as part of the IONM protocol, which can provide a better way to assess cerebral blood flow and the possibility for a patient to suffer a stroke due to micro-emboli (7).

Sources:

1. “Carotid Endarterectomy.” Mayo Clinic, December 11, 2018. https://www.mayoclinic.org/tests-procedures/carotid-endarterectomy/about/pac-20393379.
2. “Carotid Endarterectomy.” Johns Hopkins Medicine, November 19, 2019. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/carotid-endarterectomy.
3. Maini, Baltej S., Thomas F. Mullins, Jude Catlin, and Patricia O’Mara. “Carotid Endarterectomy: A Ten-Year Analysis of Outcome and Cost of Treatment.” Journal of Vascular Surgery 12, no. 6 (1990): 732–40. https://doi.org/10.1067/mva.1990.25015.
4. Domenick Sridharan, Natalie, Partha Thirumala, Rabih Chaer, Jeffrey Balzer, Becky Long, Donald Crammond, Michel Makaroun, and Efthymios Avgerinos. “Predictors of Cross-Clamp-Induced Intraoperative Monitoring Changes during Carotid Endarterectomy Using Both Electroencephalography and Somatosensory Evoked Potentials.” Journal of Vascular Surgery 67, no. 1 (2018): 191–98. https://doi.org/10.1016/j.jvs.2017.04.064.
5. Domenick, Natalie A., Rabih Chaer, Partha Thirumala, Jeffrey Balzer, Michel Makaroun, Edith Tzeng, and Efthimios Avgerinos. “Somatosensory Evoked Potentials and Electroencephalography during Carotid Endarterectomy Predict Late Stroke but Not Death.” Annals of Vascular Surgery 34 (2016): 18–19. https://doi.org/10.1016/j.avsg.2016.05.031.
6. UNO, Masaaki, Kenji YAGI, Hiroyuki TAKAI, Naoki OYAMA, Yoshiki YAGITA, Keita HAZAMA, Hideki NAKATSUKA, and Shunji MATSUBARA. “Comparison of Single and Dual Monitoring during Carotid Endarterectomy.” Neurologia medico-chirurgica 61, no. 2 (2021): 124–33. https://doi.org/10.2176/nmc.oa.2020-0286.
7. Jahangiri, Faisal R, Marie Liang, Misty Huckabey, Naomi Baloney, and Sarah Sharifi. “Carotid Endarterectomy Surgeries: A Multimodality Intraoperative Neurophysiological Monitoring Approach.” Cureus, 2022. https://doi.org/10.7759/cureus.26556.