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The Role of Intraoperative Neurophysiological Monitoring in Carotid Endarterectomy

The brain is a vital component of the human body and requires oxygen to function. While the result of a lack of oxygen to other living things may vary, the brain has a particular course of action that will take place: its cells can die within just minutes, and a stroke may occur. Thus, one might wonder how the brain could be placed in such a delicate and vulnerable situation. Well, one answer could be through a condition known as carotid artery stenosis.

Carotid artery stenosis occurs when deposits of plaque clog the carotid artery [1]. The carotid artery is on either side of your neck, and it is responsible for delivering blood to the head [2]. However, when there is a blockage, it means that the brain is not receiving adequate oxygen, which can lead to a stroke [2]. The most common type of stroke that may occur here is known as a transient ischemic attack (TIA). A TIA can present with a sudden onset of symptoms such as numbness, dizziness, weakness to one side of the body, vision loss, slurred speech, and/or severe headache [1, 2]. While all these symptoms seem quite alarming, the “good” thing about a TIA is that it occurs for a brief period and is only a temporary blockage [1]. However, experiencing a TIA presents a much larger issue and puts an individual at a high risk for developing another stroke. Nonetheless, whether you have had a TIA or not, if any of the symptoms are present, it is best to seek treatment and be on the cautious side.

Usually, lifestyle changes, medications, or surgery are the treatment options available for a clogged artery. Based on the diagnosis, severity can be determined so that appropriate treatments can be implemented. If a patient presents with more than 50% of the artery being blocked and they are deemed high risk for stroke, a carotid endarterectomy (CEA) is likely to be offered [3]. This surgical procedure involves removing the plaque buildup from the carotid arteries. It can be done under local anesthesia or general anesthesia [4]. Once anesthetized, the healthcare team can begin the surgery. They will start by making an incision on the side of the patient’s neck over the carotid artery that has been affected [5]. The surgeon will then cut open the artery. A shunt may be placed during the procedure so that blood flow can continue to the brain [5]. With the shunt in place, the team will work to remove the plaque from the artery. The shunt can then be removed, and the artery can be closed [5]. Finally, the incision on the neck will be stitched. After the procedure, the provider will be able to advise best and assess the appropriate recovery time. 

Nonetheless, like all surgical operations, there are risks involved. However, the risks associated with a CEA procedure can be fatal. A patient can have numerous complications, but one of the most concerning is a stroke during their procedure [3, 5]. Therefore, utilizing a tool that can mitigate these dangers is essential for the future of healthcare. Luckily, such a tool exists.

Intraoperative Neurophysiological Monitoring (IONM) is a technique used during surgery to monitor the nervous system during procedures where there is a risk of injury to the brain, spinal cord, and nerves [6]. IONM can provide real-time feedback that alerts the surgeon to any damage that may occur and allows the team to adjust accordingly to prevent any potential, permanent complications [6, 7]. This can help reduce the risk of irreversible neurological damage and improve surgical outcomes [8].

In carotid endarterectomy (CEA), using Intraoperative Neuromonitoring (IONM) is very beneficial for several reasons. This technique involves monitoring brain activity through methods like Electroencephalogram (EEG) and Somatosensory Evoked Potentials (SSEP) during the surgery, especially when the carotid arteries are temporarily clamped. These tools help doctors identify any changes that could suggest reduced blood flow to the brain, which is known as ischemia.

Additionally, issues can arise when trying to redirect blood flow through shunts in the carotid arteries, which can complicate the surgery and increase risks for the patient. However, IONM can help determine the right time to use a shunt by showing significant changes in brain activity on the EEG. If the shunt is positioned correctly, the EEG will reflect this, suggesting that potential damage to the brain has been avoided.

Research highlights the importance of this approach. In various studies, patients who had regular shunts were compared with those who had more selectively placed shunts. Authors found that the stroke rate was much lower in the selectively shunted group, at only 0.5%, compared to 4.4% for those who had routine shunting. Authors also noted that quickly fixing any significant technical issues during surgery could lower both the risk of complications and the chances of artery narrowing in the long term. Overall, the methods used in IONM have demonstrated effectiveness in reducing the risk of stroke during this type of surgery.

Carotid artery stenosis is a recognized medical condition that can be effectively treated using carotid endarterectomy (CEA). However, the neurophysiological monitoring techniques employed during these procedures, which can significantly impact patient outcomes, are not as widely recognized. This lack of awareness limits our ability to explore intraoperative neuromonitoring (IONM) further and apply its techniques in other intricate surgical interventions. Therefore, it is essential to enhance awareness about the critical role IONM plays across various surgical procedures. By doing so, we can gather more data and insights that could lead to improved patient outcomes.

References:

1.     Mayo Clinic (n.d.). Carotid artery disease. https://www.mayoclinic.org/diseases-conditions/carotid-artery-disease/symptoms-causes/syc-20360519.

2.     Cleveland Clinic (n.d.) Carotid Artery Disease (Carotid Artery Stenosis). https://my.clevelandclinic.org/health/diseases/16845-carotid-artery-disease-carotid-artery-stenosis.

3.     Stoke Association (n.d.) Carotid artery disease. https://www.stroke.org.uk/stroke/types/ischaemic/carotid-artery-disease.

4.     Mayo Clinic (n.d.). Carotid Endarterectomy.  https://www.mayoclinic.org/tests-procedures/carotid-endarterectomy/about/pac-20393379.

5.     Johns Hopkins Medicine (n.d.). Carotid Endarterectomy. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/carotid-endarterectomy.

6.     Johns Hopkins Medicine (n.d.). Intraoperative Neurophysiological Monitoring (IONM) Unit. https://www.hopkinsmedicine.org/neurology-neurosurgery/specialty-areas/ionm.

7.     American Society of /Neurophysiological Monitoring (n.d.). New to IONM. https://asnm.org/new-to-ionm/.

8.     Stanford Medicine (n.d.). Intraoperative Neurophysiological Monitoring Program. https://med.stanford.edu/neurology/divisions/neuromonitoring.html.

9.     Hartman, Joe. (2013, May 4). Neuromonitoring Carotid Endarterectomy Procedure, Intraoperative Neuromonitoring. https://intraoperativeneuromonitoring.com/neuromonitoring-carotid-endarterectomy-procedures/.

Published: Aug 01, 2025

https://www.globalinnervation.com/blog/ionm-for-cea

New paper published:

Nataraja, V., Ravindran, J., Steelman, A., Turner, J. F., & Jahangiri, F. R. (2025). Wired for Relief: Assessing the Risks and Rewards of DBS in Treatment-Resistant Obsessive Compulsive Disorder. J of Neurophysiological Monitoring, 3(2), 88–100. https://doi.org/10.5281/zenodo.16222883.

https://jneurophysiologicalmonitoring.com/index.php/pub/article/view/88

At Global Innervation LLC, Sara Martins, our soon-to-be graduating Group 6 candidate from the United Kingdom, created this infographic for the "Diploma in Surgical Neurophysiology."

#ionm #surgery #neuromonitoring #intraoperative #anesthesia #sensorymapping #phasereveral #neurosurgery #corticalmapping #emg #mep #neuroscience #patient #education  #neurophysiology #globalinnervation 

At Global Innervation LLC, Donovan Schultz, our new Group 6 candidate from South Africa, created this infographic for the "Diploma in Surgical Neurophysiology."

#ionm #surgery #neuromonitoring #intraoperative #anesthesia #sensorymapping #phasereveral #neurosurgery #corticalmapping #emg #mep #neuroscience #patient #education  #neurophysiology #globalinnervation 

At Global Innervation LLC, , our new Group 6 candidate from South Africa, created this infographic for the "Diploma in Surgical Neurophysiology."

#ionm #surgery #neuromonitoring #intraoperative #surgery #anesthesia #pelvicfloor #baldder #eus #urinarysphincter #emg #mep #neuroscience #patient #education  #anesthesia #neurophysiology #globalinnervation #SDR #dorsalroot #rhizotomy

Jacques Nel, our new Group 6 candidate from South Africa, created this infographic for the "Diploma in Surgical Neurophysiology" at Global Innervation LLC.

#ionm #surgery #neuromonitoring #intraoperative #surgery #anesthesia #anatomy #physiology #neuroscience #patient #education  #anesthesia #neurophysiology #globalinnervation #pionm #pelvicfloor #mapping #tetheredcord

Dr. Sajid Ali, our new Group 6 candidate from Rawalpindi, Pakistan, created this infographic for the "Postdoctoral Fellowship in Surgical Neurophysiology" at Global Innervation LLC.

#ionm #surgery #neuromonitoring #intraoperative #surgery #anesthesia #nmj #anatomy #physiology #tof #neuroscience #patient #education  #anesthesia #neurophysiology #globalinnervation #tcr #tetheredcord