Comparison of Cerebral Oximetry and Neurological Status Testing in the Awake Patient in the Detection of Cerebral Ischemia During Carotid Endarterectomy

Comparison of Cerebral Oximetry and Neurological Status Testing in the Awake Patient in the Detection of Cerebral Ischemia During Carotid Endarterectomy - a Randomized Controlled Trial

This randomized controlled study compares two methods of intraoperative cerebral ischemia monitoring during carotid endarterectomy performed under regional anesthesia: neurological testing in the awake patient and near-infrared spectroscopy (NIRS). The study aims to determine whether NIRS is equivalent to awake neurological testing in detecting cerebral ischemia during carotid artery clamping and in guiding the use of an intraluminal shunt.

Study Overview

• Status: Active, not recruiting
• Conditions: Near Infrared Spectroscopy; Carotid Arteriosclerosis
• Intervention / Treatment: Behavioral: Awake Neurological Testing; Device: Near-Infrared Spectroscopy (NIRS) Monitoring

Detailed Description

Cerebral ischemia during carotid endarterectomy (CEA) remains one of the most important causes of perioperative neurological morbidity and mortality. During carotid artery clamping, cerebral perfusion depends on the adequacy of collateral circulation, most importantly through the Circle of Willis. Inadequate collateral flow may lead to hypoperfusion, resulting in transient or permanent ischemic brain injury. For this reason, intraoperative cerebral monitoring is widely used to identify patients who require placement of an intraluminal shunt during carotid cross-clamping in order to maintain adequate cerebral blood flow.

In patients undergoing CEA under regional anesthesia, awake neurological testing is considered a reliable method for detecting cerebral hypoperfusion. By continuously assessing verbal communication and contralateral hand motor function, the surgical team can identify early neurological deterioration indicating cerebral ischemia. However, this approach is operator-dependent, subjective, and cannot provide continuous quantitative data on cerebral perfusion. In addition, subtle or subclinical ischemic events may go undetected by neurological testing alone.

Near-infrared spectroscopy (NIRS) is a non-invasive monitoring technique that measures regional cerebral oxygen saturation and reflects changes in cerebral perfusion. NIRS provides continuous, real-time, and objective assessment of cerebral oxygenation during surgery. A decrease in NIRS values during carotid artery clamping has been associated with cerebral hypoperfusion and may indicate a need for shunt placement. Despite increasing use of NIRS in vascular surgery, its diagnostic accuracy and equivalence to awake neurological testing for detection of cerebral ischemia during CEA have not been definitively established.

This prospective randomized controlled trial is designed to compare awake neurological testing and NIRS monitoring for the detection of intraoperative cerebral ischemia during carotid endarterectomy. The study will be conducted at the Clinic for Vascular and Endovascular Surgery, University Clinical Center of Serbia, between January 1, 2026 and January 1, 2028. Adult patients with symptomatic or asymptomatic carotid artery stenosis who meet criteria for surgical treatment will be eligible for inclusion. The indication for carotid endarterectomy will be established based on duplex ultrasonography and multislice computed tomography (CT) angiography of the carotid and cerebral vessels.

After providing written informed consent, patients will be randomized electronically in a 1:1 ratio into two groups. In both groups, carotid endarterectomy will be performed under cervical block anesthesia, allowing continuous neurological assessment. Near-infrared spectroscopy will be recorded in all patients; however, the decision to insert an intraluminal shunt will be guided by the randomized monitoring method.

In the Awake Neurological Testing group (TUBS), shunt placement will be based on the occurrence of neurological deficits during carotid cross-clamping, including impaired verbal communication or decreased motor function of the contralateral hand. In the NIRS group, shunt placement will be based on a decrease of more than 20% from baseline in regional cerebral oxygen saturation measured by near-infrared spectroscopy.

Preoperative evaluation will include duplex ultrasound of the carotid arteries, CT angiography, detailed physical and neurological examination by a neurologist, and magnetic resonance imaging (MRI) of the brain. Postoperative brain MRI will be performed within 7 days after surgery to detect both clinically apparent ischemic events and silent ischemic brain lesions (new ischemic brain MRI lesions). These silent lesions are considered important markers of perioperative cerebral ischemia and may have prognostic significance.

The primary outcome of the study is the rate of intraoperative cerebral ischemia, defined as the need for intraluminal shunt placement during carotid artery clamping based on the assigned monitoring method. Secondary outcomes include postoperative neurological deficits, ischemic stroke, transient ischemic attack, all-cause mortality, and the occurrence of new ischemic brain lesions on postoperative MRI. In addition, the agreement between awake neurological testing and NIRS monitoring will be evaluated using kappa statistics, and the optimal NIRS threshold associated with ischemic brain injury will be determined.

A total of 160 patients (80 in each group) will be enrolled. This sample size is based on calculations for diagnostic accuracy and agreement between methods, assuming a sensitivity of 75%, specificity of 85%, a kappa value of 0.35, a power of 80%, and a type I error rate of 5%. Statistical analysis will include descriptive and inferential methods, including parametric and non-parametric tests, as well as univariate and multivariate models to identify factors influencing the sensitivity and specificity of both monitoring strategies. Analyses will be performed using both per-protocol and intention-to-treat approaches.

This study aims to determine whether near-infrared spectroscopy provides a reliable and clinically equivalent alternative to awake neurological testing for intraoperative cerebral ischemia monitoring and shunt decision-making during carotid endarterectomy.

• Study Type: Interventional
• Enrollment (Actual): 160
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Serbia
  • Belgrade, Serbia, 11000
    • Clinic for Vascular and Endovascular Surgery, University Clinical Center of Serbia

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients with asymptomatic and symptomatic narrowing of the carotid artery in whom operative treatment is indicated, diagnosed by initial Duplex ultrasonographic examination or CT angiography.
• Written consent of the patient to participate in the study

Exclusion Criteria:

• - previous hemorrhagic stroke
• non-atherosclerotic carotid disease
• significant atherosclerotic changes in the aortic arch
• hypercoagulable and conditions with embologenic potential (congenital or acquired thrombophilia, malignant disease, atrial fibrillation, significant heart failure and valvular disease)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Awake Neurological Testing (TUBS) Group; Patients in this group will undergo carotid endarterectomy under regional anesthesia. Intraluminal shunt placement will be guided by awake neurological testing, including verbal communication and contralateral hand motor function, to detect intraoperative cerebral ischemia. NIRS monitoring will be recorded but will not guide shunt use.	Behavioral: Awake Neurological Testing; Neurological monitoring during carotid endarterectomy under regional anesthesia. Intraluminal shunt placement is guided by verbal communication and contralateral hand motor testing to detect cerebral ischemia. NIRS monitoring is recorded but not used to guide shunt placement.
Active Comparator: Near-Infrared Spectroscopy (NIRS) Group; Patients in this group will undergo carotid endarterectomy under regional anesthesia. Intraluminal shunt placement will be guided by near-infrared spectroscopy (NIRS), with shunt use indicated by a decrease of more than 20% in cerebral oxygenation compared to baseline. Awake neurological testing will be performed and recorded but will not guide shunt placement.	Device: Near-Infrared Spectroscopy (NIRS) Monitoring; Continuous monitoring of regional cerebral oxygen saturation during carotid endarterectomy under regional anesthesia. Intraluminal shunt placement is guided by a decrease of more than 20% from baseline NIRS values. Awake neurological testing is recorded but not used for shunt decisions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
primary outcome	to compare the incidence of intraoperative cerebral ischemia during carotid artery clamping in carotid endarterectomy when tested in the awake state, i.e. by spectroscopy (NIRS method)	two years

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Secondary outcome	to compare the frequency of ischemic brain damage in carotid endarterectomy after testing in the awake state or by spectroscopy (NIRS method)	2 years

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Secondary Outcome Measure 2	determine the threshold for changes in brain parenchyma perfusion values obtained by spectroscopy (NIRS method) that indicate ischemic brain damage	2 years

Collaborators and Investigators

• Sponsor: Clinic for Vascular and Endovascular Surgery, University Clinical Center of Serbia

Study record dates

Study Major Dates

• Study Start (Actual): December 22, 2025
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027

Study Registration Dates

• First Submitted: March 6, 2026
• First Submitted That Met QC Criteria: March 17, 2026
• First Posted (Actual): March 20, 2026

Study Record Updates

• Last Update Posted (Actual): March 20, 2026
• Last Update Submitted That Met QC Criteria: March 17, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: carotid endarterectomy; near infrared spectroscopy; neuromonitoring; Stenosing occlusive carotid disease; protective shunt
• Additional Relevant MeSH Terms: Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Carotid Artery Diseases; Investigative Techniques; Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Imaging; Chemistry Techniques, Analytical; Spectrum Analysis; Spectroscopy, Near-Infrared
• Other Study ID Numbers: 1787/38-1

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No