Risk factors for a decrease in somatosensory evoked potential amplitude during carotid endarterectomy with routine...

Carotid endarterectomy (CEA) is an effective preventive treatment for stroke, but carries a risk of cerebral hypoperfusion during carotid artery clamping. Intraoperative monitoring of somatosensory evoked potentials (SSEPs) is commonly used to detect hypoperfusion. However, predictors of significant SSEP amplitude decrease remain unclear. This study aimed to identify risk factors associated with substantial SSEP amplitude decreases during CEA with routine shunting and characterize patients at increased risk for intraoperative cerebral hypoperfusion.

We retrospectively analyzed patients who underwent CEA at Kushiro Kojinkai Memorial Hospital from January 2008 to December 2022. All patients received routine shunting and intraoperative SSEP monitoring. A significant decrease in SSEP amplitude was defined as a ≥ 50% decrease in the N20-P25 amplitude. Associations between SSEP changes and clinical or imaging findings were evaluated using univariable and multivariable analyses.

Of 485 consecutive patients, 467 were included. The median age was 71 years, 82% were male, and 27% had symptomatic carotid disease. A significant SSEP amplitude decrease occurred in 88 patients (18.8%). Independent risk factors included symptomatic disease (p = 0.017), severe contralateral carotid stenosis (≥70% or occlusion, p = 0.02), and hypoplasia of either A1 segment (p < 0.001). In contrast, beta-blocker use was associated with a reduced risk of SSEP amplitude decreases (p = 0.04). The incidence of significant decrease in SSEP amplitude increased with the severity of contralateral stenosis and varied by A1 segment morphology.

Preoperative assessment of these factors may help identify patients at increased risk of intraoperative cerebral hypoperfusion and reduce neurological complications associated with this preventive procedure.