CORONADO, CALIF. – Cranial nerve injury occurred in 4.6% of patients who participated in the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), with 34% resolution at 1 month and 80.8% at 1 year, a detailed analysis demonstrated.
While cranial nerve injury (CNI) is the most common neurologic complication of carotid endarterectomy, its reported incidence “is highly variable, ranging from 3% to 30% and depends on the intensity and the methods that are used for evaluation,” Dr. Robert J. Hye said at the annual meeting of the Western Vascular Society. “When using clinical criteria as in CREST, the incidence varies from 5% to 8%, and most injuries resolve in a few weeks. But in rare cases it can result in significant long-term disability.”
Dr. Robert J. Hye
Most publications that have evaluated CNI discuss the frequency of nerve injury, not resolution or the time to healing. “Previous publications have identified prolonged operations, urgent operations, and re-exploration as predictors of CNI,” said Dr. Hye of the department of general and vascular surgery at Kaiser Permanente, San Diego. “Advocates of CAS [carotid artery stenting] have equated CNI with minor stroke, mitigating some of the benefit of CEA over CAS.”
He and his associates conducted the present study in an effort to evaluate the incidence, predictive factors, and resolution and also to compare health-related quality of life in patients with and without CNI in CREST, a trial conducted at 117 centers in the United States and Canada in which 2,502 patients were randomized to receive either CAS or CEA. Researchers in that trial observed no difference in outcome in the combined primary endpoint of stroke, MI, and death, but periprocedural stroke was significantly more common in the CAS group and periprocedural MI in the CEA group. Quality of life analyses were performed at 2 weeks, 1 month, and 12 months after the interventions (N. Engl. J. Med. 2010;363:11-23).
For the current analysis, patients with CNI were identified from the CREST database and classified using case report forms, adverse event reports, and clinical follow-up notes. Adjudication of the CNIs was performed by two neurologists and one vascular surgeon. Patients with only cutaneous sensory symptoms were excluded from analysis, and postprocedural outcomes were assessed at 30 days and 12 months. The researchers used the SF-36 and disease-specific Likert scales to measure health-related quality of life.
The mean age of patients at baseline was 68 years. Dr. Hye reported that CNI occurred in 53 of 1,151 (4.6%) randomized to CEA who received their operation within 30 days. CNIs were also noted in five additional patients: three who crossed over from CAS to CEA and two who did not undergo CEA within 30 days of randomization. In contrast to prior studies, CNI was significantly more common when general anesthesia was used, but there were no other demographic or procedural characteristics that were predictive of CNI. About one-third of CNIs (34%) were resolved at 30 days, and 80.8% were resolved at 1 year. CNI had a small effect on quality of life, negatively impacting only swallowing and eating at 2 and 4 weeks but not at 1 year (P less than .001).
Injuries to cranial nerves IX and X were most common, followed by injuries to the marginal mandibular branch of the facial nerve and the hypoglossal nerves. All of the hypoglossal injuries resolved, while injuries involving cranial nerves IX and X were least likely to resolve.
Dr. Hye acknowledged certain limitations of the trial, including the fact that CNI diagnosis was made from a clinical standpoint, and there were no routine otolaryngologic exams. “It’s likely that some of the subtle injuries were missed and that the incidence of cranial nerve injury is underestimated,” he added. “On the other hand, patients did have postoperative exams by experienced neurologists and vascular surgeons, so not many of the injuries should have been missed. Another unique thing about the study is the [quality of life] tools [we used]. They may be insufficiently sensitive to detect the consequences of CNI.”
Dr. Hye went on to note that the persistence of CNI at 1 year in CREST is higher than in most other reports available in the medical literature (19.2% vs. 7%-12%, respectively). “We’re not really sure why this is the case,” he said. “It may be that the postoperative assessment in CREST was more detailed and detected more subtle residual deficits from the CNIs.”
The study was funded by the National Institutes of Health, with supplemental funding from Abbott Vascular Inc. Dr. Hye reported having no financial disclosures.