SAN FRANCISCO – Cognitive function improved for most patients in the year after they underwent endarterectomy for carotid stenosis, according to the results of an ongoing prospective study.
Benefits seem to come gradually from improved blood flow, said Dr. Zoher Ghogawala, a neurosurgeon at Yale University in New Haven, Conn. “After 1 month, there was no change in any of the domains we measured,” he said. “However, if we followed these patients for a year, there was significant improvement.”
Although carotid endarterectomy is a well-established technique to treat carotid stenosis as a means of preventing stroke, its effects on cognitive function are poorly understood, Dr. Ghogawala said.
To learn more, he and his colleagues enrolled 36 patients from three sites. To estimate the extent that these patients' circulation was compromised, the researchers generated quantitative phase-contrast magnetic resonance angiography (qMRA) flow maps for their internal and middle cerebral arteries. This technology images blood flow in multiple phases of the cardiac cycle and then calculates volume, velocity, and direction.
The researchers used this technique because conventional MR techniques usually do not show changes in blood flow.
Using these data, they found that 12 patients had middle cerebral artery (MCA) flow impairment (defined as at least 15% less flow than the contralateral side) and 18 had impairment of internal carotid artery flow.
Lower blood flows were associated with a higher rate of stenosis. “It's what you might expect,” said Dr. Ghogawala.
Following surgery, new qMRA maps showed improved blood flow in these patients. Of the 12 patients who had preoperative impairment in MCA blood flow, 10 had improved flow after surgery.
After a month, there were no significant improvements in cognitive functioning. But in 29 patients who completed follow-up at 1 year, there was improvement in executive functioning (as measured by the Trail Making Test, Part B), verbal fluency (Controlled Oral Word Association FAS test), and memory (total recall score on the Hopkins Verbal Learning Test).
Scores improved on the Trail Making Test in all 9 patients with improvement in blood flow following surgery, compared with 8 of 20 patients with no improvement.
The presence of a right-sided lesion and impairment in middle cerebral artery blood flow were both significant, independent predictors of improved Trail Making Test scores.
Dr. Ghogawala said that patients with those features may have benefited the most because their cognitive function had been most impaired by their constricted blood flow.
Dr. Ghogawala disclosed that one of his coauthors received research support from VasSol Inc., the company that made the technology for producing the qMRA maps used in the study. Another coauthor owns shares in the company.
'After 1 month, there was no change, [but after] a year, there was significant improvement.'
Source DR. GHOGAWALA
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Technology May Have Future
This study that may become more important as the debate between CAS and CEA continues and further questions develop regarding intervention vs. medical management for asymptomatic patients. If these findings are reproducible on a larger scale, this might become an important testing modality for asymptomatic patients to determine who might benefit from intervention. If the technology proves successful, it would be very interesting to see if there are differences between CAS and CEA with regard to improvement in cognitive function.
LINDA HARRIS, M.D., is vice chair, faculty development, department of surgery, Millard Fillmore Gates Hospital-Kaleida, Buffalo, N.Y.