SAN FRANCISCO (EGMN) – 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, Connecticut, who reported on the study at the annual meeting of the Congress of Neurological Surgeons. “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.”

The benefit of surgery also appeared to be most pronounced in those with a right-sided lesion or impairment in middle cerebral artery blood flow.

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. Overall, 61% had right-sided stenosis and 39% had left-sided stenosis; 54% were male, and 14% were symptomatic at presentation.

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 calculated the ratio of contralateral to ipsilateral flow rates. 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, who also is director of the Wallace Trials Center at Greenwich (Connecticut) Hospital.

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 (on the Controlled Oral Word Association FAS test), and memory (total recall score on the Hopkins Verbal Learning Test). The changes were statistically significant (P less than .05).

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 in blood flow.

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.

“Further study is needed to understand the cerebral flow limitations associated with reversible dementia in some patients,” he concluded.

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.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

旧金山(EGMN)——据一项前瞻性研究结果显示，在因颈动脉狭窄行动脉内膜切除术之后1年，大部分患者的认知功能均有所改善。

 

研究者从3个不同地点招募了36例患者，存在大脑中动脉右侧狭窄和左侧狭窄的患者分别占总人数的61%和39%，51%为男性，且有14%的患者在研究开始时便存在临床症状。研究者通过定量相位对比法磁共振血管成像术(qMRA)获取了患者脑动脉的中间和内侧分支的血流成像图，对其一个心动周期中多个时间点的血流变化情况进行了检测，并同时计算了其血管容量、血液流速和方向。利用上述数据，研究者就对侧大脑动脉血液流速相较于同侧大脑动脉流速值的比值进行了估算。

 

结果表明，在术前有12例患者大脑中动脉(MCA)血供受损(定义为与对侧分支血液流速相比降低至少15%)，另有18例患者存在颈内动脉血供受损。患者术后再次接受了qMRA检查，在术前存在MCA血供受损的12例患者中有10例术后血供状况改善。

 

患者在术后1个月时认知功能无显著改善，但其中29例患者1年后的随访结果表明，其在大脑执行功能(测试方法：路径描绘测验B部分)、语言流畅度(测试方法：语意流畅测验)和记忆能力(测试方法：霍普金斯词汇学习测验总体记忆能力评分)等指标方面均有所改善。上述变化均具备统计学显著性(P＜0.05)。在术后血供状况改善的9例患者中，路径描绘测验得分全部增加，相比之下，在血供无改善的20例患者中仅有8例接受该测验得分增加。右侧大脑中动脉病变或血供受损是路径描绘测验分数的显著、独立预测因子。

 

鉴于患者上述相关指标显著改善需要较长时间(1年)，可以推断，患者认知功能的改善可能得益于术后其脑部血供的逐渐恢复。

 

研究者声明接受VasSol公司的经济资助。

 

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