Neuropsychological changes associated with carotid endarterectomy

Cognitive testing in patients undergoing carotid endarterectomy

OBJECTIVES

To determine by literature review the effect of carotid endarterectomy (CEA) as a modulator of cognitive function in patients with carotid arterial disease. Derive recommendations for standardising cognitive testing of patients with carotid arterial disease.

DESIGN AND METHODS

The English language literature was interrogated using a CD-ROM driven medline search using carotid endarterectomy and cognitive function as keywords between 1986-1995. These subsets were scanned and papers of direct relevance or commonality were selected. Cited papers prior to 1986 from these references were then sought directly.

RESULTS

There are few controlled studies reporting on the effect of CEA. There is no consensus in the literature for the effect of CEA on cognition or which tests should be used. Studies reporting a benefit for CEA lack a control group and fail to eliminate the effect of practice. Reports suggesting cognitive impairment following CEA performed follow-up tests early.

CONCLUSIONS

There are many methodological problems with the study of cognitive function before and after carotid endarterectomy and wide disagreement in the interpretation of results. Further studies should contain control groups, use tests resistant to practice and be performed when the effects of surgery and anaesthesia are passed.

[Effects of carotid endarterectomy on various neuropsychologic parameters. A neuropsychologic longitudinal study]

Carotid endarterectomy was performed in 25 patients with symptomatic cerebrovascular disease. All patients underwent detailed neuropsychological investigations immediately before surgery, immediately after surgery, and again after a follow-up period of 14 months. Immediately after surgery the flicker fusion frequency was temporarily reduced, indicating an impairment of global cognitive functioning. Postoperatively, verbal attention was found to be improved, particularly in younger patients, in patients with TIA, and in patients with left-sided operation. Finally, visual retention (Benton) was improved at the end of the observation period, especially in older patients and in patients with left-sided operation. Considering the complexity of pathologic brain perfusion, the effects of carotid endarterectomy can only be explained if a multidimensional approach is adopted.

Neuropsychological improvement versus practice effect following unilateral carotid endarterectomy in patients without stroke

Patients who were admitted to hospital for a recent transient ischemic attack were entered into one of three groups based on medical and surgical characteristics; those with an abnormal neurological examination or a focal abnormality on CT Scan were omitted from the study. The two surgical groups (12 patients each) underwent either a left or right endarterectomy for a symptomatic atheroma of the ipsilateral carotid artery. The control group consisted of 12 patients who either demonstrated minor or nonexistent carotid abnormalities or a TIA distribution that was contralateral to what would otherwise have been a surgically treatable lesion. Patients were tested before surgery and again 6-8 weeks later with the WAIS, WMS, and other neuropsychological measures. Significant improvement on some measures at follow-up was strictly equivalent across all groups and was attributed to practice effects.

Outcome from carotid endarterectomy. Neuropsychological performances, depressive symptoms and quality of life: 8-month follow-up

A preliminary study was carried out on a population of twenty-five consecutive and unselected patients undergoing carotid endarterectomy. A matched control group of subjects suffering from same pathology, but unoperated, was compared to experimental sample. A battery of neuropsychological tests, the Zung Self-Rating Depression Scale and the Jachuck's Quality of Life Impairment Scale were administered one week before surgery, two weeks after (surgical sample only) and then eight months later. The research shows that carotid endarterectomy does not impair neuropsychological performances, but produces some improvement, reaching significant level in the case of Word Fluency 1 and Similarities tests; depressive scores remained substantially unchanged, while quality of life improved slightly.

Neuropsychological evaluation in transient ischaemic attack and minor stroke

Two groups of patients with transient ischaemic attack and minor stroke without detectable haemodynamic stenotic lesions were evaluated by neuropsychological tests and compared with a control group. The mean values of the scores adjusted for age and educational background demonstrated that the patients with transient ischaemic attack did not have a worse performance than normal subjects in any of the tests, the patients with minor stroke had a worse performance than normals, particularly in Rey's figure-copying test (P less than 0.025), and the latter test was not affected by educational background or age of the subjects. The results are discussed with reference to other case series, and the importance of age and cerebral damage in causing intellectual impairment evaluated by neurophysiological tests is stressed.

Neuropsychological changes associated with stenoses or occlusions of the carotid arteries. A comparative psychometric study

A total of 33 patients with a relevant stenosis or occlusion of extracranial arteries were tested for a number of neuropsychological functions. Most of them [22] suffered from transient ischemic attacks, 6 from strokes, 5 were asymptomatic. Compared to an age-matched population of normals, patients showed an impairment in their mnemic functions, and attention under stress as well as in their psychomotor function. The degree of neuropsychological impairment was independent of the unilaterality or bilaterality of carotid stenoses. The results illustrate the neuropsychological deficit even in asymptomatic patients and those with complete recovery from transient neurological deficits.

Neuropsychological functions after carotid endarterectomy

Psychological testing was performed on 23 patients (mean age 60.7 years) with unilateral or bilateral stenoses of the carotid arteries prior to and 10 months after carotid endarterectomy. Intellectual functions were slightly improved, mnemic functions impaired, psychomotor functions and dimension of personality remained unchanged. Carotid endarterectomy, although improving neuropsychological functions in a few cases, on average does not cause a significant improvement. This underscores the preventive character of the surgical intervention.

Mental status outcomes following carotid endarterectomy: a six-month analysis

Fifty-one male and two female patients were divided into the following three groups: (a) patients with symptomatic carotid artery disease who received carotid endarterectomies, (b) patients with symptomatic carotid artery disease who either declined or were not candidates for carotid endarterectomies, and (c) patients who received a surgical procedure unrelated to cerebral functioning. The three groups were not significantly different in terms of age or educational level. The subjects were examined using the WAIS, Wechsler Memory Scale, Halstead-Reitan Neuropsychological Battery, Sickness Impact Profile, and Profile of Mood States. The assessments were conducted presurgery and repeated at a 6 month follow-up. The results of two-way analyses of variance revealed a significant trials effect for a majority of the variables, including the average impairment rating and the full scale WAIS IQ. However, significant group x trials interactions were not found for either the neuropsychological measures or the quality of life indices. The results did not support the conclusion of improved mental status or increased psychosocial well-being in patients who received carotid endarterectomies.

Intellectual function in patients with transient ischaemic attacks (TIA) or minor stroke. Long-term improvement after carotid endarterectomy

Psychological testing was performed in 25 patients (mean age 56 years) with transient ischaemic attacks and/or minor strokes and with angiographically verified internal carotid artery stenosis. The effects of carotid endarterectomy on intellectual functions were evaluated postoperatively at 2 weeks and 8 months respectively. Preoperatively the mean test values were below the normal level for all tests indicating a general intellectual impairment for the group as a whole. This may reflect multi-infarct dementia in statu nascendi. At the early postoperative test session some test results were statistically significantly worse than the preoperative. 8 months postoperatively the mean values for all tests had improved as compared with the preoperative values. This improvement reached a statistically significant level in 6 tests. When the side of operation was considered a pattern emerged: in the 12 patients with left-sided endarterectomies improvement was significant for tests mainly related to left-hemisphere function (Word Pairs Test, Story Recall, Trail Making B, Similarities) and in the 13 patients with right-sided endarterectomies significant improvement occurred in the functions mainly related to the right hemisphere (Visual Gestalts, Block Design, Digit Span backwards). This relationship between side of operation and improvement in lateralized functions cannot be explained by retest effects. It is concluded that TIA's and minor strokes per se may impair intellectual function, and that reversal of deterioration and even improved mental state may follow carotid endarterectomy.

Preoperative neurobehavioral impairment in cerebral revascularization candidates

We examined level of performance in 40 candidates for cerebral revascularization and found substantial variability on general indices of neuropsychological performance. Patients differed by duration of their longest ischemic attack, by surgery type, but not by time since onset of their first ischemic attack. Duration of the longest ischemic attack correlated highly with neuropsychological summary scores. In contrast, symptom duration was unrelated to level of performance in 18 additional patients with histories consistent with cerebrovascular ischemia who did not undergo surgery subsequently. We concluded that initial status on neuropsychological tests is an important variable to consider in postoperative followup of patients undergoing cerebral revascularization. More detailed clinical history and finer grained analysis of neuropsychological data promised to reveal additional relationships among clinical symptoms, neurobehavioral data, and underlying neuropathology.

Test-retest IQ changes of epilepsy patients: assessing the influence of practice effects

A number of recent studies have emphasized the role of practice effect on test-retest changes in performance often seen on neuropsychological tests. An attempt is made to separate the influence of practice effect from other functional changes in the test-retest differences observed on the WAIS for a sample of adult epilepsy patients. Fifty-eight epilepsy patients were divided into three groups based on their WAIS test-retest score changes. Their corresponding test-retest performance on the Halstead-Reitan Battery and changes in seizure frequency were compared and analyzed. Results indicated that there was a correspondence between improvement in neuropsychological test performance, reduced seizure frequency, and improvement on the WAIS. It was concluded that test-retest changes in neuropsychological test performance reflected changes in psychological functioning of these individuals rather than the influence of practice effect. Some general issues relating to the question of disentangling the influence of practice effect from other functional changes in status were raised and discussed.

Neuropsychological changes following carotid endarterectomy

Fifty-five subjects undergoing carotid endarterectomy were grouped according to side of operation, i.e. right, left and bilateral. There subjects were administered a comprehensive neuropsychological battery prior to and six months following surgery. The performance of these subjects was compared with a control group undergoing surgical procedures that did not involve the brain or cerebral vasculature, and a second control group composed of patients with cerebrovascular symptoms who were not operated. It was found that as a group the endarterectomy subjects improved on a greater percentage of measures. When various subgroups were examined, it was found that the right operated stroke patients improved on significantly more measures than any other group. The difference between right and left stroke patients was significant, but there was no difference between right and left TIA patients in the extent of improvement. These findings were discussed in terms of possible underlying mechanisms.

The effect of carotid endarterectomy on mental functioning

In order to ascertain the effect of carotid endarterectomy on mental functioning, carotid endarterectomy patients suffering from transient ischemic attacks (TIA) were compared preoperatively and postoperatively with cholecystectomy patients. Preoperatively, a tendency toward poorer verbal memory and greater well-being is found in carotid endarterectomy patients. Postoperatively, the overall mental functioning of the carotid endarterectomy patients is not significantly improved, though verbal fluency does show improvement. The well-being of both groups is significantly greater following operation. The complaints of the carotid endarterectomy patients during the (last) TIA had already diminished before operation and after operation remained practically on the same level. Preoperatively and postoperatively, no clear connection exists between mental functioning and age of patients in this experiment, not between mental functioning and the side of the operation. Finally, in the case of 5 patients, no long-term (4.5 months) effect of carotid endarterectomy could be indicated.

Psychiatric screening on a neurological ward

Two psychiatric screening instruments, the Mini-Mental State (MMS), a test for cognitive disturbance, and the General Health Questionnaire (GHQ), were administered to 197 neurological in-patients. The results suggest a high rate of psychiatric disturbance. The highest rate of cognitive disturbance detected by the MMS was found in patients with Parkinson's disease. The highest rates of emotional disturbance indicated by GHQ scores were related to myasthenia gravis and multiple sclerosis. MMS scores but not GHQ scores were related to standard tests of cognition, the diagnosis of cerebral pathology, and CAT scan abnormality. The results also demonstrate that the GHQ does not adequately detect patients with cognitive impairment. It is concluded that in populations at high risk for cognitive impairment a tandem screening procedure utilizing tests for both cognitive and emotional disorders is needed.

Neuropsychological effects of electroconvulsive therapy

Although ECT as the treatment of choice for psychotic depression has been in use for many years, little is known about the neocortical residual of such treatments inferred from behavioral measures. The major portion of the literature has been concerned with inferred or observed changes in affective state. The present study compared pre- and posttreatment performances on the Halstead-Reitan neuropsychological battery of 20 patients who were receiving ECT from two different machines. Most Ss gave indicators of cerebral impairment prior to treatment when performance of one side of the body was contrasted with performance of the other side. After treatment, there was an increased number of Ss who evidenced signs consistent with damage to the right cerebral hemisphere. Some concern was raised that a large number of patients who eventually are subject ot ECT because of depression behave in this way because of an undiagnosed neocortical dysfunction. There is some suggestion that the effect of the procedure is to either create or intensify a right hemisphere focus as inferred from behavioral measures.

Intellectual and personality changes associated with carotid endarterectomy

Eleven patients with at least 40-50% carotid artery stenosis were given intelligence and personality tests just prior to and 6 weeks after carotid endarterectomy, a surgical procedure designed to remove arteriosclerotic blockage. When compared with 8 control patients, endarterectomy patients showed increases in Perceptual-Organization IQ, decreases in time to complete a perceptual motor task, and significant reductions in suspicion, confusion, disorientation, and other personality symptoms generally associated with senility.

Retest reliability of the Halstead Impairment Index in a normal, a schizophrenic, and two samples of organic patients

In a 1974 study Matarazzo, et al. reported the test-retest reliability of the Halstead-Reitan Neuropsychological Battery for a sample of normal young men and a comparison group of older Ss with cerebrovascular disease. The present study extended this earlier one by addition of comparable test-retest findings from two additional comparison groups: a sample of chronic schizophrenic Ss and a sample of organic patients who underwent endarterectomy. Despite the lack of comparability across the four samples on many dimensions, including age and test-retest interval, the results again reveal a high degree of clinical as well as purely psychometric reliability for most of the tests in the neuropsychological battery and the additional suggestion for further research that the test-retest instability found for some of the Ss in the schizophrenic sample may, itself, hold promise of differential clinical significance in the diagnosis of a "schizophrenic" vs. "organic" process.

Cerebral function before and after carotid endarterectomy

Twenty men had their cerebral function measured preoperatively and three months after carotid endarterectomy using the Halstead-Reitan neuropsychological test battery. Thirteen patients were cerebrally impaired preoperatively, but 12 of them improved appreciably after surgery. Changes in internal carotid arterial blood flow measured preoperatively showed no significant correlation with the improvement in neuropsychological status. We think that carotid endarterectomy carries an even better prophylaxis for the brain as a whole than had been thought.