Italian multicenter study on reversible cerebral ischemic attacks: population characteristics and methodology

Transient ischemic attacks: an update

This is a review of extant concepts of transient ischemic attacks (TIAs), their definitions, prognostic significance, pathogenesis, physiology, and management. The natural history of TIAs depends upon the risk factors of the population group studied, so that therapeutic trials should be controlled and randomized and not dependent upon published natural history data. A strong association between TIAs and coronary artery disease has now been established. It may be difficult to establish the cause or pathogenesis of TIAs in any given patient in view of the relatively poor correlation between the patient's symptoms and location of arterial plaques. Recent studies have suggested mechanisms aside from impaired perfusion or embolization from carotid plaques or vertebral basilar disease. There are no proven indications for carotid endarterectomy, a procedure which has been excessively used in the United States, but presently ongoing prospective, randomized, controlled multi-center studies will likely resolve this important issue. Neither is there scientific validation for the use of long-term anticoagulants, but data support the efficacy of ASA in reducing the incidence of stroke and myocardial infarction in patients with TIAs.

One year follow-up of patients clinically preselected for excessive risk of stroke

From a consecutive series of 812 patients at risk of stroke we selected 100 who seemed to be at high risk (excessive stroke risk--ESR) on the following clinical criteria: either multiple reversible ischemic attacks in one carotid territory or multiple (or bilateral) severe stenotic carotid lesions. The patients of the first subgroup received medical therapy and those of the second were referred for surgery. The 100 patients were followed up for 12 months, during which 29 patients had cerebral ischemic events: 17 having stroke and 12 TIA. This study suggests that it is possible to identify beforehand subgroups of ESR patients, thereby facilitating the selection of patients for brain protection and avoiding huge trials of unselected cerebrovascular patients.

Haemodynamics and oxygen metabolism in patients after reversible ischaemic attack or minor ischaemic stroke assessed with positron emission tomography

Regional cerebral blood flow (CBF), blood volume (CBV) and oxygen metabolic rate (CMRO2) were evaluated and compared among normals, patients with recent reversible ischaemic attacks (RIAs) and patients with chronic minor infarction using positron emission tomography. Average CBF together with CMRO2 significantly decreased in the infarction group in the middle cerebral artery territory of the affected hemisphere while the mean values for RIAs were intermediate between the other two groups. CBV also reduced, however it was more preserved compared to flow as seen in decreased CBF/CBV values. Significant interhemispheric difference was found in CBF/CBV ratio, but it did not clearly correlate with OEF changes. Higher OEF was noted only in the restricted brain regions of RIAs where CBF showed large hemispheric asymmetry. However, in other regions, the coupled decline of blood flow and metabolism was found which suggests tissue damage or neuronal cell loss in the brain with previous RIA symptoms.

Italian multicenter study of reversible cerebral ischemic attacks. Part 5. Risk factors and cerebral atherosclerosis

As part of a prospective study, the influence of several premorbid and environmental factors on the presence, extent and severity of cerebral vessel atherosclerosis was studied in 462 patients with clinical diagnosis of RIA who underwent cerebral angiography. The extent and severity of atherosclerosis of the cerebral vessels was quantified using extracranial and intracranial cerebrovascular scores (ECS, ICS) based on the number and severity of the lesions in 11 extracranial and 21 intracranial arterial segments. Results of univariate and multivariate analyses indicate that the presence of atherosclerotic changes of cerebral vessels, as shown by angiography, was strongly related with age in both sexes. The lesions were more frequent in males, in particular under age 55. Elevated cholesterol was associated with a higher incidence of atherosclerotic lesions. Smoking was associated with a higher incidence of extracranial lesions. Age, smoking and history of hypertension were the best predictors of the extent and severity of cerebral vessel atherosclerosis.

Italian multicenter study on reversible cerebral ischemic attacks: VI--Prognostic factors and follow-up results

A total of 462 patients (mean age 52 years) affected by reversible focal ischemic attacks (RIAs) were followed prospectively in 8 neurologic institutions in Italy for 4 years. All cases were evaluated with a cerebral angiography and 21% of angiograms were normal. At the end of the follow-up period the cumulated probability for death, stroke, cardiac event and new RIA was respectively 7%, 8%, 3% and 36%. The predictive value of the baseline characteristics of this series was evaluated by a multifactorial analysis which showed that RIA and stroke (specific cerebrovascular risk) were more likely to develop in patients with a history of more than one RIA and in those in whom multiple vascular territories were involved. Moreover, previous myocardial infarction, intermittent claudication, angina pectoris, time elapsed since the first attack, and duration and severity of the attack itself were independently associated with general cardiovascular risk (death, stroke and myocardial infarction). We conclude that predictive factors, and thus also pathogenetic mechanisms, may be different for general cardiovascular risk and specific cerebrovascular risk in RIA patients.

Three-year neuropsychological follow-up of patients with reversible ischemic attacks

A short neuropsychological test battery designed to measure language, memory and visuospatial abilities was administered to 217 patients with reversible ischemic attacks. Patients were tested twice: the first time more than one month, but less than one year, from the last ischemic episode, and the second time three years later. A comparison between the first and the second testing session did not disclose any significant worsening. The degree of atherosclerosis and the occurrence of further ischemic episodes during the follow-up period were found to be unrelated to change in performance at the test battery. These results seems to challenge the hypothesis that multi-infarct dementia may follow apparently reversible, or even clinically silent, ischemic episodes.

The Italian Multicenter Study of reversible cerebral ischemic attacks: IV--Blood pressure components and atherosclerotic lesions

Utilizing the initial BP assessment in the 462 patients who entered the Italian Multicenter Study of reversible cerebral ischemia, an analysis of the effect of each BP component in respect of presence, extent and severity of atherosclerotic lesions, as displayed by angiography, was carried out separately for lesions located at either intra- or extracranial level. In a multivariate statistical model, among the following variables: sex, age, systolic BP, diastolic BP, cholesterol and smoking, systolic BP was found the best predictor of extent and severity of atherosclerotic lesions at extracranial level. None of the same variables was predictive of the severity of intracranial atherosclerosis. The results of this clinical study may confirm the indication, coming from physiopathologic observations, of a predominant role of systolic hypertension in the process of maintenance and acceleration of atherosclerosis in the large pre-cerebral arteries.

Focal cerebral ischemia and migraine

Consistent literature data on the cerebrovascular risk in migraineous patients are lacking. Available preliminary clinical data (Italian Cooperative Cross-Sectional Case-Control Study) suggest that migraine can hardly be considered a relevant pathogenetic associated risk factor of focal cerebral ischemia.

Clinical-CT correlations in TIA, RIND, and strokes with minimum residuum

An approach to the controversy of the physiopathology and classification of ischemic stroke is attempted in this study. The computed tomographies (CT) of 88 patients with transient ischemic attacks (TIA), 46 with reversible ischemic neurologic deficits (RIND) and 70 with ischemic strokes with minimum residuum (SMR) are analysed. The incidence of focal ischemic lesions on CT is 25% in TIA and RIND and 35% in SMR, when the study was performed after the first 24 hours. The incidence of cerebral infarction was much lower when the CT was performed within the first 24 hours after the clinical event. No significant differences in size or location of the infarction were found between the different groups. Deep infarctions were smaller than superficial ones. TIA duration correlated neither with the incidence of CT abnormalities nor with the size of the lesions. No correlation was found between doppler or oculoplethysmography abnormalities, clinical groups and CT findings. In reference to the structural lesions that underlie the clinical syndromes, TIA, RIND and SMR should not be considered as different groups.

Italian multicenter study on reversible cerebral ischemic attacks: III--Influence of age and risk factors on cerebrovascular atherosclerosis

The influence of age and other risk factors (history of hypertension and diabetes, cigarette smoking, dyslipidemia) on cerebral atherosclerosis was studied in 462 patients with RIA who had cerebral angiography. The degree of atherosclerosis was quantified using extracranial and intracranial cerebrovascular scores (ECS, ICS) based on the number and severity of the lesion in 11 extracranial and 21 intracranial arterial segments. Thirty-six percent of the patients under age 45 had a normal angiogram compared with 17% of the patients over 45. In the subgroup of patients with abnormal angiogram the mean ECS and ICS vascular scores were not significantly different in the two age groups. Cigarette smoking was the only risk factor to show a strong association with the extracranial score, and it was independent of the effect of age and other risk factors.