CT evaluation in patients with transient ischemic attack. Correlation between clinical and angiographic findings

The Impact of Transient Ischemic Attack (TIA) on Brain and Behavior

Transient ischemic attack (TIA) was originally defined as self-resolving focal cerebral ischemia with symptoms lasting <24 h. The newer definition also added the limitation that there should be no evidence of acute brain tissue infarction, to recognize that acute injury to the brain can result from ischemia of <24-h duration. However, several recent findings suggest that having a TIA correlates with deficits that can persist far beyond the resolution of clinical symptoms, even in the absence of imaging evidence of ischemic tissue injury. These deficits may be the result of subtle perturbations to brain structure and/or function that are not easily appreciated using the standard clinical and imaging tools that are currently employed in practice. Here, we will discuss evidence that suggests that TIA may lead to lasting changes to the structure and function of the brain.

Factors Associated with Cognitive Decline in Transient Ischemic Attack Patients

Chronic cerebrovascular disease and large ischemic stroke are both associated with cognitive impairment. Much less is known about the acute cognitive sequelae of transient ischemic attack (TIA). Although often overlooked, there is increasing evidence that cognitive impairment does occur following TIA. In some patients, cognitive changes persist after resolution of focal neurological deficits, but the temporal profile of these symptoms is unknown. In addition, clinical and imaging correlates of cognitive impairment after TIA have not been systematically studied. This under-studied and recognized problem has significant implications for TIA patient management. In this review, we summarize the evidence currently available and identify future research priorities.

Transient ischemic attack: definition, diagnosis, and risk stratification

Transient ischemic attack (TIA) can convey a high imminent risk for the development of a major stroke and is therefore considered to be a medical emergency. Recent evidence indicates that TIA with imaging proof of brain infarction represents an extremely unstable condition with early risk of stroke that is as much as 20 times higher than the risk after TIA without tissue damage. The use of neuroimaging in TIA is therefore critical not only for diagnosis but also for accurate risk stratification. In this article, recent advances in diagnostic imaging, categorizations, and risk stratification in TIA are discussed.

1H-MR spectroscopy changes in transient ischemic attack patients and their correlation with perfusion-weighted imaging

PURPOSE

We investigated whether patients with transient ischemic attack (TIA) have metabolic changes in the brain.

METHODS

35 patients with clinically diagnosed TIA were prospectively included in our study. Clinical and neurological data were compiled. 1H-MR spectroscopy and perfusion-weighted imaging were performed in all patients within 3 days of the onset of symptoms.

RESULTS

In TIA patients, the N-acetylaspartate (NAA)/choline (Cho) ratio in noninfarcted regions was significantly decreased in the symptomatic hemisphere (1.33 +/- 0.38) compared with the asymptomatic hemisphere (1.51 +/- 0.41, p < .05). Patients with a history of prior TIA had a significantly decreased NAA/Cho ratio in both the symptomatic (p < .05) and asymptomatic (p < .05) hemispheres compared with TIA patients without a prior TIA. TIA patients with diffusion-weighted imaging lesions had a significantly increased lactate/NAA ratio in both the symptomatic (p < .05) and asymptomatic (p < .05) hemispheres compared with TIA patients without lesions. The relative cerebral blood flow (rCBF) value was directly related to the symptomatic Cho/creatine (Cr) value (r = 0.81, p < .01). The higher the rCBF value, the higher the symptomatic Cho/Cr value.

CONCLUSIONS

TIA patients have neurological deficits that are transient; however, metabolic damage to the brain is present up to 3 days after the onset of the symptoms. These metabolic changes are not restricted to the symptomatic hemisphere or to areas close to ischemic lesions and the changes are related in the CBF.

Head Computed Tomography Findings Predict Short-Term Stroke Risk After Transient Ischemic Attack

Background and Purpose— Current guidelines recommend the use of head CT in the evaluation of patients with transient ischemic attack (TIA), but data supporting its value are sparse.

Methods— Patients who presented to 1 of 16 emergency departments of a large Northern California health maintenance organization and received a diagnosis of TIA from November 1997 through February 1998 were enrolled and followed up for 90 days. Clinical, demographic, and outcome data were obtained from computerized databases and medical records. Physicians blinded to patient characteristics and outcomes abstracted head CT findings from radiology reports. Abstracted findings included evidence of old or new infarct, periventricular white-matter disease, cerebral atrophy, cerebral vascular calcification, and nonischemic lesions.

Results— Head CT was performed in 67% of eligible patients (n=322) diagnosed with TIA. Evidence of a new infarct was seen on head CT in 13 patients (4%). A nonischemic cause of TIA symptoms was found in 4 patients (1.2%). During follow-up, 10.9% of TIA patients experienced subsequent stroke. After adjustment for confounders, risk for stroke during follow-up was significantly higher in those with a new infarct on head CT compared with others with TIA (odds ratio, 4.06; 95% confidence interval, 1.16 to 14.14; P =0.028). Old infarction, periventricular white-matter disease, cerebral atrophy, and cerebral vascular calcification were not predictors of subsequent risk of stroke.

Conclusions— Evidence of a new infarct on head CT in patients presenting with TIA is associated with increased short-term risk for stroke. Head CT appears to have prognostic value in patients with TIA and, for this reason alone, may be justified in their evaluation.

Hemodynamic and metabolic changes in transient ischemic attack patients: a magnetic resonance angiography and (1)H-magnetic resonance spectroscopy study performed within 3 days of onset of a transient ischemic attack

BACKGROUND AND PURPOSE

We investigated whether patients with transient ischemic attack (TIA) have systemic low flow to the brain or an abnormal intracranial flow distribution caused by an abnormal anatomy of the circle of Willis. Furthermore, we investigated whether metabolic changes were present in the brain.

METHODS

Forty-four patients with clinically diagnosed TIA were prospectively included in our study. Clinical and neurological data were compiled. MR imaging; quantitative flow measurements of the internal carotid, middle cerebral, and basilar arteries; MR angiography of the circle of Willis; and (1)H-MR spectroscopy were performed in all patients within 3 days of onset of symptoms.

RESULTS

Compared with control subjects, TIA patients did not have altered flow volume in any of the arteries and had normal flow distribution through the circle of Willis. In TIA patients, the N-acetylaspartate (NAA)/choline ratio in noninfarcted regions was significantly decreased in the symptomatic hemisphere (1.73+/-0.16) compared with the asymptomatic hemisphere (1.84+/-0.19, P<0.05) and control subjects (1.90+/-0.17, P<0.001). In the symptomatic hemisphere, the lactate/NAA ratio was significantly increased (0.04+/-0.08) compared with control subjects (0.00+/-0.01, P<0.05). Patients with a history of prior TIA had a significantly decreased NAA/choline ratio in both the symptomatic (P<0.05) and asymptomatic (P<0.05) hemispheres compared with TIA patients without a prior TIA.

CONCLUSIONS

TIA patients have neurological deficits that are transient; however, metabolic damage to the brain is present up to 3 days after the onset of the symptoms. These metabolic changes are not restricted to the symptomatic hemisphere or to areas close to ischemic lesions.

Cerebral perfusion SPECT in transient ischemic attack

PURPOSE

The purpose of our study is to evaluate the efficacy of cerebral perfusion single photon emission computerized tomography (SPECT) in patients with transient ischemic attack (TIA).

METHODS

Thirty-seven patients with TIA were collected for study. All patients had transient focal neurological symptoms or signs with complete recovery within 24 h after onset. The patients underwent cerebral perfusion SPECT between 6 h and 11 days after onset, with 10 cases performed within 24 h (group A), nine cases performed between 1 and 3 days (group B), 11 cases performed between 3 and 5 days (group C), and seven cases performed after more than 5 days (group D). A semi-quantitative method was used for analyzing the SPECT data, and the difference ratios between lesion side and contralateral normal side were calculated on each pair of regions of interest.

RESULTS

In total, 78.4% (29/37) of patients had reduced perfusion in the cerebral cortical regions or deep nuclei, and the regions with reduced perfusion corresponded with clinical presentations of the patients. The abnormal rate with reduced perfusion was 90.0% in group A, 77.8% in group B, 72.7% in group C and 71.4% in group D. Cross cerebellar diaschisis (CCD) was present in seven patients, and all of the primary cerebral perfusion defects of these patients were located at the territory of left or right middle cerebral artery.

CONCLUSION

Cerebral perfusion SPECT is a potential tool to detect cerebral perfusion defects and CCD in patients with TIA. Although the perfusion defect may persist more than 5 days after onset, we suggest cerebral perfusion SPECT should be performed as soon as possible.

Lesions visualized by contrast-enhanced magnetic resonance imaging in transient ischemic attacks

In patients with transient ischemic attacks (TIAs), contrast-enhanced magnetic resonance imaging (MRI) is more sensitive to visualize the recent ischemic lesions than conventional MRI. We examined the clinical characteristics of TIA patients presenting with enhanced lesions visualized by contrast-enhanced MRI. We retrospectively evaluated 64 patients with carotid TIAs. We evaluated the frequency and topography of TIA associated infarcts on contrast-enhanced MRI and compared the clinical background of patients with and without such lesions. Twenty-three patients underwent plain MRI only, while the remaining 41 patients underwent contrast-enhanced MRI. Of the latter 41 patients, 16 had abnormal enhanced lesions (39%: group L), while 25 had no lesions (61%: group NL). In group L, all lesions were spotty, and they were located in the cerebral cortex in 13 patients (81%), the subcortex in two (12%), and the perforator territory in one (6%). Aphasia or confusional state, hypertension, and emboligenic cardiac or arterial disease (stenosis > or =50%) were more frequently observed in group L than in group NL (38 vs. 8%, 81 vs. 48%, and 93 vs. 60%, respectively, P<0. 05). The TIA patients with enhanced lesions on MRI may be associated with an emboligenic cardiac or arterial disease, severe neurologic symptom compared to those without them.

Relationships of cerebral MRI findings to ultrasonographic carotid atherosclerosis in older adults : the Cardiovascular Health Study. CHS Collaborative Research Group

Cerebral magnetic resonance imaging (MRI) has demonstrated a high prevalence of infarct-like lesions, white matter hyperintensities, and evidence of cerebral atrophy in older adults. While these findings are generally believed to be related to ischemia and atherosclerosis, their relationship to atherosclerosis in the carotid arteries remains to be explored. Study subjects were part of the multicenter Cardiovascular Health Study, a cross-sectional study of 3502 women and men >/=65 years of age undergoing cranial MRI and carotid ultrasonography. MRI infarcts were detected in 1068 participants (29.3%) and measurable carotid plaque in 2745 (75.3%). MRI infarcts, ventricular and sulcal widening, and white matter score were strongly associated with carotid intimal-medial thickness (IMT) and stenosis degree after adjustment for age and sex (all P<0. 01). Associations with plaque characteristics were less strong and less consistent; MRI infarcts were weakly associated only with surface irregularity, and ventricular size was weakly associated only with lesion density (both P<0.04). In contrast, sulcal widening was strongly related to plaque characteristics, with scores being higher in those with heterogeneous and irregular plaque (both P<0. 009). Adjustment for other risk factors, and for carotid IMT/stenosis, removed associations of MRI findings with plaque characteristics except for weak relationships remaining between MRI infarcts and surface irregularity and between sulcal score and heterogeneous plaque (both P<0.03). MRI abnormalities show strong and consistent relationships with increasing carotid IMT and stenosis degree but less strong associations with plaque characteristics, especially after adjusting for IMT and stenosis.

Persisting perfusion defect in transient ischemic attacks: a new clinically useful subgroup?

BACKGROUND AND PURPOSE

Cerebral infarction and prolonged regional hypoperfusion have been described in patients with transient ischemic attacks (TIAs). The aim of this study was to compare the sensitivity of single-photon emission CT (SPECT) with that of brain CT and to evaluate the clinical significance of differentiation of TIA patients with or without focal hypoperfusion.

METHODS

From a hospital-based population, we studied the SPECT and CT findings in 76 consecutive patients, without a stroke history, who presented with TIA in the carotid artery territory. The recorded variables were the time of SPECT, imaging (<36 or > or = 36 hours), clinical presentation, history of previous TIA(s), duration of the presenting attack (<2 or > or = 2 hours), vascular risk factors, and etiology. We used both visual and semiquantitative analyses for the SPECT evaluation. Acetazolamide challenge was not performed.

RESULTS

The overall SPECT sensitivity was 36% (27/76). When brain CT and SPECT were performed in the same patients, the SPECT sensitivity was significantly higher than that of CT (19/59 [32%] versus 8/59 [14%]; P=.007). The SPECT sensitivity was not dependent on the time of investigation, duration of attacks, history of TIA(s), or the clinical presentation. The vascular risk and etiologic factors were not significantly different between the patients with or without prolonged focal hypoperfusion. Logistic regression did not identify any variable to discriminate the two groups.

CONCLUSIONS

Despite its better sensitivity compared with CT, SPECT performed without the acetazolamide test provides no additional clinically useful information on the vascular risk factors and etiology in TIA patients.

Baseline silent cerebral infarction in the Asymptomatic Carotid Atherosclerosis Study

BACKGROUND AND PURPOSE

In a group of patients with high-grade asymptomatic carotid artery stenosis, we prospectively determined the prevalence and radiological characteristics of clinically asymptomatic brain infarction evident on computed tomography. Risk factors and extent of carotid disease were also determined.

METHODS

Patients randomized into the Asymptomatic Carotid Atherosclerosis Study (ACAS) underwent a neurological history, a detailed stroke/transient ischemic attack questionnaire, and a detailed neurological examination. Computed tomography scans were examined by standardized criteria developed as part of a quality-control program supervised by a neuroradiologist. The presence, location, and size of all cerebral infarctions evident by computed tomography were determined.

RESULTS

Among 1132 patients, 848 had no history of stroke or transient ischemic attack. One hundred twenty-six patients (15%) had a silent infarct; 95 (11%) had one, 24 (3%) had two, and 7 (1%) had three or more infarcts. The infarct size was small and deep for 117 patients (72%), less than one-half lobe for 45 (28%), and one-half to less than one lobe for 1 (0.5%). The silent infarcts were evenly distributed ipsilaterally and contralaterally to the study artery but were significantly more frequent in the right hemisphere (P < .05). Factors associated with silent infarction were abnormal gait (P < .001), abnormal deep tendon reflexes or plantar responses (P = .038), but not degree of carotid stenosis. Silent infarction was less frequent among this totally asymptomatic cohort (15%) compared with those with transient ischemic attacks (34/139, 25%; P < .001).

CONCLUSIONS

Silent infarction in the setting of asymptomatic carotid stenosis is not uncommon, but silent infarctions are rarely sizable. The clinical significance of silent cerebral infarction in patients with asymptomatic carotid artery stenosis has yet to be established.

Efficacy of carotid endarterectomy for asymptomatic carotid stenosis. The Veterans Affairs Cooperative Study Group

BACKGROUND

The efficacy of carotid endarterectomy in patients with asymptomatic carotid stenosis has not been confirmed in randomized clinical trials, despite the widespread use of operative intervention in such patients.

METHODS

We conducted a multicenter clinical trial at 11 Veterans Affairs medical centers to determine the effect of carotid endarterectomy on the combined incidence of transient ischemic attack, transient monocular blindness, and stroke. We studied 444 men with asymptomatic carotid stenosis shown arteriographically to reduce the diameter of the arterial lumen by 50 percent or more. The patients were randomly assigned to optimal medical treatment including antiplatelet medication (aspirin) plus carotid endarterectomy (the surgical group; 211 patients) or optimal medical treatment alone (the medical group; 233 patients). All the patients at each center were followed independently by a vascular surgeon and a neurologist for a mean of 47.9 months.

RESULTS

The combined incidence of ipsilateral neurologic events was 8.0 percent in the surgical group and 20.6 percent in the medical group (P < 0.001), giving a relative risk (for the surgical group vs. the medical group) of 0.38 (95 percent confidence interval, 0.22 to 0.67). The incidence of ipsilateral stroke alone was 4.7 percent in the surgical group and 9.4 percent in the medical group. An analysis of stroke and death combined within the first 30 postoperative days showed no significant differences. Nor were there significant differences between groups in an analysis of all strokes and deaths (surgical, 41.2 percent; medical, 44.2 percent; relative risk, 0.92; 95 percent confidence interval, 0.69 to 1.22). Overall mortality, including postoperative deaths, was primarily due to coronary atherosclerosis.

CONCLUSIONS

Carotid endarterectomy reduced the overall incidence of ipsilateral neurologic events in a selected group of male patients with asymptomatic carotid stenosis. We did not find a significant influence of carotid endarterectomy on the combined incidence of stroke and death, but because of the size of our sample, a modest effect could not be excluded.

TIA, RIND, minor stroke: a continuum, or different subgroups? Dutch TIA Study Group

The results of CT were studied prospectively in 606 patients with a transient ischaemic attack (TIA), 422 patients with a reversible ischaemic neurological deficit (RIND), and 1054 patients with a minor stroke, were all entered into a multi-centre clinical trial. CT scanning showed a relevant ischaemic lesion in 13% (95% confidence interval 10-16%) of TIAs, 35% (95% confidence interval 30-40%) of RINDs, and 49% (95% confidence interval 46-52%) of minor strokes (p less than 0.000001). Even within the 24 hour margin, relevant infarcts occurred more often with longer attacks, but were still found in some patients with attacks lasting less than a minute. The type and location of the infarcts were similar in the three groups. These findings suggest that the differences between TIAs, RINDs, and minor strokes are quantitative rather than qualitative.

Comparative evaluation of SPECT, CT and CW Doppler data in patients with ischemic lesions of the brain

We report the SPECT, CT and CW Doppler findings in a series of 117 patients with cerebral ischemic lesions and correlate them with the clinical findings. SPECT-PAO proved to be more sensitive in localizing focal lesions than CT, which in 50% of the cases was normal or yielded an image of cerebral atrophy. In the latter cases CW Doppler ultrasound on the supraaortic trunks showed changes, circumscribed or diffuse. On the CW Doppler and SPECT evidence we consider that the CT image of cerebral atrophy may denote an alteration of the cerebral blood flow and metabolism and should be assessed in this light in the diagnosis and prognosis of cerebral ischemic lesions.

Cerebral infarction verified by cranial computed tomography and prognosis for survival following transient ischemic attack

Of 564 consecutive patients with transient ischemic attack, 350 (62%) had cranial computed tomography performed. Except for date of admission and smoking history, there were few differences between the patients evaluated with computed tomography and the 214 who were not. Cerebral infarcts were found in 59 (17%) of the 350 tomographic evaluations. Previous clinically diagnosed stroke, older age, and male sex were all significantly associated with the occurrence of tomographically verified infarcts (p less than 0.05). After controlling for stroke history and other important covariates, patients with tomographically verified infarcts had significantly shorter survival times than did patients without evidence of infarction on computed tomography (p = 0.035). Thus, cranial computed tomography findings appear to have important prognostic value for estimating survival following transient ischemic attack.

Are CT infarcts a separate risk factor in patients with transient cerebral ischaemic episodes?

CT cerebral infarcts have been reported in a number of studies of patients with transient ischaemic episodes. The hypothesis that these asignomatic infarcts, i.e. without associated clinical neurological deficit reflect the ability of the brain to limit the extent of neuronal damage through its collateral circulation was tested in 50 patients undergoing both CT scanning and cerebral angiography. Out of 50 patients there were 15 patients with a total of 17 infarcts on CT scan. Fourteen of 50 patients had evidence of diminished collateral reserve capacity on cerebral angiography. Ten of these 14 patients (71%) had CT evidence of infarction, in contrast to an incidence of five out of 36 patients (14%) without evidence of diminished collateral reserve. These results indicate that CT infarcts and collateral cerebral circulation must be evaluated as prognostic factors in patients with T.I.A.s.

The Willis lecture: transient ischemic attacks, scientific method, and new realities

First described by Thomas Willis in 1679 and defined in the 1950s, transient ischemic attack is universally agreed to be an episode of focal neurologic deficit in a vascular distribution, sudden in onset and resolving without residual deficit in less than or equal to 24 hours. Transient ischemic attack is diagnosed by characteristic history and absence of residua on neurologic examination. After these criteria had been accepted, regional cerebral blood flow and computed cranial tomography in the 1970s, later positron emission tomography, and even more recently, magnetic resonance imaging reveal prolonged pathophysiologic and metabolic disturbances even in persons with all the definitional characteristics of transient ischemic attack. These persistent abnormalities necessitate reexamination of the validity of the concept of transient ischemic attack. Furthermore, our group suspects that transient ischemic attack is probably only a marker, and not itself the risk factor, for the cerebral infarction which frequently follows transient ischemic attack. Additionally, the surprising frequency with which cerebral infarction, unrecognized by patient or physician, is revealed using neuroimaging techniques has created a need to redefine the categories heretofore used for diagnosis and assessment of therapy and prognosis for transient ischemic attack and cerebral infarction.

Computed tomography in patients with transient ischaemic attacks: when is a transient ischaemic attack not a transient ischaemic attack but a stroke?

In a prospective community-based study, 184 patients with transient ischaemic attacks (TIAs) were identified from a study population of about 105,000 between 1981 and 1986. Computed tomography (CT) was attempted in all those with cerebral ischaemic attacks (n = 152, 83%); patients with amaurosis fugax only (n = 32, 27%) were not scanned routinely. Scans were obtained in 120 (79%) of those with cerebral attacks and 12 (38%) of those with amaurosis fugax. The scans were reported by a neuroradiologist who was blinded to the patients' clinical features. Of 120 (27%:95% confidence interval 19-35) scans in patients with cerebral attacks, 32 showed a focal area of hypodensity or cortical loss, but in only 14 (12%:95% confidence interval 6-18) was this in an area of the brain appropriate to the patients' symptoms. There were no significant differences in the clinical features, the duration of attacks or the prognosis (i.e., risk of death, stroke or myocardial infarction) of patients with and without ischaemic lesions on CT. It is concluded that patients with clinically definite TIAs who have a presumed ischaemic and appropriately sited lesion on CT should not be re-classified as having had a stroke.

Current management of amaurosis fugax. The Amaurosis Fugax Study Group

We present a consensus on the pathophysiology, etiology, diagnosis, and treatment of amaurosis fugax. The phenomenon is defined and described, and the roles that extracranial and ocular vascular diseases play are discussed. Nonvascular ophthalmic and neurologic disorders that can be confused with amaurosis fugax are listed, and an algorithm for evaluation (which includes ophthalmic examination, laboratory studies, and noninvasive carotid artery studies) is given. Treatment of atherosclerosis, carotid artery disease, and other causes of amaurosis fugax are also discussed.

SPECT study of cerebral blood flow reactivity after acetazolamide in patients with transient ischemic attacks

We investigated 15 patients with one or more transient ischemic attacks (TIAs) in the internal carotid artery territory within the month following the most recent TIA. Cerebral blood flow (CBF) was measured by single-photon emission computed tomography, using intravenous xenon-133 before and after injection of 1 g acetazolamide. Six patients had severe carotid stenosis or occlusion; the other nine patients had no significant carotid lesions. Twenty age-matched volunteers free of neurologic symptoms or history were used as controls. Mean CBF in the sylvian region was not significantly different between patients and controls. Seven patients exhibited a focal hypoperfusion at rest in the symptomatic hemisphere, and their hypoperfused areas were hyporeactive after administration of acetazolamide. Seven other patients exhibited hyporeactive areas after acetazolamide administration while their CBF tomograms at rest were normal. Thus, CBF abnormalities were detected in 14 of the 15 patients. Our findings suggest that CBF measured early after acetazolamide administration could be useful to confirm the clinical diagnosis of TIA. In the nine patients with no significant lesion of the internal carotid artery, the areas of hypoperfusion were small and were probably related to the focal ischemic event. In the six patients with severe lesions of the internal carotid artery, abnormalities were of variable size and intensity but were often large and pronounced. The discrepancy between these two subgroups of patients could be ascribed to the hemodynamic influence of the internal carotid artery lesions. Moreover, our findings may provide some insight into the pathophysiology of TIAs.

Cerebral infarction in patients with transient ischemic attacks

Cranial computed tomography of 284 patients with transient ischemic attacks (TIAs) and without previous stroke was evaluated. The sample population included patients with carotid and/or vertebrobasilar TIAs. Computed tomography revealed cerebral infarction in 34 patients, including 5 with multiple infarctions. The lesion location was consistent with TIA symptoms in 16 patients. In another 16 patients, however, the lesion location did not correspond to the TIA symptoms; these lesions were attributed to previous silent infarctions. Two patients with multiple infarctions had both symptomatic and asymptomatic lesions. Age and carotid stenosis were each significantly related to an increased chance of detecting cerebral infarction (either symptomatic or asymptomatic). No significant relationship between race, gender, hypertension, diabetes, cardiac disease, or smoking and the incidence of infarction was found by either univariate or multivariate analyses.

Computed tomography in reversible ischaemic attacks: clinical and prognostic correlations in a prospective study

Two hundred and nineteen patients admitted with reversible atherothrombotic ischaemic attacks were prospectively evaluated by computed tomography. Of these patients, 122 were diagnosed as suffering from transient ischaemic attacks, 58 from reversible ischaemic neurological deficits and 39 from reversible ischaemic neurological deficits with incomplete resolution. In 133 cases the ischaemic event affected the carotid system, in 63 the vertebrobasilar system and in 23 cases the system could not be determined. Brain infarctions were observed in 64 patients (29.2%), cerebral atrophy in 96 (44.4%) and dilatation of a ventricle in 17 (7.8%). The frequency of brain infarction was related to the duration of the neurological deficit, being 20.5% in those with transient ischaemic attacks, 37.9% in those with reversible ischaemic neurological deficits and 43.6% in patients with reversible ischaemic neurological deficits with incomplete resolution (P = 0.005). Ischaemic lesions were closely correlated with abnormalities on supra-aortic trunk angiography or Doppler ultrasonography. During an average follow-up period of 21 months, a higher percentage of recurrence was found in those patients with CT infarctions, but the difference was not significant.

Cerebral blood flow, computerized tomography and angiography in 562 cases of cerebrovascular insufficiency

The measurement of cerebral blood flow (CBF) in addition to cerebral computerized tomography (CT) and angiography is most reliable in cases of transient ischemic attacks (TIA) and prolonged reversible ischemic neurologic deficits (PRIND). Alterations of CBF can be detected in symptom-free intervals. The cerebrovascular reactivity to CO2 stimulus is regarded as an especially suitable tool to prove the cerebrovascular reserve. If it is diminished, cerebral angiography should be carried out since it will often show major obstructive lesions. Angiography shows no sure correlation between CBF and collateral circulation. Strong opthalmic pathways in unilateral occlusion of the internal carotid artery (ICA) often coincide with compensated or only slightly alterated CBF and relatively small infarcts in CT. In about 70% of cases of ICA occlusion, CT shows an infarct mostly in region of the middle cerebral artery (MCA). Largest infarct volumes were found in the anterior area. Although resting CBF was normal in 55% of cases of unilateral ICA occlusion, CO2 reactivity was impaired in 68% of these Cases.

The role of cranial computed tomography in carotid surgery

In patients who present with TIA, RIND, or CVA, the cranial CT scan can rule out other etiologies for neurologic symptoms. In addition to the clinical presentation, the CT scan allows further stratification of patients being considered for carotid endarterectomy. We propose that patients be classified as TIA (+), TIA (-), RIND (+), or CVA (-). The CT scan has defined a new subgroup of patients, TIA (+) and RIND (+)--the Silent Cerebral Infarction. Patients who are categorized as TIA (+), RIND (+), and CVA (+) (cerebral infarction on CT or by history) are at increased risk for intraoperative ischemia and postoperative neurologic deficit. As such, they should be selectively shunted based on intraoperative EEG monitoring or routinely shunted. There is a strong association between ulcerative plaque at the carotid bifurcation and cerebral infarction on CT. The CT scan is a critical diagnostic procedure in evaluating the patient with an acute neurologic event. Patients with negative CT scans are candidates for early operation. Carotid endarterectomy should generally be delayed for 4 to 6 weeks in patients with positive CT scans.

Cranial CT scan in transient global amnesia

The occurrence of cerebral infarction in patients with transient global amnesia (n = 43) was evaluated by CT scan and compared to that of patients with transient ischemic attacks (TIA) (n = 58) and with no neurological disease (n = 52). Significant differences were demonstrated between TGA and TIA patients in relation to the control group, but no differences were found between patients with TGA and TIA. Our study suggests a vascular mechanism for TGA and that TGA could be considered a low risk TIA in most cases.

Prolonged disturbances of regional cerebral blood flow in transient ischemic attacks

Regional cerebral blood flow (rCBF) was measured over both hemispheres in 20 patients with unilateral transient ischemic attacks (TIA) of the territory of the internal carotid artery on the day of the TIA. rCBF was estimated with the nontraumatic Xenon 133-inhalation technique using the initial slope index. 13 patients experienced their first TIA, 7 had several attacks. In 14 patients the first rCBF-measurement was performed during the presentation of clinical symptoms. The 2nd rCBF-measurement was done on day 2, the last one on day 7. Scans of the 15 patients studied with CT were normal. On day 1 mean rCBF of the TIA-side was significantly lower than that of the contralateral hemispheres. 22% of all areas showed a significant reduction of flow compared to mean rCBF. Mean rCBF of both the TIA- and the contralateral side was significantly reduced compared to the bi-hemispheric mean rCBF of a control group with no history of TIA or completed strokes but at least 2 risk factors for cerebrovascular disease. Whereas mean rCBF did not change in the contralateral side it increased significantly (+6.9%) in the TIA-side from day 1 to day 2 but not from there to day 7. This is reflected by the increase of the total number of ROI with normal flow from day 1 to day 2. Considering the actual flow and the flow course of that tissue which was believed to be responsible for the clinical symptoms the following regional patterns were observed: normal rCBF in 6 patients; early return to normal concomitant to the clinical course (n = 4).(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid endarterectomy in patients with actively changing neurological deficits--correlations with CT brain scans

The place of carotid endarterectomy in patients with actively changing neurological deficits (ACND) is yet to be defined. This is a study of 15 patients with ACND who underwent carotid endarterectomy. All patients had demonstrable neurological deficits at the time of surgery. However no patient had severe devastating symptomatology or decreased levels of consciousness. Eight patients (Group I) were classified as stroke-in-evolution (SIE) according to Millikan. Seven other patients (Group II) were also unstable with deficits of recent onset but did not demonstrate a classical progressive or stepwise deterioration. Average internal carotid stenosis was 80% (range 50-90%). In each of the Group I patients CT scans of the brain demonstrated cerebral infarction in the area appropriate to the deficit. CT scans were performed in four of the Group II patients, two of whom showed cerebral infarction while two were normal. Seven of the eight Group I patients improved after surgery while one progressed to a completed stroke. Six of the seven Group II patients improved following surgery while one died on the third postoperative day. These results suggest an improved outlook with surgery when compared either with the natural history of SIE or with the results when anticoagulants alone are used.

Headache in transient ischemic attacks (TIA)

The evaluation of headache in patients with transient ischemic attacks (TIA) has various sources of difficulty, the definition of TIA being the most relevant. The classical definition needs to be supplemented with a normal CT scan if a misleading diagnostic statement is to be avoided. The clinical features of 90 patients suffering from TIA and who had contrast-enhanced CT scans are reported. Headache occurred in 30% of the patients. Headache prevailed in patients with vertebrobasilar TIA compared with carotid TIA (p less than 0.05). Headache prevailed as a preceding (24 h) and/or concomitant sign compared with other neurological symptoms (77.8% of the patients). Headache was ipsilateral, in the anterior half of the head in the carotid TIA and in the posterior half of the head in the vertebrobasilar TIA. In about 50% of the patients generalized non-localized headache occurred. Headache usually preceded the neurological symptoms in cases of arterial occlusion (20 carotid, 3 vertebral artery), usually appearing during or after the attack in cases without arterial occlusion. Only 2 cases out of 20 with positive CT scan had headache. These two patients suffered from a rather large hypodense lesion. The other 18 patients showed lacunar lesions. Different hypotheses concerning the physiopathology of the headache associated with TIA are discussed.

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.

Cerebral infarction with transient signs (CITS): do TIAs correspond to small deep infarcts in internal carotid artery occlusion?

Among 75 patients in whom internal carotid artery (ICA) occlusion was discovered on angiography, 5 presented with transient ischemic attacks (TIAs) without suffering a stroke. Although neurological examination was normal, all had evidence for one (in one instance two) hypodense lesion suggesting infarction contralateral to the neurological dysfunction on computed tomography (CT). These infarcts were small and deeply located, being indistinguishable from lacunes in most cases. We suggest that cerebral infarction with transient signs ( CITS ) may be a usual finding in patients with ICA occlusion who suffer isolated TIAs. In these cases, CITS may correspond to incomplete cerebral necrosis related to a well-developed collateral supply, or to recurrent ischemia in the region of an old "silent" infarct. CITS should be differentiated from TIAs, which may be diagnosed only in absence of visible structural lesion.

Regional cerebral blood flow in patients with transient ischemic attacks studied by Xenon-133 inhalation and emission tomography

Cerebral blood flow CBF was studied in 14 patients with transient ischemic attacks TIA and arteriosclerotic neck vessel disease. CBF was measured by a rapidly rotating single photon emission computerized tomograph using Xenon-133 inhalation. This method yields images of 3 brain slices depicting CBF with a spatial resolution of 1.7 cm. Based primarily on the clinical evidence and on the angiographical findings embolism was considered the pathogenetic factor in 10 cases, whereas chronic hemodynamic insufficiency rendered symptomatic by postural factors probably accounted for the symptoms in 4 patients. Of the 14 patients, all studied days to weeks after the most recent TIA, four showed hypoperfused areas on the CBF-tomograms and with roughly the same location hypodense areas on CT-scanning, i.e. areas of complete infarction. However, an additional five patients showed reduction of CBF in areas with no abnormality on the CT-scan. The abnormal blood flow pattern was found to be unchanged after clinically successful reconstructive vascular surgery. This suggests the presence of irreversible ischemic tissue damage without gross emollition (incomplete infarction). It is concluded, that TIAs are often harmful events, as no less than 9 of the 14 patients studied had evidence of complete and/or incomplete infarction. Thorough examination and rational therapy should be instituted as soon as possible to prevent further ischemic lesions.

CT and arteriographic comparison of patients with transient ischemic attacks--correlation with small infarction of basal ganglia

Fifty patients presenting clinically with TIAs were examined angiographically. Twenty one patients (42%) had no abnormality. Twenty patients (40%) had stenosis or occlusion in the MCA, ACA or intracranial carotid, whereas 11 (22%) had involvement of their extracranial internal carotid artery. Seven of the 28 CTs performed showed basal ganglia infarcts. This suggests that the cause for the TIA was an infarct in the vascular territory of a lenticulostriate artery.