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

Patterns of brain computed tomography infarction and carotid plaque echogenicity

PURPOSE

It was suggested that in the absence of cardioembolism the discrete subcortical and cortical infarctions on brain computed tomography (CT) are most likely associated with carotid atheroma, whereas the hemodynamic infarctions, diffuse widespread white matter lesions, lacunae and basal ganglia infarctions are most likely associated with other pathologic conditions. The aim of this study was to determine the ultrasonic characteristics of carotid plaques and the degree of stenosis that were associated with the different brain CT infarction patterns and normal CT (pattern A, discrete subcortical and cortical infarctions; pattern B, hemodynamic infarctions, diffuse widespread white matter lesions, lacunae and basal ganglia infarctions).

METHODS

Four hundred nineteen carotid plaques (315 patients), producing 50% to 99% stenosis on duplex scanning, were studied. These plaques were imaged on duplex scanning, captured, digitized, and normalized (standardized) in a computer. Subsequently, their gray scale median (GSM) was evaluated to distinguish quantitatively the hypoechoic (low GSM) from the hyperechoic (high GSM) plaques. The brain CT infarction patterns of A, B, or normal CT on the ipsilateral hemisphere were noted.

RESULTS

The pattern A brain CT infarction was associated with carotid plaques having median GSM of 11 and median degree of stenosis of 80%, as contrasted with pattern B (median GSM, 28.5; median degree of stenosis, 75%) or normal CT (median GSM, 22; median degree of stenosis, 75%) (Kruskal-Wallis test, P <.001 for the GSM and P =.002 for the degree of stenosis). In the logistic regression analysis only the GSM and not the degree of stenosis distinguished the plaques associated with the three CT patterns.

CONCLUSIONS

The pattern A brain CT infarction was associated with hypoechoic plaques suggesting an involvement of extracranial carotid artery embolization, whereas the pattern B was associated with hyperechoic plaques suggesting an involvement of other mechanisms (hemodynamic, intracranial small and large vessel disease).

Correlates of embolic events detected by means of transcranial Doppler in patients with carotid atheroma

PURPOSE

This study identified in patients with carotid plaques the associations of emboli detected by means of transcranial Doppler (TCD) with cerebrovascular symptoms, brain computed tomography (CT) infarction patterns, and the attributes of plaques (echodensity, degree of stenosis).

METHODS

Eighty carotid plaques (in 59 patients), producing 50% to 99% stenosis, were imaged on duplex scanning and analyzed echomorphologically in a computer with the gray scale median (GSM). The GSM facilitated the quantitative distinction of dark (low GSM) from bright (high GSM) plaques. Stenosis was assessed with duplex scanning. Emboli were counted on TCD in the ipsilateral middle cerebral artery for half an hour. The brain CT infarction patterns (pattern A: discrete subcortical and cortical; pattern B: hemodynamic, diffuse white matter lesions, basal ganglia infarctions, lacunes) and normal CT and cerebrovascular symptoms on the ipsilateral hemisphere were noted.

RESULTS

Emboli were more frequent in symptomatic (median count, 3) than asymptomatic (median count, 0) hemispheres (Mann-Whitney U test, P =.031) and in hemispheres with pattern A infarction (median count, 3.5) than in hemispheres with pattern B infarction or normal CT (median count, 0; Kruskal-Wallis test, P =.047). The increased embolic count was associated with decreased GSM (Spearman correlation, P =.045, r = -0.22), but not with high degrees of stenosis (Spearman correlation, P =.44, r = 0.086).

CONCLUSION

Emboli were more frequent in symptomatic than asymptomatic hemispheres and in CT pattern A harboring hemispheres than in CT pattern B or normal hemispheres. They were more frequent in the presence of low-plaque echodensity, but not in the presence of a high degree of stenosis. These data support the embolic nature of cerebrovascular symptomatology and CT pattern A infarctions.

Stroke: pathogenesis, investigations, and prognosis--Part II of III

The aim of this review is to present the current knowledge regarding stroke. It will appear in three parts (in part I the epidemiology, clinical picture, and risk factors were discussed, while part III will consist of the management and rehabilitation). In the present part (II) the pathogenetic and pathophysiologic aspects of stroke are described. Regarding the investigations apart from the history and clinical examination and general investigations, the following specialized investigations and their role are discussed in detail: Computed tomography (CT), magnetic resonance imaging (MRI), xenon-blood-flow, positron emission tomography (PET), cerebral angiography, magnetic resonance angiography (MRA), ultrasonography, transcranial Doppler (TCD), echocardiography, Holter monitoring, and biopsies. In addition, taking into account the information from the above-cited modalities a prognosis for the final outcome is presented.

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.

Functional circulation images by angio-CT in the assessment of small deep cerebral infarctions

We analyzed circulation time (rABCT) and vascular volume density images obtained by angio-computerized tomography (angio-CT) in 63 patients with small deep cerebral infarctions. Abnormalities in the rABCT image were found in 88% of the patients and in the vascular volume image in 48%. Two groups with different clinical pictures were picked out by rABCT changes: one with major-vessel involvement, the other with small-vessel involvement. The perfusional changes found were mainly due to altered vascular canalization rather than to altered vasomotility. The hemodynamic theory could explain the spatial relations between perfusion changes and CT hypodense areas without needing assumptions linking blood flow and metabolism.

Mapeamento Cerebral

O mapeamento cerebral é uma técnica digital que gera mapas topográficos coloridos da atividade eletrencefalográfica captada sobre o escalpo. O eletrencefalograma após passar por um microcomputador, que realiza a análise quantitativa em várias faixas de freqüência, pode ser visualizado em um monitor colorido (EEG digital). Posteriormente, as épocas do EEG digital são selecionadas para a realização dos mapas, impressão final e arquivo em disquetes. Este método tem demonstrado ser ON em várias doenças neurológicas e psiquiátricas e deve ser realizado sempre em conjunto com o EEG digital. Achamos que dentro de alguns anos os aparelhos de EEG digital/mapeamento cerebral substituam as máquinas que realizam o EEG convencional.

Large striatocapsular infarcts: clinical presentation and pathogenesis in comparison with lacunar and cortical infarcts

In a well-defined prospective series of 247 patients with a first-ever supratentorial brain infarct, 15 patients (6%; 95% confidence interval 3-9%) had a large striatocapsular infarct. Twelve (80%) had signs of cortical dysfunction, whereas risk factor profile, frequency of significant carotid stenosis, and frequency of potential cardioembolic sources did not differ between patients with striatocapsular and those with cortical infarction. However, patients with striatocapsular infarction more frequently had potential cardioembolic source and significant carotid stenosis than patients with lacunar infarction. Our findings show that large striatocapsular infarcts differ from lacunar infarcts with regard to both presenting signs and symptoms, and pathogenesis, whereas they resemble infarcts involving the cortex. Such patients should therefore be managed and treated as patients with cortical infarction.

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.

Semiquantitative regional cerebral blood flow evaluation using 123I-IMP SPECT in a case showing transient ischemic attack caused by putaminal hemorrhage

A 69-year-old woman presented a transient cerebral ischemic attack, showing left arm weakness and slurred speech which recovered within 4 h of onset, while computed tomography indicated a putaminal hemorrhage. The regional cerebral blood flow distribution, measured semiquantitatively by use of 123I amphetamine emission tomography, was disturbed, which persisted more than one month up to a maximum of 4.5 months from the onset of symptoms. This case illustrates a variety of putaminal hemorrhage of good functional and vital prognosis, and provides an example in which the regional cerebral blood flow disturbances might persist for more than one month up to 4.5 months after the occurrence of a transient ischemic attack caused by a putaminal hemorrhage.

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.

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.

X-ray computed tomography (CT) study of small, deep and recent infarcts (SDRIs) of the cerebral hemispheres in adults. Preliminary and critical report

The evolution of CT signs of small, deep infarcts of the cerebral hemispheres in thirty adults, in the first five weeks, has been retrospectively studied. The relevant literature has been reviewed and an attempt has been made to present a synthesis, accompanied by a commentary. It is impossible now to give the frequency of each type of evolution, but the main data are as follows: The shortest delay of visibility of an hypodense area is about 17 to 19 h, but at 27 h the densities may still be normal. The evolution of the hypodense area is also variable: after a minimum attenuation is reached--at approximately 72 h--there is a risk of "fogging effect", which reduces the visibility of ischemic lesions; it could be seen from the end of the 1st week to the beginning of the 4th, but its frequency and its duration have yet to be better determined. In our series, contrast enhancement has been found in the gray matter of the basal ganglia between the 8th and the 22nd days--but according to some observations recorded in the literature, it may be found from the second to the twenty sixth day--and there was no obvious contrast enhancement in the white matter. The significance of the evolving CT signs is discussed in connection with the clinical applications, principally in the management of these patients, and with the attempts to correlate the clinical and CT findings.

Topographic electroencephalographic study of transient ischemic attacks

Twenty-five patients with TIAs in the carotid artery distribution were studied by means of computed mapping of EEG (CME) and conventional EEG. In addition, CT scan and cerebral angiography, and in 10 patients rCBF measurements were performed. The CME provided topographic maps of the average power spectra for each of 6 frequency bands from 2.0 to 29.5 Hz which were displayed two-dimensionally in a color-coded isopower format. EEG abnormalities were analyzed and the results of the two different methods of EEG interpretation were compared. Sixty-eight percent of the patients showed unilateral abnormalities on CME appropriately lateralized to the clinical symptoms even after these symptoms had cleared completely. Furthermore, 88% of those who were examined within 2 weeks of last TIA showed corresponding CME abnormalities. Only 3 out of 10 TIA patients who had rCBF studies showed reduction of blood flow on the appropriate hemisphere, whereas 7 of the 10 patients had corresponding CME abnormalities. Comparing the results of the CME and of conventional EEG reading revealed the CME to be slightly more sensitive in detecting asymmetrical voltage depression of background activity than the conventional reading of the EEG, while the latter detected low amplitude sporadic activities which were missed by CME. Both methods were equally sensitive in detecting slow wave foci and non-transient symmetrical changes. The two most significant points of this report are the following: first, 68% of the TIA patients studied had residual unilateral abnormalities in CME in their symptom-free period. In the subset of patients subjected to rCBF studies only 30% showed residual flow aberrations, whereas 70% of the same subset demonstrated unilateral abnormalities in CME. Second, though conventional EEG reading by an experienced electroencephalographer can nearly match the performance of CME the CME format makes subtle but useful EEG findings readily available to the uninitiated. The CME also quantifies the data making objective comparisons more amenable to software manipulations for further studies.