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

A Novel Model for Studying Voltage-Gated Ion Channel Gene Expression during Reversible Ischemic Stroke

The dysfunction of voltage-gated ion channels contributes to the pathology of ischemic stroke. In this study, we developed rat models of transient ischemic attack (TIA) and reversible ischemic neurological deficit (RIND) that was induced via the injection of artificial embolic particles during full consciousness, that allow us to monitor the neurologic deficit and positron emission tomography (PET) scans in real-time. We then evaluated the infarction volume of brain tissue was confirmed by 2,3,5-triphenyl tetrazolium chloride (TTC) staining, and gene expressions were evaluated by quantitative real-time PCR (qPCR). We found that rats with TIA or RIND exhibited neurological deficits as determined by negative TTC and PET findings. However, the expression of voltage-gated sodium channels in the hippocampus was significantly up-regulated in the qPCR array study. Furthermore, an altered expression of sodium channel β-subunits and potassium channels, were observed in RIND compared to TIA groups. In conclusion, to our knowledge, this is the first report of the successful evaluation of voltage-gated ion channel gene expression in TIA and RIND animal models. This model will aid future studies in investigating pathophysiological mechanisms, and in developing new therapeutic compounds for the treatment of TIA and RIND.

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.

Imaging findings and referral outcomes of rapid assessment stroke clinics

AIM

A rapid assessment stroke clinic (RASC) was established to provide a rapid diagnostic service to individuals with suspected transient cerebral or ocular ischaemia or recovered non-hospitalized strokes. In this report we review imaging findings and clinical outcomes of patients proceeding to the carotid surgery programme.

METHODS

Between October 2000 and December 2002, 1339 people attended the RASC. The findings of head CT and carotid Doppler ultrasound of the 1320 patients who underwent brain and carotid imaging were reviewed, and the number subsequently proceeding to carotid angiography and intervention was reported.

RESULTS

CT head scans were normal in 57% of cases; 38% demonstrated ischaemia or infarction; and 3% yielded incidental or other significant findings not related to ischaemia. On screening with carotid Doppler ultrasound, 7.5% showed greater than 50% stenosis on the symptomatic side. A total of 83 patients (6.2%) proceeded to cerebral angiography and 65 (4.8%) underwent carotid endarterectomy or endovascular repair.

CONCLUSION

Rapid-access neurovascular clinics are efficient in selecting patients for carotid intervention, but this is at a cost and the number of potential strokes prevented is small. Alternative management pathways based on immediate medical treatment need to be evaluated.

Differences in the outcome of patients with TIA versus minor stroke

In the Swedish aspirin low dose trial (SALT) 101 patients were enrolled from the Department of Medicine, Falun. 42 patients had experienced TIA/amaurosis fugax, whereas 59 patients had suffered a minor stroke/retinal infarction. History of hypertension treated or known untreated occurred statistically more frequently in the minor stroke group at randomisation (P less than 0.01) and the mean diastolic blood pressure (DBP) was higher in the minor stroke group during the observation time (P less than 0.05; ANOVA). The minor stroke group had less favourable outcomes according to survival curves (stroke or death) during a mean observation time of 34 months in each group (P less than 0.05 at 29 months). The findings of the present trial suggest that hypertension and the higher mean DBP during the observation time might explain the better outcome of end points of stroke or death in patients with TIA.

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.

High frequency of asymptomatic visual field defects in subjects with transient ischaemic attacks or minor strokes

The hypothesis that asymptomatic visual field defects can be found in patients with carotid transient ischaemic attacks (TIA) or minor strokes was tested. Twenty-two consecutive male patients with TIA and 18 patients with minor strokes from the carotid artery territory were examined by perimetry, cerebral computerised tomography and regional cerebral blood flow. Asymptomatic visual field defects were found in many TIA and minor stroke patients, 29% (5/17) and 57% (8/14), respectively (NS). Eighty-five per cent (11/13) of the scotomas were solely or predominantly located in the upper part of the visual field (P = 0.008 for absolute defects and P = 0.03 for relative defects). We conclude that both carotid territory TIA and minor stroke patients have a high frequency of asymptomatic visual field defects, predominantly located in the upper part of the visual field.

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.

Extended use of cranial CT in the evaluation of patients with stroke and transient ischaemic attacks

The hypothesis was explored that patterns of ischaemic brain damage shown by CT may be of greater value in estimating the relevance of angiographic stenosis in the carotico-vertebral arteries in some patients than presenting clinical features. Five angiographic and six CT abnormalities were defined and charted independently in a blinded manner in 312 patients whom clinical features and subsequent management were known. Charts were combined for statistical analysis. Statistically significant associations were found between two types of CT lesion and angiographic abnormalities, but these were present in only 18% of cases. The distribution of clinical features did not differ significantly within this subset compared to the whole population, from which it was concluded that the hypothesis was upheld. Furthermore significantly more patients in this subset were subjected to carotid endarterectomy, suggesting that management decisions may have been modulated by CT findings in some patients.

An overview of the contribution of regional cerebral blood flow studies in cerebrovascular disease: is there a role for single photon emission computed tomography?

Regional cerebral blood flow (rCBF) findings and their application to cerebrovascular disease are reviewed. Although the coupling of cerebral blood flow and metabolism are best studied with positron emission tomography, single-photon emission computed tomography measurements of rCBF can contribute to patient management. Potential indications for the use of rCBF functional brain imaging include differential diagnosis, early prediction of late recovery in the late subacute and chronic phases of stroke (3 months or more postonset), and evaluation of vasospasm following subarachnoid hemorrhage.

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.

Is the EEG really normal in lacunar stroke?

Electroencephalograms of 12 patients with a recent lacunar infarct, 12 patients with a recent cortical infarct and 12 control patients were studied without previous information about the clinical features and the corresponding CT scan findings. EEG assessment included both visual and computerised analysis, in both the eyes closed and the eyes open condition. The specificity and the sensitivity of the EEG in the diagnosis of lacunar infarction in this study were both 0.8 (95% confidence limits 0.5-1). The positive predictive value of diagnosing a lacunar infarct on the basis of the EEG was 0.7 (95% confidence limits 0.4-0.9). The chance-corrected coefficient of agreement (kappa) between CT scanning and EEG was 0.75. Thus, in contrast to the results of previous studies, most EEGs of patients with recent lacunar infarction show rather specific abnormalities.

The role of computed tomography in patients with lacunar stroke in the carotid territory

In a prospective study of 78 patients presenting with recent clinical features of a supratentorially located lacunar infarct (LI), serial CT-scanning with contiguous 6, 5 or 3 mm slices was carried out. LI was found in 59 patients (76%; 95% confidence limits 65-85%). Lesions other than lacunar infarcts were found in 5 patients (6%; 95% confidence limits 2-14%); in only 14 patients could no abnormalities be detected (18%; 95% confidence limits 10-28%). There was no relationship between the detection rate on CT on the one hand and the type of lacunar syndrome, the number of previous TIA's, and the duration or severity of the neurological deficit on the other. A new protocol of CT-scanning for screening LI is advocated for situations where no MRI facilities are available or no patient cooperation can be obtained.

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.

The shaking limb--a lacunar syndrome

A 76 year old man with shaking movements of the fingers, weakness of the arm and lacunar infarctions on computed tomographic scan is described. The shaking limb should be included in the group of lacunar syndromes.

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.

Focal parenchymal lesions in transient ischemic attacks: correlation of computed tomography and magnetic resonance imaging

Twenty-two patients with the clinical diagnosis of transient ischemic attacks were prospectively evaluated by computed tomography (CT) and proton magnetic resonance imaging (MRI). Nineteen patients also underwent cerebral angiography. The MRI studies were performed with a prototype super-conductive magnet using a 0.6 Tesla or a 1.5 Tesla magnetic field. Two pulse sequence techniques were used resulting in T1 and T2 weighted images. All studies were interpreted descriptively by a single neuroradiologist in a blinded fashion, with special attention to focal parenchymal abnormalities. Patients with previously documented clinical strokes or reversible ischemic neurologic deficits lasting more than 24 hours were excluded. The CT scans revealed focal areas of abnormalities in 7 of 22 patients (32%), while the MRI scans showed focal changes in 17 patients (77%). All the CT lesions were clearly visualized on MRI. The MRI changes were better seen on T2 weighted images as areas of increased signal intensity. There was a marked preponderance of deep hemispheric lesions on both CT and MRI studies. Focal parenchymal abnormalities were not limited to the symptomatic vascular territory. We conclude that MRI reveals focal parenchymal changes in the majority of patients with transient ischemic attacks and is more sensitive than late generation CT scans. However, specificity appears to be poor, and may limit clinical usefulness. While the significance of the MRI "lesions" remains speculative, they may represent markers of chronic cerebrovascular disease in these patients.

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.

Computerized tomographic abnormalities in patients with transient episodes of focal neurological dysfunction

Forty patients with episodes of transient neurological dysfunction lasting less than 24 hr had abnormal CT scan findings. Eight patients had intracranial mass lesions and 32 had vascular lesions i.e. ischemic, infarction, hematoma. Seventeen patients had hypodense lesions consistent with tissue infarction; whereas 12 patients had isodense enhancing lesions consisting with tissue ischemia. In eight patients with isodense enhancing lesions, this was no neurological deterioration following carotid endarterectomy. In 3 patients who had transient ischemic attacks with CT evidence of hypodense lesions there was clinical and CT deterioration following carotid surgery.