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H C Koennecke

Publications and source records attributed to H C Koennecke.

At least 19 recordsLinked to original sources
PubMed2003

Navigated diffusion-weighted imaging with interpolated phase-correction for high-resolution imaging of stroke.

Stroke imaging was revolutionised with the introduction of diffusion-weighted MRI (DWI). The commonly used echoplanar DWI suffers from geometrical distortion near the skull base and the frontal regions and from reduced spatial resolution and fat suppression. To allow a voxel-by-voxel comparison between high-resolution spin-echo images, we implemented spin-echo-based DWI. Motion artefacts were eliminated by phase correction in hybrid frequency-Fourier domain using navigator echoes. In a novel approach, distorted navigator echoes which did not eliminate motion artefacts were replaced with interpolated navigator echoes, leading to restored image information. Navigated DWI yielded high-resolution images in 21 of 24 patients with brain ischaemia, allowing diagnosis of even small or diffuse zones of ischaemia. We determined the spatial distribution and mean of T(2)- and DWI signal intensity and apparent diffusion coefficients (ADC), using a multidimensional histogram-based analysis. Mean ADC were decreased in ischaemic areas less than 9 days old. The technique may also be useful for high-resolution DWI of tissue other than the brain.

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PubMed2001

Prophylactic antipyretic treatment with acetaminophen in acute ischemic stroke: a pilot study.

Fever is associated with poor outcome in acute stroke. Forty-two consecutive, normothermic patients with acute ischemic stroke were, within 24 hours from symptom onset, randomized to either receive 4 g acetaminophen daily (n = 20) or matched placebo (n = 22). Fever of greater than 37.5 degrees C occurred in 36.4% of patients in the placebo group, compared with 5.0% in the acetaminophen group (Fisher's exact test, p = 0.014). Prophylactic antipyretic treatment with acetaminophen may be effective in the prevention of fever after acute ischemic stroke.

Acetaminophen↗
PubMed2001

Diffusion-weighted magnetic resonance imaging in two patients with polycythemia rubra vera and early ischemic stroke.

Polycythemia rubra vera (PRV) is a rare myeloproliferative disorder with a high risk of ischemic stroke. Although thrombosis of large cerebral arteries is the most frequently presumed pathomechanism, various infarct patterns have been described in patients with PRV and ischemic stroke. We report two patients with mild acute ischemic strokes and known PRV, in whom a scattered lesion pattern was detected by diffusion-weighted magnetic resonance imaging (DWI), but was not visible on computed tomography (CT) and conventional magnetic resonance imaging (MRI). Further diagnostic work-up including extra- and transcranial Doppler sonography (ECD, TCD), transesophageal echocardiography (TEE), magnetic resonance angiography and Holter monitoring revealed no obvious sources of cerebral embolism in both cases. However, TEE in one patient demonstrated spontaneous echo contrast (SEC) in the left atrium. In both patients the symptomatology resolved completely. The detection of a scattered infarct pattern by DWI in patients with PRV and acute ischemic stroke has not been reported previously. DWI findings together with the SEC in one patient emphasize the assumption that a prothrombotic state with subsequent arterial embolism rather than local arterial thrombosis may be the underlying pathomechanism of stroke in some patients with PRV. Adding DWI to the diagnostic work-up may help to clarify etiology in patients with PRV and acute ischemic stroke.

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PubMed2001

[Prerequisites, indications and contraindications of IV-lysis of ischemic stroke with rt-PA].

BACKGROUND AND PURPOSE: To evaluate prerequisites, safety, and efficacy of i.v.-thrombolysis of ischemic stroke with rtPA in an academic medical center. METHODS: Over a period of 2 years and 10 months all patients admitted with a diagnosis of stroke were recruited. Inclusion and exclusion criteria for i.v.-thrombolysis were combined from large scale randomized controlled trials, the time window, however, could be extended up to 4 hours in subjects with a negative CT-scan. Prespecified outcome parameters were the modified Rankin Scale (mRS) and the Barthel Index (BI) at 3 months, and symptomatic hemorrhagic complications. Additionally, time parameters, such as onset-admission-time, door-Ct-time, door-needle time, and onset-needle time were recorded. RESULTS: During the reported period 103 patients underwent i.v.-thrombolysis, corresponding to 14.9% of all patients with ischemic stroke, and 47% of patients with ischemic stroke arriving in < 3 hours after symptom onset. The mean baseline NIHSS was 14, the mean mRS 13 (3-34), the mean age 70 (+/- 12) years. The following time intervals were observed: Onset-admission-time 64 min., door-CT-time 27 min., admission-needle-time 80 min., and onset-needle-time 142 min. There were 4 symptomatic intracerebral hemorrhagic transformations, including 3 parenchymal hemorrhages, 2 of them lethal, and one with almost full recovery. According to the mRS, 39% of patients had a good (mRS 0-1), 72% a good to moderate recovery (mRS 0-2). The corresponding figures for the BI were 60% BI 95-100 and 72% BI > 90. The mortality was 15%. CONCLUSION: The i.v.-thrombolysis of ischemic stroke with rt-PA demands appropriate organisation of the pre- and in-hospital phase and can be performed safely and efficaciously in daily clinical routine if inclusion and exclusion criteria as well as all safety measures during the critical phase after therapy are strictly obeyed.

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PubMed2001

Scattered brain infarct pattern on diffusion-weighted magnetic resonance imaging in patients with acute ischemic stroke.

BACKGROUND AND PURPOSE: Infarct patterns on brain imaging contribute to the etiologic classification of ischemic stroke. However, the association of specific subtypes of infarcts and etiologic mechanisms is often weak, and acute lesions are frequently missed on initial computed tomography (CT). Diffusion-weighted imaging (DWI) is superior in visualizing acute ischemic lesions as compared to CT and conventional magnetic resonance imaging (MRI). In our prospective study, we addressed the question whether a distinct pattern of infarction on DWI is associated with infarct etiology and clinical outcome. METHODS: Sixty-two patients with clinical signs of acute ischemic stroke and negative acute CT upon admission underwent DWI within 10 days after the ictus. Neurological status was documented using the NIH stroke scale. A scattered lesion pattern was defined by at least 2 separate hyperintense DWI lesions within the territory of one of the major cerebral arteries. Ischemic lesions were defined as acute if the region was demarcated strongly hyperintense in all DW images, and if the apparent diffusion coefficient was below normal. RESULTS: In 32 patients, DWI revealed a scattered lesion pattern, while in 30 patients a single acute lesion was detected. In patients with scattered lesions, potential arterial or cardiac embolic sources were detected in 26 patients (81.3%), as compared to 5 patients (16.6%) in the group with single lesions (chi(2) test, p < 0.0001). The neurological status of patients with scattered lesions improved significantly more than among patients with single lesions (Mann-Whitney test, p < 0.0003). CONCLUSION: A scattered lesion pattern on DWI in patients with acute brain infarction and negative initial CT scan is associated with an embolic etiology and may indicate a favorable clinical outcome.

Adult↗
PubMed2001

Transtentorial herniation after unilateral infarction of the anterior cerebral artery.

BACKGROUND: Fatal cerebral herniation is a common complication of large ("malignant") middle cerebral artery infarcts but has not been reported in unilateral anterior cerebral artery (ACA) infarction. CASE DESCRIPTION: We report a 47-year-old woman who developed an acute left hemiparesis during an attack of migraine. Cranial CT (CCT) was normal but demonstrated narrow external cerebrospinal fluid compartments. Transcranial Doppler sonography was compatible with occlusion of the right ACA. Systemic thrombolytic therapy with tissue plasminogen activator was initiated 105 minutes after symptom onset. Follow-up CCT 24 hours after treatment revealed subtotal ACA infarction with hemorrhagic conversion. Two days later, the patient suddenly deteriorated with clinical signs of cerebral herniation, as confirmed by CCT. An extended right hemicraniectomy was immediately performed. Within 6 months, the patient regained her ability to walk but remained moderately disabled. CONCLUSIONS: This is the first reported case of unilateral ACA infarct leading to almost fatal cerebral herniation. Narrow external cerebrospinal fluid compartments in combination with early reperfusion, hemorrhagic transformation, and additional dysfunction of the blood-brain barrier promoted by tissue plasminogen activator and migraine may have contributed to this unusual course.

Cerebral Hemorrhage↗
PubMed2001

Intravenous tPA for ischemic stroke team performance over time, safety, and efficacy in a single-center, 2-year experience.

BACKGROUND AND PURPOSE: Safety and efficacy concerns toward thrombolysis for ischemic stroke prevail among many neurologists because of the risks of hemorrhage and the small proportion of suitable patients. We therefore prospectively assessed feasibility, safety, efficacy, and team performance in a single center to prove whether thrombolytic treatment is practical in daily clinical routine. METHODS: Patients were prospectively recruited over a 2-year period. Major inclusion and exclusion criteria from large, randomized controlled trials were combined. Prespecified outcome parameters were the modified Rankin scale (MRS) and the Barthel Index (BI) at 3 months and symptomatic hemorrhagic complications. In addition, certain time intervals during the diagnostic process preceding thrombolysis were prospectively recorded. RESULTS: Within 2 years a total of 75 patients underwent intravenous thrombolysis, corresponding to 9.4% of all admitted patients with stroke and 14.9% of patients with ischemic stroke. Mean+/-SD age was 68+/-13 (range 34 to 90) years; median baseline National Institutes of Health Stroke Scale score was 13+/-6 (range 2 to 34). Thrombolysis was started at an average time of 144 minutes after symptom onset, and 13 patients (17.3%) were treated beyond 3 hours. Two cerebral hemorrhages (2.7%) occurred. Outcome according to the MRS was good (MRS 0 to 1) in 40%, moderate (MRS 2 to 3) in 32%, and poor (MRS 4 to 5) in 13%; the corresponding results, as measured by the BI, were 61% (BI 95 to 100, good), 16% (BI 55 to 90, moderate), and 8% (BI 0 to 50, poor). The mortality rate was 15%. Over 2 years the median door-to-CT time decreased from 30 to 22 minutes (27%), and the door-to-needle time was shortened from 96 to 73 minutes (14%). The mean number of patients treated per month increased from 2 to 4. CONCLUSIONS: Thrombolytic therapy can be performed safely and efficaciously in daily clinical routine. More than a minority of acute stroke patients might be eligible for intravenous thrombolysis. The performance of a stroke team can be improved over time, subsequently increasing the proportion of eligible patients and thereby the efficiency of the method.

Adult↗
PubMed2001

Compliance with secondary prevention of ischemic stroke: a prospective evaluation.

BACKGROUND AND PURPOSE: Compliance with pharmacological therapy is essential for the efficiency of secondary prevention of ischemic stroke. Few data exist regarding patient compliance with antithrombotic and risk factor treatment outside of controlled clinical trials. The aim of the present study was to assess the rate of and predictors for compliance with secondary stroke prevention 1 year after cerebral ischemia and to identify reasons for noncompliance. METHODS: Patients with a diagnosis of ischemic stroke or TIA and antithrombotic discharge medication were prospectively recruited. At 1 year, the proportion of patients compliant with antithrombotic treatment and with medication for risk factors (eg, hypertension, diabetes, hyperlipidemia) was evaluated through structured telephone interviews. In addition, the reasons for nontreatment with antithrombotic and risk factor medication were determined. Independent predictors for compliance were analyzed by logistic regression analyses. RESULTS: Of 588 consecutive patients admitted to our stroke unit, 470 had a discharge diagnosis of cerebral ischemia (TIA 26.2%, cerebral infarct 73.8%) and recommendations for antithrombotic therapy. At 1 year, 63 patients (13.4%) had died and 21 (4.5%) were lost to follow-up, thus, 386 could finally be evaluated. Of the patients, 87.6% were still on antithrombotic medication, and 70.2% were treated with the same agent prescribed on discharge. Of the patients with hypertension, diabetes, and hyperlipidemia, 90.8%, 84.9%, and 70.2% were still treated for their respective risk factors. Logistic regression analyses revealed age (OR 1.03, 95% CI 1.00 to 1.06), stroke severity on admission (OR 1.09, 95% CI 1.00 to 1.20), and cardioembolic cause (OR 4.13, 95% CI 1.23 to 13.83) as independent predictors of compliance. CONCLUSIONS: Compliance with secondary prevention in patients with ischemic stroke is rather good in the setting of our study. Higher age, a more severe neurological deficit on admission, and cardioembolic stroke cause are associated with better long-term compliance. Knowledge of these determinants may help to further improve the quality of stroke prevention.

Age Factors↗
PubMed1999

Neurogenic hypertension. A new MRI protocol for the evaluation of neurovascular compression of the cranial nerves IX and X root-entry zone.

OBJECTIVE: Neurovascular compression of the rostral ventrolateral medulla (RVLM) has been implicated in the pathogenesis of essential hypertension. Although MRI has been widely used to evaluate the morphologic relation of structures in this region, spatial resolution of the previously used techniques was limited. This article describes the use of a new MRI protocol that combines two sequences with improved spatial resolution and complementary image information as well as a set of defined criteria for image analysis. METHODS: MRI of the brain stem was performed in 60 hypertensive and 50 normotensive subjects using a 3D-CISS and a 3D-FISP-MRA sequence. Neurovascular contact in the RVLM was independently assessed by four readers using predefined criteria and compared with a consensus finding. Agreement was expressed by kappa statistics on a 0 to 1 scale. RESULTS: Left-sided neurovascular contact within the RVLM was found in 13 (22%) hypertensive and 6 (12%) control subjects. The inter-reader agreement for positive and negative findings ranged from 0.47 to 0.79; agreement to the consensus finding ranged from 0.65 to 0.90. CONCLUSIONS: The combination of 3D-CISS and arterial flow-sensitive 3D-FISP, together with the evaluation criteria defined in this study, can be used for describing the finer anatomic features of the brain stem, and in particular for investigation of neurovascular contact of the IX/X cranial nerve root-entry zone. The high quality of images and the substantial or almost perfect reader-consensus agreement should make this protocol useful for future investigations of the neurovascular compression syndrome in patients with essential hypertension and possibly in other neurovascular compression syndromes, such as trigeminal neuralgia and hemifacial spasm.

Adult↗
PubMed1998

[Effect of cardiac embolism sources on origin of territorial cerebral infarcts].

BACKGROUND AND PURPOSE: To test the association of cardiac sources of embolism with territorial type brain infarcts. METHODS: From a prospective cerebral ischemia data base the 106 consecutive patients with territorial type cerebral infarcts on computerized tomography were analyzed. The 85 consecutive patients with lacunar lesions served as a comparison group. The association of cardiac sources of embolism with territorial types infarcts was assessed using univariate Chi Square tests and logistic regression models. Cardiac sources of embolism were defined as:atrial fibrillation, left cardiac thrombi, valvular vegetations, wall motion and valvular abnormalities, left atrial enlargement, open foramen ovale, septal aneurysm, mitral valve prolaps, and aortic arch atherothrombosis (all findings--except for atrial fibrillation--assessed by echocardiography). RESULTS: Atrial fibrillation was significantly associated with territorial type infarcts (odds ratio 2.2, 95% confidence interval 1.01-4.8). This effect was independent of additional cardiac diseases, other cardiac abnormalities, carotid artery stenosis, and patient age. Most likely due to the small sample size, left cardiac thrombi only showed a non-significant trend towards an association with territorial infarcts (odds ratio 3.0, 95% confidence interval 0.7-12.3). The rate of all other cardiac findings did not differ significantly between the comparison groups. CONCLUSION: Atrial fibrillation and cardiac thrombi showed an association with territorial type infarcts. Other so-called cardiac sources of embolism--except for mechanical valves and bacterial endocarditis which were not represented in our sample--revealed no clinically relevant association with embolic brain infarct pattern.

Adult↗
PubMed1998

[Therapy of cerebral arteriovenous malformations].

The rapid development of modern endovascular, microsurgical, and radiation therapies has considerably expanded the treatment options for encephalic arteriovenous malformations (AVMs). Surgery has the longest history. Single or staged intravascular procedures (embolizations) using fast-acting glues, sclerotic agents, and thrombogenic coils serve to reduce the size of AVM to that suitable for extirpation and may reduce the risk of surgery. Radiation ("gamma-knife") therapy, most frequently used in small, non-operable AVMs, is also viewed by some authors as an alternative or even superior tool in small, operable malformations. Partial embolization to reduce the mass-effect of space-occupying AVMs, to reverse diaschisis, and to treat AVM-related seizure disorders is being discussed and practiced. Given the in part competing or even controversial options, the selection of optimal treatment for AVM patients is becoming increasingly difficult. Current management is impeded by the paucity of information on the exact risks of invasive therapies and by insufficient criteria for identifying patients at risk of spontaneous bleeding during the natural course, including the seriousness of such hemorrhage.

Cerebral Angiography↗
PubMed1998

Morbidity of intracranial hemorrhage in patients with cerebral arteriovenous malformation.

BACKGROUND AND PURPOSE: Decisions on invasive arteriovenous malformation (AVM) treatment are currently based on natural-course risk estimates of AVM bleeding and assumptions on morbidity from cerebral hemorrhage in general. However, morbidity of AVM hemorrhage has rarely been reported. We sought to assess the morbidity of intracranial hemorrhage in patients with cerebral AVMs. METHODS: From a prospective AVM database, 119 patients were analyzed: 115 had a hemorrhage as the diagnostic event, and 27 of them suffered a second hemorrhage during follow-up; an additional 4 patients had other diagnostic symptoms but bled during follow-up. The type (parenchymal, subarachnoid, intraventricular) and location of AVM hemorrhage were determined by CT/MR brain imaging. Disability and neurological impairment were assessed with the Barthel Index, the Rankin Scale, and the National Institutes of Health Stroke Scale, with a mean follow-up time of 16.2 months. RESULTS: Of the 115 incident hemorrhages, 34 (30%) were subarachnoid, 27 (23%) parenchymal, 18 (16%) intraventricular, and 36 (31%) in combined locations. In 54 patients (47%; 95% confidence interval [CI], 38% to 56%) the incident hemorrhage resulted in no neurological deficit, and an additional 43 patients (37%; 95% CI, 28% to 46%) were independent in their daily activities (Rankin 1). Fifteen patients (13%; 95% CI, 7% to 19%) were moderately disabled (Rankin 2 or 3), and 3 (3%; 95% CI, 0% to 6%) were severely disabled (Rankin > or =4). Parenchymal hemorrhages were most likely to result in a neurological deficit (52%). Type and morbidity of hemorrhage during follow-up were similar to incident events. Twenty (74%) of 27 patients with both incident and follow-up hemorrhages were normal or independent (Rankin 0 or 1). None of the patients with a hemorrhage during follow-up died during the observation period. CONCLUSIONS: Hemorrhage from cerebral AVMs appears to have a lower morbidity than currently assumed. This finding encourages a reevaluation of the risks and benefits of invasive AVM treatment.

Activities of Daily Living↗
PubMed1998

Feeding artery pressure and venous drainage pattern are primary determinants of hemorrhage from cerebral arteriovenous malformations.

PURPOSE: The purpose of this study was to define the influence of feeding mean arterial pressure (FMAP) in conjunction with other morphological or clinical risk factors in determining the probability of hemorrhagic presentation in patients with cerebral arteriovenous malformations (AVMs). METHODS: Clinical and angiographic data from 340 patients with cerebral AVMs from a prospective database were reviewed. Patients were identified in whom FMAP was measured during superselective angiography. Additional variables analyzed included AVM size, location, nidus border, presence of aneurysms, and arterial supply and venous drainage patterns. The presence of arterial aneurysms was also correlated with site of bleeding on imaging studies. RESULTS: By univariate analysis, exclusively deep venous drainage, periventricular venous drainage, posterior fossa location, and FMAP predicted hemorrhagic presentation. When we used stepwise multiple logistic regression analysis in the cohort that had FMAP measurements (n = 129), only exclusively deep venous drainage (odds ratio [OR], 3.7; 95% confidence interval [CI], 1.4 to 9.8) and FMAP (OR, 1.4 per 10 mm Hg increase; 95% CI, 1.1 to 1.8) were independent predictors (P < 0.01) of hemorrhagic presentation; size, location, and the presence of aneurysms were not independent predictors. There was also no association (P = 0.23) between the presence of arterial aneurysms and subarachnoid hemorrhage. CONCLUSIONS: High arterial input pressure (FMAP) and venous outflow restriction (exclusively deep venous drainage) were the most powerful risk predictors for hemorrhagic AVM presentation. Our findings suggest that high intranidal pressure is more important than factors such as size, location, and the presence of arterial aneurysms in the pathophysiology of AVM hemorrhage.

Adult↗
PubMed1997

Risk of spontaneous haemorrhage after diagnosis of cerebral arteriovenous malformation.

BACKGROUND: A small proportion of strokes are caused by cerebral arteriovenous malformations (AVM). Treatment to prevent intracranial haemorrhage itself carries risks, and untreated AVM may in many cases have a good prognosis. We investigated the risk of subsequent symptomatic bleeding in the clinical course of AVM in patients with and without an initial haemorrhage. METHODS: 281 unselected, consecutive, prospectively enrolled patients with cerebral AVM were grouped according to their initial clinical presentation--142 presented with and 139 without haemorrhage. The frequency of AVM haemorrhages during the subsequent clinical course (before the start of endovascular, surgical, or radiation treatment) in the two groups was compared by means of Kaplan-Meier life-tables, log-rank test, and multivariate proportional-hazards regression models. Haemorrhage was defined as a clinically symptomatic event with signs of acute bleeding on computed tomography or magnetic resonance brain imaging. FINDINGS: During mean follow-up of 8.5 months for the haemorrhage group and 11.9 months for the non-haemorrhage group, haemorrhages occurred in 18 (13%) of the former patients and in three (2%) of the latter (p=0.0002). The annual risk of haemorrhage was 17.8% and 2.2%, respectively. In the multivariate regression model, the adjusted hazard ratio for haemorrhage at initial presentation was 13.9 (95% CI 2.6-73.8; p=0.002). Deep venous drainage (hazard ratio 4.1 [1.2-14.9], p=0.029) and male sex (9.2 [2.1-41.3], p=0.004) were also significantly associated with subsequent haemorrhage, but no significant association was found for age or AVM size. The annual rate of spontaneous haemorrhage was 32.6% for men and 10.4% for women in the haemorrhage group compared with 3.3% for men and 1.3% for women in the non-haemorrhage group. Among patients with haemorrhage at initial presentation, the risk of haemorrhage fell from 32.9% in year 1 to 11.3% in subsequent years (34.2% to 31.0% in men; 31.1% to 5.5% in women). INTERPRETATION: In AVM, patients initially presenting with haemorrhage have a higher risk of subsequent bleeding than those presenting with other symptoms. The risk is higher in men than in women.

Adult↗
PubMed1997

[Association of hypertension and diabetes mellitus with microangiopathic cerebral infarct patterns].

OBJECTIVE: To test the hypothesis of a positive association of hypertension and diabetes mellitus with cerebral small-vessel disease infarct patterns. METHODS: Using a prospective stroke database, the 152 patients with computertomographic signs of small-vessel disease (lacunes and/or leucoaraiosis)--including as a subgroup of 85 cases with multiple lacunes and/or leucoaraiosis-were compared with 106 patients featuring pial artery infarcts. Statistical analyses of the rates of hypertension and diabetes included univariate tests (odds ratios) and a logistic regression model comprising the additional variables hypercholesterolemia, cigarette smoking, carotid stenosis, atrial fibrillation, and left cardiac thrombus. RESULTS: Multivariate testing revealed a significant association of hypertension and diabetes with multiple lacunar infarcts and/or leucoaraiosis (hypertension: odds ratio 2.0; 95% confidence interval 1.04-3.7; diabetes: odds ratio 1.9; 95% confidence interval 1.01-3.8), whereas for the total group of patients with small-vessel disease lesions no such effect was found. Among the other tested variables, only atrial fibrillation/left cardiac thrombus showed a significant negative association (odds ratio 0.5; 95% confidence interval 0.2-0.9) with lacunes/leucoaraiosis. CONCLUSION: Independent of other risk factors and other possible causes of stroke, both hypertension and diabetes appear to be strong determinants of multiple lacunar infarcts and/or leucoaraiosis.

Adult↗
PubMed1997

Microemboli on transcranial Doppler in patients with spontaneous carotid artery dissection.

High-intensity transient signals on transcranial Doppler sonography (TCD) are associated with atherosclerotic stenosis of the internal carotid artery. Few data exist regarding the detection of high-intensity transient signals in dissected carotid arteries. In the present study, 6 patients with spontaneous carotid dissection, defined by magnetic resonance techniques and duplex sonography, were examined by TCD. Both middle cerebral arteries were monitored simultaneously for 30 minutes. Four of the patients had ipsilateral cerebral ischemia, while 2 presented with other symptoms. High-intensity transient signals were detected in the middle cerebral artery ipsilateral to the dissection in 3 of the 4 patients with cerebral ischemia and in none of the patients with other presenting symptoms. No microemboli were found contralateral to the dissected arteries. Microemboli can be detected distally from dissected carotid arteries. The present findings support the assumption that embolism is a major cause of stroke in patients with carotid dissection, and suggest that high-intensity transient signals are more common among patients with cerebral ischemia secondary to dissection.

Adult↗
PubMed1997

Microemboli in patients with vertebrobasilar ischemia: association with vertebrobasilar and cardiac lesions.

BACKGROUND AND PURPOSE: Microembolic high-intensity transient signals (HITS) on transcranial Doppler ultrasound (TCD) are associated with carotid stenosis, artificial heart valves, and other cardiac conditions. Only one case report describes stroke-related HITS in the posterior cerebral circulation. This study was designed to assess prospectively the prevalence of asymptomatic microemboli in vertebrobasilar ischemia and to determine whether potential cardioembolic sources, vertebral or basilar occlusive disease, and infarct subtypes predict the detection of HITS. METHODS: We investigated 52 consecutive patients with acute or recent vertebrobasilar ischemia within 48 hours after admission. TCD monitoring was performed according to established criteria for 20 minutes on each posterior cerebral artery. Fetal origin of the posterior cerebral artery was an exclusion criterion and ruled out by carotid compression. RESULTS: Microembolic signals were detected in 10 patients (19.2%). In a multivariate logistic regression analysis that included all independent variables, potential cardiac sources were significantly associated with HITS (odds ratio [OR], 14.3; 95% confidence interval [CI], 1.6 to 128.4), in particular when more than one cardiac abnormality (OR, 32.7; CI, 4.1 to 259.3) or a high-risk source (OR, 14.0; 95% CI, 2.3 to 84.9) was found. Vertebrobasilar vessel lesions and infarct subtype were not related to the detection of microemboli. CONCLUSIONS: Cardiac sources of embolism are a determinant of HITS in posterior cerebral circulation ischemia, suggesting that cardioembolic infarcts in that territory might be more common than suspected. Vertebrobasilar vessel abnormalities are less likely to lodge microemboli, which may indicate histopathological changes different from carotid artery disease.

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