[Cerebrovascular diagnostics: imaging]

Imaging of the cerebral vasculature relies mostly on computed tomography angiography (CTA), magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). Although DSA is still the gold standard, many questions can be answered with CTA and/or MRA thanks to recent technological advances. The following article describes the advantages and disadvantages of these techniques with regard to different questions. Basic principles regarding the different techniques are explained.

Thrombus attenuation does not predict angiographic results of mechanical thrombectomy with stent retrievers

BACKGROUND AND PURPOSE

Mechanical thrombectomy with stent retrievers in acute stroke has emerged as a promising new technique, with the highest recanalization rate of the therapeutic procedures available thus far. However, in up to 20% of the cases, mechanical thrombectomy with stent retrievers results in poor angiographic outcomes, with Thrombolysis in Cerebral Infarction scores ≤2a. The purpose of this study was to investigate whether thrombus attenuation on the initial CT scan can predict the angiographic outcome of the recanalization procedure in MCA occlusions.

MATERIALS AND METHODS

The data of 70 patients with acute MCA occlusions who underwent endovascular treatment with stent retrievers in our department were included. We analyzed thrombus attenuations, angiographic outcome, and periprocedural thrombus fragmentation.

RESULTS

The mean thrombus attenuation was 49.8 ± 7.8 HU and the mean difference from the attenuation of the contralateral MCA was 9.9 ± 8.0 HU. There were no significant differences in the thrombus attenuations of occlusions that were successfully recanalized (modified Thrombolysis in Cerebral Infarction ≥2b) and those that were not. Neither were there significant correlations of thrombus attenuations and periprocedural thrombus fragmentations that occurred in 64.3%. We found a nonsignificantly higher rate of recanalizations with modified Thrombolysis in Cerebral Infarction ≥2b when the difference from the attenuation of the contralateral MCA was between 1-20 HU.

CONCLUSIONS

In contrast to results of other revascularization procedures as published in a recent study, the angiographic result of mechanical thrombectomy with stent retrievers is not predicted by thrombus attenuation.

Mobile stroke unit for diagnosis-based triage of persons with suspected stroke

BACKGROUND

In this feasibility study, we tested whether prehospital diagnostic stroke workup enables rational decision-making regarding treatment and the target hospital in persons with suspected stroke.

METHODS

A mobile stroke unit that delivers imaging (including multimodal brain imaging with CT angiography and CT perfusion), point-of-care-laboratory analysis, and neurologic expertise directly at the emergency site was analyzed for its use in prehospital diagnosis-based triage of suspected stroke patients.

RESULTS

We present 4 complementary cases with suspected stroke who underwent prehospital diagnostic workup that enabled direct diagnosis-based treatment decisions and reliable triage regarding the most appropriate medical facility for that individual, e.g., a primary hospital vs specialized centers of a tertiary hospital.

CONCLUSIONS

This preliminary report demonstrates the feasibility of prehospital diagnostic stroke workup for immediate etiology-specific decision-making regarding the necessary time-sensitive stroke treatment and the most appropriate target hospital.

Assessment and management of patients with cognitive impairment and dementia in primary care

OBJECTIVES

To evaluate care provided by primary care physicians in community practice to older patients presenting with cognitive impairment and dementia.

DESIGN

Secondary analysis of an intervention study.

SETTING

Primary care clinics.

PARTICIPANTS

101 patients 75 years and older enrolled in the ACOVE-2 study who presented with a new cognitive problem, new dementia, or prevalent dementia.

MEASUREMENTS

Patients assessment and management were evaluated from medical record review and caregiver interviews.

RESULTS

Among 34 patients presenting with a new cognitive problem, half received a cognitive assessment comprising of a test of memory and one other cognitive task, 41% were screened for depression and 29% were referred to a consultant. Of the 27 patients with newly diagnosed dementia, 15% received the components of a basic neurological examination, one-fifth received basic laboratory testing and for one third the medical record reflected an attempt to classify the type of dementia. Counseling was under-reported in the medical record compared to the caregiver interview for the 101 patients with dementia, but even the interview revealed that about half or fewer patients received counseling about safety and accident prevention, caregiver support or managing conflicts. Less than 10% were referred to a social worker.

CONCLUSION

This small but detailed evaluation suggests patients presenting with cognitive problems to primary care physicians do not consistently receive basic diagnosis and management.

The posterior reversible encephalopathy syndrome: what's certain, what's new?

The posterior reversible encephalopathy syndrome is an increasingly recognised disorder. Most patients have several symptoms; seizures are the most frequent, often multiple or status epilepticus. A combination of seizures, visual disturbance and/or headache, in particular, should lead to an early brain MRI to reveal the typical pattern of bilateral hyperintensities on fluid attenuated inversion recovery imaging, predominantly in the parieto-occipital region. There seem to be many possible triggers, including abrupt arterial hypertension, impaired renal function, pregnancy, immunosuppressive therapies and various inflammatory conditions. The clinical outcome is excellent, with recovery within a few days, while the MRI abnormalities resolve much more slowly. Little is known about the best management. Seizures do not normally progress to chronic epilepsy so antiepileptic drugs should be discontinued after about 3 months.

A comparison of 2 stroke devices: the new Aperio clot-removal device and the solitaire AB/FR

BACKGROUND AND PURPOSE

Several studies have shown promising results for the use of self-expandable intracranial stents for the treatment of acute ischemic stroke. This new technique combines immediate flow restoration after stent deployment with high recanalization rates. In the present study, the safety and efficacy of the new Aperio clot-removal device was tested in comparison with the Solitaire AB device.

MATERIALS AND METHODS

The experiments were performed in swine with a weight of 35-50 kg following established models. The experimental thrombi were prepared by using a new flow model (Thrombus Loop) to produce radiopaque thrombi. Thrombi were cut into lengths of 10 mm and injected into the target vessel. The occlusion was verified by DSA and rated with the help of the TICI score. A microcatheter was placed distal to the thrombus. The devices were placed with the proximal third within the thrombus and were retrieved under continuous aspiration in their released state into the guiding sheath. We performed 23 procedures with the Aperio device and 18 procedures with the Solitaire AB and FR devices. Control angiograms were obtained 3 and 5 minutes after device deployment to evaluate the flow restoration. The number of attempts to reach a TICI 2/3 score was recorded as well as the time to recanalization and the device-related complications. Vasospasm, vascular perforation, intramural arterial dissection, or embolization of a previously uninvolved territory was defined as a device-related complication.

RESULTS

Defined radiopaque thrombi from whole blood could reliably be created by using the Thrombus Loop. Both devices demonstrated a high recanalization rate of 100% (TICI 3) in the target vessel with no device-related complications. No significant differences were found between the 2 devices.

CONCLUSIONS

In this small study, we could show that radiopaque thrombi of whole blood with a defined diameter could be reliably created by using the Thrombus Loop. The new "stent-retriever" (Aperio System) seems to be a very efficient and safe addition to the existing repertoire of clot-removal devices.

[Mimikry of herpes encephalitis by glioblastoma multiforme]

Herpes encephalitis (HSE) is an acute illness. Imaging is an important part of the diagnostic work-up of HSE. In early stages one can see a manifestation in the insular cortex as well as in the fornix. These MRI findings are rather typical for HSE. We present three cases treated in our hospital over the past ten years. In these cases the clinical symptoms and signs as well as the morphological findings were compatible with the HSE diagnostic criteria. Later on, a glioblastoma multiforme was found in all three cases.

Olanzapine-induced anaphylactic shock: a case report

Olanzapine is a second-generation antipsychotic, which is also used as a mood stabilizer. We report a case of a 33-year-old psychiatric patient, with bipolar affective disorder, who developed anaphylaxis as a late reaction to olanzapine. This case report shows the possibility, although rare, of a severe late anaphylactic reaction to olanzapine.

Stent-assisted mechanical recanalization for treatment of acute intracerebral artery occlusions

BACKGROUND AND PURPOSE

The purpose of this study was to demonstrate a new approach to the use of a self-expanding stent in the treatment of acute ischemic stroke.

METHODS

Twenty-two consecutive patients with acute intracerebral artery occlusions were treated with a self-expandable intracranial stent, which was withdrawn in its unfolded state. For this technique, we used the Solitaire AB/FR, which is the only intracranial stent that is fully recoverable. Eight patients had an occlusion of the basilar artery, 12 had a middle cerebral artery occlusion, and 2 had terminal carotid artery occlusions; 6 of these had to be treated first for an acute occlusion originating in the internal carotid artery. Recanalization results were assessed by follow-up angiography immediately after the procedure. Neurologic status was evaluated before and after treatment (90-day follow-up) according to the National Institutes of Health Stroke Scale and modified Rankin scale.

RESULTS

Successful revascularization was achieved in 20 of 22 (90.9%) patients (thrombolysis in cerebral infarction [TICI] 2a/b and 3), a TICI 3 state was accomplished in 12 patients, and partial recanalization or slow distal branch filling with filling of more than two-thirds of the vessel territory was achieved in 8 patients (TICI 2b). There was immediate flow restoration in 21 of 22 (95.4%) cases after deployment of the device. The stent was removed in its unfolded state in all patients. The mean time from stroke symptom onset to recanalization was 277 minutes, with a standard deviation of 118 minutes. Mean National Institutes of Health Stroke Scale score on admission was 19.4, with a standard deviation of 5.7. Almost two-thirds of the patients (63.6%) improved by > 10 points on the National Institutes of Health Stroke Scale at discharge, and 50% showed a modified Rankin scale score of ≤ 2 at 90 days (59% with a modified Rankin scale ≤ 3). Mortality was 18.1%. In 1 case, an asymptomatic intracranial hemorrhage was detected on control computed tomography, and 2 patients had a symptomatic intracranial hemorrhage.

CONCLUSIONS

Withdrawal of an unfolded, fully recoverable, intracranial stent yielded very promising angiographic and clinical results. It combines the advantages of prompt flow restoration and mechanical thrombectomy.

[CT diagnostics of carotid artery stenosis]

CT angiography can be used to evaluate carotid artery stenosis with high diagnostic safety. In contrast to the gold standard digital subtraction angiography (DSA) it is a non-invasive procedure which yields information regarding the degree of stenosis as well as information about plaque morphology. Due to multiple reconstruction planes in 3 levels in maximum intensity projections (MIP) and the possibility to perform volume rendering (VR) reconstruction more information about the extent of carotid disease can be acquired. Due to the bolus tracking technique optimum contrast medium enhancement of the carotid artery with simultaneous minimization of venous artifacts is possible.

[Multiple aneurysms of intracranial arteries in neurofibromatosis Recklinghausen type 1]

We report on a 58 year old female patient with neurofibromatosis Recklinghausen type 1 (NF-1) in whom multiple intracranial aneurysms could be proven. Vascular changes in patients with NF-1 are frequent and concern primarily the aorta, the kidney arteries, the coronary and gastrointestinal arteries. Our case shows that in patients with NF-1 intracranial artery changes like aneurysms, maybe in need of treatment, are possible.

The Oxidation Behaviour of Ruthenium in the Presence of Platinum and its Effect on the Electrocatalytic Activity of Pt-Ru Fuel Cell Catalysts

Pt-Ru electrocatalysts are commonly applied anode materials for low-temperature fuel cells, as the addition of ruthenium improves the CO tolerance of the otherwise CO-sensitive platinum catalysts, either by an electronic effect or by electro-oxidation via oxygen-containing adsorbates in the so-called bifunctional mechanism. However, since bulk ruthenium oxidation already takes place at potentials of less than 1.0V vs. RHE and hydrous ruthenium oxide is suggested to be the active species in the bifunctional mechanism, the amount and specific nature of ruthenium oxides play an important role in fuel cell catalysis. Two Pt-Ru catalyst systems with distinctly different Pt-Ru separation have been studied: a carbon-supported Pt-Ru alloy electrocatalyst (Pt-Ru) and a mixture of carbon-supported Pt and carbon-supported Ru (Pt/Ru). Controlled heat-treatment experiments were carried out in air atmosphere at 100°C and 500°C to study the effect of deliberate ruthenium oxidation on the catalyst structure and electrochemical performance. At a heat-treatment temperature of 100°C, the Pt-Ru alloy appears less sensitive towards oxidation than the Pt/Ru mixture, although its lattice parameter increases from about 3.880Å to 3.907Å indicating that part of the ruthenium is pulled out of the alloy phase to form a (amorphous) ruthenium oxide. After heat-treatment at 500°C in air, X-ray patterns of the Pt-Ru alloy and the Pt/Ru mixture look almost alike. However, transmission electron micrographs reveal a distinctly different separation between the Pt and the Ru oxide phase with the Pt-Ru alloy system having many more Pt/Ru neighbour sites available. Complementary XPS measurements show a higher share of electrocatalytically inactive ruthenium oxide in the Pt/Ru mixture catalyst heat-treated at 100°C. The onset of the methanol oxidation reaction (MOR) for the different catalysts increases in the order Pt-Ru < Pt/Ru < Pt independent of the treatment underlining the importance of Pt/Ru site distribution and ruthenium oxide content for the electrocatalytic activity.

[Bilateral spontaneous carotid artery dissection in osteogenesis imperfecta (type I)]

We report on a 36-year-old patient with an acute cerebral infarction due to a spontaneous dissection of both internal carotid arteries in conjunction with type I osteogenesis imperfecta. Spontaneous dissections of cerebral arteries (DCA) represent a common cause of cerebral infarctions in younger patients. Our case shows that a hereditary connective tissue disorder should be considered in all patients with "spontaneous" DCA. The identification of an - initially unknown - hereditary connective tissue disorder may con-tribute to primary and secondary prophylaxis of cerebral ischemia.

Revascularization in acute ischaemic stroke using the penumbra system: the first single center experience

BACKGROUND AND PURPOSE

This is the first single center experience illustrating the effectiveness of the penumbra system (PS) in the treatment of large vessel occlusive disease in the arena of acute ischaemic stroke. The PS is an innovative mechanical thrombectomy device, employed in the revascularization of large cerebral vessel occlusions in patients via the utilization of an aspiration platform.

METHODS

This is a prospective, non-randomized controlled trial evaluating the clinical and functional outcome in 29 patients with acute intra-cranial occlusions consequent to mechanical thrombectomy by the PS either as mono-therapy or as an adjunct to current standard of care. Patients were evaluated by a neurologist and treated by our in house interventional neuro-radiologists. Primary end-points were revascularization of the occluded target vessel to TIMI grade 2 or 3 and neurological outcome as measured by an improvement in the NIH Stroke Scale (NIHSS) score after the procedure.

RESULTS

Complete revascularization (TIMI 3) was achieved in 21/29 (72.4%) of patients. Partial revascularization (TIMI 2) was established in 4/29 (13.8%) of patients. Revascularization failed in four (13.8%) patients. Nineteen (19) patients (65.5%) had at least a four-point improvement in NIHSS scores. Modified Rankin scale scores of < or =2 were seen in 37.9% of patients. There were no device-related adverse events. Symptomatic intra-cranial hemorrhage occurred in 7% of patients.

CONCLUSIONS

The PS has the potential of exercising a significant impact in the interventional treatment of ischaemic stroke in the future.

[Mechanical recanalization]

Although several studies and registries have focused on new interventional systems for the treatment of acute ischemic stroke, a standard procedure has not yet been established. The procedure itself is still controversially discussed but studies have shown that patients who were successfully treated with mechanical recanalization had a better clinical outcome.

[Magnetic resonance imaging and computed tomography findings in lacunar brain infarctions]

Lacunar brain infarctions belong to the most common causes of stroke and are typically located in basal ganglia with embolic, atheromatous or thrombotic etiology. Lipohyalinosis, often as a result of a long history of hypertension, can also be a cause of lacunar lesions. At present more than 20 different lacunar syndromes have been described. However clinical findings may be variable ranging from clinically"silent" to focal neurologic deficits to cognitive impairment. Magnetic resonance imaging (using diffusion-weighted sequences) generally allows diagnosis in most cases of acute lacunar infarcts and is superior to computed tomography especially in cases of additional leucoaraiosis.

[Acute disseminated encephalomyelitis]

Acute disseminated encephalomyelitis (ADEM) is an acute widespread autoimmune demyelinating condition, which principally affects the white matter of the brain and spinal cord. It usually follows an infection or vaccination. The typical presentation is that of multifocal neurologic disturbances accompanied by change in mental status. CSF analysis reveals lymphocytic pleocytosis and elevated protein content, but may also yield normal results. MRI is regarded as the diagnostic imaging modality of choice and typically demonstrates involvement of deep cerebral hemispheric and subcortical white matter as well as lesions in the basal ganglia, gray-white junction, diencephalon, brainstem, cerebellum and spinal cord. Unlike multiple sclerosis (MS), ADEM has a monophasic course and a favorable long-term prognosis.

[Magnetic resonance spectroscopy for inflammatory brain diseases]

Magnetic resonance spectroscopy (MRS) is a non-invasive method for investigation of cerebral metabolite concentrations in various pathologic conditions. The clinical use of MRS for intracranial disorders is well established. In this review the characteristic MRS findings for the most important inflammatory brain diseases will be discussed.