Anastasios Chatzikonstantinou

Publications of Anastasios Chatzikonstantinou

• Asymptomatic and symptomatic carotid stenosis: an obsolete classification?

  Authors: Anastasios Chatzikonstantinou, Marc E Wolf, Anke Schaefer, Michael G Hennerici

  Stroke research and treatment. 01/2012; 2012:340798.

  Since many years, clinical decisions about the management of patients with carotid stenosis have been based on the distinction between "asymptomatic" and "symptomatic" presentations. This was alsoSince many years, clinical decisions about the management of patients with carotid stenosis have been based on the distinction between "asymptomatic" and "symptomatic" presentations. This was also reflected by the design of previous studies on the surgical versus conservative treatment and of current studies on interventional treatment versus surgery. Both terms, however, only address different phases of activity of the one and the same condition and blur the significant message that carotid stenosis is a most important marker of systemic atherosclerosis, which is accompanied by a much higher risk of cardiovascular events rather than stroke. As a consequence, early diagnosis and followup during best medical treatment, life-style management, regular cardiovascular assessment, and good control of all vascular risk factors should be recommended in all patients with carotid stenosis-whether identified in the long-lasting "silent" or short-lasting "vulnerable" period lasting only a few weeks after cerebral ischemia. Patients in this short time window benefit from additional carotid intervention, under the condition of an individually favorable benefit-risk ratio ("individual vulnerability").

• Ischemic stroke in young adults: classification and risk factors.

  Authors: Anastasios Chatzikonstantinou, Marc E Wolf, Michael G Hennerici

  Journal of neurology. 09/2011;

  Our aim was to analyze an important subgroup represented by young adult patients (19-45 years) with acute ischemic stroke according to stroke classification (including the novel ASCO score), infarctOur aim was to analyze an important subgroup represented by young adult patients (19-45 years) with acute ischemic stroke according to stroke classification (including the novel ASCO score), infarct types and risk factors. All patients up to 45 years of age with an acute ischemic stroke confirmed by MRI and treated in our stroke unit from 2006 to 2009 were recruited for this study. Patients were neurologically examined and underwent thorough stroke work-up. One hundred four patients (58 women, 46 men) with a mean age of 38 ± 6.9 years were evaluated. The mean NIHSS score (±SD) was 3 ± 5 on admission and 1 ± 4 on discharge. The classification using TOAST/ASCO (grade 1) was as follows: Macroangiopathic 10.6%/8.7%, cardiac origin 21.2%/10.6%, microangiopathic 9.6%/9.6%, other causes 19.2%/13.5% and undetermined 39.4%/19.2% (for A0S0C0O0). The most common risk factors were smoking (55.2%), hypertension (31.4%) and hyperlipidemia (27.6%). Twenty nine of 74 patients with TEE (39.2%) had a patent foramen ovale (PFO). Hypoplastic posterior circulation (21.9%) and migraine (21.0%) were also quite common. Young adult ischemic stroke patients share many of the characteristic risk factors with the general elderly ischemic stroke population. If regular work-up includes TEE, a high percentage of young patients reveal comorbidities with PFO, hypoplasia of the posterior circulation and migraine. The ASCO classification should be favored for a better classification of coexisting stroke subtypes and lower number of undetermined etiologies in this patient group.

• Features of acute DWI abnormalities related to status epilepticus.

  Authors: Anastasios Chatzikonstantinou, Achim Gass, Alex Förster, Michael G Hennerici, Kristina Szabo

  Epilepsy research. 07/2011; 97(1-2):45-51.

  We analyzed the phenomenon of transient regional diffusion-weighted MRI (DWI) hyperintensity in a series of status epilepticus (SE) patients with respect to seizure type, epileptogenic lesions andWe analyzed the phenomenon of transient regional diffusion-weighted MRI (DWI) hyperintensity in a series of status epilepticus (SE) patients with respect to seizure type, epileptogenic lesions and EEG findings. A prospective series of 54 patients (30 men, 24 women, mean age 61.5 years) admitted with SE was analyzed with regard to clinical semiology, EEG and MRI findings including DWI and EEG recordings in the acute peri-ictal phase. DWI abnormalities occurred most frequently in patients with complex-partial SE (27/50%) and generalized SE (18/33.3%). Forty patients (74.1%) had symptomatic, 13/24.1% cryptogenic and 1/1.9% idiopathic epilepsies. On DWI, the hippocampus was affected in 37/68.5% cases, often in combination with other brain areas (15/40.5%), in particular the pulvinar was affected in 14/25.9% patients. Bilateral DWI changes were found in 8/14.8% patients. No correlation with a specific seizure type was observed. In 21/38.9%, DWI changes were ipsilateral to the epileptogenic brain lesion (p<0.001) and in 5/9.3% contralateral, whereas in the majority of patients, either bilateral changes or no specific epileptogenic lesion were found. EEG abnormalities correlated with lateralization of DWI abnormalities in 44/81.5% (p<0.001). The most common localization of DWI abnormalities associated with ictal activity was the hippocampus and the pulvinar. Combined DWI-MRI and EEG analysis provides clues to seizure localization and propagation, as well as to identify brain structures affected by continuous or frequent ictal activity. This large series of patients with different features (SE type and cause, various epileptogenic lesions) demonstrates the heterogeneity of the phenomenon of peri-ictal DWI changes.

• Noise reduction and image quality improvement of low dose and ultra low dose brain perfusion CT by HYPR-LR processing.

  Authors: Radko Krissak, Charles A Mistretta, Thomas Henzler, Anastasios Chatzikonstantinou, Johann Scharf, Stefan O Schoenberg, Christian Fink

  PloS one. 01/2011; 6(2):e17098.

  To evaluate image quality and signal characteristics of brain perfusion CT (BPCT) obtained by low-dose (LD) and ultra-low-dose (ULD) protocols with and without post-processing by highly constrainedTo evaluate image quality and signal characteristics of brain perfusion CT (BPCT) obtained by low-dose (LD) and ultra-low-dose (ULD) protocols with and without post-processing by highly constrained back-projection (HYPR)-local reconstruction (LR) technique. Simultaneous BPCTs were acquired in 8 patients on a dual-source-CT by applying LD (80 kV, 200 mAs, 14×1.2 mm) on tube A and ULD (80 kV, 30 mAs, 14×1.2 mm) on tube B. Image data from both tubes was reconstructed with identical parameters and post-processed using the HYPR-LR. Correlation coefficients between mean and maximum (MAX) attenuation values within corresponding ROIs, area under attenuation curve (AUC), and signal to noise ratio (SNR) of brain parenchyma were assessed. Subjective image quality was assessed on a 5-point scale by two blinded observers (1: excellent, 5: non-diagnostic). Radiation dose of ULD was more than six times lower compared to LD. SNR was improved by HYPR: ULD vs. ULD+HYPR: 1.9±0.3 vs. 8.4±1.7, LD vs. LD+HYPR: 5.0±0.7 vs. 13.4±2.4 (both p<0.0001). There was a good correlation between the original datasets and the HYPR-LR post-processed datasets: r = 0.848 for ULD and ULD+HYPR and r = 0.933 for LD and LD+HYPR (p<0.0001 for both). The mean values of the HYPR-LR post-processed ULD dataset correlated better with the standard LD dataset (r = 0.672) than unprocessed ULD (r = 0.542), but both correlations were significant (p<0.0001). There was no significant difference in AUC or MAX. Image quality was rated excellent (1.3) in LD+HYPR and non-diagnostic (5.0) in ULD. LD and ULD+HYPR images had moderate image quality (3.3 and 2.7). SNR and image quality of ULD-BPCT can be improved to a level similar to LD-BPCT when using HYPR-LR without distorting attenuation measurements. This can be used to substantially reduce radiation dose. Alternatively, LD images can be improved by HYPR-LR to higher diagnostic quality.

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• Cerebral Microbleeds Are Uncommon in Ischemic Stroke Associated with Nonvalvular Atrial Fibrillation.

  Authors: Anastasios Chatzikonstantinou, Olaf Willmann, Kristina Szabo, Michael G Hennerici

  Journal of neuroimaging : official journal of the American Society of Neuroimaging. 11/2009;

  ABSTRACT BACKGROUND AND PURPOSE Patients with cardioembolic ischemic stroke from nonvalvular atrial fibrillation (NVAF) are candidates for long-term anticoagulation. This study examines theABSTRACT BACKGROUND AND PURPOSE Patients with cardioembolic ischemic stroke from nonvalvular atrial fibrillation (NVAF) are candidates for long-term anticoagulation. This study examines the prevalence of cerebral microbleeds (MBs) in stroke patients with NVAF. METHODS A total of 132 consecutive ischemic stroke patients with NVAF admitted to our Stroke Unit were recruited if complete magnetic resonance (MR) imaging studies including T2* imaging had been performed within less than 72 hours. National Institutes of Health Stroke Scale scores were documented and cerebrovascular risk factors were monitored. RESULTS Among 132 patients (mean age 74.1 +/- 9.8 years), only 9 (6.8%) had MBs (mean number 6.2) as detected on T2* MR images. No statistically significant differences between patients without versus with MBs were observed regarding arterial hypertension, diabetes, hyperlipidemia, and coronary heart disease. However, small vessel disease (SVD) was significantly more frequent in patients with MBs than without MBs (44.4% vs. 12.2%; P < .05) and significantly more patients with MBs experienced repeated strokes (44.4% vs. 14.6%; P < .05). CONCLUSIONS In contrast to studies reflecting a high incidence of MBs in stroke patients of various subtypes, MBs occurred less frequently in patients with cardioembolic acute ischemic stroke associated with NVAF. In patients with severe SVD or repeated cerebrovascular events, special caution should be taken regarding oral anticoagulation. J Neuroimaging 2009;XX:1-5.

• Successive affection of bilateral temporomesial structures in a case of non-paraneoplastic limbic encephalitis demonstrated by serial MRI and FDG-PET.

  Authors: Anastasios Chatzikonstantinou, Kristina Szabo, Caroline Ottomeyer, Rolf Kern, Michael Hennerici

  Journal of neurology. 06/2009;

• Transient Ischemic Attack Patients with Fluctuations Are at Highest Risk for Early Stroke.

  Authors: Anastasios Chatzikonstantinou, Olaf Willmann, Theo Jäger, K Szabo, Michael G Hennerici

  Cerebrovascular diseases (Basel, Switzerland). 05/2009; 27(6):594-598.

  Background: The management and risk of early stroke are unclear in patients with fluctuating neurological symptoms. We aimed to evaluate the clinical course of these patients presenting within 24 hBackground: The management and risk of early stroke are unclear in patients with fluctuating neurological symptoms. We aimed to evaluate the clinical course of these patients presenting within 24 h after onset of acute cerebral ischemia symptoms. Methods: All patients with transient ischemic signs/symptoms consecutively admitted to our Emergency Stroke Unit were recruited. Patients were neurologically examined and underwent prompt CCT plus MRI imaging for visualization of early signs of ischemia. Results: Among 122 patients, 84 (69%) had single symptoms, 33 (27%) showed rapidly relapsing and remitting symptoms - in 5 cases (4%) symptom duration could not reliably be assessed. 11/122 (9%) suffered a stroke during hospitalization. ABCD(2) scores did not predict early strokes: 2/11 (18.2%) were in the 'lower risk', 7/11 (63.6%) in the 'moderate risk' and only 2/11 (18.2%) in the 'high risk' group (p = 0.103). 3/11 patients (27.3%) revealed lesions in neuroimaging, but surprisingly 8/11 (72.7%, p = 0.132) did not. However, patients with fluctuations in neurological status were significantly more likely to suffer a stroke: 9/122 versus 2/122 with stable symptoms (p < 0.05). Patients with small vessel disease were common in all (53/ 122; 43.4%) and within those who suffered an early stroke (6/11; 54.5%). Conclusions: Patients with unstable transient ischemic attacks immediately after onset of clinical symptoms are at high risk for subsequent stroke - they may benefit from Stroke Unit management and potential early thrombolysis once they develop strokes.

• Arrest of endogenous ocular nocardiosis under linezolid therapy.

  Authors: Urs Vossmerbaeumer, Ulrich H M Spandau, Kathrin Kleinhuber, Sabine Zeller, Anastasios Chatzikonstantinou, Stephan Ruggiero, Rainer Birck

  Acta ophthalmologica. 11/2008;

• Ophthalmodynamometric measurement of central retinal vein pressure as surrogate of intracranial pressure in idiopathic intracranial hypertension.

  Authors: Jost B Jonas, Katrin Pfeil, Anastasios Chatzikonstantinou, Florian Rensch

  Graefe's archive for clinical and experimental ophthalmology = Albrecht von Graefes Archiv für klinische und experimentelle Ophthalmologie. 08/2008; 246(7):1059-60.

  BACKGROUND: Since a direct non-invasive measurement of the cerebrospinal fluid pressure is not available, it was the purpose of the study to describe the non-invasive determination of the centralBACKGROUND: Since a direct non-invasive measurement of the cerebrospinal fluid pressure is not available, it was the purpose of the study to describe the non-invasive determination of the central retinal vein pressure as an estimate of an elevated cerebrospinal fluid pressure. METHODS: A 28-year-old female patient with blurred vision, nuchal pain and prominent optic discs underwent modified ophthalmodynamometry to determine the central retinal vein pressure as surrogate of the intracranial pressure. A Goldmann contact lens with a pressure sensor mounted into its holding ring was placed onto the cornea. Pressure was applied to the globe by slightly pressing the contact lens until the central retinal vein started to pulsate/collapse. RESULTS: Despite an abnormally high central retinal vein pressure (OD: 17 arbitrary units; OS: 33 arbitrary units), the neurological examination including magnetic resonance imaging of the brain was unremarkable on the first day. A lumbar puncture revealed a cerebrospinal fluid pressure of 25 cm H(2)O, which was at the upper limit of the normal range. Over the next 2 days, ophthalmodynamometry showed increasing measurements of the central retinal vein pressure for both eyes, parallel to elevated cerebrospinal fluid pressure measurements by lumbar puncture, leading to the diagnosis of idiopathic intracranial hypertension. After treatment, the cerebrospinal fluid pressure returned to normal levels, parallel to a decrease in the central retinal vein pressure as determined by ophthalmodynamometry. CONCLUSIONS: Ophthalmodynamometry of the central retinal vein was helpful in the diagnosis of an elevated intracranial pressure, with direct lumbar pressure measurement running parallel to the ophthalmodynamometric measurements.