Miroslava Zivkovic

Weekly variation of hospital admissions for stroke in Nis (Serbia)

OBJECTIVES Weekly variability in stroke occurrence could be related to the change in behaviors of patients or medical personnel that occur during certain periods of the week. The aim of the present study was to examine the weekly variation in hospital admissions for stroke in Nis (Serbia), as well as to investigate how the demographic factors influenced these changes. PATIENTS AND METHODS The main data source for this study was the Nis Stroke Registry. During the study period (1996-2007) a total of 9675 stroke patients were registered. According to stroke subtypes, all registered patients were divided into three groups: patients with subarachnoid hemorrhage (SAH) (438 or 4.5%), patients with intracerebral hemorrhage (ICH) (1576 or 16.3%) and patients with ischemic stroke (IS) (6946 or 71.8%). Analyses were conducted separately for SAH, ICH and IS. Each stroke type was stratified by gender, age group and education level. RESULTS We have showed that there is a significant weekly variability in the number of SAH (p=0.028) and IS (p<0.001) admissions, with the minimum number of admissions on Sundays (39.27 and 14.04% less than expected), and the maximum one on Tuesdays (21.46% more than expected) and Wednesdays (10.96% more than expected), respectively. We have also registered more SAH (p=0.015) and IS (p<0.001) admissions on weekdays than on weekend days. CONCLUSION Results of this hospital-based study confirm that there is a pattern in the variation of the number of stroke admissions on the weekly level. Reasons for the weekly variation of hospital admissions for stroke cannot be determined from the present study.

Hospitalizations due to spontaneous intracerebral hemorrhage in the region of Nis (Serbia): 11-year time-series analysis

BACKGROUND The study of seasonal variability of intracerebral hemorrhage (ICH) occurrence may contribute to a better understanding of the nature of this disease and open up new perspectives in its prevention. The aim of this study was to test seasonal patterns in the number of admissions of ICH patients and determine which months have maximal and minimal number of admissions. METHODS The main data source for this study was a hospital-based registry at the Clinic of Neurology in Nis, Serbia. During the studied period (1997-2007) a total of 1569 ICH patients were registered. Time series, consisting of the monthly number of hospitalized patients, for the 128 months of the study duration, has been successfully modeled using the multiplicative Auto Regressive Integrated Moving Average (ARIMA) model. RESULTS Using the maximum likelihood method, utilizing Melrads algorithm, the parameters of this ARIMA model have been calculated: constant (estimate 12.068, p<0.001), auto regressive-AR(1) (estimate 0.866, p<0.001), moving average-MA(1) (estimate 0.775, p<0.001), seasonal moving average-SMA(12) (estimate -0.198, p=0.036). ARIMA modeling has been successful and showed that there is a clear seasonal pattern in the data analyzed. CONCLUSION Based on the seasonal multiplicative ARIMA model and the seasonal time series decomposition, we showed that, in the period covered by the study, the peak of admissions occurred in March, and the trough of admissions was found in August.

Diagnostic value of neurophysiological tests in the diagnosis of brain death--do we need changes in national guidelines?

For a final diagnosis of brain death one needs particular proof that the brain has fully stopped functioning. In this respect, diagnostic tests need to be used to confirm the clinical findings. Since in different countries there are various national guidelines for the determination of brain death, the aim of this study is to point to the diagnostic value of electroencephalography (EEG) and evoked potentials (EP) in verifying brain death. The need is emphasized for the two methods to be used in combination, and, accordingly, for the current national guidelines to be changed in our country and also in other countries round the world.

Slower EEG alpha generation, synchronization and “flow”—possible biomarkers of cognitive impairment and neuropathology of minor stroke

Background We investigated EEG rhythms, particularly alpha activity, and their relationship to post-stroke neuropathology and cognitive functions in the subacute and chronic stages of minor strokes. Methods We included 10 patients with right middle cerebral artery (MCA) ischemic strokes and 11 healthy controls. All the assessments of stroke patients were done both in the subacute and chronic stages. Neurological impairment was measured using the National Institute of Health Stroke Scale (NIHSS), whereas cognitive functions were assessed using the Montreal Cognitive Assessment (MoCA) and MoCA memory index (MoCA-MIS). The EEG was recorded using a 19 channel EEG system with standard EEG electrode placement. In particular, we analyzed the EEGs derived from the four lateral frontal (F3, F7, F4, F8), and corresponding lateral posterior (P3, P4, T5, T6) electrodes. Quantitative EEG analysis included: the group FFT spectra, the weighted average of alpha frequency (αAVG), the group probability density distributions of all conventional EEG frequency band relative amplitudes (EEG microstructure), the inter- and intra-hemispheric coherences, and the topographic distribution of alpha carrier frequency phase potentials (PPs). Statistical analysis was done using a Kruskal–Wallis ANOVA with a post-hoc Mann–Whitney U two-tailed test, and Spearman’s correlation. Results We demonstrated transient cognitive impairment alongside a slower alpha frequency (αAVG) in the subacute right MCA stroke patients vs. the controls. This slower alpha frequency showed no amplitude change, but was highly synchronized intra-hemispherically, overlying the ipsi-lesional hemisphere, and inter-hemispherically, overlying the frontal cortex. In addition, the disturbances in EEG alpha activity in subacute stroke patients were expressed as a decrease in alpha PPs over the frontal cortex and an altered “alpha flow”, indicating the sustained augmentation of inter-hemispheric interactions. Although the stroke induced slower alpha was a transient phenomenon, the increased alpha intra-hemispheric synchronization, overlying the ipsi-lesional hemisphere, the increased alpha F3–F4 inter-hemispheric synchronization, the delayed alpha waves, and the newly established inter-hemispheric “alpha flow” within the frontal cortex, remained as a permanent consequence of the minor stroke. This newly established frontal inter-hemispheric “alpha flow” represented a permanent consequence of the “hidden” stroke neuropathology, despite the fact that cognitive impairment has been returned to the control values. All the detected permanent changes at the EEG level with no cognitive impairment after a minor stroke could be a way for the brain to compensate for the lesion and restore the lost function. Discussion Our study indicates slower EEG alpha generation, synchronization and “flow” as potential biomarkers of cognitive impairment onset and/or compensatory post-stroke re-organizational processes.

The Role of Oxidative Stress in Pathogenesis of Diabetic Neuropathy: Erythrocyte Superoxide Dismutase, Catalase and Glutathione Peroxidase Level in Relation to Peripheral Nerve Conduction in Diabetic Neuropathy Patients

Distal symmetrical polyneuropathy is the most common form of neurological complications in diabetes mellitus (DM). It is sensory-motor polyneuropathy dominated by sensitive symptoms and signs, primarily decrease or loss of sensibility in distal parts of extremities, or positive symptoms of prickling, burning pain and tingling. These symptoms can be extremely unpleasant for patients but at the same time they are a huge therapeutic problem as well. Motor symptoms and signs in early phase of DSP are often absent, although by neurophysiologic tests motor fibers damaging signs can be detected and this damage often leads to loss of functions in patients in advanced phase of the disease. The most significant clinical consequence of sensitive and autonomic fibers damage is feet ulceration, what is a leading cause for hospitalization and for lower extremities amputations, if trauma factors are excluded. Thus, diabetic DSP is important not only for clinical reasons but for economic ones as well, especially regarding the fact that DM prevalence is rapidly growing. For many years scientists have done numerous researches for therapeutic solutions to prevent, delay or slow the progression of the disease, aiming to better understanding of ethiopathogenesis of this disease. Special attention has been paid to oxidative stress (OS) role in pathogenesis of DM and diabetic neuropathy. Despite numerous experimental confirmations of OS in diabetic patients, there is still controversy about whether oxidative stress is just a side effect or it is a possible cause of diabetic neuropathy. More than thousand studies about this problem have already been reported and since this problem is not completely solved, further investigations are required. Therefore, a good knowledge of biochemistry of oxidative stress, cell signal transduction and antioxidative protection is necessary.

New daily persistent headache — rare primary or secondary phenomena caused by carotid-cavernous fistula? A case report

Carotid cavernous fistulas (CCF) are dural arteriovenous fistulas which include pathological communications between the arterial system and the venous cavernous sinus situated at the wall of the cavernous sinus. It can be demonstrated by wide range clinical presentations. The presented case shows a very modest clinical presentation of CCF which was present over a few months only as new daily persistent headache without initial positive findings on performed computer tomography of the head, but rapidly worsened over a period of few days.