Dariusz Latka

Multifractality of cerebral blood flow

Scale invariance, the property relating time series across multiple scales, has provided a new perspective of physiological phenomena and their underlying control systems. The traditional “signal plus noise” paradigm of the engineer was first replaced with a model in which biological time series have a fractal structure in time (Fractal Physiology, Oxford University Press, Oxford, 1994). This new paradigm was subsequently shown to be overly restrictive when certain physiological signals were found to be characterized by more than one scaling parameter and therefore to belong to a class of more complex processes known as multifractals (Fractals, Plenum Press, New York, 1988). Here we demonstrate that in addition to heart rate (Nature 399 (1999) 461) and human gait (Phys. Rev. E, submitted for publication), the nonlinear control system for cerebral blood flow (CBF) (Phys. Rev. Lett., submitted for publication; Phys. Rev. E 59 (1999) 3492) is multifractal. We also find that this multifractality is greatly reduced for subjects with “serious” migraine and we present a simple model for the underlying control process to describe this effect.

Validation and cross-cultural adaptation of the Polish version of the Oswestry Disability Index.

Study Design. Validation of a translated, culturally adapted questionnaire. Objective. To translate and culturally adapt a Polish version of the Oswestry Disability Index (ODI) and to validate its use in Polish patients. Summary of Background Data. The ODI is among the most popular questionnaires used to evaluate back pain–related disability. To our knowledge no validated Polish version of the index was available at the time our study was initiated. Methods. The questionnaire was translated and culturally adapted by 2 independent translators and approved by expert committee. Final version was included in the booklet consisting in addition of a previously validated Roland–Morris disability questionnaire, VAS for low back and leg and 3 Likert scale questions (pain medications, pain frequency, disability). It was tested on 169 patients with chronic low back pain, 164 (97%) of them were enrolled, and 84 of 164 (53%) returned the completed retest booklet within 2 to 14 days after the baseline test. There were no differences between the 2 groups in demographic and clinical parameters. Test-retest reliability, internal consistency, and construct validity were investigated. Results. The mean ODI (standard deviation [SD]) was 48.45 (18.94); minimum 2, maximum 94. The Cronbach &agr; for baseline questionnaires (n = 164) was 0.90. Concurrent validity, measured by comparing ODI responses with the results of the Roland–Morris disability questionnaire score was very good (r = 0.607, P < 0.001). The correlation with VAS back was fair (r = 0.37, P < 0.001) and with VAS leg was good (r = 0.56, P < 0.001). The tested ODI had excellent test-retest reliability, the intraclass correlation coefficient was 0.97 and standard error of measurements was 3.54, the resulting minimal detectable changes at the 95% confidence level was 10. Conclusion. The results of this study indicate that the Polish version of the ODI is a reliable and valid instrument for the measurement of disability in Polish-speaking patients with lower back pain.

Fractal Rigidity in Migraine

Abstract We study the middle cerebral artery blood flow velocity in humans using transcranial Doppler ultrasonography. Scaling properties of time series of the axial flow velocity averaged over a cardiac beat interval may be characterized by two exponents. The short-time scaling exponent (STSE) determines the statistical properties of fluctuations of blood flow velocities in short-time intervals while the Hurst exponent describes the long-term fractal properties. In many migraineurs the value of the STSE is significantly reduced and may approach that of the Hurst exponent. This change in dynamical properties reflects the significant loss of short-term adaptability and the overall hyperexcitability of underlying cerebral blood flow control system. We call this effect fractal rigidity.

Treatment of lumbar disc herniation with radiculopathy. Clinical practice guidelines endorsed by The Polish Society of Spinal Surgery

INTRODUCTION Herniated lumbar disc (HLD) is arguably the most common spinal disorder requiring surgical intervention. Although the term is fairly straightforward, the exact pathology and thus the clinical picture and natural history may vary. Therefore, it is immensely difficult to formulate universal guidelines for surgical treatment. AIM The aim of this paper is to organize the terminology and clear the inconsistencies in phraseology, review treatment options and gather available published evidence to address the clinical questions to create a set of clinical guidelines in relevant to the topic. METHODS AND RESULTS Twelve queries, addressing optimal surgical treatment of the HLD have been formulated. The results, based on the literature review are described in the present work. The final product of the analysis was a set of guidelines for the surgical treatment of symptomatic HLD. Categorized into four tiers based on the level of evidence (I-III and X), they have been designed to assist in the selection of optimal, effective treatment leading to the successful outcome. CONCLUSIONS The evidence based medicine (EBM) is becoming ever more popular among spinal surgeons. Unfortunately this is not always feasible. Lack of uniform guidelines and numerous conflicts of interest introduce flaws in the decision making process. The key role of experts and professional societies is to provide high value recommendation based on the most current literature. Present work contains a set of guidelines for the surgical treatment of HLD officially endorsed by the Polish Spine Surgery Society.

Traumatic brain injury in Poland from 2009-2012: A national study on incidence.

Abstract Background: Traumatic brain injury (TBI) remains one of the leading causes of mortality and morbidity worldwide. The purpose of this study was to provide data on epidemiology of TBI in Poland during 2009–2012. Methods: The national data on hospitalizations with TBI as a primary diagnosis was obtained from the National Health Fund of Poland. The sub-set of two diagnosis-related groups (DRG) was used for analysis. The incidence and mortality were calculated with the emphasis on diagnosis. The external causes of injuries were investigated based on the representative sample. Results: Within the study period there were 194 553 hospitalizations due to the TBI in two DRGs. The overall incidence was 126.52/105/year (95% CI = 125.96–127.09). The most common diagnosis was concussion, with an incidence of 81.66/105/year, and the most prevalent structural injury was subdural haematoma (15.27/105/year). The predominant external causes were traffic accidents (40.52%) followed by falls (32.77%). Conclusions: The incidence of TBIs in Poland compared with other countries in Europe is relatively low. The incidence of concussions mirrored current treatment guidelines rather than real epidemiology.

Accuracy of the Free-hand Placement of Pedicle Screws in the Lumbosacral Spine Using a Universal Entry Point: Clinical Validation.

Study Design: Retrospective radiographic study. Objective: To evaluate the accuracy of the free-hand placement of pedicle screws (PSs) using a new method of localization of entry points. Summary of Background Data: The PSs are essential in modern spinal surgery but their placement can be technically demanding. To improve this accuracy, numerous aids have been developed, some of them technologically advanced. Despite advances in technology the free-hand technique is still very popular. A simple geometric method of localization of entry points is proposed, designed to improved anatomic orientation. Methods: The radiographic and clinical data of 92 consecutive patients who underwent primary placement of PS in the lumbar spine were retrospectively analyzed. Postoperative computed tomography scans were used to assess the accuracy of screw placement using both quantitative and anatomic criteria. Results: A total of 85 patients with 410 screws were included in the study. Twenty screws were malpositioned, thus the overall accuracy was 95.12%. Of all levels instrumented the breach rate for the L1 level was highest (21.43%) and the difference was statistically significant. Two screws in 2 patients were symptomatic, causing radicular pain. Both underwent successful revisions. Conclusions: The proposed method of PS placement is safe and reliable for all levels from L2 to S1, with the accuracy similar to image-guided navigation systems.

Virtual Reality Based Simulators for Neurosurgeons - What We Have and What We Hope to Have in the Nearest Future

High levels of manual skills, good visual-motor coordination, excellent imagination and spatial awareness are the main factors determining the success of neurosurgeons. Proficiency in neurosurgical skills used to be acquired through hands-on training in cadaver labs and in real operating theatres under master neurosurgeon supervision. Most recently, virtual reality (VR) and augmented reality (AR) computer simulations have also been considered as tools for education in the neurosurgical training. The authors review existing solutions and present their own concept of a simulator which could become the useful tool for planning, simulation and training of a specific neurosurgical procedure using patient’s imaging data. The benefits of simulator are particularly apparent in the context of neurovascular operations. It is the field in which it is very difficult for young neurosurgeons to gain proficiency because of the lack of experience caused by the competition between microsurgery and endovascular techniques.

Treatment of degenerative cervical spondylosis with radiculopathy. Clinical practice guidelines endorsed by The Polish Society of Spinal Surgery

INTRODUCTION Degenerative cervical spondylosis (DCS) with radiculopathy is the most common indication for cervical spine surgery despite favorable natural history. Advances in spinal surgery in conjunction with difficulties in measuring the outcomes caused the paucity of uniform guidelines for the surgical management of DCS. AIMS The aim of this paper is to develop guidelines for surgical treatment of DCS. For this purpose the available up-to-date literature relevant on the topic was critically reviewed. METHODS AND RESULTS Six questions regarding most important clinical questions encountered in the daily practice were formulated. They were answered based upon the systematic literature review, thus creating a set of guidelines. The guidelines were categorized into four tiers based on the level of evidence (I-III and X). They were designed to assist in the selection of optimal and effective treatment leading to the most successful outcome. CONCLUSIONS The evidence based medicine (EBM) is increasingly popular among spinal surgeons. It allows making unbiased, optimal clinical decisions, eliminating the detrimental effect of numerous conflicts of interest. The key role of opinion leaders as well as professional societies is to provide guidelines for practice based on available clinical evidence. The present work contains a set of guidelines for surgical treatment of DCS officially endorsed by the Polish Spine Surgery Society.