Publications by authors named "Karel Brabec"

3 Publications

  • Page 1 of 1

Alteration of cortical but not spinal inhibitory circuits in idiopathic scoliosis.

J Spinal Cord Med 2020 Mar 23:1-8. Epub 2020 Mar 23.

Department of Neurology, Third Faculty of Medicine, Charles University and Faculty Hospital Kralovske Vinohrady, Prague, Czech Republic.

The pathogenesis of adolescent idiopathic scoliosis (AIS), including the role of brain and spinal inhibitory circuits, is still poorly elucidated. The aim of this study was to identify which central inhibitory mechanisms are involved in the pathogenesis of AIS. A prospective neurophysiological study, using a battery of neurophysiological tests, such as cutaneous (CuSP) and cortical (CoSP) silent periods, motor evoked potentials (MEP) and paired-pulse transcranial magnetic stimulation (ppTMS). Neurophysiological laboratory. Sixteen patients with AIS (14 females, median age 14.4) and healthy controls. MEPs were obtained after transcranial magnetic stimulation (TMS) and recorded from the abductor pollicis muscle (APB). ppTMS was obtained at interval ratios (ISI) of 1, 2, 3, 6, 10, 15 and 20 ms. The cortical silent period (CoSP) was recorded from the APB. The cutaneous silent period (CuSP) was measured after painful stimuli delivered to the thumb while the subjects maintained voluntary contraction of the intrinsic hand muscles. The data were analyzed and compared with those from healthy subjects. The CoSP duration was significantly prolonged in AIS patients. A significantly higher amplitude of ppTMS for ISI was found in all AIS patients, without remarkable left-right side differences. No significant difference in MEP latency or amplitude nor in the CuSP duration was obtained. Our observation demonstrates evidence of central nervous system involvement in adolescent idiopathic scoliosis (AIS). Lower intracortical inhibition, higher motor cortex excitability, and preserved spinal inhibitory circuits are the main findings of this study. A possible explanation of these changes could be attributed to impaired sensorimotor integration predominantly at the cortical level.
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March 2020

Estimation of p,p'-DDT degradation in soil by modeling and constraining hydrological and biogeochemical controls.

Environ Pollut 2018 Aug 11;239:179-188. Epub 2018 Apr 11.

Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 753/5, Brno, 62500, Czech Republic; Norwegian Institute for Water Research, Oslo, NO-0349, Norway. Electronic address:

Despite not being used for decades in most countries, DDT remains ubiquitous in soils due to its persistence and intense past usage. Because of this it is still a pollutant of high global concern. Assessing long term dissipation of DDT from this reservoir is fundamental to understand future environmental and human exposure. Despite a large research effort, key properties controlling fate in soil (in particular, the degradation half-life (τ)) are far from being fully quantified. This paper describes a case study in a large central European catchment where hundreds of measurements of p,p'-DDT concentrations in air, soil, river water and sediment are available for the last two decades. The goal was to deliver an integrated estimation of τ by constraining a state-of-the-art hydrobiogeochemical-multimedia fate model of the catchment against the full body of empirical data available for this area. The INCA-Contaminants model was used for this scope. Good predictive performance against an (external) dataset of water and sediment concentrations was achieved with partitioning properties taken from the literature and τ estimates obtained from forcing the model against empirical historical data of p,p'-DDT in the catchment multicompartments. This approach allowed estimation of p,p'-DDT degradation in soil after taking adequate consideration of losses due to runoff and volatilization. Estimated τ ranged over 3000-3800 days. Degradation was the most important loss process, accounting on a yearly basis for more than 90% of the total dissipation. The total dissipation flux from the catchment soils was one order of magnitude higher than the total current atmospheric input estimated from atmospheric concentrations, suggesting that the bulk of p,p'-DDT currently being remobilized or lost is essentially that accumulated over two decades ago.
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August 2018

Intrathecal Baclofen in Spinal Spasticity: Frequency and Severity of Withdrawal Syndrome.

Pain Physician 2015 Jul-Aug;18(4):E633-41

Department of Neurology, Third School of Medicine, Hospital Kralovske Vinohrady, Charles University, Prague, Czech Republic; Department of Neurosurgery, Third School of Medicine, Hospital Kralovske Vinohrady, Charles University, Prague, Czech Republic.

Background: Intrathecal baclofen (ITB) delivered by programmable pump devices represents an important modality for long-term treatment of severe spinal spasticity.

Objective: One of the serious adverse events is a withdrawal syndrome after sudden interruption of ITB delivery. In this study, we analyzed the frequency and severity of this complication. Treatment recommendations follow.

Study Design: Case study.

Setting: Academic medical center.

Methods: A total of 54 ITB pumps were successfully implanted in 39 patients with severe intractable spasticity (24 with spinal cord injury, 15 with multiple sclerosis, 24 men, age range 21-59 years).

Results: Eight patients developed a withdrawal syndrome on total a daily dose of ITB between 90-420 μg/day. Seven patients had catheter-related complications. In one patient, pump failure was observed due to its corrosion. Within the group, baclofen withdrawal syndrome occurred once in 20.1 pump-years counted out of 160.4 pump-years of ITB treatment.

Limitations: Small sample size.

Conclusions: ITB withdrawal syndrome is a rare but life-threatening event and prompt diagnosis before treatment initiation is critical. The reported events were mostly mild due to the acute treatment regime and probably due to a lower dose of ITB. A prerequisite for successful ITB treatment is a deep knowledge of complications and their prompt management in the hands of a multidisciplinary team in specialized centers.
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February 2016