Change search
Refine search result
12 51 - 85 of 85
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51. Mordaka, Justyna
    et al.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    van Schijndel-de Nooij, M.
    de Lange, R.
    Guerra Casanova, L.J.
    Carter, E.L.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Influence of rotational kinematics on pedestrian head injuries2007In: Proc. IRCOBI Conf. International Research Council On the Biomechanics of Impact, 2007, p. 83-94Conference paper (Refereed)
  • 52.
    Nilsson, Mats
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Fryxell Westerberg, Annika
    Department Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden.
    Borg, Jörgen
    Department Clinical Sciences, Karolinska Institutet, Danderyd Hospital, Stockholm, Sweden.
    Wadell, Carl
    Bioservo Technologies AB, Kista, Sweden.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    A clinical study of a grip strengthening gloveManuscript (preprint) (Other academic)
  • 53.
    Nilsson, Mats
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Fryxell Westerberg, Annika
    Wadell, Carl
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Borg, Jörgen
    Grip strengthening glove to improve hand function in patients with neuromuscular disorders: A feasibility studyIn: Journal of NeuroEngineering and Rehabilitation, ISSN 1743-0003, E-ISSN 1743-0003Article in journal (Other academic)
  • 54.
    Nilsson, Mats
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Ingvast, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    The SEMGlove system for improving the grasping capabilityManuscript (preprint) (Other academic)
  • 55.
    Nilsson, Mats
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Ingvast, Johan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    The Soft Extra Muscle System for Improving the Grasping Capability in Neurological Rehabilitation2012In: 2012 IEEE-EMBS Conference on Biomedical Engineering and Sciences, IECBES 2012, New York: IEEE , 2012, p. 412-417Conference paper (Refereed)
    Abstract [en]

    This paper introduces the SEM Glove (Soft Extra Muscle Glove), a comfortable aid which automatically improves the grasping capability of a human independently of the particular task being performed. The technical solution partly mimics a biological solution and at the same time functions in symbiosis with the biological system. The technical invention is also applicable to other parts or regions of the human body that might need supporting forces or torques. A key feature is that a controlling and strengthening effect is achieved without the need for an external mechanical structure in the form of an exoskeleton. The paper includes a description of the physical design, the contents and the system design.

  • 56.
    Nilsson, Mats
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Nyberg, Tobias
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    An innovative electrophysiological device for rehabilitation of brain lesionsManuscript (preprint) (Other academic)
  • 57.
    Nilsson, Mats
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Nyberg, Tobias
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    EEG based control of a brain-computer interface for neuromuscular stimulationManuscript (preprint) (Other academic)
  • 58.
    Nordberg, Axel
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Antoni, Per
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Fibre reinforced Thiol-Ene patch fixation of bone fracturesManuscript (preprint) (Other academic)
  • 59.
    Nordberg, Axel
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Evaluation of fiber reinforced adhesive fixation of vertebral fractures; an experimental and numerical studyManuscript (preprint) (Other academic)
  • 60.
    Nordberg, Axel
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Montañez, Maria I.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Ramakrishnan, Subashiyni
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Higly adhesive DOPA primers for fibre reinforced Thiol-Ene patch fixation of bone fractures.Manuscript (preprint) (Other academic)
  • 61.
    Nordberg, Axel
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Fixation of vertebral fractures with fibre reinforced adhesive implants2007Conference paper (Refereed)
  • 62.
    Nordberg, Axel
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Brolin, Karin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Beckman, Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Vertebral fractures fixation with composite patch fibre reinforced adhesives2007In: Bio-medical materials and engineering, ISSN 0959-2989, E-ISSN 1878-3619, Vol. 17, no 5, p. 299-308Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim is to investigate fixation of cervical vertebral fractures by patching it with a composite laminate of adhesive and fibres, in comparison with use of only adhesives. Material and methods: The composite fixation was tested on bonded roe deer vertebrae. 25 specimens were sawed in two halves, creating a generic fracture, and thereafter bonded. The adhesives used were a dental system, Scotchbond XT, and a cyanoacrylate, M-bond 200. The fibres used were unidirectional carbon fibres and randomly distributed E-glass fibres. The composites were applied as a 7 mm wide patch circumferential along the induced fracture. Reference specimens for comparison were also made. The ultimate tensile strength was tested in an Instron 5567. The failure site was examined with a microscope. Strain vectors were tracked using Digital Speckle Analysis. Results: Scotchbond XT + E-glass fibres gave best results, with a tensile strength of 3.5 N/mm circumferential length (24.3% of reference). All composites had lower stiffness than cortical bone. The dental adhesive fibre composites gave better results than the cyanoacrylate fibre composites. In all cases fibre reinforced adhesive composite gave better results than adhesive without fibre reinforcement. Conclusion: Fibre-adhesive composite is a promising technique for fixating cervical vertebral fractures.

  • 63.
    Pedersen, Kyrre
    et al.
    Department of Neurosurgery, Karolinska University Hopsital.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Jacobsson, Anders
    Department of Epidemiology, National Board of Health and Welfare.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering. Department of Neurosurgery, Karolinska University Hopsital.
    A National Survey of Traumatic Brain Injuries Admitted to Hospital in Sweden from 1987 to 20102015In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208Article in journal (Refereed)
  • 64. Pedersen, Kyrre
    et al.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Jacobsson, Anders
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    von Holst, Hans
    KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).
    A National Survey of Traumatic Brain Injuries Admitted to Hospitals in Sweden from 1987 to 20102015In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208, Vol. 45, no 1, p. 20-27Article in journal (Refereed)
    Abstract [en]

    Background: With an increasing and aging population, there is a global demand for improving the primary prevention strategies aimed at reducing traumatic brain injuries (TBIs). The objective of the present epidemiological study was to evaluate the pattern of TBI in Sweden over a 24 years period (1987-2010). Methods: The Swedish Hospital Discharge Register was used, where in-patient care with a main diagnosis of TBI according to ICD9/10 was included. External factors, age and gender distribution was evaluated. Results: A decreasing number of annual incidence was observed, that is, from 230 to 156 per 100,000 inhabitants. A steady decrease of concussion was observed while other intracranial injuries increased especially traumatic subdural hemorrhage and subarachnoid hemorrhage. The study identified 3 groups of patients young, adults and elderly. The highest incidence and the largest increase of incidence were seen in the oldest age group (85+ years) while the population under 65 years had a decreasing incidence of TBI. The most frequent etiology was fall accidents (57%) with a relative constant trend over the study period. Conclusions: More effort should be focused on different strategies for different age groups, especially the elderly group. A well-planned strategy for primary prevention guidelines for different age groups will have the chance to further reduce not only the health-care costs but also complications among elderly care. (C) 2015 S. Karger AG, Basel

  • 65. Peloso, Paul M
    et al.
    Carroll, Linda J
    Cassidy, J David
    Borg, Jörgen
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Holm, Lena
    Yates, David
    Critical evaluation of the existing guidelines on mild traumatic brain injury.2004In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, no 43 Suppl, p. 106-12Article in journal (Refereed)
    Abstract [en]

    The purpose of guidelines is to reduce practice variability, but they need to be evidence-based. We examine current mild traumatic brain injury guidelines, critique their basis in evidence and examine their variability in recommendations. A systematic search of the literature found 38,806 abstracts, with 41 guidelines. There were 18 sports-related guidelines, 13 related to admission policies, 12 related to imaging and 5 related to neuropsychological assessment. Some guidelines addressed several areas. Only 5 guidelines reported a methodology for the assembly of evidence used to develop the guideline. After appraising the guidelines against a validated index, we found that 3 of the 41 guidelines could be categorized as evidence-based. Two of these focused on paediatric patients and 1 on adult patients. Limited methodological quality in the current guidelines results in conflicting recommendations amongst them.

  • 66.
    Peloso, Paul M.
    et al.
    Department of Internal Medicine, University of Iowa Health Center, Iowa City, Iowa, USA.
    von Holst, Hans
    Department of Neurosurgery, Karolinska Institutet, Stockholm, Sweden.
    Borg, Jörgen
    Department of Neuroscience, Rehabilitation Medicine, Uppsala University, Uppsala, Sweden.
    Mild traumatic brain injuries presenting to Swedish hospitals in 1987-20002004In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 36, no 43, p. 22-27Article in journal (Refereed)
    Abstract [en]

    Objective: To evaluate the incidence and causes of mild traumatic brain injury in Sweden.Design: Retrospective, population-based incidence cohort study.Subjects: All persons presenting to hospitals in Sweden between 1987 and 2000 with a discharge diagnosis of ICD-9 code 850 and ICD-10 code S0.60.Methods: Data source was the Hospital Discharge Register at the National Board of Health and Welfare (Sweden). Incidence rates are stratified by age, gender, mechanism of injury and length of hospital stay.Results: Men had a mean of 209 mild traumatic brain injuries per 100,000 inhabitants and women averaged 148 per 100,000. Men had more mild traumatic brain injury than women at all ages. There were 2 incidence peaks, in the age strata 16-20 years and those over 65 years. Falls were the most common cause of mild traumatic brain injury overall and occurred commonly under the age of 10 years and over the age of 65 years. Motor vehicle and bicycle injuries were the second and third most common causes of mild traumatic brain injury, and had their peak incidence in those aged 16-35 years.Conclusion: Preventative strategies for mild traumatic brain injury should be age and gender specific.

  • 67. Ruan, J. S.
    et al.
    Prasad, P.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    On the consequences of head size following impact to the human head [2] (multiple letters)2006In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 39, no 2, p. 383-385Article in journal (Refereed)
  • 68.
    Thaning, Elin
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Asplund, Maria
    KTH, School of Technology and Health (STH).
    Nyberg, Tobias
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Inganäs, Olle
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Stability of PEDOT materials intended for implantsManuscript (Other (popular science, discussion, etc.))
    Abstract [en]

    This study presents a set of experiments designed to study the stability over time of the conducting polymer poly(3,4-ethylene dioxythiophene) (PEDOT), under simulated physiological conditions. Especially, the influence of switching the counter ion used in electropolymerisation, from surfactant polystyrene sulphonate (PSS) to heparin, was investigated. Electropolymerised PEDOT was exposed to different solutions at 37 °C over a 5-6 weeks study period. Two methods were used to study changes over time, spectroscopy and cyclic voltammetry. Phosphate buffer solution (PBS) and diluted hydrogen peroxide (H2O2) (0.01 M) were used to simulate in vivo environment. Some PEDOT electrodes in PBS were also subject to voltage pulsing to further stress the material.

     

    The vast part of the samples of both types lost both electroactivity and optical absorbance within the study period, when exposed to H2O2. An overall slightly higher stability of PEDOT:PSS compared to PEDOT:heparin could be seen. The time dependence of the decline also differed, with a linear decrease of electroactivity for PEDOT:heparin while for PEDOT:PSS a comparably stable appearance initially, followed by a marked decrease after 8-15 days.

     

    Polymers were relatively stable in PBS throughout the study period, with around 80% of electroactivity remaining after five weeks. Disregarding a slight drop in electroactivity during the first day, voltage pulsing in PBS did not increase degradation (tested over 11 days). Delamination of PEDOT exposed to PBS was however a significant problem, especially for polymer on ITO substrates.

     

    PEDOT is sensitive to oxidising agents, also in the dilute concentrations used here, and counter ion influences the time course of degradation. Even without oxidising agents, some decline in electroactivity can be expected and it is unclear whether this decrease will continue over time, or if the polymer will stabilise. Such stabilisation was however not seen within the five weeks studied here. Delamination of polymer is likely to be a problem on implantation, especially with unwisely chosen substrates, and might be an even more serious threat to long term applications than degradation in biological fluids.

  • 69.
    Thaning, Elin M.
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Asplund, Maria
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Nyberg, Tobias
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Inganäs, Olle W.
    Biomolecular and Organic Electronics, IFM, Linköping University.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Stability of Poly(3,4-ethylene dioxythiophene) Materials Intended for Implants2010In: Journal of Biomedical Materials Research - Part B Applied Biomaterials, ISSN 1552-4973, Vol. 93B, no 2, p. 407-415Article in journal (Refereed)
    Abstract [en]

    This study presents experiments designed to study the stability of the conducting polymer poly(3,4-ethylene dioxythiophene) (PEDOT), under simulated physiological conditions using phosphate-buffered saline (PBS) and hydrogen peroxide (H2O2) (0 01M) at 37 degrees C over a 5- to 6-week period Voltage pulsing in PBS was used as an additional test environment The influence of switching the counter ion used in electropolymerization from polystyrene sulphonate (PSS) to heparin was investigated Absorbance spectroscopy and cyclic voltammetry were used to evaluate the material properties Most of the samples in H2O2 lost both electroactivity and optical absorbance within the study period, but PEDOT.PSS was found slightly more stable than PEDOT heparin. Polymers were relatively stable in PBS throughout the study period, with around 80% of electroactivity remaining after 5 weeks, disregarding delamination, which was a significant problem especially for polymer on indium tin oxide substrates Voltage pulsing in PBS did not increase degradation. The counter ion influenced the time course of degradation in Oxidizing agents.

  • 70.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering. KI.
    Organic bioelectrodes in clinical neurosurgery2013In: Biochimica et Biophysica Acta - General Subjects, ISSN 0304-4165, E-ISSN 1872-8006, Vol. 1830, no 9, p. 4345-4352Article in journal (Refereed)
    Abstract [en]

    Background: Clinical neurosurgery deals with surgical procedures and intensive care of illnesses in the human central and peripheral nervous system. Neurosurgery should be looked upon as a high-tech specialty and very much dependent on new technological innovations aiming at improvements of patient's treatment and outcome. During the last decades neurosurgery has improved substantially thanks to the introduction of applied imaging technologies such as computerized tomography and magnetic resonance tomography, and new surgical modalities such as the microscope, brain navigation and neuroanesthesiology. Neurosurgical disorders, which should have the potential to benefit from conductive organic bioelectrodes, include traumatic brain and spinal cord injury and peripheral nerve injuries due to external violence in the restoration of healthy communication. This holds true also for cerebral nerves altered in their functions due to benign and malignant brain and spinal cord tumors. Further, new innovative devices in the field of functional nervous tissue disorders make the use of organic conductive electrodes attractive by considering the electrical neurochemical properties of neural interfaces. Conclusions: Although in its infancy, conducting organic polymers as bioelectrodes have several potential applications in clinical neurosurgery. The time it takes for new innovations and basic research to be transferred into clinical neurosurgery should not take too long. However, a prerequisite for successful implementation is the close interdisciplinary collaboration between engineers and clinicians. This article is part of a Special Issue entitled Organic Bioelectronics-Novel Applications in Biomedicine.

  • 71.
    Von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701). Karolinska Institutet, Stockholm, Sweden .
    Spinal cord injury worldwide2010In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208, Vol. 34, no 3, p. 192-192Article in journal (Refereed)
  • 72.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Traumatic Brain Injury2007In: Handbook in Neuroepidemiology, KTH Royal Institute of Technology, 2007, Feigin V, p. 193-234Chapter in book (Refereed)
  • 73.
    Von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701). Karolinska University Hospital, Sweden.
    Traumatic brain injury: Evidence-based management and epidemiology updates2009In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208, Vol. 33, no 4, p. 314-315Article in journal (Refereed)
  • 74.
    von Holst, Hans
    et al.
    KTH.
    Cassidy, J. David
    Mandate of the who collaborating centre task force on mild traumatic brain injury2004In: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 36, p. 8-10Article in journal (Refereed)
    Abstract [en]

    In collaboration with outside experts, the WHO Collaborating Centre for Neurotrauma at the Karolinska Institute, Stockholm, Sweden, has assembled a task force to undertake a best-evidence synthesis of the literature on mild traumatic brain injury. The task force has addressed the epidemiology, diagnosis, prognosis, treatment and economic costs of mild traumatic brain injury in order to make recommendations to reduce the medical as well as the social consequences of mild traumatic brain injury.

  • 75.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Protective Material2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A protective material/structure is provided that reduces the risk of injury for a person after contact with said material/structure, and is based on a structure where an inner and outer shell can move relative to each other. The shells are separated by spikes or thin beams and the outer shell covers or envelops the spikes. The spikes or beams are constructed so that they permit displacement of the outer shell relative to the inner shell in the event of an oblique impact against the protective material/structure. The spikes or beams are designed to be thin/slim and can be made of flexible polymer materials such as plastics, rubber or fibers. This enables the spikes to give way after a tangential/rotational impact and thereby efficiently reduce the negative effects of such an impact on the brain. The material/structure can be used in e.g. helmets, vehicle interiors, vehicle exteriors, indoor house building material, boxing gloves and the like.

  • 76.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Kleiven, Sveinsveink
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Ho, Johnson
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Non-invasive brain injury evaluation2009Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A non-invasive method for measuring intracranial pressure (ICP) is provided. A numerical model such as finite element model is developed in order to calculate the ICP, strain or stress for patients who suffers from hematoma, edema or tumor. The method can further provide local maximum principle strain that can provide information about possible subsequent brain injury, such as diffuse axonal injury, in sensitive region of the brain. Based on computer tomography or magnetic resonance images an individual diagnosis and treatment plan can be formed for each patient.

    (FR)L'invention concerne un procédé non invasif visant à mesurer la pression intracrânienne (ICP). Un modèle numérique tel qu’un modèle par éléments finis est développé afin de calculer l’ICP, la déformation ou la contrainte pour des patients souffrant d’un hématome, d’un œdème ou d’une tumeur. Le procédé peut en outre fournir le maximum local de déformation principale qui peut donner des informations concernant d’éventuelles lésions cérébrales subséquentes, comme des lésions axonales diffuses, dans une région sensible du cerveau. Sur la base d’une tomographie informatisée ou d’images par résonance magnétique, un diagnostic et un plan de traitement individualisés peuvent être formulés pour chaque patient.

  • 77.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering. Section of Neurosurgery, Division of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Li, Xiaogai
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Consequences of the dynamic triple peak impact factor in traumatic brain injury as measured with numerical simulation2013In: Frontiers in Neurology, ISSN 1664-2295, E-ISSN 1664-2295, Vol. 4 MARArticle in journal (Refereed)
    Abstract [en]

    There is a lack of knowledge about the direct neuromechanical consequences in traumatic brain injury (TBI) at the scene of accident. In this study we use a finite element model of the human head to study the dynamic response of the brain during the first milliseconds after the impact with velocities of 10, 6, and 2 meters/second (m/s), respectively. The numerical simulation was focused on the external kinetic energy transfer, intracranial pressure (ICP), strain energy density and first principal strain level, and their respective impacts to the brain tissue. We show that the oblique impacts of 10 and 6 m/s resulted in substantial high peaks for the ICP, strain energy density, and first principal strain levels, however, with different patterns and time frames. Also, the 2 m/s impact showed almost no increase in the above mentioned investigated parameters. More importantly, we show that there clearly exists a dynamic triple peak impact factor to the brain tissue immediately after the impact regardless of injury severity associated with different impact velocities. The dynamic triple peak impacts occurred in a sequential manner first showing strain energy density and ICP and then followed by first principal strain. This should open up a new dimension to better understand the complex mechanisms underlying TBI. Thus, it is suggested that the combination of the dynamic triple peak impacts to the brain tissue may interfere with the cerebral metabolism relative to the impact severity thereby having the potential to differentiate between severe and moderate TBI from mild TBI.

  • 78.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering. Karolinska Institutet, Sweden .
    Li, Xiaogai
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Decompressive craniectomy (DC) at the non-injured side of the brain has the potential to improve patient outcome as measured with computational simulation2014In: Acta Neurochirurgica, ISSN 0001-6268, E-ISSN 0942-0940, Vol. 156, no 10, p. 1961-1967Article in journal (Refereed)
    Abstract [en]

    Decompressive craniectomy (DC) is efficient in reducing the intracranial pressure in several complicated disorders such as traumatic brain injury (TBI) and stroke. The neurosurgical procedure has indeed reduced the number of deaths. However, parallel with the reduced fatal cases, the number of vegetative patients has increased significantly. Mechanical stretching in axonal fibers has been suggested to contribute to the unfavorable outcome. Thus, there is a need for improving treatment procedures that allow both reduced fatal and vegetative outcomes. The hypothesis is that by performing the DC at the non-injured side of the head, stretching of axonal fibers at the injured brain tissue can be reduced, thereby having the potential to improve patient outcome. Six patients, one with TBI and five with stroke, were treated with DC and where each patient's pre- and postoperative computerized tomography (CT) were analyzed and transferred to a finite element (FE) model of the human head and brain to simulate DC both at the injured and non-injured sides of the head. Poroelastic material was used to simulate brain tissue. The computational simulation showed slightly to substantially increased axonal strain levels over 40 % on the injured side where the actual DC had been performed in the six patients. However, when the simulation DC was performed on the opposite, non-injured side, there was a substantial reduction in axonal strain levels at the injured side of brain tissue. Also, at the opposite, non-injured side, the axonal strain level was substantially lower in the brain tissue. The reduced axonal strain level could be verified by analyzing a number of coronal sections in each patient. Further analysis of axial slices showed that falx may tentatively explain part of the different axonal strain levels between the DC performances at injured and opposite, non-injured sides of the head. By using a FE method it is possible to optimize the DC procedure to a non-injured area of the head thereby having the potential to reduce axonal stretching at the injured brain tissue. The postoperative DC stretching of axonal fibers may be influenced by different anatomical structures including falx. It is suggested that including computational FE simulation images may offer guidance to reduce axonal strain level tailoring the anatomical location of DC performance in each patient.

  • 79.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering. Section of Neurosurgery, Division of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden .
    Li, Xiaogai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Higher impact energy in traumatic brain injury interferes with noncovalent and covalent bonds resulting in cytotoxic brain tissue edema as measured with computational simulation2015In: Acta Neurochirurgica, ISSN 0001-6268, E-ISSN 0942-0940, Vol. 157, no 4, p. 639-648Article in journal (Refereed)
    Abstract [en]

    Cytotoxic brain tissue edema is a complicated secondary consequence of ischemic injury following cerebral diseases such as traumatic brain injury and stroke. To some extent the pathophysiological mechanisms are known, but far from completely. In this study, a hypothesis is proposed in which protein unfolding and perturbation of nucleotide structures participate in the development of cytotoxic edema following traumatic brain injury (TBI). An advanced computational simulation model of the human head was used to simulate TBI. The consequences of kinetic energy transfer following an external dynamic impact were analyzed including the intracranial pressure (ICP), strain level, and their potential influences on the noncovalent and covalent bonds in folded protein structures. The result shows that although most of the transferred kinetic energy is absorbed in the skin and three bone layers, there is a substantial amount of energy reaching the gray and white matter. The kinetic energy from an external dynamic impact has the theoretical potential to interfere not only with noncovalent but also covalent bonds when high enough. The induced mechanical strain and pressure may further interfere with the proteins, which accumulate water molecules into the interior of the hydrophobic structures of unfolded proteins. Simultaneously, the noncovalent energy-rich bonds in nucleotide adenosine-triphosphates may be perturbed as well. Based on the analysis of the numerical simulation data, the kinetic energy from an external dynamic impact has the theoretical potential to interfere not only with noncovalent, but also with covalent bonds when high enough. The subsequent attraction of increased water molecules into the unfolded protein structures and disruption of adenosine-triphosphate bonds could to some extent explain the etiology to cytotoxic edema.

  • 80.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Li, Xiaogai
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Numerical Impact Simulation of Gradually Increased Kinetic Energy Transfer Has the Potential To Break Up Folded Protein Structures Resulting in Cytotoxic Brain Tissue Edema2013In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 30, no 13, p. 1192-1199Article in journal (Refereed)
    Abstract [en]

    Although the consequences of traumatic brain injury (TBI) and its treatment have been improved, there is still a substantial lack of understanding the mechanisms. Numerical simulation of the impact can throw further lights on site and mechanism of action. A finite element model of the human head and brain tissue was used to simulate TBI. The consequences of gradually increased kinetic energy transfer was analyzed by evaluating the impact intracranial pressure (ICP), strain level, and their potential influences on binding forces in folded protein structures. The gradually increased kinetic energy was found to have the potential to break apart bonds of Van der Waals in all impacts and hydrogen bonds at simulated impacts from 6 m/s and higher, thereby superseding the energy in folded protein structures. Further, impacts below 6 m/s showed none or very slight increase in impact ICP and strain levels, whereas impacts of 6 m/s or higher showed a gradual increase of the impact ICP and strain levels reaching over 1000 KPa and over 30%, respectively. The present simulation study shows that the free kinetic energy transfer, impact ICP, and strain levels all have the potential to initiate cytotoxic brain tissue edema by unfolding protein structures. The definition of mild, moderate, and severe TBI should thus be looked upon as the same condition and separated only by a gradual severity of impact.

  • 81.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Li, Xiaogai
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Quantification of Stretching in the Ventricular Wall and Corpus Callosum and Corticospinal Tracts in Hydrocephalus before and after Ventriculoperitoneal Shunt Operation2013In: Journal of Applied Mathematics, ISSN 1110-757X, E-ISSN 1687-0042, p. 350359-Article in journal (Refereed)
    Abstract [en]

    In this study, we establish a quantitative model to define the stretching of brain tissue, especially in ventricular walls, corpus callosum (CC) and corticospinal (CS) fiber tracts, and to investigate the correlation between stretching and regional cerebral blood flow (rCBF) before and after ventriculoperitoneal shunt operations. A nonlinear image registration method was used to calculate the degree of displacement and stretching of axonal fiber tracts based on the medical images of six hydrocephalus patients. Also, the rCBF data from the literature was analyzed and correlated with the strain level quantified in the present study. The results showed substantial increased displacement and strain levels in the ventricular walls as well as in the CC and CS fiber tracts on admission. Following shunt operations the displacement as well as the strain levels reduced substantially. A linear correlation was found to exist between strain level and the rCBF. The reduction in postoperative strain levels correlated with the improvement of rCBF. All patients improved clinically except for one patient due to existing dementia. These new quantitative data provide us with new insight into the mechanical cascade of events due to tissue stretching, thereby provide us with more knowledge into understanding of the role of brain tissue and axonal stretching in some of the hydrocephalus clinical symptoms.

  • 82.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Li, Xiaogai
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    The dynamic triple peak impact factor in traumatic brain injury influences native protein structures in gray and white matter as measured with computational simulation2013In: Neurological Research, ISSN 0161-6412, E-ISSN 1743-1328, Vol. 35, no 8, p. 782-789Article in journal (Refereed)
    Abstract [en]

    Background: Traumatic brain injuries (TBIs) cause a substantial burden to the patient, relatives, and the society as a whole. Much experience and knowledge during the last two decades have improved the neurosurgical treatment as well as the outcome. However, there is still much debate on what actually happens when external kinetic energy is transferred to the head immediately after a TBI. Better knowledge about the cascades of mechanical events at the time of accident is a prerequisite to further reduce the burden in all categories and improve the neurosurgical care of TBI patients. Methods: In the present study, we use the finite element modeling of the human brain to numerically simulate impact velocities of 10, 6, and 2 m/s to clarify some of the immediate consequences of the external kinetic energy transfer focusing on the gray (GM) and white matters (WM). Results: The numerical simulation was focused on the external kinetic energy transfer with a level of 227.3 J reaching the head, intracranial pressure (ICP), strain energy density, 1st principal strain level, and their respective impacts on the brain tissue. The results show that, for a 10 m/s impact, a total internal potential energy of 208.6 J was absorbed, of which 14.3% (29.81 J) was absorbed by the scalp, 22.05% (46.0 J) by the outer compact bone, 17.12% (35.72 J) by the porous bone, 27.44% (57.23 J) by the inner compact bone, and 7.31% (15.24 J) by the facial bone. The rest of the internal potential energy was defined to reach the GM (3.6%, 7.51 J) and the WM 1.59% (3.31 J). Also, the ICP, strain energy density, and 1st principal strain levels, defined as the dynamic triple peak impact factor, influenced the GM and WM with their own impact peaks during the first 10 ms after the accident and were the highest for the 10 and 6 m/s impacts, while the 2 m/s impact had only a slight influence on the GM and WM structures. Conclusions: The present study shows for the first time that following an impact of 10 m/s, 88.31% of the calculated external kinetic energy was absorbed by the external parts of the head before the remaining energy of 5.19% reached the GM and WM. GM absorbed about twice as much of the energy compared to the WM. It is suggested that the dynamic triple peak impact factor may have a profound effect on native protein structures in the cerebral metabolism after a TBI.

  • 83.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Li, Xiaogai
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Increased strain levels and water content in brain tissue after decompressive craniotomy2012In: Acta Neurochirurgica, ISSN 0001-6268, E-ISSN 0942-0940, Vol. 154, no 9, p. 1583-1593Article in journal (Refereed)
    Abstract [en]

    At present there is a debate on the effectiveness of the decompressive craniotomy (DC). Stretching of axons was speculated to contribute to the unfavourable outcome for the patients. The quantification of strain level could provide more insight into the potential damage to the axons. The aim of the present study was to evaluate the strain level and water content (WC) of the brain tissue for both the pre- and post-craniotomy period. The stretching of brain tissue was quantified retrospectively based on the computerised tomography (CT) images of six patients before and after DC by a non-linear image registration method. WC was related to specific gravity (SG), which in turn was related to the Hounsfield unit (HU) value in the CT images by a photoelectric correction according to the chemical composition of brain tissue. For all the six patients, the strain level showed a substantial increase in the brain tissue close to the treated side of DC compared with that found at the pre-craniotomy period and ranged from 24 to 55 % at the post-craniotomy period. Increase of strain level was also observed at the brain tissue opposite to the treated side, however, to a much lesser extent. The mean area of craniotomy was found to be 91.1 +/- 12.7 cm(2). The brain tissue volume increased from 27 to 127 ml, corresponding to 1.65 % and 8.13 % after DC in all six patients. Also, the increased volume seemed to correlate with increased strain level. Specifically, the overall WC of brain tissue for two patients evaluated presented a significant increase after the treatment compared with the condition seen before the treatment. Furthermore, the Glasgow Coma Scale (GCS) improved in four patients after the craniotomy, while two patients died. The GCS did not seem to correlate with the strain level. We present a new numerical method to quantify the stretching or strain level of brain tissue and WC following DC. The significant increase in strain level and WC in the post-craniotomy period may cause electrophysiological changes in the axons, resulting in loss of neuronal function. Hence, this new numerical method provides more insight of the consequences following DC and may be used to better define the most optimal size and area of the craniotomy in reducing the strain level development.

  • 84.
    von Holst, Hans
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Nguyen, Hung
    Wikander, Jan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Innovation Driven Research Education: Vol. 1: An Introduction2010Book (Refereed)
  • 85.
    Wikander, Jan
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Ingvast, Johan
    Kraftförstärkande handske2006Patent (Other (popular science, discussion, etc.))
12 51 - 85 of 85
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf