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Publications (4 of 4) Show all publications
Strömbäck Alvarez, V., Halldin, P. & Kleiven, S. (2014). Influence of Neck Muscle Tone on Brain Tissue Strain during Pedestrian Impacts. In: 11th World Congress on Computational Mechanics (WCCM XI), 5th European Conference on Computational Mechanics (ECCM V), July 20 - 25, 2014, Barcelona, Spain: . Paper presented at 11th. World Congress on Computational Mechanics 8WCCM XI), 5th. European Conference on Computaional Mechanics (ECCM V), Barcelona, Spain, July 20-25, 2014.
Open this publication in new window or tab >>Influence of Neck Muscle Tone on Brain Tissue Strain during Pedestrian Impacts
2014 (English)In: 11th World Congress on Computational Mechanics (WCCM XI), 5th European Conference on Computational Mechanics (ECCM V), July 20 - 25, 2014, Barcelona, Spain, 2014Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Unprotected pedestrians are an exposed group in rural traffic were the most vulnerable humanbody region is the head and the source of many fatal injuries. Brain tissue strain has been shown to correlate well with brain injuries in a detailed FE model [1]. This study was performed to gain a better understanding of the influence that the neck muscle tone has on brain tissue strain during pedestrian head impacts. The study was carried out using a detailed whole body FE model with a detailed neck [2], [3] and brain model [4]. To determine the influence of the muscle tone, a series of simulations were performed where the vehicle speed,pedestrian posture and muscle tone were varied. A generalized hood was also used to get the same impact surface in the different simulations and isolate the influence on strain due changed head kinematics. The influence of increased muscle stiffness was also isolated by adding the increased stiffnes momentaraly before head impact. Hence, the head kinematics did not have time to change and a change in strain was asumed to only be due to the changed neck stiffness. It has previously been shown that the neck muscle tone has a relatively small influence on head kinematics compared to posture, and hence head impact orientation [5]. The influence on brain tissue strain levels was however highly sensitive to impact point on a detailed vehicle due to the complex impact surface. When impacting a generalized surface the diffrences in strain between all simulations were significantly reduced and the influence due to muscle tone was in the same level as due to posture. The isolated influence of increased neck stiffness due to muscle tone was lower than the influence due to slightly changed head impact orientation. The increased neck stiffnes was therefore considered relatively unsignificant when considering brain injuries due to first impact on a vehicle structure in pedestrain accidents.

Keywords
Pedestrian accident, Neck Muscle Tone, FE model, Brain injuries
National Category
Other Medical Engineering
Research subject
Applied Medical Technology
Identifiers
urn:nbn:se:kth:diva-157814 (URN)
Conference
11th. World Congress on Computational Mechanics 8WCCM XI), 5th. European Conference on Computaional Mechanics (ECCM V), Barcelona, Spain, July 20-25, 2014
Note

QC 20150217

Available from: 2014-12-16 Created: 2014-12-16 Last updated: 2015-02-17Bibliographically approved
Alvarez, V., Halldin, P. & Kleiven, S. (2014). The Influence of Neck Muscle Tonus and Posture on Brain Tissue Strain in Pedestrian Head Impacts. Paper presented at 10 November 2014 through 12 November 2014. 58th SAE Stapp Car Crash Conference, STAPP 2014, 58
Open this publication in new window or tab >>The Influence of Neck Muscle Tonus and Posture on Brain Tissue Strain in Pedestrian Head Impacts
2014 (English)In: 58th SAE Stapp Car Crash Conference, STAPP 2014, Vol. 58Article in journal (Refereed) Published
Abstract [en]

Pedestrians are one of the least protected groups in urban traffic and frequently suffer fatal head injuries. An important boundary condition for the head is the cervical spine, and it has previously been demonstrated that neck muscle activation is important for head kinematics during inertial loading. It has also been shown in a recent numerical study that a tensed neck musculature also has some influence on head kinematics during a pedestrian impact situation. The aim of this study was to analyze the influence on head kinematics and injury metrics during the isolated time of head impact by comparing a pedestrian with relaxed neck and a pedestrian with increased tonus. The human body Finite Element model THUMS Version 1.4 was connected to head and neck models developed at KTH and used in pedestrian-to-vehicle impact simulations with a generalized hood, so that the head would impact a surface with an identical impact response in all simulations. In order to isolate the influence of muscle tonus, the model was activated shortly before head impact so the head would have the same initial position prior to impact among different tonus. A symmetric and asymmetric muscle activation scheme that used high level of activation was used in order to create two extremes to investigate. It was found that for the muscle tones used in this study, the influence on the strain in the brain was very minor, in general about 1-14% change. A relatively large increase was observed in a secondary peak in maximum strains in only one of the simulated cases. 

Place, publisher, year, edition, pages
SAE International, 2014
Keywords
Brain tissue strain, Finite element method, Muscle tonus, Pedestrian accidents, Accidents, Brain, Chemical activation, Kinematics, Muscle, Strain, Brain tissue, Impact response, Inertial loadings, Maximum strains, Muscle activation, Neck muscle activation, Pedestrian impact
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-246646 (URN)10.4271/2014-22-0003 (DOI)2-s2.0-85059470111 (Scopus ID)
Conference
10 November 2014 through 12 November 2014
Note

QC 20190618

Available from: 2019-06-18 Created: 2019-06-18 Last updated: 2019-06-18Bibliographically approved
Strömbäck Alvarez, V., Halldin, P. & Kleiven, S. (2014). The Influence of Neck Muscle Tonus and Posture on Brain Tissue Strain in Pedestrian Head Impacts. Stapp Car Crash Journal, 58, ​63-101
Open this publication in new window or tab >>The Influence of Neck Muscle Tonus and Posture on Brain Tissue Strain in Pedestrian Head Impacts
2014 (English)In: Stapp Car Crash Journal, ISSN 1532-8546, Vol. 58, p. ​63-101Article in journal (Refereed) Published
Abstract [en]

Pedestrians are one of the least protected groups in urban traffic and frequently suffer fatal head injuries. An important boundary condition for the head is the cervical spine, and it has previously been demonstrated that neck muscle activation is important for head kinematics during inertial loading. It has also been shown in a recent numerical study that a tensed neck musculature also has some influence on head kinematics during a pedestrian impact situation. The aim of this study was to analyze the influence on head kinematics and injury metrics during the isolated time of head impact by comparing a pedestrian with relaxed neck and a pedestrian with increased tonus. The human body Finite Element model THUMS Version 1.4 was connected to head and neck models developed at KTH and used in pedestrian-to-vehicle impact simulations with a generalized hood, so that the head would impact a surface with an identical impact response in all simulations. In order to isolate the influence of muscle tonus, the model was activated shortly before head impact so the head would have the same initial position prior to impact among different tonus. A symmetric and asymmetric muscle activation scheme that used high level of activation was used in order to create two extremes to investigate. It was found that for the muscle tones used in this study, the influence on the strain in the brain was very minor, in general about 1-14% change. A relatively large increase was observed in a secondary peak in maximum strains in only one of the simulated cases.

Keywords
Pedestrian accidents, muscle tonus, finite element method, brain tissue strain
National Category
Other Medical Engineering
Research subject
Applied Medical Technology
Identifiers
urn:nbn:se:kth:diva-157681 (URN)26192950 (PubMedID)2-s2.0-84945411734 (Scopus ID)
Note

QC 20150217

Available from: 2014-12-12 Created: 2014-12-12 Last updated: 2020-03-09Bibliographically approved
Alvarez, V., Fahlstedt, M., Halldin, P. & Kleiven, S. (2013). Importance of neck muscle tonus in head kinematics during pedestrian accidents. In: 2013 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury: . Paper presented at International Research Council on the Biomechanics of Injury Conference, IRCOBI 2013; Gothenburg; Sweden; 11 September 2013 through 13 September 2013 (pp. 747-761).
Open this publication in new window or tab >>Importance of neck muscle tonus in head kinematics during pedestrian accidents
2013 (English)In: 2013 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, 2013, p. 747-761Conference paper, Published paper (Refereed)
Abstract [en]

Unprotected pedestrians are an exposed group in the rural traffic and the most vulnerable human body region is the head which is the source of many fatal injuries. This study was performed to gain a better understanding of the influence that the neck muscle tonus has on head kinematics during pedestrian accidents. This was done using a detailed whole body FE model and a detailed FE vehicle model. To determine the influence of the muscle tonus a series of simulations were performed where the vehicle speed, pedestrian posture and muscle tonus were varied. Since the human reaction time for muscle activation is in the order of the collision time, the pedestrian was assumed to be prepared for the oncoming vehicle in order to augment the possible influence of muscle tonus. From the simulations performed, kinematic data such as head rotations, trajectory and velocities were extracted for the whole collision event, as well as velocity and accelerations at head impact. These results show that muscle tonus can influence the head rotation during a vehicle collision and therefore alter the head impact orientation. The level of influence on head rotation was in general lower than when altering the struck leg forward and backward, but in the same order of magnitude for some cases. The influence on head accelerations was higher due to muscle tonus than posture in all cases.

Keywords
Finite element method, Head kinematics, Muscle tonus, Pedestrian accident
National Category
Other Medical Sciences not elsewhere specified
Identifiers
urn:nbn:se:kth:diva-133441 (URN)2-s2.0-84896633346 (Scopus ID)
Conference
International Research Council on the Biomechanics of Injury Conference, IRCOBI 2013; Gothenburg; Sweden; 11 September 2013 through 13 September 2013
Note

QC 20140609

Available from: 2013-11-01 Created: 2013-11-01 Last updated: 2017-10-12Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7908-6270

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