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Wearable systems and sensors for the assessment of motor control: Development and validation of methods for clinical assessment of idiopathic normal pressure hydrocephalus
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Medicine, Department of Clinical Sciences.
2021 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Bärbara system och sensorer för bedömning av motorisk kontroll : Utveckling och validering av metoder för klinisk bedömning av idiopatisk normaltryckshydrocefalus (Swedish)
Abstract [en]

Human gait and balance are controlled by automatic processes in the central nervous system, and in sensory and proprioceptive systems. If a disturbance occurs in any of these complex structures, it may lead to balance and gait problems. Equally important are the systems controlling the upper extremity functions where reach, grasp and manipulation skills may be affected. For the neurodegenerative disease idiopathic normal pressure hydrocephalus (iNPH), balance and gait disturbances are cardinal symptoms. Motor control of the upper extremities is also affected. In clinic today, physical impairment of persons with iNPH is commonly visually assessed using subjective, course tests with ordinal scales with the risk of missing minor changes. There is a lack of objective and quantitative ways to measure motor control in daily patient care. The aim of this thesis was to develop and validate tools for objective assessment of parameters that affect motor control in persons with iNPH.

Postural stability in stance and walking was assessed using gyroscopes in patients with iNPH, healthy elderly (HE) and patients with ventriculomegaly (VM). Compared to HE, patients with iNPH had reduced postural stability and relied less on vision. iNPH patients also had a lower trunk sway velocity than VM during walking. The gyroscopic system could quantitatively assess postural deficits in iNPH, making it a potentially useful tool for diagnosis and for clinical follow-up. The differences found during gait also suggests that walking, rather than quiet stance, should be further investigated for facilitating differential diagnosis compared to other patient groups with ventriculomegaly.

The gait in patients with iNPH is according to guidelines defined as slow, shuffling with a low foot-lift, and wide based. To objectively quantify the latter two features, a system (Striton) was developed in-house to assess the increased distance between the feet and the peak heel-height at the push-off phase of the gait cycle. It was validated in experimental setups, compared to gold standard motion capture systems (MCS), on healthy elderly (HE), through test-retest and day-to-day evaluations, and in four patients with iNPH. Striton demonstrated high correlations, in step-width and in heel-height, compared with the MCS. The mean step-width in the HE was 5.2 ± 0.9 cm (mean±Standard Deviation) and the heel-height 16.7±0.6 cm. Test-retest and day-to-day variations were small, ±0.5 cm in step-width and ±1.2 cm in heel-height, and differences in the parameters were seen between HE and iNPH both before and after surgery. Thus, Striton has the potential of quantitatively assessing gait parameters in HE and iNPH in a valuable manner.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2021. , p. 50
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 2130
Keywords [en]
Gait, step-width, heel-heigt, balance, trunk sway, idiopathic normal pressure hydrocephalus, IMU, Inter-rater reliability, kinematics
National Category
Medical Engineering Neurology
Research subject
medical informatics
Identifiers
URN: urn:nbn:se:umu:diva-182784ISBN: 978-91-7855-523-9 (print)ISBN: 978-91-7855-524-6 (electronic)OAI: oai:DiVA.org:umu-182784DiVA, id: diva2:1549168
Public defence
2021-06-04, Betula, Norrlands Universitetssjukhus, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Note

Disputationen sänds även via Zoom.

Available from: 2021-05-12 Created: 2021-05-04 Last updated: 2021-12-06Bibliographically approved
List of papers
1. Trunk sway in idiopathic normal pressure hydrocephalus: quantitative assessment in clinical practice
Open this publication in new window or tab >>Trunk sway in idiopathic normal pressure hydrocephalus: quantitative assessment in clinical practice
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2017 (English)In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, p. 62-70, article id 54Article in journal (Refereed) Published
Abstract [en]

Background: In diagnosis and treatment of patients with idiopathic normal pressure hydrocephalus (iNPH), there is need for clinically applicable, quantitative assessment of balance and gait. Using a body worn gyroscopic system, the aim of this study was to assess postural stability of iNPH patients in standing, walking and during sensory deprivation before and after cerebrospinal fluid (CSF) drainage and surgery. A comparison was performed between healthy elderly (HE) and patients with various types of hydrocephalus (ventriculomegaly (VM)).

Methods: Trunk sway was measured in 31 iNPH patients, 22 VM patients and 58 HE. Measurements were performed at baseline in all subjects, after CSF drainage in both patient groups and after shunt surgery in the iNPH group.

Results: Preoperatively, the iNPH patients had significantly higher trunk sway compared to HE, specifically for the standing tasks (p < 0.001). Compared to VM, iNPH patients had significantly lower sway velocity during gait in three of four cases on firm support (p < 0.05). Sway velocity improved after CSF drainage and in forward-backward direction after surgery (p < 0.01). Compared to HE both patient groups demonstrated less reliance on visual input to maintain stable posture.

Conclusions: INPH patients had reduced postural stability compared to HE, particularly during standing, and for differentiation between iNPH and VM patients sway velocity during gait is a promising parameter. A reversible reduction of visual incorporation during standing was also seen. Thus, the gyroscopic system quantitatively assessed postural deficits in iNPH, making it a potentially useful tool for aiding in future diagnoses, choices of treatment and clinical follow-up. 

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Idiopathic normal pressure hydrocephalus, Trunk sway, Balance, Gait, Gyroscope
National Category
Biomedical Laboratory Science/Technology
Identifiers
urn:nbn:se:umu:diva-138239 (URN)10.1016/j.gaitpost.2017.02.017 (DOI)000405044400011 ()28259041 (PubMedID)2-s2.0-85014113899 (Scopus ID)
Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2023-03-23Bibliographically approved
2. Portable Sensors Add Reliable Kinematic Measures to the Assessment of Upper Extremity Function
Open this publication in new window or tab >>Portable Sensors Add Reliable Kinematic Measures to the Assessment of Upper Extremity Function
2019 (English)In: Sensors, E-ISSN 1424-8220, Vol. 19, no 5, article id 1241Article in journal (Refereed) Published
Abstract [en]

Ordinal scales with low resolution are used to assess arm function in clinic. These scales may be improved by adding objective kinematic measures. The aim was to analyze within-subject, inter-rater and overall reliability (i.e., including within-subject and inter-rater reliability) and check the system's validity of kinematic measures from inertial sensors for two such protocols on one person. Twenty healthy volunteers repeatedly performed two tasks, finger-to-nose and drinking, during two test sessions with two different raters. Five inertial sensors, on the forearms, upper arms and xiphoid process were used. Comparisons against an optical camera system evaluated the measurement validity. Cycle time, range of motion (ROM) in shoulder and elbow were calculated. Bland-Altman plots and linear mixed models including the generalizability (G) coefficient evaluated the reliability of the measures. Within-subject reliability was good to excellent in both tests (G = 0.80-0.97) and may serve as a baseline when assessing upper extremities in future patient groups. Overall reliability was acceptable to excellent (G = 0.77-0.94) for all parameters except elbow axial rotation in finger-to-nose task and both elbow axial rotation and flexion/extension in drinking task, mainly due to poor inter-rater reliability in these parameters. The low to good reliability for elbow ROM probably relates to high within-subject variability. The sensors provided good to excellent measures of cycle time and shoulder ROM in non-disabled individuals and thus have the potential to improve today's assessment of arm function.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
inter-rater reliability, inertial sensor, kinematics, upper limb, arm function
National Category
Physiotherapy
Identifiers
urn:nbn:se:umu:diva-158105 (URN)10.3390/s19051241 (DOI)000462540400260 ()30870999 (PubMedID)2-s2.0-85062987798 (Scopus ID)
Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2023-03-24Bibliographically approved
3. Novel, clinically applicable method to measure step-width during the swing phase of gait
Open this publication in new window or tab >>Novel, clinically applicable method to measure step-width during the swing phase of gait
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2020 (English)In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 41, no 6, article id 065005Article in journal (Refereed) Published
Abstract [en]

Objective: Step-width during walking is an indicator of stability and balance in patients with neurological disorders, and development of objective tools to measure this clinically would be a great advantage. The aim of this study was to validate an in-house-developed gait analysis system (Striton), based on optical and inertial sensors and a novel method for stride detection, for measuring step-width during the swing phase of gait and temporal parameters.

Approach: The step-width and stride-time measurements were validated in an experimental setup, against a 3D motion capture system and on an instrumented walkway. Further, test-retest and day-to-day variability were evaluated, and gait parameters were collected from 87 elderly persons (EP) and four individuals with idiopathic normal pressure hydrocephalus (iNPH) before/after surgery.

Main results: Accuracy of the step-width measurement was high: in the experimental setup mean error was 0.08 +/- 0.25 cm (R = 1.00) and against the 3D motion capture system 0.04 +/- 1.12 cm (R = 0.98). Test-retest and day-to-day measurements were equal within +/- 0.5 cm. Mean difference in stride time was -0.003 +/- 0.008 s between Striton and the instrumented walkway. The Striton system was successfully applied in the clinical setting on individuals with iNPH, which had larger step-width (6.88 cm, n = 4) compared to EP (5.22 cm, n = 87).

Significance: We conclude that Striton is a valid, reliable and wearable system for quantitative assessment of step-width and temporal parameters during gait. Initial measurements indicate that the newly defined step-width parameter differs between EP and patients with iNPH and before/after surgery. Thus, there is potential for clinical applicability in patients with reduced gait stability.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2020
Keywords
gait, swing phase, step-width, inertial measurement unit, wearable, optical sensor
National Category
Neurosciences
Identifiers
urn:nbn:se:umu:diva-173753 (URN)10.1088/1361-6579/ab95ed (DOI)000548816000001 ()32442989 (PubMedID)2-s2.0-85087528902 (Scopus ID)
Available from: 2020-07-31 Created: 2020-07-31 Last updated: 2023-03-24Bibliographically approved
4. Single sensor measurement of heel-height during the push-off phase of gait
Open this publication in new window or tab >>Single sensor measurement of heel-height during the push-off phase of gait
2021 (English)In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 42, no 10, article id 105016Article in journal (Refereed) Published
Abstract [en]

Objective: In healthy gait a forceful push-off is needed to get an efficient leg swing and propulsion, and a high heel lift makes a forceful push-off possible. The power of the push-off is decreased with increased age and in persons with impaired balance and gait. The aim of this study was to evaluate whether a wearable equipment (Striton) and algorithms to estimate vertical heel-height during gait from a single optical distance sensor is reliable and feasible for clinical applications.

Approach: To assess heel-height with the Striton system an optical distance sensor was used to measure the distance to the floor along the shank. An algorithm was created to transform this measure to a vertical distance. The heel-height was validated in an experimental setup, against a 3D motion capture system (MCS), and test-retest and day-to-day tests were performed on 10 elderly persons. As a reference material 83 elderly persons were included, and heel-height was measured before and after surgery in four patients with the neurological disorder idiopathic normal pressure hydrocephalus (iNPH).

Main results: In the experimental setup the accuracy was high with a maximum error of 2% at all distances, target colours and inclination angles, and the correlation to the MCS was R = 0.94. Test-retest and day-to-day tests were equal within ±1.2 cm. Mean heel-height of the elderly persons was 16.5 ± 0.6 cm and in the patients with iNPH heel-height was increased from 11.2 cm at baseline to 15.3 cm after surgery.

Significance: Striton can reliably measure heel-height during gait, with low test-retest and day-to-day variability. The system was easy to attach, and simple to use, which makes it suitable for clinical applications.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2021
Keywords
heel-height, optical sensor, heel-height variability, push-off phase
National Category
Medical Engineering
Research subject
medical informatics
Identifiers
urn:nbn:se:umu:diva-182776 (URN)10.1088/1361-6579/ac325c (DOI)000723408600001 ()34678800 (PubMedID)2-s2.0-85122532235 (Scopus ID)
Note

Previously included in thesis in manuscript form. 

Available from: 2021-05-04 Created: 2021-05-04 Last updated: 2023-11-06Bibliographically approved

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