Title: Muscle Pathology and Gait in Children with Duchenne Muscular Dystrophy
1Muscle Pathology and Gait in Children with
Duchenne Muscular Dystrophy
- Donovan J. Lott, PT, PhD, CSCS
- May 19, 2009
- Mentors
- Steve Kautz, PhD
- Krista Vandenborne, PhD, PT
2Professional Background
- Clinical work as physical therapist
- PhD studying soft tissue mechanics of neuropathic
foot - Quantifying muscle plasticity UF
- Phase I of K12
- Developing aims for K award
3Duchenne Muscular Dystrophy (DMD)
- X-linked recessive disorder
- 40 of cases are spontaneous mutations
- 1 in 3,500 male births
- Shortened life span
- No cure100 lethal
4Pathophysiology
5Pathophysiology
2yr
6Weakness
Pseudohypertrophy
Impaired mobility
Postural changes
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8Interests
- How muscle pathology is related to gait function
in children with DMD - How/if rehabilitation strategies can favorably
impact gait mechanics
9- Background and Preliminary Data
- Disease Progression/Pathology
- Quantitative muscle strength testing
- Non-invasive magnetic resonance imaging (MRI) and
spectroscopy (MRS) - Gait
- Basic measures
- Kinematics Kinetics
- Brief thoughts on rehabilitation in patients with
DMD
10Disease Progression/PathologyStrength
- Weakness becomes more evident with increasing age
- Lower extremities weaker than upper extremities
- Proximal weaker than distal
- MMTs inferior to quantitative tests
(Lue et al., 1992 McDonald et al., 1995 Marden
et al., 2005)
11Disease Progression/PathologyStrength
Preliminary Data
- Biodex isokinetic dynamometer
- Isometric tests
- Knee extensors
- Ankle plantarflexors
- Ankle dorsiflexors
12Preliminary Data Participants
29 boys with DMD, 12 healthy controls
13Disease Progression/PathologyStrength
Preliminary Data
Torque of Plantarflexors
Torque of Dorsiflexors
Normalized Torque (Nm/cm2)
Normalized Torque (Nm/cm2)
Torque of Quadriceps
Normalized Torque (Nm/cm2)
14Disease Progression/PathologyWhy MRI/MRS?
- Noninvasive/nondestructive
- Detailed information
- Quantitative
- Sensitive
- MRI
- Cross-sectional area (CSA)
- Qualitative fatty infiltration
- Contractile area
- MRS
- Quantification of
- intramuscular lipids
15Disease Progression/PathologyMRI Preliminary
Data CSA
TA
Sol
MG
LG
1-4 Quadriceps
4
1
3
2
16Disease Progression/PathologyMRI Preliminary
Analyses
-
( ) - ( )
T1 weighted gradient echo Image with fat
suppression
T1 weighted gradient echo Image without fat
suppression
Subtraction image
For determining Intramuscular Fat content and
Contractile Area
17Disease Progression/PathologyMRS
- Various metabolites have been quantified with
1H-MRS in children with DMD (Sharma et al., 2003
Hsieh et al., 2007 and 2009) - We have begun to quantify lipids for fatty
infiltration in patients with DMD
18Disease Progression/PathologyPreliminary Data
1H-MRS
CON
DMD
DMD
CON
Lipid
Water
Water
Lipid
19Disease Progression/PathologyPreliminary Data
1H-MRS
Cross-sectional
Longitudinal
Nonambulatory
DMD subjects D1 - 13.8 y/o D2 - 8.8 y/o D3 8.9
y/o
CON DMD
20Gait
- Little work has been done
- Mostly heterogenous groups or small sample
- More descriptive in nature (Hsu Furumasu, 1993)
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22GaitPreliminary DataSpatiotemporal Parameters
Healthy control subject
DMD subject
23GaitPreliminary DataSpatiotemporal Parameters
-Stride and step lengths were shorter in DMD
subjects (p lt 0.05) -Trend for greater base of
support and slower gait velocity (p lt 0.09)
CON DMD
24Gait
- Activity Monitor
- ActiGraph
- Functional Assessment
- 30 foot walk
25GaitActiGraph
- Walking and non-ambulatory activity
- Can estimate energy expenditure (METs)
15 y/o healthy boy
14 y/o boy with DMD
26GaitPreliminary Data for 30 foot walk
Longitudinal
Nonambulatory
DMD subjects D1 - 13.8 y/o D2 - 8.8 y/o D3 8.9
y/o
27GaitPreliminary Data
28Gait
- A few recent studies have utilized state-of-the
art 3D motion capture systems for kinematics and
kinetics of gait
29Gait
DMD Control
Pelvic Tilt
Hip Power
- Ankle Plantarflexion - Dorsiflexion
Ankle Power
(DAngelo et al., 2009)
30GaitFuture work needed in DMD
- Better understand how pathology is related to
gait - Longitudinal data on gait biomechanics
- Older (9-14 years) participants
31Rehabilitation
- Current thoughts/strategies re physical therapy
for those with DMD - Stretch to prevent contractures
- Orthoses for decreasing impact/progression of
contractures - Positioning/chest therapy for later stages
- No sufficient data in the literature to justify a
sound exercise prescription for DMD
(Grange Call, 2007)
32Rehabilitation
- Muscle Damage Disuse Atrophy
33Rehabilitation
- Possible rehabilitation strategies to implement
and study - Stretching as a protective mechanism (Koh et al.,
2003) - Strengthening (de Lateur Giaconi, 1979 Kaczor
et al., 2007) - Trunk control/stabilization
34Overall Objectives
- Examine the relationship between gait and disease
progression in children with DMD - Pilot rehabilitation interventions to target
improvement in gait without enhancing muscle
pathology
35Thank you
- University of Florida
- Biomechanics
- Steve Kautz
- DMD Imaging team
- Krista Vandenborne
- Glenn Walter
- Claudia Senesac
- Roxanna Bendixen
- Sean Forbes
- Sean Germain
- Ravneet Vohra
- Ishu Arpan
- Jasjit Deol
- Alicia Kinsey
- Jessica Blank
University of Toronto Sunita Mathur University
of Pennsylvania Lee Sweeney
MRI/MRS conducted at the AMRIS facility, McKnight
Brain Institute, UF
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37Disease Progression/PathologyMRI Preliminary Data
CSA of Triceps Surae
CSA of TA
CSA of Quads
1-4 Quadriceps
TA
4
1
3
2
2
3
1
1-3 Triceps Surae