Muscular Dystrophy and Related Disorders Flashcards
Disorders of motor nerve
Polio
CMT
ALS
Disorders of NMJ
Myasthenia Gravis
Disorders of mm
Muscular Dystrophy (MD) Spinal Muscular Atrophy (SMA)
MD and SMA Characterized by…
Progressive weakness Mm atrophy Contracture formation Progressive disability Sometimes shortened lifespan Usually of genetic origin Not curable, but treatable
Duchenne MD
Onset 1-4
X-linked - male offspring inherit the disease from their asymptomatic mothers
Rapid progression
Becker MD
Onset 5-10
X-linked
Slower progression
Congenital MD
Onset birth
Recessive
Slow progression
Shortened lifespan
Congenital Myotonic
Onset birth
Slow progression
Significant intellectual impairment
Fascioscapulohumeral MD
Onset 1st decade
Slow progression
Late loss of ambulation
Variable life expectancy
SMA type 1
Aka Werdnig-Hoffman Acute
Onset 0-3 mos
Recessive
Severe hypotonia
Death within 1st year
SMA type 2
Aka Wednig-Hoffman Chronic
Onset 3 mos-4 years
Recessive
Rapid progression then stabilizes
Moderate to severe hypotonia
Shortened lifespan
SMA type 3
Aka juvenile onset
5-10 years
Recessive
Slow progression
Milder impairments
Dystrophinopathy mutation
DMD
In gene coding for the protein dystrophin
Mm doesn’t hold together well
-Causes a disruption in the linkage btwn the subsarcolemma cytoskeleton and extracellular matrix
Eventually becomes fibrous, fatty, and non-contractile
DMD Morbidity
Related to respiratory insufficiency and/or heart failure
1/3 of DMD cases…
Spontaneous mutations
Rate of approx 1 in 10,000
DMD dx
Blood work…
CK levels are significantly elevated
Genetic testing…
By blood work $$$
Mm biopsy…
Specimens show degeneration and loss of fibers, increased fat and connective tissue
EMG…
Low amplitude, short duration polyphasic motor unit action potentials
Clinical Presentation DMD
Possible delayed onset of motor milestones, especially late walking
Tripping, falling, poor ability to run or resistance to running, inability to keep up with peers
Toe walking
Pseudohypertrophy of the calves
Progressive weakness
Lordosis
Waddling gait
Gower’s Sign
Toe walking
CP
ASD
DMD
Medical Management DMD
Prenatal care - genetic counseling
Early dx - CK levels
Nutritional management - obesity is a significant problem
Orthopedic management - contracture lengthening, spinal stabilization
Cardiopulmonary management - including PFT (when ambulation decreases, this problem gets worse)
Prednisone
Kids that take this have some preservation of cardiopulmonary function
DMD
Birth to 2 years
Late acquisition of milestones, especially walking
DMD
3-5 years
Toe walking
Clumsiness
Pseudohypertrophy of calves
Gower’s Sign
DMD
6-8 years
Toe walking Lordosis Inability to climb stairs sans assistance Wide-based waddling gait Can't rise from floor sans help
DMD
9-11
Walks with braces - controversial
Scoliosis
May have orthopedic surgery
Beginning respiratory insufficiency
DMD
12-14 years
Loss of ambulation Increased respiratory difficulties Obesity Contractures Progression of scoliosis Dependent for transfers Needs assist with ADL's
DMD
15-17 years
Dependent in most ADLs
May need assisted ventilation
DMD
18+ years
Totally dependent
Assisted ventilation
Death comes after a period of declining respiratory fx
Scoliosis DMD
Develops as the age of the child with DMD increases
Significant curves are generally not noticed until after 11 years of age
Increases with more sitting time
Becomes fixed over time
Respiratory DMD
Respiratory musculature atrophies
Coughing becomes ineffective
Pulmonary infections become more frequent
Major cause is progressive weakness of these mm
Cardiac DMD
Dystrophin deficiency results in cardiomyopathy, arrhythmias, and CHF
Posterobasal portion of left ventricle more affected than other parts
Heart mm involvement generally occurs later than skeletal mm involvement
Cognition DMD
High rate of intellectual impairments
This deficit not progressive and not related to disease severity
IQ scores fall approx 1 SD below mean
Verbal scores affected more than performance scores
Importance of treatment
DMD
Proper tx can prolong QOL
Parental counseling
Prolong ambulation
Any tx most optimal the better the pt’s physical condition is
Glucocorticoid corticosteroids
DMD
Prednisone
Deflazacort - less SEs, not FDA approved
Creatine monohydrate
Natural body-building substance
Increases in mm levels of creatine and improvements in maximal exercise performance and recovery from exercise in healthy subjects
Orthopedic tx
DMD
Spinal fixation when scoliosis exceeds 30-degrees
Pelvic obliquity
Achilles tendon lengthening
Fasciotomies
Tib post transpositions
Percutaneous tenotomies
Pulmonary tx
DMD
Nasal positive pressure ventilation at night to assist breathing and to provide a rest for overworked respiratory mm
Cardiac tx
DMD
ECHO and ECG monitoring
Cardiac medications for arrhythmias may be necessary
3 phases of DMD presentation
Early of ambulatory stage
Transitional phase during loss of ambulation
Later/wheelchair stage when the child or young adult is wheelchair bound and dependent for most of his functional activities
Functional T + M
DMD
Stable performance or declining performance
Assessing strength, pulmonary function, and functional tasks in combination
PEDI
6MWT***
Brooks grades for UE
VIgnos for LE
MMT for DMD
Must be a routine part of the PT eval of the child with myopathy
No correlation btwn rate of decline and wheelchair use
Hand-held myometry and various fixed tensiometer systems have been used in attempts to better quantify mm strength in boys with DMD
ROM in DMD
Loss of…
Full ankle DF
Knee extension
Hip extension
***Important to measure
Bracing at night
Important
Kids should get 4-6 hours of prolonged stretch in evening or when they are asleep
AVOID in DMD
Maximal resistive strength training
Eccentric exercise
GOOD for DMD
Submax exercise
Endurance training - swimming, cycling
Primary goal as PTs when working with pts with DMD
Maintenance of ambulation
Signs of overwork weakness in pts with DMD
Feeling weaker rather than stronger 30 min after exercise
Excessive DOMS 24-48 hours after exercise
Severe mm cramping
Heaviness in the extremities
Prolonged SOB
Myotonic Dystrophy (MTD)
Autosomal dominant disorder on chromosome 19
Symptoms first noticed during adolescence and are characterized by myotonia, a delay in mm relaxation time, and mm weakness
As weakness progresses, myotonia decreases
Many pts also have cognitive impairment, cataracts, diabetes, and cardiac arrhythmias
These guys need very close medical management
DMD and assistive devices
Don’t really benefit
Usually go from walking to wheelchair
DMD Knee Flexion Extension Curve
When ambulation almost lost, the first loading response starts to disappear
Once this occurs, they lose their ambulation within about 6 mos
Myotonia
Difficulty to relax muscles
Percussion myotonia
If you hit the mm bellies, they will contract
Limb Girdle Muscular Dystrophy
Group of progressive mm dystrophies that affect PROXIMAL musculature
Initial presentation can be quite variable extending from early childhood into adulthood
Heterogeneous
Gower to get up from chair
Waddling gait
Congenital Myopathy
A group of diseases including nemaline myopathy, central core myopathy, and centronuclear myopathy
Results from abnormalities of sarcomeric proteins
Characterized by weakness and mm atrophy that typically present at birth
Mm, brain, and eye abnormalities
Fukuyama CMD
Walker-Warburg syndrome
Muscle-eye-brain disease
SMA
Manifested by a loss of anterior horn cells
Results in phenotypic spectrum of disease states that have been divided into three types based on a functional classification system
Clinical Presentation
SMA type 1
Mother complains of decreased fetal movement during her pregnancy
At birth, the affected child is hypotonic and may have difficulty feeding
Mm wasting often severe and spontaneous movements are infrequent and of small amplitude
Head lag
Landau drape over examiner’s hand
Clinical Presentation
SMA type 2
Affects infants, but is more benign than type 1
Presentation later in the first year of life when child is not pulling to stand
Characterized by weakness and wasting of extremities and trunk musculature
Fasciculations are common
Mini-polymyoclonus
May learn to walk with bracing
Clinical Presentation
SMA type 3
Symptoms of progressive weakness, wasting, and fasciculations
Age of presentation can vary from the toddler years into adulthood, the latter of which some would classify as type IV
Proximal mm are usually involved first and because of age of presentation, this disease may be confused with the MDs
Decreased DTRs
Contractures unusual
Progressive spinal deformities uncommon as long as child remains ambulatory
Genetic testing will show a deletion of SMN gene on fifth chromosome
Pts with DMD
Absent DTRs
SMA Prognosis
Can be aided by a good developmental history
Symptoms that begin prior to 2 years of age have a relatively poorer prognosis (amb til around 12)
Symptoms after 2 years of age typically ambulate til 44
CMTD
One of the most common inherited neurological disorders
aka Hereditary Motor and Sensory Neuropathy (HMSN) or Peroneal muscular atrophy
Primarily affect peripheral nerves
CMT1
Caused by abnormalities in myelin sheath
CMT1A
Autosomal dominant disease that results from duplication of gene on chromosome 17
PMP-22 important in myelin sheath
CMTD Typical Presentation
Weakness of foot and lower leg mm
Foot deformities - cavus or cavo-varus and hammertoes
“Inverted champagne bottle” due to loss of mm bulk
Later on may occur in hands, which can affect fine motor skills
CMTD Strength Training
Most useful if it begins before nerve degeneration and mm weakness progression to the point of disability
Low-impact or no-impact exercises recommended…
Biking, swimming
CMTD Increased Pressure and Callus Formation…
Lateral border of foot and heel
Head and base of 5th MT
CMTD Shoes
High toe box to accommodate hammer/claw toes
Orthotics can sometimes be used to accommodate pes cavus and equally distribute foot pressure
AFO’s can be used to maintain everyday mobility and prevent injury
CMTD Thumb splints
Can help with hand weakness and loss of fine motor skills
CMTD Assistive Device Use
Should be used before disability sets in because devices may prevent mm strain and reduce mm weakening
Neuromm diseases include…
Disorders of motor nerve
Disorders of NMJ
Disorders of mm
