muscular dystrophies Flashcards
(17 cards)
definition of muscular dystrophies
group of inherited diseases characterised by progressive muscle degeneration and weakness
usually caused by defective/absent glycoproteins eg dystrophin in muscle membrane
what is the most common muscular dystrophy
duchenne muscular dystrophy - X linked
lose ability to walk by 12 and need vent support by 20yes
signs suggestive of DMD
- imbalance of lower limb strength
- delayed motor milestones,
- frequent falls,
- abnormal gait,
- muscle pain,
- calf hypertrophy,
- speech and language delay,
- difficulty with jumping, running, climbing steps, and rising from the floor
- lower extremity musculotendinous contractures
- deminished muscle tone and deep tendon reflexes
- normal sensation
- gower’s sign
Ix for DMD
creatinine kinase - high
genetic testing - Xp21 mutation may be present in DMD and Becker muscular dystrophy
mx of DMD at ambulatory stage
- MDT - sx mx, prolong func and QOL
- steroid - oral pred
- physio
- psychological care
- measure FVC annually
- surgery for musculotendinous contractures eg achilles - rarely recommended now
what are the different muscular dystrophies
X-linked muscular dystrophies
- Duchenne
- Becker
- Emery-Dreifuss
Limb-girdle muscular dystrophies[2]
Facioscapulohumeral muscular dystrophy
Myotonic dystrophy
Congenital muscular dystrophies.
Spinal muscular atrophy (SMA)
RFs for muscular dystrophy
family hx
male
benefit of steroid in DMD
- delaying loss of ambulation;
- preservation of respiratory function (delaying the need for mechanical ventilation);
- avoiding or delaying scoliosis surgery;
- delaying the onset of cardiomyopathy;
- preservation of upper limb function;
- increased survival
mx of DMD in non-ambulatory phase
- steroid, physio, exercise
- psych and neuropalliative care
- OT
- resp mx
- ?surgery for scoliosis
- if cardiac sx or** age 10 and above** - cardioprotective drugs (ACEi) prophlactically + beta-blocker when sx
mx for DMD for late non-ambulatory
- steroid + physio
- psych
- assisted ventilation
- cardioprotection
- consider rx for rhythm abnormalitis
- Left ventricular assist device
- gastrostomy tube if required
when do you need resp support in DMD
Nocturnal Non-invasive ventilation is introduced for
* symptomatic for nocturnal hypoventilation with some combination of fatigue, morning headaches, daytime drowsiness, frequent nocturnal awakenings, and dyspnoea
* forced vital capacity (FVC) below 50% predicted or maximum inspiratory pressure below 60 cm H₂O.
daytime NIV
* (SpO₂) below 95%,
* partial pressure of CO₂ above 45 mmHg,
* symptoms of dyspnoea when awake
lung volume recruitment self-inflating manual ventilation bag or a mechanical insufflation-exsufflation device is used to provide deep lung inflation beyond the patient’s inspiratory capacity once or twice daily
* FVC is 60% predicted or less
manual and mech assisted cough when
* FVC less than 50% predicted
* Peak flow less than 270
* maximum expiratory pressure is less than 60 cm H₂O.
when is tracheostomy required in DMD
rarely when have other resp support - needed if:
* patient preference,
* inability to use non-invasive ventilation (e.g., due to cognitive impairment),
* three failed extubation attempts during a critical illness despite optimum use of non-invasive ventilation and mechanically assisted cough,
* ailure of non-invasive methods of cough assistance to prevent aspiration.
mx for spinal muscular atrophy
- psychosocial and neuropalliative care
- symptom mx
3.
complications of DMD
resp failure
loss of mobility
osteoporosis - steroids
vertebral compression fractures
wht loss/ malnutrition
sexual dysfunction
impaired growth
delayed puberty
constipation
cardiac failure
GORD
gastroparesis
bladder dysfunction
excessive daytime sleepiness and morning headaches
adrenal insufficiency
monitoring for muscular dystrophy
see every 6mo - review function, strength, range of movement
monitor BP and urine glucose while on steroids
FVC annually in DMD
non-ambulatory: seated FVC, maximum inspiratory and expiratory pressures, assisted peak cough flow, and blood oxyhaemoglobin saturation by pulse oximetry (SpO₂) should be measured at least every 6 months
ECG
cardiac MRI
height every 6mo until attained final height - non standing height using arm span, ulnar length, tibia length, knee height, and segmentally measured recumbent length
assess pubertal status every 6mo starting age 9
nutrition every 6mo
bone health - lateral spine XR every 1-2yrs when on steroids, every 2-3yrs otherwise
monitor for scoliosis
screen for mental health at every visit
Px of muscular dystrophy
DMD is life limiting - LE is 41
cant walk by 12yrs
cardiomyopathy by 18yrs
vent support by 20 yrs
px of other dystrophies varies
px of spinal muscular atrophy
earlier onset of sx is associated with shorter survival
number of copies of SMN2 gene predicts survival and disease severity
type 1 has worst px - months-yrs
SMA 2 decades
SMA 3 normal LE
