muscular dystrophies Flashcards
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
