Inherited muscle disorders Flashcards
Name some common signs of muscle disorder
Weakness (proximal, symmetricaal, persistant), greater than wasting, normal sensation, normal tendon reflexes
Contractures
What is myotonia?
WHere the relaxation of muscles is impaired
What is rhabdomyolysis?
Breakdown of damaged skeletal muscle
What is cardiomyopathy
Disease of the heart muscle
What does EMG stand for
Electromyography - used as a diagnostic step
What particular chemical will be raised in muscle disorder?
Creatine kinase (also endocrine tests)
WHat antibodies would be raised with muscle disorders?
CTD: ANA, Rheumatoid factor, Anti DNA, anti ro/la
Polymyositis: Anti Jo1, Dermatomyositis anti Mi2
What is dystrophin?
protein found in the muscle fibre membrane
What muscular dystrophies are X-linked
Duchenne and becker,
Emery-dreifuss syndrome
What Muscular dystrophies are autosomal domiant?
Fasioscapulohumeral muscular dystrophy, myotonic muscular dystrophy, scapuloperoneal dystrophy, oculopharyngeal, limb girdle (LGMD1) and distal
How does Duchenne muscular dystrophy presenr
X-linked, recessive, dystrophin mutation onset 3-5 years, progressive muscle weakness with walking difficulties. Waddling gait and gowers sign
What is gowers sign?
When squating, patient has to use their hands to “walk” up their body
What are the clinical features of DUchenne dystrophy?
Muscle pseudohypertrophy (especially calf) due to replacement of muscel with collagen and adipose
Scoliosis, contractures, dilated cardiomyopathy, low IQ, premature death via cardiac/resp failure
What does dystrophin do?
Stablises muscle membrane during contractionrelaxation, links extracellular matrix and intracellular cytoskeleton
Wnables muscle fibres to differentiate into fast glycolytic type, organisation of postsynaptic membrane and AChRs
What are the presentations of becker muscular dystrophy?
X limked recessive, in frame dystrophin mutations. Onset >7yrs, slowly progressive, proximal weakness initially.
toe walking, Gower’s sign, severity correlated with muscle dystrophin levels
Calf hyertrophy, cardiomyopathy, resp muscle invlvement, scoliosis, mild learning disabilities
is DUchenne MD more common than Becker
Yes, but both are much more likely in males
How does Facioscapulohumeral dystrophy present
Note there are 2 types (FSHD1 and FSHD2)
Weakness of: face (ptosis, cant whistle), upper extremity, scapular winging, biceps, peroneal muscles (foot drop)
Also cardiac, hearing, epilepsy, learning disabilities
WHat is the commonest form of adult muscular dystrophy?
Myotonic MD
How does myotonic MD present
Autosomal domiant, muscular wasting, myotonia, cataracts, cardiac issues, endocrine changes (DM1 and DM2)
Frontal balding, sleep apnoea, hypersomnolence (sleepiness) diabetes and hypogonadism
What is myotonia?
Inability of muscle to relax after contraction
What is sleep apnoea
Walls of throat relax and narrow in sleep.
What is hypogonadism
When the body does not produce enough of hormoned for puberty
What is the difference between type 1 and 2 myotonic muscular dystrophy
Generally type 1 is more serious, with anticipation, while type 2 isnt
What does ataxia mean
Disturbance of coordination and/or gait and/or speech
What are the two types of ataxic gait
Cerebellar and sensory
How can be cerebellar ataxia arise?
Acquired - Vascular, drugs/toxins, inflammatory, tumours, hypothyroidism, deficiecy, prions, paraneoplastic
Hereditary : Autosomal recessive (friedreichs) Autosomal dominant cerebellar ataia (ADCA)
Autosomal dominant episodic ataxia, mitochondial disorders
Is friedreichs ataxia autosomal recessive, or dominant?
recessive
What are the clinical features of freidreich ataxia
Gait and limb ataxia, onset before 25 (usually 10) pes cavus/high arch
Areflexia in lower limb, pyramidal weakness, Impaired joint position sense, WHeelcahir dependence, hypertrophic cardiomyopathy, scoliosis, diabetes.
