Inherited muscle disorders

Question 1

Name some common signs of muscle disorder

Answer 1

Weakness (proximal, symmetricaal, persistant), greater than wasting, normal sensation, normal tendon reflexes

Contractures

Question 2

What is myotonia?

Answer 2

WHere the relaxation of muscles is impaired

Question 3

What is rhabdomyolysis?

Answer 3

Breakdown of damaged skeletal muscle

Question 4

What is cardiomyopathy

Answer 4

Disease of the heart muscle

Question 5

What does EMG stand for

Answer 5

Electromyography - used as a diagnostic step

Question 6

What particular chemical will be raised in muscle disorder?

Answer 6

Creatine kinase (also endocrine tests)

Question 7

WHat antibodies would be raised with muscle disorders?

Answer 7

CTD: ANA, Rheumatoid factor, Anti DNA, anti ro/la

Polymyositis: Anti Jo1, Dermatomyositis anti Mi2

Question 8

What is dystrophin?

Answer 8

protein found in the muscle fibre membrane

Question 9

What muscular dystrophies are X-linked

Answer 9

Duchenne and becker,

Emery-dreifuss syndrome

Question 10

What Muscular dystrophies are autosomal domiant?

Answer 10

Fasioscapulohumeral muscular dystrophy, myotonic muscular dystrophy, scapuloperoneal dystrophy, oculopharyngeal, limb girdle (LGMD1) and distal

Question 11

How does Duchenne muscular dystrophy presenr

Answer 11

X-linked, recessive, dystrophin mutation onset 3-5 years, progressive muscle weakness with walking difficulties. Waddling gait and gowers sign

Question 12

What is gowers sign?

Answer 12

When squating, patient has to use their hands to “walk” up their body

Question 13

What are the clinical features of DUchenne dystrophy?

Answer 13

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

Question 14

What does dystrophin do?

Answer 14

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

Question 15

What are the presentations of becker muscular dystrophy?

Answer 15

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

Question 16

is DUchenne MD more common than Becker

Answer 16

Yes, but both are much more likely in males

Question 17

How does Facioscapulohumeral dystrophy present

Note there are 2 types (FSHD1 and FSHD2)

Answer 17

Weakness of: face (ptosis, cant whistle), upper extremity, scapular winging, biceps, peroneal muscles (foot drop)

Also cardiac, hearing, epilepsy, learning disabilities

Question 18

WHat is the commonest form of adult muscular dystrophy?

Answer 18

Myotonic MD

Question 19

How does myotonic MD present

Answer 19

Autosomal domiant, muscular wasting, myotonia, cataracts, cardiac issues, endocrine changes (DM1 and DM2)

Frontal balding, sleep apnoea, hypersomnolence (sleepiness) diabetes and hypogonadism

Question 20

What is myotonia?

Answer 20

Inability of muscle to relax after contraction

Question 21

What is sleep apnoea

Answer 21

Walls of throat relax and narrow in sleep.

Question 22

What is hypogonadism

Answer 22

When the body does not produce enough of hormoned for puberty

Question 23

What is the difference between type 1 and 2 myotonic muscular dystrophy

Answer 23

Generally type 1 is more serious, with anticipation, while type 2 isnt

Question 24

What does ataxia mean

Answer 24

Disturbance of coordination and/or gait and/or speech

Question 25

What are the two types of ataxic gait

Answer 25

Cerebellar and sensory

Question 26

How can be cerebellar ataxia arise?

Answer 26

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

Question 27

Is friedreichs ataxia autosomal recessive, or dominant?

Answer 27

recessive

Question 28

What are the clinical features of freidreich ataxia

Answer 28

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.