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Neuromuscular disorders, myopathies

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Neuromuscular disorders, myopathies Zsuzsanna Ar nyi Neuromuscular disorders Radiculopathies Plexopathies Mononeuropathies Polyneuropathies Motoneuron diseases ... – PowerPoint PPT presentation

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Title: Neuromuscular disorders, myopathies


1
Neuromuscular disorders, myopathies
  • Zsuzsanna Arányi

2
Neuromuscular disorders
  • Radiculopathies
  • Plexopathies
  • Mononeuropathies
  • Polyneuropathies
  • Motoneuron diseases
  • Disorders of the neuromuscular junction
  • Myopathies

3
Symptoms of muscle disease
  • Muscle pain and fatigue exercise intolerance
  • Proximal and symmetric weakness
  • Waddling gait difficulty of rising from sitting,
    climbing stairs Gowers sign
  • Hyperextension of the knee
  • Increased lordosis of the lumbar spine, scoliosis
  • Contractures, tight Achilles tendons
  • Myopathic face
  • Muscle atrophy pseudohypertrophy
  • Myotonia
  • Tendon reflexes are normal or depressed

4
Diagnosis of muscle diseases
  • Creatinine kinase levels increased in many
    myopathies (sign of muscle fiber necrosis)
  • ENG / EMG differentiation between neurogenic and
    myogenic weakness
  • Muscle biopsy signs of muscle fiber abnormality,
    inflammation, immunostaining of muscle
    constituents
  • Genetic testing

5
Types of muscle diseases
  • Hereditary muscle diseases
  • Muscle dystrophies
  • Muscle channelopathies
  • Mitochondrial myopathies
  • Metabolic myopathies
  • Acquired muscle diseases
  • Inflammatory myopathies
  • Endocrine and toxic myopathies
  • Infectious muscle diseases

6
Muscle dystrophies
  • Hereditary myopathies, characterized by
    progressive weakness and muscle atrophy
  • Genetic defect of proteins constituting the
    sarcolemma-associated cytoskeleton system

7
Sarcolemma-associated cytoskeleton system
8
Duchenne muscular dystrophy
  • Dystrophinopathy
  • First described in 1881- dystrophin gene
    discovered in the early 1980's
  • Cause deficiency of dystrophin, resulting in
    progressive loss of muscle fibers
  • Beckers type reduced amount of dystrophin more
    benign course
  • X-chromosome linked
  • 1 in 3500 live births, occurs in boys, girls are
    carriers

9
Duchenne muscular dystrophy
  • Onset at 3-5 years
  • Initial symptoms difficulty getting up from deep
    position and climbing steps, waddling gait
  • Weakness most pronounced in limb-girdle muscles,
    trunk erectors craniobulbar muscles are spared
  • Skeletal deformities
  • Cardiomyopathy
  • Inability to walk by 9-11 years
  • Death occurs usually in the 3rd decade, from
    respiratory insufficiency

10
Duchenne muscular dystrophy
Gowers sign
11
Duchenne muscular dystrophy
Normal Duchenne
dystrophy
  • Diagnosis
  • Lack of immunostaining of dystrophin in muscle
    biopsy specimen
  • Demonstration of deletion in the dystrophin gene

12
Limb-girdle dystrophies
  • Causes
  • Sarcoglycanopathies
  • Calpain deficiency
  • Caveolin deficiency
  • Dysferlin deficiency etc.
  • Sarcoglycanopathies comprise about 10 of
    autosomal recessive limb-girdle dystrophies
  • a, ß, ?, d sarcoglycans

13
Sarcoglycanopathies
  • Clinical presentation
  • Age of onset and severity is heterogeneous,
    usually starts between 2 and 20 years
  • Clinically often indistinguishable from
    Duchenne-dystrophy
  • No cardiac involvement
  • Diagnosis
  • Normal dystrophin immunostaining, abnormal
    immunostaining with sarcoglycans
  • Genetic examination, where available

14
Sarcoglycanopathies
Sarcoglycanopathy
Normal
15
Myotonic dystrophy
  • Prevalence 1 in 8000
  • Cause CTG repeat expansion in a gene on chr. 19
  • Autosomal dominant inheritance, with anticipation
  • Multisystemic disease
  • Myotonia hyperexcitability of muscle membrane ?
    inability of quick muscle relaxation
  • Progressive muscular weakness and wasting, most
    prominent in cranial and distal muscles
  • Cataracts, frontal balding, testicular atrophy
  • Cardiac abnormalities, mental retardation

16
Myotonic dystrophy
17
Myotonic dystrophy
18
Myotonic dystrophy
19
Facioscapulohumeral dystrophy
  • Prevalence 1 in 20,000
  • Autosomal dominant
  • Age of onset infancy to middle age
  • Progressive muscular weakness and atrophy
    involving the face, scapular, proximal arm and
    peroneal muscles ? myopathic face, winging of
    the scapula, inability to raise the arms, foot
    drop
  • Life span is not significantly affected

20
Facioscapulohumeral dystrophy
21
Facioscapulohumeral dystrophy
22
Muscle channelopathies
23
Myotonia congenita
  • Mutation in the muscle Cl gene
  • Autosomal dominant form Thomsen, autosomal
    recessive form Becker
  • Symptoms
  • Myotonia (hyperexcitability of the muscle
    membrane) muscle stiffness and abnormal muscle
    relaxation, warm-up phenomenon
  • Hypertrophied muscles
  • Therapy phenytoin, mexiletin

24
Myotonia congenita
25
Inflammatory muscle diseases
  • Dermatomyositis
  • Polymyositis
  • Inclusion body myositis
  • Other systemic autoimmun diseases (SLE, Sjögren
    sy. etc.)

26
Dermatomyositis
  • Humorally mediated autoimmune disease affecting
    the muscles and skin (microangiopathy)
  • Symptoms progress over weeks, months
  • Rash on the face, neck
  • Periorbital oedema
  • Pain and weakness of proximal limb muscles, neck
    flexors
  • Dysphagia
  • Cardiac abnormalities, interstitial lung disease
  • Often paraneoplastic

27
Dermatomyositis
28
Polymyositis
  • Cell-mediated immune response against muscle
    fibers
  • Symptoms are similar to DM, no skin involvement
  • Less often paraneoplastic than DM

29
Diagnosis / therapy of DM, PM
  • Blood CK levels are elevated
  • EMG myogenic findings
  • Muscle biopsy inflammation
  • DM perivascular infiltration, mainly in the
    perimysium
  • PM endomysial inflammation
  • Therapy immunosuppression, long-term treatment
    with corticosteroids (1 mg/day)

30
Endocrine and toxic myopathies
  • Toxic myopathies
  • Drugs aimed at reducing blood lipid levels
    statins, clofibrate
  • Corticosteroids
  • Alcohol
  • Heroin

31
Endocrine and toxic myopathies
  • Endocrine myopathies
  • Thyreotoxic myopathy
  • Hypothyreodism
  • Hyperparathyreodism
  • Adrenal insufficiency
  • Hypokalemia

32
Neuromuscular junction
Presynaptic dysfunction Lambert-Eaton syndrome,
botulism Postsynaptic dysfunction Myasthenia
gravis
33
Myasthenia gravis
  • Prevalence 10-15 in 100 000
  • May occur at any age
  • Cause autoimmune response against the ACh
    receptors of the postsynaptic membrane of the
    neuromuscular junction ? abnormal neuromuscular
    transmission ? fatigue and weakness
  • Often associated with thymoma or persistent
    thymus
  • Association with other autoimmune disorders is
    also common (e.g. thyroiditis, rheumatoid
    arthritis etc.)

34
Myasthenia gravis
  • Symptoms
  • Fluctuating weakness, exacerbated by exertion,
    fatigue and improved by rest
  • No atrophy, reflex abnormality, sensory loss
  • Clinical forms
  • Ocular form- ptosis, double vision
  • Bulbar form- dysphagia, dysarthria, weakness of
    chewing
  • Generalized form- weakness of limbs, with
    proximal emphasis

35
Myasthenia gravis
  • Diagnosis
  • Repetitive stimulation
  • Iv. Tensilon test
  • Treatment
  • Cholin-esterase inhibitors (Mestinon)
  • Immunsuppressive treatment corticosteroids
    azathiopirine
  • Thymectomy
  • Plasmapheresis in myasthenic crisis
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