58 Musculoskeletal 3 Flashcards
Which investigations are use in muscle diseases? (5).
Clinical exam. Electromyograph. Nerve conductions studies. MRI. Serum/Blood investigations.
Name two diseases of the basal lamina:
Merlin deficiency.
Integrin VII deficiency (limb girdle syndrome).
What is motor neurone disease?
Which cells does it involve? (3).
Widespread degeneration of motor neurones.
Anterior horn cells, brain stem nuclei, Betz cells.
What are the signs of motor neurone disease? (4).
Fasciculation.
Wasting.
Spasticity.
Brisk reflexes.
Which gene is responsible for spinal muscular atrophy?
What is the course of SMA?
SMN1 gene.
Begins very young to aged 15.
3 severities: very early death to adult survival with disability.
What is the genetic and molecular basis of Duchenne muscular dystrophy?
X linked recessive disorder.
Dystrophin protein - uncontrolled Ca entry into cell.
When and how does Duchenne muscular dystrophy present?
2-4 years of age.
Proximal muscle weakness with calf muscle hypertrophy. Elevated CPK.
What is the prognosis for Duchenne muscular dystrophy?
Wheelchair by 12.
Dead by 25 due to cardiomyopathy.
What is Becker dystrophy?
Variant of DMD, with later onset and slower progression.
Which proteins are affected in limb girdle dystrophy? (3)
Nuclear membrane related proteins.
Emerins, laminin A/C.
What is limb girdle dystrophy?
Genetic basis?
Dystrophy of pelvic/shoulder girdle.
Autosomal recessive condition.
What is the genetic defect seen in facioscapulohumeral dystrophy?
Fibre changes?
Large telomeric deletion.
Autosomal dominant.
Angular, atrophic fibres.
What are the effects of facioscapulohumeral dystrophy?
Associated with?
Weakness of face + shoulder.
Progressive deafness, retinal vasculopathy.
What is the genetic basis of myotonic dystrophy?
CTG repeat expansion in X19.
Autosomal dominant.
When is the onset of myotonic dystrophy?
What are the effects? (4)
Onset 20-30 years.
Weakness of face, limb girdle + proximal muscles.
Myotonia (persistent contraction after voluntary effort has ceased).
What are the histological changes seen in myotonic dystrophy? (4)
Type 1 fibre atrophy.
Type 2 fibre hypertrophy (compensation).
Central nuclei.
Motheaten, targetoid + ring fibres.
What is polymyositis?
How does it present?
Inflammatory muscle disorder.
Weakness, pain and swelling of proximal muscles.
What is dermatomyositis?
Complement deposition in capillaries causes muscle ischaemia.
What are the histological findings in polymyositis and dermatomyositis?
Perimysial inflammation with B cells.
Endomysial inflammation with T cells.
How is polymyositis treated?
Corticosteroids and azathioprine.
What is inclusion body myositis? (3)
Clinically like polymyositis. But…
Shows filamentous intracellular inclusions.
Responds poorly to corticosteroid + azathioprine.
How do congenital myopathies present? (2)
Name two:
Hypotonia + floppiness in infancy.
Congenital fibre type disproportion.
Congenital nuclear myopathy.
What is the cause of malignant hyperthermia?
Prolonged rise in intracellular calcium ions.
How does myasthenia graves present?
Age/sex, effects (3)
Female 20-30.
Fluctuating weakness affecting ocular, bulbar and proximal muscles.
What is the molecular basis of myasthenia graves?
What is it commonly associated with?
IgG against ACh receptor proteins.
Thymus hyperplasia.
What is Lambert-Eaton myasthenic syndrome?
How does it present?
Paraneoplastic disorder associated with small cell carcinoma of lung (oat cell cancer).
Weakness of proximal muscle and girdles.
What is the molecular basis of Lambert-Eaton myasthenia syndrome?
IgG binds to pre-synaptic calcium channels, preventing release of ACh.
What changes are seen on muscle biopsy in myasthenia syndromes?
No specific/little changes.
Where are muscle biopsies taken from? (3).
Deltoid.
Biceps.
Quadriceps.
What is core disease:
Genetics:
Histology:
Presentation?
Autosomal dominant.
Cores of inactivity to NADH-Tr in type 1 fibres.
When child starts to walk.
How does nemaline myopathy present? (4)
Genetics?
Neonatal hypotonia.
Respiratory insufficiency.
High arched palate.
Kyphoscoliosis.
Autosomal recessive.
What histological changes are seen in mitochondrial myopathies?
Whorled cristae.
Accumulation of lipid on Oil Red O stain.
Which drugs can induce myopathy? (3).
Statins.
Steroid.
Heroin/ecstasy:
What type of myopathy does heroin and ecstasy precipitate?
Features? (3).
Acute necrotising myopathy.
Rhabdomyolysis.
Myoglobinuria.
Renal failure.
