MYOPATHIES Flashcards
What characterises a myopathy?
Weakness most often proximal
What are the clinical features of myopathies?
Weakness Loss of tone (often hard to distinguish) Wasting Preserved reflexes Myotonia Pain (rarely)
What is myotonia?
Persistence of contraction during attempted relaxation, often for several seconds.
How might you distinguish a lower motor neuron lesion from a myopathy?
Preservation of reflexes
Which of the myopathies display myotonia?
Myotonic distrophy
Paramyotonia congenita
Hyperkalaemic periodic paralysis
Congenital myotonia.
What are the X-linked myopathies?
Duchenne’s muscular dystrophy
Becker’s muscular dystrophy
Emery-Dreifuss dystrophy
What are the autosomal dominant myopathies?
Fascio-scapulo-humeral dystrophy
Scapulo-peroneal dystrophy
Myotonic dystrophy
What are the mitochondrial inherited myopathies?
Chronic progressive external opthalmoplegia
Kearns-Sayre syndrome
What is the underlying pathology of Duchenne muscular dystrophy?
Absence of dystrophin, a protein vital for connecting cytoskeleton of muscle to extracellular matrix.
By what age does Duchenne muscular dystrophy become apparent?
3-4
By what age is a child with Duchenne muscular dystrophy usually wheelchair bound?
10
What is the mean life expectancy of someone with Duchenne muscular dystrophy?
20
What complication will most patients with Duchenne muscular dystrophy die of?
Respiratory failure
Cardiomyopathy
Usually die in the third decade
What are the clinical features of Duchenne muscular dystrophy?
Initial proximal muscle weakness Pseudohypertrophy of calves due to accumulation of fat and connective tissue Gower's sign Waddling gait Difficulty standing up
What is Gower’s sign with reference to muscular dystrophy?
Patient attempts to climb their own legs when rising to an erect position.
What will blood tests of someone with Duchenne muscular dystrophy show?
Grossly elevated creatinine kinase.
What are the managements option for Duchenne muscular dystrophy?
Management is supportive
Steroids may provide short term improvement
What is the underlying pathology of Becker’s muscular dystrophy?
Altered dystrophin (as opposed to absent dystrophin in Duchenne)
When do the symptoms of Becker’s muscular dystrophy begin?
Around the age of 10