muscle and nerve disease Flashcards
what is the function of a muscle?
Intricate machine designed to convert chemical energy → mechanical energy
what are the components of this process:
Intricate machine designed to convert chemical energy → mechanical energy
Structural components
Contractile mechanism
Excitation-contraction coupling (ion channels)
Energy system
what are the symptoms of muscle disease?
Weakness of skeletal muscle
Short of breath (respiratory muscles)
Poor swallow / aspiration (bulbar muscles)
Cardiomyopathy
Cramp, pain, stiffness, myoglobinuria
(Babies: poor suck / feeding / failure to thrive / floppy)
what are the signs of muscle disease?
Wasting / hypertrophy
Normal or reduced tone and reflexes
Motor weakness…NOT sensory
what are the investigations for muscle disease
History and examination Creatine Kinase (CK) EMG Muscle biopsy Structure Biochemistry Inflammation Genetic testing
what are congenital classifications of muscle disease?
Structural: muscular dystrophies
Contractile: congenital myopathies
Coupling: channelopathies
Energy: enzymes / mitochondria
what are acquired classifications of muscle disease?
Metabolic (Ca2+, K+)
Endocrine (thyroid, adrenal, vit D)
Inflammatory muscle disease
Iatrogenic: medication (steroids / statins)
are there specific treatments for muscular dystrophies?
no
what is channelopathies?
disorders of Ca2+, Na+, K+ and Cl- channels
often paroxysmal symptoms e.g. periodic paralysis / myotonia
partially treatable
what is metabolic myopathy?
Exercise induced: early = disorders of carbohydrate metabolism
late = disorders of lipid metabolism
Mitochondrial problems
partially treatable
what are Polymyositis and dermatomyositis?
are disorders of the body’s connective tissues, which include tendons, ligaments and the dense sheets of collagen-based tissue that cover the ends of the muscles. These diseases cause swelling and tenderness in the muscles (polymyositis) and sometimes the skin (dermatomyositis).
what separates polymmyositis and dermatomyositis?
Characteristic rash of DM
High CK, autoantibodies, tumour screen (esp DM)
EMG & biopsy
Polymyositis: CD8 cells
Dermato: humeral-mediated, B cells and CD4 cells
what is the treatment for Polymyositis and dermatomyositis (DM)
immunosuppression
what is the clinical presentation myasthenia gravis?
Fatiguable weakness
Ocular: eyelids (ptosis)
muscles of eye movement (diplopia)
Generalised: limbs
bulbar (chew, swallow, talk)
breathing
what are the investigations for myasthenia gravis?
AChR, Anti MuSK antibodies
Neurophysiology (Repetitive stimulation, Jitter)
CT chest (thymoma)