Muscle and Nerve Diseases Flashcards
What energies do muscles convert?
Chemical energy into mechanical energy
What are some components required for a muscle to convert chemical energy into physical energy?
Structural components
Contractile mechanism
Excitation-contraction coupling (ion channels)
Energy system
What are some symptoms of muscle disease?
Weakness of skeletal muscles
Shortness of breath if respiratory muscles
Poor swallow/aspiration if bulbar muscles
Cardiomyopathy
Cramp
Pain
Stiffness
Myoglobinuria
What are signs of muscle disease?
Wasting/hypertrophy
Normal or reduced tone and reflexes
Motor weakness, no sensory reflex
What investigations are done for muscle disease?
History and examination
Creatine kinase (CK)
EMG
Muscle biopsy (structure, biochemistry, inflammation)
Genetic testing
What are the different categories of congenital/genetic muscle diseases?
Structural (muscular dystrophies)
Contractile (congenital myopathies)
Coupling (channelopathies)
Energy (enzymes/mitochrondia)
What are the different classifications of acquired muscles diseases?
Metabolic (Ca, K)
Endocrine (thyroid, adrenal, vitamin D)
Inflammatory muscle disease
Iatrogenic (medication such as steroids or statins)
Is CK often high or low in muscular dystrophies?
High due to cell degeneration
What are examples of mucular dystrophies?
Duchenne’s/Becker’s (dystrophin)
Fascioscapulohumeral/oculopharyngeal/limb girdle
Myotonic dystrophy (cataracts)
Are there any specific treatments for muscular dystrophies yet?
No
What are channelopathies?
Disorders of Ca, Na, K and Cl channels
What are common symptoms of channelopathies?
Paroxysmal symptoms such as periodic paralysis/myotonia
What is myotonia?
Inability to relax voluntary muscles after vigorous effort
What are energy production muscle disorders also known as?
Metabolic myopathy
What is are metabolic myopathy disorders induced by?
Exercise induced
Early are disorders of carbohydrate metabolism
Late are disorders of lipid metabolism
Mitochondrial problems
What are inflammatory muscle diseases also called?
Inflammatory myopathies
What are examples of inflammatory myopathies?
Polymyositis
Dermatomyositis (DM)
What is the clinical presentation of inflammatory myopathies?
Painful, weak muscles
Characteristic rash of DM
What is seen in blood tests for inflammatory myopathies?
High CK
Autoantibodies
What investigations are done for inflammatory myopathies?
EMG
Biopsy
How does the biopsy for polymyositis and dermatomyositis differ?
Polymyositis shows CD8 cells
Dermatomyositis shows humeral-mediated, B cells and and CD4 cells
What is the treatment for inflammatory myopathies?
Immunosuppression
What is an example of a disorder of the neuromuscular junction?
Myasthenia gravis
What is the clinical presentation of myasthenia gravis?
Fatiguable weakness:
Ptosis
Diplopia
Limb weakness
Bulbar weakness (chew, swallow, talk)
Breathing weakness
What investigations are done for myasthenia gravis?
Blood test (AChR, anti MuSK antibodies)
Neurophysiology (repetative stimulation, jitter)
CT chest (thymoma)
What is the treatment for myasthenia gravis?
Symptomatic treatment - acetycholinesterase inhibitory (pyridostigmine)
Immunosuppresion - prednisolone, steroid saving agent (such as azathioprine)
Thymectomy (operation to remove thymus)
What is the operation to remove the thymus called?
Thymectomy
What does the term “peripheral nerves” consist of?
Sensory axons (small fibre (pain and temperature) and large fibre (joint position sense and vibration))
Motor axons
Autonomic axons
Nerve sheath (myelin)
What are examples of diseases of peripheral nerves?
Root disease
Lesion of individual peripheral nerve
Generalised peripheral neuropathy
What is the clinical presentation of root disease?
Myotomal wasting and weakness
Reflex change
Dermatomal sensory change
What do lesions of individual peripheral nerves cause?
Compressive/entraopment neuropathy
Vasculitis
What is the clinical presentation of lesions of individual peripheral nerves?
Wasting and weakness of innervated muscle
Specific sensory change
What are the 2 different kinds of peripheral neuropathy?
Axonal loss or demyelination
What are some causes of peripheral neuropathy?
Genetic
Metabolic (diabetes, alcohol, renal failure, B12)
Toxic (drugs)
Infectious (lyme, HIV, leprosy)
Malignancy (demyelinating)
Inflammatory demyelinating (acute is Guillain Barre syndrome, chronic is chronic inflammatory demyelinating polyneuropathy)
What is acute peripheral neuropathy due to inflammation called?
Guillain Barre syndrome
What is chronic peripheral neuropathy due to inflammation called?
Inflammatory demyelinating polyneuropathy
What is the clinical presentation of peripheral neuropathy?
Sensory and motor symptoms
Usuallt starting distally and moving proximally
What investigations are done for nerve disease?
Blood tests
Genetic analysis
Nerve conduction studies
Lumbar puncture (CSF analysis)
Nerve biopsy
What is the general treatment for nerve diseases?
Treat the cause (such as stop drug, surgery, immunoglob)
What is an example of a disorder of anterior horn cell?
Motor neuron disease (MND)
What does MND stand for?
Motor neuron disease
What is motor neuron disease also known as?
Amyotrophic lateral sclerosis (ALS)
What does ALS stand for?
Amyotrophic lateral sclerosis
What does MND usually first affect?
Limb, then bulbar muscles, then respiratory
Does MND show UMN or LMN signs?
Combination of both UMN and LMN signs
What are some LMN signs of MND?
Muscle fasciculations, wasting and weakness
What are some UMN signs of MND?
Increased tone, brisk reflexes
Does motor neuron disease have any sensory involvement?
No sensory involvement
Other than physical symptoms, what else can MND cause?
10% have cognitive decline
What is the prognosis of MND?
Median 3-5 years from symptom onset, 2-3 years from diagnosis
50% die within 14 months of diagnosis
How is MND diagnosied?
Unique combination of UMN and LMN signs with no sensory signs
EMG
What is the treatment for MND?
Supportive (PEG feed, non-invasive ventilation, physio, OT, SALT, care)
Riluzole
Anticipatory/palliative care
