Muscle and Nerve Disease Flashcards
What are the main components of the motor system?
UMN, anterior horn cell, LMN, nerve ending, ACh, ACh receptor, NMJ
What is the main function of muscle?
Contraction and relaxation
Intricate machine designed to convert chemical energy to mechanical energy
What are the main parts of the muscle structure?
Structural components, Excitation-contraction coupling, energy production by breakdown of glycogen and fatty acids, and contractile mechanism (myosin fibres)
What are some symptoms of muscle disease?
Weakness of skeletal muscle - resp. and swallowing is important
Cardiac symptoms
Cramps/ muscle pain and stiffness
Myoglobinuria as breakdown product in urea
Babies - floppy, poor suck, feeding issues
What is used for investigation of muscle disease?
History and exam
Bloods - creatine kinase CK, electromyography (EMG), muscle biopsy, and genetic testing
What are some congenital/ genetic cause for muscle disease?
Contractile - congenital myopathies
Structural - muscular dystrophies
Coupling - channelopathies
Energy - metabolic myopathies
What are some acquired causes of muscle disease?
Electrolyte disturbance - esp. K+
Endocrine - thyroid, adrenal, Vit D deficiency
Autoimmune inflammatory muscle disease
Iatrogenic - medication (steroids and statins)
What are the 2 types of inflammatory muscle disease?
Polymyositis vs dermatomyositis (DM)
Describe inflammatory muscle disease
Autoimmune, any age, acute or subacute, painful, weak muscles
Characteristic rash of DM
High CK, autoantibodies and tumour screen needed for DM
What is used for diagnosis and treatment of inflammatory muscle disease?
EMG and biopsy
Treatment is immunosuppression
What is myasthenia gravis?
A neuromuscular junction disorder leading to weakness of skeletal muscles
What is the clinical presentation of myasthenia gravis?
Fatigable weakness
Ocular - ptosis and diplopia
Generalised - limbs, bulbar (chew, swallow, talk) and breathing
What is used for investigation of myasthenia gravis?
ACh receptor or anti-MuSK antibodies
Neurophysiology
CT chest
What is used for symptomatic treatment of myasthenia gravis?
Cholinesterase inhibitors
What treatment is used for disease modifying in myasthenia gravis?
Immunoglobulin/ plasma exchange, steroids, steroids sparing immunosuppression, thymectomy
What does a peripheral nerve consist of?
Axons - sensory (small for pain and temp. and large fibres for joint perception and vibration), motor and autonomic
Nerve sheath - myelin
What is a root disease which causes peripheral nerve disease?
Commonly degenerative disc disease
How does a lesion of individual peripheral nerve cause peripheral nerve disease?
Compressive/ entrapment neuropathy
Vasculitis - mononeuritis multiplex
What can cause peripheral nerve disease?
Root disease
Lesion of individual peripheral nerve
Generalised peripheral neuropathy - motor/sensory or both and possible autonomic features
What are the 2 types of generalised peripheral neuropathy?
Axonal vs demyelinated
What are the causes for generalised peripheral neuropathy?
Hereditary, metabolic (diabetes and alcohol), toxic - drugs, infections, malignancy - paraneoplastic and inflammatory
What are the symptoms of peripheral nerve disease?
Sensory - loss of sensation, abnormal sensation and pain
Motor - muscle thinning and weakness
Autonomic - skin changes, BP, bowel and bladder
What are some signs of peripheral nerve disease?
Sensory
Motor - LMN
Distribution - root (myotome/ dermatome), single nerve, generalised nerve so distal first
What investigations are used in peripheral nerve disease?
Blood tests, nerve conduction studies/EMG, lumbar puncture, nerve biopsy and genetic analysis
What is the treatment for peripheral nerve disease?
Treat the cause
Stop drug, surgery and immunoglobulin
What is motor neuron disease affecting in the spinal cord?
Anterior horn cell disease
Describe motor neuron disease
Amyotrophic lateral sclerosis
Usually a limb first then progresses quickly to bulbar then resp.
Prognosis is median 3-5 years from onset
What are the signs of motor neuron disease?
Combination of LMN and UMN signs
LMN - muscle fasciculations, wasting, weakness
UMN - spasticity, brisk reflexes and extensor plantar
No sensory involvement
How is motor neuron disease diagnosed?
Clinical - combination of UMN and LMN signs and no sensory signs
EMG
Genetics
What is the treatment for motor neuron disease?
Supportive - physio, OT, SALT, PEG feed, non-invasive ventilation, care
Riluzole - glutamate antagonist
Anticipatory/ palliative care
