Muscle and Nerve Diseases Flashcards by Robbie Pollock

Image showing the motor pathway

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Muscle converts chemical energy to what?

designed to convert chemical energy → mechanical energy

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What are the components of the process needed to convert chemical energy to mechanical energy?

Structural components
Contractile mechanism
Excitation-contraction coupling (ion channels)
Energy system

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What are the symptoms of msucle disease?

• Weakness of skeletal muscle

^{Short of breath (respiratory muscles)}

^{Poor swallow/aspiration (bulbar muscles)}

Cardiomyopathy
Cramp, pain, stiffness, myoglobinuria - start to destroy muscle and myoglobin is peed out and will turn urine dark brown/bloody

(Babies: poor suck / feeding / failure to thrive / floppy)

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What are the signs of muscle disease?

Wasting/hypertrophy
Normal or reduced tone and reflexes
Motor weakness…NOT sensory

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What investigations can be carried out for muscle disease?

History and examination
Creatine Kinase (CK)
EMG - evaluating and recording the electrical activity produced by skeletal muscles
Muscle biopsy

^Structure

^Biochemistry

^Inflammation

• Genetic testing

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What are the 2 categories that muscle disease can be put into?

congenital/genetic

acquired

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What are some types of genetic/congenital muscle diseases and examples?

Structural: muscular dystrophies

Contractile: congenital myopathies

Coupling: channelopathies

Energy: enzymes/mitochondria

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What are some examples of aquired muscle diseases?

Metabolic (Ca2+, K+)

Endocrine (thyroid, adrenal, vit D)

Inflammatory muscle disease

Iatrogenic: medication (steroids / statins)

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When do muscular dystrophies start?

young or old onset

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What is the severity of muscular dystrophies?

Progressive, variable severity

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What happens in muscular dystrophies?

Cell degeneration (often high CK)

muscle diseases that results in increasing weakening and breakdown of skeletal muscles over time

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What are some examples of muscular dystrophies?

Duchenne’s/Becker’s (dystrophin) - most common

Facioscapulohumeral/oculopharyngeal/limb girdle

Myotonic dystrophy (cataracts)

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What is the treatment of muscular dystrophies?

No specific treatments yet

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What cannels do Channelopathies effect and what are the symptoms? and treatment?

disorders of Ca2+, Na+, K+ and Cl- channels

often paroxysmal symptoms e.g. periodic paralysis / myotonia - toruble relaxing muscle

partially treatable - drugs can alter channels

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How are energy production (metabolic myopathy) induced and what is the reason?

Exercise induced: early = disorders of carbohydrate metabolism
late = disorders of lipid metabolism

Mitochondrial problems

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Are problems with energy production treatable?

partially treatable - alter diet

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WHat are the 2 types of inflammatory muscle disease and their difference?

Polymyositis vs dermatomyositis (DM)

DM also comes with a rash

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WHat are the features of inflammatory muscle disease?

Any age

Acute or subacute, painful, weak muscles

Characteristic rash of DM

How can inflammatory muscle diseases be diagnosed and investigated?

High CK, autoantibodies, tumour screen (esp DM)
EMG & biopsy
Polymyositis: CD8 cells
Dermato: humeral-mediated, B cells and CD4 cells

What is the treatment of inflammatory muscle diseases?

immunosuppresion

What else may be present alongside DM apart from a rash

Often all have a underlying tumour in DM – 50%

If you treat DM then miss tumour then problem

Where do disorders of neuromuscular junction effect?

How is ACh taken up from the synaptic cleft?

When you release ACH into synaptic cleft there is a recycling system and cholinesterase is what dose this

What is Myasthenia Gravis?

affects neuromuscular junction a rare long-term condition that causes muscle weakness

What is the clinical presentation of Myasthenia Gravis?

Clinical presentation = Fatiguable weakness: - Ocular: eyelids (ptosis) muscles of eye movement (diplopia) - Generalised: limbs bulbar (chew, swallow, talk) breathing

What investigations are carried out for Myasthenia Gravis?

AChR, Anti MuSK antibodies - looking ofr the antibody that is causing it Neurophysiology (Repetitive stimulation, Jitter) CT chest (10% have an underlying thymoma)

What is the treatment of myathenia gravis?

* Symptomatic - Acetylcholinesterase inhibitor (pyridostigmine) - inhibits acetylcholinesterase from breaking down acetylcholine into choline and acetate, thereby increasing both the level and duration of action of the neurotransmitter acetylcholine * Immunosuppression ^{Prednisolone - block cholinesterase so much more ACH but not removing antibody so use an immunosuppressant to try and reduce it} ^{Steroid saving agent (e.g. azathioprine)} * Immunoglobulin/plasma exchange * Thymectomy

Where does peripheral nerve disease affect?

What do peripheral nerves consist of?

•Sensory axons: - Small fibres (pain + temperature) - Large fibres (joint position sense + vibration) * Motor axons * Autonomic axons * Nerve sheath (myelin)

Whata re the 3 different types of nerve disease?

* Root disease * Lesion of individual peripheral nerve ^{Compressive/entrapment neuropathy} ^{Vasculitic (mononeuritis multiplex)} • Generalised peripheral neuropathy ^{Motor/sensory/both} ^{+/- autonomic features}

Generalised peripheral neuropathy can either be __________ or \_\_\_\_\_\_\_\_\_

Axonal vs demyelinating

WHat are the causes of generalised peripheral neuropathy?

Hereditary Metabolic: diabetes, alcohol, renal failure, B12 Toxic: drugs Infectious: Lyme, HIV, leprosy Malignancy: paraneoplastic Inflammatory demyelinating: ^{Acute = Guillain Barre syndrome} ^{Chronic = chronic inflammatory demyelinating polyneuropathy}

What are the symptoms and signs of nerve root nerve disease?

Myotomal wasting and weakness Reflex change Dermatomal sensory change symptoms and signs tend to be quite localised to the are of the nerve root

What are the symptoms and signs of individual nerve disease?

Wasting and weakness of innervated muscle Specific sensory change

What are the symptoms and signs of generalised peripheral neuropathy

Sensory and motor symptoms, usually starting distally and moving proximally

What are the investigations for nerve disease?

Investigations depend on the cause: * Blood tests * Genetic analysis * Nerve Conduction Studies * Lumbar puncture (CSF analysis) * Nerve biopsy (nb sensory nerve)

What is the treatment of nerve disease?

Treat the cause eg stop drug, surgery, immunoglob

Where do disorders of the anterior horn cell effect?

As the anterior horn cell is affected, what else is therefore effected?

LMN

What is motor neuron disease?

an uncommon condition that affects the brain and nerves. It causes weakness that gets worse over time. It's nearly always fatal and can significantly shorten life expectancy, but some people live with it for many years

Where does motor neuron disease spread to and from?

Usually limb → bulbar (swallowing, speech etc)→ respiratory

What are the signs of motor neuron disease?

combination of UMN and LMN signs: LMN = muscle fasciculations, wasting, weakness UMN = increased tone, brisk reflexes No sensory involvement 10%+ have cognitive decline

What is the prognosis of motor neuron disease?

Median 3-5 years from symptom onset, 2-3 years from diagnosis 50% die within 14 months of diagnosis

What is the diagnosis of motor neuron disease?

Basically a clinical diagnosis Unique combination of UMN + LMN signs with no sensory signs EMG - an electrodiagnostic medicine technique for evaluating and recording the electrical activity produced by skeletal muscles

What is the treatment of motor neuron disease?

Supportive - important: PEG feed, non invasive ventilation, physio, OT, SALT, care Riluzole - not great Anticipatory / palliative care