Muscle and Nerve Disease Flashcards
Define muscle
An intricate machine designed to convert chemical energy to mechanical energy
What is the components of muscle to allow it to perform its function
Excitation-contraction coupling
The contractile mechanism
Structural components
The energy system
What is symptoms of muscle disease
Poor suck / feeding / failure to thrive / floppy
Weakness of skeletal muscle
Short of breath (respiratory muscles)
Poor swallow (aspiration)
Cardiomyopathy
Cramp, pain, myoglobinuria
What is signs of muscle disease
Wasting
Hypertrophy (due to overuse)
Normal or reduced tone and reflexes
Motor weakness
(not sensory)
What sign is seen in myoglobinura (breakdown of muscle into myoglobin)
Excreted urine is black
What investigations take place in muscle disease
History and examination
CK - blood test
EMG - electrical stimulation to check id muscle working
Muscle biopsy (Structure, Biochemistry, Inflammation)
Genetic testing
Why do you test for CK in the blood
Is a muscle enzyme and elevation shows muscle disease is present
What is 6 different muscle disease classifications
Muscular dystrophies
Channelopathies
Metabolic muscle disease
Inflammatory muscle disease
Congenital myopathies
Iatrogenic - medication
Name all the proteins involved in the muscle muscular apparatus attaching the extracellular matrix to the intracellular matrix of the muscle in order to make myosin fibres contract
Laminin
Dystroglycan complex
Sacroglycan complex
Dystophin
Actin
Myosin fibrils
What is life threatening muscle disease symptoms and progressions
Respiratory muscles causing shortness of breath resulting in hypoventilation
Poor swallowing leading to aspiration pneumonia
cardiomyopathy leading to CVD and arrhythmias
What occurs if anything goes wrong with any of the protein apparatus linking the extracellular and intracellular matrix of the muscle
End up with a muscular disease
What is the cause of muscular dystrophies
Genetic,
something goes wrong with the components of the muscle
What is the affect of muscular dystophies
Affects the mechanism of the muscle
What are examples of muscular dystrophies
Duchenne’s MD Becker’s MD Facioscapulohumeral MD Myotonic dystrophy Limb-Girdle MD
What is the cause of Duchennes MD
Absence of dystrophin protein that helps keeps muscle cells intact
What muscular dystrophy is a milder form of duchnennes MD
Beckers MD
What is typical symptoms and signs of duchesses and beckers MD
Hypertrophy
but Weakness of muscle
How does hypertrophy occur in muscular dystrophies
Due the fatty infiltration of muscle replacement
What symptoms are present inFacioscapulohumeral MD
Facial, scapula, and
bicep weakness
What does Limb- Girdle MD present with
Upper and lower limb proximal weakness
What is the cause of muscle channelopathies
Disturbed function of Ca, Na and Cl channels subunits or the proteins that regulate them
What is the result of muscle channelopathies
If something wrong with the channel can either not get the muscle to contract or cant get the muscle to relax
What is the patterns of symptoms in muscle channelopathties affecting potassium ion channels
Intermittent symptoms:
Normal then can have symptoms for a few days then they go away, then re-occcur at a later date
What are examples of Potassium channel problems
Familial hypokalemic periodic paralysis
Hyperkalemic periodic paralysis
What are examples of chloride channel problems
Paramyotonia congenita
Myotonia congenita
What kind of disease is Hyperkalemic/hypokalemic
Organic disease
What is the characteristic feature of myotonia congenita
Cant relax
Present with stiffness as muscle have a continual low level contraction
Once contract - cant relax e.g. shake hand and won’t let go
Why is paramyotonia termed paradoxical
Because it becomes worse with exercise whereas as myotonia congenita, is alleviated by exercise
What is the cause of metabolic muscle disease
Enzyme defect in energy metabolism
Disorders of what metabolism can result in metabolic muscle disease, and how?
Disorders of carbohydrate metabolism and lipid metabolism
As have problem with glycogen storage and fat storage which is the energy storage needed for muscle activity
When do symptoms of Disorders of carbohydrate metabolism (CM) and lipid metabolism (LM) show
Weakness shows on significant (CM) or prolonged exertion (LM)
What occurs in mitochondrial myopathies
Prominent muscle weakness
How does endocrinopathy cause metabolic muscle diseease
Hormone abnormality can cause muscle weakness
Or
The treatment can cause a steroid induced myopathy
What is an example of causes of biochemical abnormalities resulting in metabolic muscle disease
Drugs resulting in low potassium levels
What is two Inflammatory muscle diseases
Polymyositis - just affects muscle
Dermatomyositis - affects muscle and skin
What is Dermatomyositis associated with
Paraneoplastic - caused by underlying tumour
What is the overall presentation of Inflammatory muscle disease
Painful weak muscle
Feeling unwell (due to system inflammation)
Characteristic rash: eyes (red), around the knuckles
What is the investigations for of inflammatory muscle disease
CK blood test
EMG, shows inflammation and myopathic cells
Biopsy
PM = CD8 cells
DM = human mediate, be cells and CD4 cells
What is the treatment of inflammatory muscle disease
Immunosuppression - through high dose steroids
What is an Iatrogenic cause of muscle disease
Statins for cholesterol resulting in degeneration of muscle
What is a common neuromuscular junction disorder
Myasthenia gravis
What is the clinical presentation of myasthenia gravis
Fatiguable weakness:
Limbs Eyelids (ptosis) Muscles of mastication (chewing), swallow Talking SOB diplopia
When can myasthenia gravis become fatal
When the generalised weakness affects you breathing - can lead to aspiration pneumonia
What is the cause of myasthenia gravis
Due defect in the action of acetylcholine at neuromuscular junctions a
What muscle does myasthenia gravis not affect
Cardiac muscle
Why is the presentation if myasthenia gravis fatiguable weakness occur later on in the day
As Muscle is strong to begin with, but becomes weaker overtime throughout the day, this is because limited ACH to overcome barrier used up by the end of the day so symptoms appear later on
Investigations for myasthenia gravis
Antibody testing
(AChR ab, Anti MuSK ab)
Neurophysiology
- Repetitive stimulation (contract muscle and see fatigue in Jitter)
CT chest
What are you investigating for in a chest x ray for myasthenia gravis
Thyoma benign tumour arising from thymus tissue as is sometimes associated with myasthenia gravis
What is the different treatment management for myasthenia gravis
Symptomatic
Immunosuppression
Immunoglobulin/plasma exchange
Thymectomy
What is used in symptomatic treatment of myasthenia gravis
Acetylcholinesterase inhibitor
- block ach breakdown, more ach available to overcome block
What is used in immunosupression treatment of myasthenia gravis
Prednisolone
Azathioprine (steroid saving agent)
stops antibody production
What is the function of immunoglobulin and plasma exchange treatment in myasthenia gravis
Plasma -Get rid of the antibody
Immunoglobulin - bind to antibody and prevent it working
What is the function of a thymectomy in myasthenia gravis
Remove thymus, as overactive thyroid produces antibodies
What are the two antibodies playing a role in myasthenia gravis
anti-acetylcholine receptor (AChR) antibody
anti-muscle-specific tyrosine kinase (MuSK) antibody
What is present in the periphery
Motor axons
Sensory axons
Autonomic fibres
Where is the two areas nerve disease can occur
Occurs proximal in the nerve (just as it leaves the spine) = root
or
Distally in the periphery nerve
What is is causes of root disease
Degenerative spine disease
Inflammation
Infiltration
What can cause lesion of individual peripheral nerve
Compressive /Entrapment neuropathy
Vasculitic
What is the affect of entrapment neuropathy
Localised affect with signs an symptoms related to that nerve trapped
What occurs in vasculitic of peripheral nerves
Inflammation of blood vessels affects the blood supply to the nerve
What is it called when vasculitic happen to numerous peripheral nerves
mononeuritis multiplex
What is vasculitic also associated with
Other inflammatory and autoimmune disease
What is affected in generalised peripheral neuropathy
Motor, sensory axons and autonomic fibres
What is a characteristic feature of peripheral neuropathy pathology
Affects the longest nerves first
as they require more energy for the distant synapse to occur
What is the causes of generalised peripheral neuropathy
Metabolic: Diabetes, alcohol, renal, B12
Toxic: drugs
Hereditary
Infectious: Lyme, HIV, leprosy
Paraneoplastic
Inflammatory demyelinating
What is the commonest cause of peripheral neuropathy
Diabetes
How does alcohol cause peripheral neuropathy
Has a central affect, killing neuronal cells
leading to cerebellar degeneration
How does a paraneoplastic malignancy cause peripheral neuropathy
Sets of inflammation around to body (fighting tumour) which affects and attacks the nervous system
What is an acute inflammatory demyelinating causing peripheral neuropathy
Guillain barre syndrome
triggered by bacterial, viral infection, few days later experience weakness
What is a chronic inflammatory demyelinating causign peripheral neuropathy
Chronic inflammatory demyelinating polyneuropathy
Reoccurrence of autoimmune attack
How does inflammatory demyelinating cause peripheral neuropathy
The body is attacks by infection which creates an auto-immune response
antibody cross reaction with antibodies on myelin sheath and damage the nerves
What is the signs and symptoms of nerve root damage in nerve disease
Myotomal wasting and weakness
Reflex change
Dermatomal sensory change
What is the signs and symptoms of individual nerve disease
Wasting and weakness of innervated muscle
Specific sensory change
very local
What is signs and symptom in generalised peripheral neuropathy
Generalised symptoms
Sensory and motor symptoms starting distally and moving proximally
What are the investigations used in nerve disease
Blood tests (Liver function)
Genetic analysis
Nerve Conduction Studies (stimuli and see nerve pattern)
Lumbar puncture (high protein in CSF analysis)
Nerve biopsy (rare and only do sensory nerve)
What is the disease that affects your anterior horn cell
Motor neurone disease AKA Amyotrophic lateral sclerosis (ALS)
Where does ALS affect motor neurones
brain, brainstem, and spinal cord.
What is the usually pathway of progression in ALS
Usually limb onset,
later bulbar
respiratory involvement
(respiratory failure is usually cause of death)
What is bulbar disease experienced in ALS patients
Impairment of function of the cranial nerves IX, X, XI and XII
So patients show alterations in speech or swallowing abilities
What is the lower motor neurone signs see in ALS
muscle fasciculations, wasting, weakness
What is upper motor neurone signs seen in ALS
increased tone, brisk reflexes
What sensory signs are seen in ALS
No sensory involvement
What is the pathology of motor neurone disease ALS
Degeneration (wearing out of) of motor neurone
no inflammation
What is the prognosis of Motor neurone disease ALS
3-5 years from symptom onset
2-3 years from diagnosis
50% die within 14 months of diagnosis
What is used in the diagnosis of motor neurone disease (ALS)
Unique combination of UMN + LMN signs with no sensory features
EMG - electrical myopathy
(stick needles in muscles and check innervation)
What is the treatment of motor neurone disease (ALS)
Supportive
(PEG, NIV, physiotherapist , Occupational Therapist, care)
Riluzole
How does riluzole work in the treatment of motor neurone disease
Is anti glutamate antagonist
blocks the affect of glutamate which is an excitatory neurotransmitter that over stimulates and damages cells
What is the affect of riluzole
Prolongs survival for a few months
In an EMG of Motor neurone disease what shouldn’t be seen
A neuropathy - because the axon is in tact
When is PEG offered in ALS
When can no longer chew or swallow
When is non invasive ventilation offered in ALS
When patient has problems breathing
