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2ND YEAR SYSTEMS: Neuro > Muscle and nerve diseases > Flashcards

Muscle and nerve diseases Flashcards

1
Q

Where does the UMN synapse first?

A

The anterior horn

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2
Q

What are the 4 components of muscle contraction?

A

Structural components

Contractile mechanism – myosin fibrils embedded in membrane and it shortens as it contracts

Excitation-contraction coupling (ion channels)

Energy system – can’t contract muscle without energy

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3
Q

Symptoms of muscle disease? (7)

A

Weakness of skeletal muscle

Short of breath (respiratory muscles)

Poor swallow / risk of aspiration (bulbar muscles)

Cardiomyopathy

Cramp (repetitive!)

Pain and stiffness

Myoglobinuria

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4
Q

What is myoglobinuria?

A

Muscle breaks down and is excreted in urine – makes urine black, looks like blood

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5
Q

Symptoms of muscle disease in babies?

A

Poor suck / feeding / failure to thrive / floppy

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6
Q

Signs of muscle disease?

A

Wasting / hypertrophy

Normal or reduced tone and reflexes (usually loss
of muscle tone)

Motor weakness…NOT sensory

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7
Q

Why might hypertrophy result from a muscle disease?

A

Muscle cannot relax

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8
Q

Investigations for muscle disease (5)

A

History and examination

Creatine Kinase (CK)

EMG - electromyography

Muscle biopsy - look at structure, biochem and inflammation

Genetic testing

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9
Q

What is significant about creatine levels?

A

sign of muscle fibre degeneration - chewing up muscle

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10
Q

Genetics and muscle disease

A

Most congenital diseases are genetic however this doesn’t mean they are present at birth – can come up later on in life

Genetics can affect all 4 components of muscle contraction

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11
Q

How do congenital / genetic muscle diseases affect each component

A

Structural: muscular dystrophies

Contractile: congenital myopathies - hypotonia and weakness, usually present from birth, with a static or slowly progressive

Coupling: channelopathies - diseases caused by disturbed function of ion channel subunits or the proteins that regulate them

Energy: enzymes / mitochondria

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12
Q

How do acquired muscle diseases affect muscles

A

Metabolic (increased or low Ca2+, K+) – severe illness

Endocrine (thyroid, adrenal, vit D- rickets?)

Inflammatory muscle disease

Iatrogenic: medication (steroids / statins) - ie steroids used to treat myopathy then result in further myopathy

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13
Q

What is Myopathy?

A

Myopathy is a disease of the muscle in which the muscle fibers do not function properly.

This results in muscular weakness.

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14
Q

Describe what Muscular dystrophies are

A

Gradually cause the muscles to weaken, leading to an increasing level of disability.

Young or older onset
progressive, variable severity

Cell degeneration (often high CK)

No specific treatments yet

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15
Q

Give examples of some muscular dystrophies

A

Duchenne’s/Becker’s
Duchenne’s - aggressive and will limit life where as becker’s has milder symptoms and has a later onset. They are 2 alterations of same gene/protein

Facioscapulohumeral

limb girdle

Myotonic dystrophy - ong-term genetic disorder that affects muscle function - muscles contract and can’t relax - cataracts is common symptom - multi-system disease

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16
Q

What are channelopathies

A

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

often paroxysmal symptoms e.g. periodic paralysis / myotonia

partially treatable

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17
Q

Metabolic myopathy

A

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

Mitochondrial problems

Partially treatable

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18
Q

Inflammatory muscle disease

A

Polymyositis

It can be associated with a skin rash and is then called ‘dermatomyositis’

Can occur at any age, acute or subacute

painful, weak muscles

symptoms can be a sign of existing cancer or may also increase the risk of malignancy - tumour screen done

High CK levels

19
Q

Tests for inflammatory muscle diseases

A

EMG

Biopsy - polymyositis - CD8 T cells
Dermato - humeral-mediated, B cells and CD4 cells

20
Q

Treatment for inflammatory muscle diseases

A

immunosuppression

21
Q

What are the classifications of muscle disease?

A

Muscular dystrophies - usually genetic - to do with structure of the muscle

Channelopathies - usually episodic

Metabolic muscle disease - an issue with the way the muscle uses energy, usually due to enzymes

Inflammatory muscle disease

Congenital myopathies

Iatrogenic - medication - statins cause inflammation or degeneration of the muscles

22
Q

What is Myasthenia Gravis

A

Disorder of the neuromuscular junction - long-term neuromuscular disease

23
Q

Investigations for Myasthenia Gravis

A

Antibodies

If negative do Neurophysiology (Repetitive stimulation, Jitter)

CT chest (thymoma about 10% have underlying)

24
Q

Treatment for Myasthenia Gravis (4)

A

Symptomatic
- Acetylcholinesterase inhibitor (pyridostigmine)

Immunosuppression

  • Prednisolone
  • Steroid saving agent (e.g. azathioprine)

Immunoglobulin / plasma exchange

Thymectomy - antibody production can be as a result of an over active thymus - even in the case where there is no thymoma

25
Q

What is peripheral nerve disease (neuropathy)?

A

disease of the nerves beyond the brain and spinal cord

26
Q

What does a peripheral nerve consist of? (4)

A

Sensory axons

  • Small fibres (pain + temperature)
  • Large fibres (joint position sense + vibration)

Motor axons

Autonomic axons

Nerve sheath (myelin)

27
Q

Generalised peripheral neuropathy affect

A

Motor / sensory / both

+/- autonomic features

28
Q

A lesion of individual peripheral nerve will cause what?

A

Compressive / entrapment neuropathy - direct pressure on a nerve - causes pain, tingling, numbness

Vasculitic (mononeuritis multiplex) - If nerve doesn’t receive blood from the vasovasorum there is mononeuritis multiplex

29
Q

Causes of generalised peripheral neuropathy (6)

A

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

30
Q

Nerve disease can be of which 3 types?

A

Root disease

Lesion of individual peripheral nerve

Generalised peripheral neuropathy

31
Q

Symptom and signs:

Nerve root disease (3)

A

Myotomal wasting and weakness

Reflex change

Dermatomal sensory change

32
Q 
Symptom and signs:
Individual nerve (2)
A

Wasting and weakness of innervated muscle

Specific sensory change

33
Q

Symptom and signs:

Generalised peripheral neuropathy

A

Sensory and motor symptoms, usually starting distally and moving proximally

34
Q

Investigations for nerve disease (5)

A

Blood tests

Genetic analysis

Nerve Conduction Studies

Lumbar puncture (CSF analysis) – invasive , not done much

Nerve biopsy (nb sensory nerve)

35
Q

Treatment of nerve diseases?

A

Treat the cause eg stop drug, surgery, immunoglobulin

36
Q

What is solely affected in spinal muscular atrophy?

A

anterior horn cell

37
Q

Motor neuron disease:

Disease progression and signs

A

Usually starts with limb → bulbar → respiratory

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

Doesn’t affect sensory just the motor part

38
Q

Prognosis of Motor Neuron disease?

A

Median 3-5 years from symptom onset

2-3 years from diagnosis

50% die within 14 months of diagnosis

39
Q

What do you usually see in an atrophic tongue

A

fasciculations, wasting and weakness (LMN signs), while spasticity causes slow tongue movements

40
Q

Treatment of motor neuron disease

A

Supportive - PEG feed, non invasive ventilation, physio, OT, SALT, care

Riluzole - delays the onset of ventilator-dependence or tracheostomy in some people and may increase survival by two to three months

Anticipatory / palliative care

41
Q

Diagnosis of motor neuron disease

A

unique combination of UMN and LMN signs with no sensory signs

Electromyography

42
Q

What is the presentation of disorders of the neuromuscular junction?

A

Fatiguable weakness:

–Limbs

–Eyelids (ptosis)

–Muscles of mastication (chewing), swallow

–Talking

–SOB - Affects all NMJ’s so can cause respiratory failure

–diplopia

Clear feature of NMJ problems is fatigue – muscles start strong and then get weaker. As day goes on – progressive problem with muscle weakness – diplopia because of muscle weakness in the eye.

43
Q

Which antibodies are searched for in Myasthenia Gravis?

A

AChR, Anti MuSK antibodies

44
Q

What is the other name for motor neuron disease?

A

Amyotrophic lateral sclerosis

2ND YEAR SYSTEMS: Neuro (32 decks)

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