Muscle and Nerve Disease

Question 1

what are the symptoms of a muscle disease?

Answer 1

weakness of skeletal muscle- limb weakness or intercostal/diaphragmatic muscles= impaired respiratory function or swallowing issues, weakening of cardiac muscle leading to heart problems, muscle pain or cramps, myoglobinuria (urine turned a very dark colour as lots of myoglobin= muscle breakdown product)

Question 2

what are the signs of muscles disease?

Answer 2

pure motor signs and not associated with sensory signs, muscle tenderness, muscle wasting or enlargement

Question 3

what are the 2 main groups which can cause muscle disease?

Answer 3

congenital/genetic or acquired

Question 4

what are some congenital/genetic muscle diseases?

Answer 4

contractile eg congenital myopathies, structural eg muscular dystrophies, coupling eg channelopathies, enery eg metabolic myopathies

Question 5

what are contractile- congenital myopathies?

Answer 5

often young onset disease with weakness and it relatively static throughout someones life

Question 6

what are structural- muscular dystrophies?

Answer 6

tend to be severe and progressive, young onset but progress quickly with muscle weakness and are often life shortening

Question 7

what are coupling- channelopathies?

Answer 7

some can give paroxysmal disorders eg paroxysmal weakness which comes on vert quickly and lasts for minutes or hours and then resolves spontaneously

Question 8

what are energy- metabolic myopathies?

Answer 8

genetic deficits in many of the enzymes that generates ATP or the breakdown of glycogen and FA or genetic defects of the mitochondria and these will cause pain on exercise

Question 9

what are some acquired muscle disorders?

Answer 9

electrolyte disturbances, endocrine, autoimmune inflammatory muscle disease, iatrogenic

Question 10

how do electrolyte disturbances cause muscle disorder?

Answer 10

especially very high to very low levels of K+ can give you muscle weakness

Question 11

how do endocrine disorders cause muscle disorder?

Answer 11

eg thyroid, adrenal or vitamin D changes can cause muscle weakness

Question 12

how do autoimmune inflammatory muscle disease cause muscle disorder?

Answer 12

2 types= polymyositis (inflammation of the muscle alone) and dermatomyositis (skin and muscles causing rash and muscle weakness), any age, generally acute onset and generate pain, weak muscles and characteristic rash of DM on face or hands- high CK and autoimmune nature so look for autoantibodies- DM often associated with underlying tumour (muscle weakness= paraneoplastic), EMG for diagnosis and immunosuppression (steroids or steroid sparing agents like azathioprine) for treatment

Question 13

what medication can cause muscle disorders?

Answer 13

steroids and statins

Question 14

what is a disorder of the NMJ?

Answer 14

myasthenia gravis

Question 15

what is myasthenia gravis?

Answer 15

an autoimmune condition that causes muscle weakness that gets progressively worse with activity and improves with rest

Question 16

who does myasthenia gravis usually affect?

Answer 16

women under 40 and men over 60

Question 17

what is strongly linked to myasthenia gravis?

Answer 17

thyomas= tumours of the thymus gland

Question 18

what is the pathophysiology of myasthenia gravis?

Answer 18

it is an autoimmune process associated with the ACh receptor antibody which blocks the ACh receptor in the NMJ so stopping ACh from activating the receipts and generating muscle contraction causing reduced muscle activity

Question 19

how does myasthenia gravis present?

Answer 19

fatiguable weakness ie worse with muscle use and improves with rest, typically minimal in the morning and worst at the end of the day

Question 20

where do symptoms of myasthenia gravis usually present and what are they?

Answer 20

most affect proximal muscles and the small muscles of the head and neck causes diplopia (muscles of eye movement), ptosis (eyelid muscles), weakness of facial movements, difficulty swallowing, chewing and slurred speech

Question 21

how is a diagnosis of myasthenia gravis made?

Answer 21

testing directly of ACh-R antibodies or anti-MuSK antibodies in the blood

Question 22

what other investigations could we go?

Answer 22

CT or MRI of the thymus gland to check for a thymoma and an edrophonium test if in doubt about the diagnosis - edrophonium blocks enzymes which breakdown ACh, so ACh at NMJ increase which relieves weakness and confirms diagnosis of myasthenia gravis

Question 23

what are the treatment options for myasthenia gravis?

Answer 23

cholinesterase inhibitors increase the amount of ACh in the NMJ so improve symptoms, immunosuppression supresses production of antibodies= steroids, thymectomy (even without thymoma) improves symptoms

Question 24

what are possible causes of peripheral nerve disease?

Answer 24

root disease, lesion on individual peripheral nerve, generalised peripheral neuropathy

Question 25

what is a root disease?

Answer 25

damage to the nerve root as it comes out of the foramen of the vertebrae and the most common cause of this is degerative disc disease

Question 26

what is a lesion of an individual peripheral nerve?

Answer 26

compression or entrapment of the nerve= neuropathy or vasculitis of blood supply of a nerve with damage to the nerve, multiple nerves affected= mono neuritis multiplex

Question 27

what is a generalised peripheral neuropathy?

Answer 27

affects motor and sensory parts of the nerves and can be one more than the other or equally and generally has autonomic features too - can be axonal or generalised peripheral neuropathy

Question 28

what is Guillain Barre syndrome?

Answer 28

an acute paralytic polyneuropathy that affects the PNS and causes acute, symmetrical, ascending weakness and can also cause sensory symptoms

Question 29

what usually causes Guillain Barre syndrome?

Answer 29

an infection and is particularly associated with campylobacter jejune, cytomegalovirus and EBV

Question 30

what is the pathophysiology go Guillain Barre syndrome?

Answer 30

occurs due to a process called molecular mimicry where B cells of the immune system against antigens on the pathogen that causes the preceding infection also match the protein on the nerve cells

Question 31

what is the presentation of Guillain Barre syndrome?

Answer 31

symmetrical ascending weakness (starting at the feet and moving up the body), reduced reflexes, maybe peripheral loss of sensation or neuropathic pain and may progress to facial nerve weakness

Question 32

what is the clinical course of Guillain Barre syndrome?

Answer 32

symptoms start usually 4 weeks of the preceding infection, symptoms in the feet and upwards

Question 33

how is Guillain Barre syndrome diagnosed?

Answer 33

made clinically using the Brighton criteria but can be supported by nerve conduction studies and lumbar punctures for CSF (raised protein with normal cell count and glucose)

Question 34

how is Guillain Barre syndrome treated?

Answer 34

IV immunoglobulins, plasma exchange, supportive care and VTE prophylaxis and if respiratory failure then intubation and ventilation

Question 35

what are the sensory symptoms?

Answer 35

loss of sensation, abnormal sensation and pain

Question 36

what are the motor symptoms?

Answer 36

muscle thinning if prolonged and weakness= common

Question 37

what are the autonomic symptoms?

Answer 37

skin discolouration or loss of hair, postural hypotension and bladder and bowel problems

Question 38

what are the sensory signs?

Answer 38

reductions and alterations in light touch, temperature, joint positions and vibration sensations

Question 39

what are the motor signs of peripheral nerve disease?

Answer 39

LMN signs

Question 40

what are the LMN signs?

Answer 40

muscle wasting, fasciculations, loss of muscle tone, weakness and reduced or loss of tendon reflexes

Question 41

describe the distribution of root disease.

Answer 41

weakness in the muscles that the nerve root supplies= myotomal weakness and loose sensation in the dermatome supplied by that nerve root

Question 42

what is motor neurone disease?

Answer 42

an umbrella term for a variety of specific diagnoses, a progressive fatal condition where the motor neurones stop functioning, there is no effect on the sensory neurones

Question 43

what is the most common type of MND?

Answer 43

amyotrophic lateral sclerosis (AML) and is well-known as this is what Stephen Hawking had

Question 44

what is the second most common type of MND?

Answer 44

progressive bulbar palsy which affects primarily the muscles of talking and swallowing

Question 45

what is the pathophysiology of MND?

Answer 45

progressive degeneration of both upper and lower motor neurones but not sensory neurones

Question 46

how does MND present?

Answer 46

typically a late middle-aged man with progressive weakness of muscles throughout the body, often in upper limbs first, increased fatigue when exercisin, dysphasia and clumsiness, signs of UMN and LMN disease

Question 47

what are the signs of UMN disease?

Answer 47

increased tone or spasticity, brisk reflexes and upping plantar reflex

Question 48

how is MND diagnosed?

Answer 48

clinical presentation and excluding other conditions which can cause motor neurone symptoms

Question 49

how is MND managed?

Answer 49

no effective treatments for halting or reversion the progression of the disease- riluzole (glutamate antagonist)= extends survival in AML by a few months, NIV (non-invasive ventilation) is also used to support breathing at night

Question 50

what do we need to do due to the poor prognosis of MND?

Answer 50

effectively break the bad news and plan end of life care