Nerve and Muscle Disease

Question 1

McArdle’s disease is autosomal recessive - T/F?

Answer 1

TRUE

Question 2

pathophysiology behind McArdle’s disease

Answer 2

myophosphorylase deficiency leading to impaired glucose release from glycogen in the muscles

Question 3

how does McArdle’s disease present?

Answer 3

1st decade of life

pt presents with muscle pain shortly after they exercise

Question 4

CK is decrease in McArdle’s disease - T/F?

Answer 4

FALSE

Question 5

why must pt stop vigorous exercising when they get pains?

Answer 5

it could lead to rhabdomyolysis + myoglobinuria = AKI

Question 6

What is myotonic dystrophy?

Answer 6

Multisystem progressive disease with delayed muscular relaxation and muscle wasting

Question 7

What is the inheritance of myotonic dystrophy?

Answer 7

Autosomal dominant

Tri nucleotide repeat on chromosome 19

Question 8

Clinical features of myotonic dystrophy

Answer 8

Sternocleidomastoid muscle + Distal limb affected 1st
Proximal limb affected later

Facial weakness (‘haggard’’ appearance

Ptosis, ophthalmoplegia & bilateral Christmas tree-like cataracts

Hollowing of temples due to temporalis muscle wasting & atrophy of jaws

Early frontal balding

Question 9

Lambert-Eaton myasthenic syndrome pathophysiology

Answer 9

Impaired release of acetylcholine by the pre-synaptic terminal

Question 10

what voltage gated channels does Lambert-Eaton syndrome affect?

Answer 10

Ca2+

Question 11

what malignancy is lambert-eaton syndrome associated with?

Answer 11

Small cell lung cancer

Question 12

clinical features of lambert-eaton syndrome

Answer 12

insidious onset of weakness of PROXIMAL muscles
Autonomic features - constipation, postural hypotension, dry mouth
Deep tendon reflexes diminished

Question 13

the upper extremities are most affected in L-E syndrome - T/F?

Answer 13

FASLE.

Lower extremities are predominantly affected - this causes a waddling gait

Question 14

Ix L-E syndrome

Answer 14

presence of anti -VGCC antibodies

repetitive electrical stimulation at 20-50Hz

CT scan to rule out malignancy (SCC)

Question 15

Tx L-E syndrome

MOA of drug

Answer 15

Amifampridine

Blocks pre-synaptic Ca2+ channels & increases quantity of ACh released

Question 16

If L-E is very severe, what medication may be used?

Answer 16

Immunosuppression or IV immunoglobulins

Question 17

What is myasthenia gravis (MG) ?

Answer 17

autoimmune disease affecting post-synaptic nicotinic acetylcholine receptors

Question 18

who does MG affect?

Answer 18

F>M

10-30 y/o

Question 19

clinical features of MG?

Answer 19

muscle fatigability occurring quickly after exercise or end of day. improves with rest

ocular features can be presenting complaint - bilateral asymmetrical ptosis & extraocular weakness causing diplopia

Proximal muscle weakness > Distal

Question 20

one complication of MG is Myasthenia crisis - what is this?

Answer 20

weakness of respiratory muscles causing ventilator failure

bronchopneurmonia - medications can precipitate this

Question 21

how to monitor the respiratory complications of MG?

Answer 21

measure vital cap & tidal volume

Question 22

at what stage do you need an intervention for the respiratory complications of MG?

Answer 22

when vital capacity falls below 15mL/kg

Question 23

what tx do you give to pt when their vital capacity falls below 15mL/kg

Answer 23

plasmapheresis
IV immunoglobulins
systemic steroids

Question 24

what is cholinergic crisis

Answer 24

too much anticholinesterase given

symptoms = sweating, hypersalivation, bronchial hypersecretions & miosis - can lead to resp failure

Question 25

what conditions are associated with myasthenia gravis?

Answer 25

thymic hyperplasia thyoma hyperthyroidism SLE

Question 26

drugs that can induce MG

Answer 26

``` gentamicin b-blockers verapamil lithium penicillamine phenytoin chloroquine ```

Question 27

Ix MG

Answer 27

antibody test - IgG against ACh receptor (anti-AChR) NOTE - in some pt this is -ve so they should be checked for anti-MuSK antibodies Repetitive nerve stimulation Thyroid function test CT thymus

Question 28

Mx of MG

Answer 28

symptomatic control - acetylcholinesterase inhibition using pyridostigmine Immunosuppression with corticosteroid & azathioprine to improve myasthenic weakness Thymectomy if thyoma is present

Question 29

Is Charcot Marie tooth (type 1) autosomal dominant - T/F?

Answer 29

TRUE

Question 30

What is Charcot Marie Tooth Disease (CMT)

Answer 30

A group of diseases affecting the peripheral nerves

Question 31

Histopathology of Charcot Marie Tooth Disease

Answer 31

Schwann cells proliferate and form concentric arrays of remyelination around the demyelinated axon resulting in 'onion bulb' appearance

Question 32

When does CMT present

Answer 32

1st or 2nd decade of life

Question 33

Clinical features of CMT

Answer 33

Motor symptoms affecting distal muscles - 'inverted champagne bottle' appearance Sensory loss follows same pattern Hyporeflexia Thoracic scoliosis

Question 34

Diagnosis of CMT

Answer 34

Genetic testing | Electrophysiological nerve conduction study (low conduction rate <38 m/s)

Question 35

What is Guillian-Barre Syndrome

Answer 35

Acute neuromuscular weakness causing demyelination and axonal injury

Question 36

What often precedes GB syndrome?

Answer 36

Campylobacter | also EBV, CMV, HIV

Question 37

Presentation of GB Syndrome?

Answer 37

Symmetrical progressive ascending sensorimotor paralysis Areflexia in lower limbs Usually stops progressing after 4 weeks from its onset

Question 38

Diagnosis of GB syndrome

Answer 38

Clinical Lumbar puncture - high protein Nerve conduction studies

Question 39

Mx of GB syndrome

Answer 39

Plasma exchange of IV immunoglobulins

Question 40

What is chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)?

Answer 40

Acquired demyelinating peripheral nervous system disease Progressive proximal & distal weakness with hyporeflexia Distal sensory loss (numbness) Tremor

Question 41

Diagnosis of CIDP

Answer 41

Clinical Nerve conduction studies CSF - high protein

Question 42

Treatment of CIDP

Answer 42

Oral steroids or IV Immunoglobulins

Question 43

What is spinal muscular atrophy

Answer 43

congenital degeneration of anterior horns of spinal cord (LMN lesion) leads to progressive muscular wasting & early death 'floppy baby syndrome' - hypotonia and tongue fasciculations

Question 44

is spinal muscular atrophy X-linked recessive?

Answer 44

NO - it is autosomal recessive

Question 45

what is poliomyelitis?

Answer 45

caused by polio virus infections causes destruction of cells in anterior horn of spinal cord (LMN death)

Question 46

how is the polio virus transmitted?

Answer 46

faecal-oral transmission

Question 47

symptoms of poliomyelitis

Answer 47

``` LMN signs basically: weakness hypotonia flaccid paralysis fasciculations hyporeflexia muscle atrophy ```