NMJ diseases

Question 1

Soma lesions

Answer 1

amyotrophic Lateral sclerosis, Poliomyelitis symptoms- muscle atrophy and weakness, hyporeflexia, fasciculations and fibrilations, eventual loss of muscle fibers being replaced by connective tissue

Question 2

Axon lesions

Answer 2

Neuropathy, toxins, drugx, axotomy

Question 3

schwann cell lesions

Answer 3

Guillan- barre syndrome, diptheria weakness, wasting, rare fasciculations, decrease in conduction velocity.

Question 4

nerve ending lesions

Answer 4

botulism, lambert eaton disease

Question 5

synptic cleft lesions

Answer 5

acetylcholine esterase absent

Question 6

End plate lesions

Answer 6

myasthenia gravis, nACh-related defects

Question 7

muscle fiber lesions

Answer 7

myotonias and muscular dystrophy - will show weakness, wasting, no fasciculations, no decrease in conduction velocity, no fluctuating amplitude of EMG or EMG signs of denervation.

Question 8

Poliomyelitis

Answer 8

viral infection that attacks the ventral spinal grey matter.

Question 9

an affected limb of polio myelitis shows

Answer 9

affected limb shows acute flaccid paralysis.

Question 10

destroyed motor neurons of poliomyelitis do not

Answer 10

regenerate but some surviving neurons my reinnervate the muscle.

Question 11

if polio affects upper cervical spinal cord

Answer 11

then diaphragm paralysis requires ventilator support

Question 12

Botulinum toxin

Answer 12

toxic protease that reduces the release of ACh by actin on proteins involved in exocytosis- paralyzes all muscles

Question 13

ways to become infected with botulism

Answer 13

eating food wound infection consuming botulinum spores

Question 14

alpha latrotoxin

Answer 14

causes massive release of ACh acts on nerve endings casuing tetanus with occasional patchy flaccid paralysis

Question 15

beta Bungarotoxin

Answer 15

reduces release by actin on proteins in nerve terminals involved in exocytosis, causes AcH depletion

Question 16

Curare

Answer 16

D-tubocurarine- plant alkaloid non-depolarising muscle relaxant that blocks ACh receptors at the NMJ

Question 17

Lambert eaton syndrome.

Answer 17

antibodies attack the voltage gated Calcium channel on neuron terminal.

• strength increases with sustained or repeated contraction in otherwise weakend patients.
• insufficient release of ACh initially but with continued attempts then you will get sufficient ACH

Question 18

lambert eaton syndrome is often associated with

Answer 18

oat cell caricinoma

Question 19

lambert eaton symptoms

Answer 19

• reduced ACh
• muscel weakness
• reduced amplitude of EPP
• many EPP’s do not attain threshold in muscle fibers
• amplitude of miniEPP is unchanged

Question 20

signs and tests of lambert eaton

Answer 20

3 Hz stimulation is gone, 20 hz shows a gradual increase

Question 21

treatment for LES

Answer 21

plasma exchange or Immunoglobin infusion. 4 aminopyridine

Question 22

Myasthenia gravis- deficiency of ACh esterase in snaptic cleft

Answer 22

• EPP amplitude is larger and longer than normal
• single motor nerve stimuli at low frequence cause singel muscel twitches
• high frequency motor nerve stimuli produce temporal summations of EPP’s and cause depolarization block

Question 23

Slow channel syndrome

Answer 23

muscle weakness, rapid fatigue, progressive atrophy, ACh binding to nACHr’s causes prolonged opening of ACh receptor channels and a depolariation block

Question 24

other forms of myasthenia gravis

Answer 24

• binding of ACh to AChR is abnormal -ACh gated channels have very brief opening times

Question 25

main symptoms of MG is

Answer 25

weakness in voluntary muscle that improves after rest and worsens with muscular activity. -diplopia, ptosis, difficulty swallowing.

Question 26

Maysthenia gravis autoimmune

Answer 26

antibodies cross link the nAChR's and it hastens resorption. weakness in ;cranial nerve muscles, limb.

Question 27

sometimes myasthenia gravis is associated with

Answer 27

tumors of the thymous gland

Question 28

test for Myasthenia Gravis

Answer 28

waning muscle EMG recordings. Tensilon test, hand clenching test

Question 29

treatment for myasthenia Gravis

Answer 29

neostigmine, pyridostigmine. Prednisone, thymectomy

Question 30

myasthenic crisis

Answer 30

breathing difficulty may be life threatening

Question 31

Chloride channel syndrome

Answer 31

fewer chloride channels are expressed and insereted incell membrane , causes slow muscular relaxation. - patients show stiffness and hypertrophy - increased excitability with smaller depolarization is required to evoke an action potential and may cause a train of acton potentials due to potassium accumulation in Traverse tubules.

Question 32

normally chloride channels

Answer 32

help keep membrane potential close to Ecl during recovery from an action potential.

Question 33

motor neuron disorder will show

Answer 33

muscle weakness, wasting, and EMG signs of denervation without decrease in conduction velocity or fluctuating amplitude of EMG.

Question 34

NMJ lesions will show

Answer 34

muscel weakness and fluctuating amplitude of EMG but not wasting, fasciculations, decrease in conduction velocity or EMG signs of denervation.