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39 Cards in this Set
- Front
- Back
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PREsynaptic or POSTsynaptic?
Myasthenia Gravis |
POST
Autoimmune Ab block ACh receptors |
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PREsynaptic or POSTsynaptic?
Lambert Eaton |
PRE
Autoimmune Ab block CALCIUM release into nerve terminal, prevents release of ACh into synaptic cleft |
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PREsynaptic or POSTsynaptic?
Botulism |
PRE
C. Botulinum toxin block release of ACh from nerve terminal into synaptic cleft |
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Lambert Eaton is associated with what other illness?
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SMALL CELL LUNG CANCER
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Myasthenia Gravis is associated with what other illness?
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Thymic disorder/tumor
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Myasthenia Gravis is more prevalent in which sex?
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FEMALES
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Lambert Eaton is more prevalent in which sex?
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MALES (2:1)
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How long does it take Botulism to manifest itself after ingestion of C. Clostridium?
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2-7 days
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Which disease of the neuromuscular junction primarily affects the LOWER limbs?
What part of the lower limbs? |
LAMBERT EATON
QUADS (proximal) |
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Which disease of the neuromuscular junction IMPROVES with REST?
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Myasthenia Gravis
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Which disease of the neuromuscular junction IMPROVES with ACTIVITY?
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Lambert Eaton
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Name 3 things that can EXACERBATE Myasthenia Gravis.
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1. HEAT
2. EXERCISE 3. TIME (later in evening) |
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Which diseases of the neuromuscular junction exhibit decreased MSRs?
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Lambert Eaton
Botulism |
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Which diseases of the neuromuscular junction exhibits BULBAR symptoms?
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Myasthenia Gravis & Botulism
- Ptosis - Dysphagia - Dysarthria |
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Which disease of the neuromuscular junction exhibits NORMAL MSRs?
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Myasthenia Gravis
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Which disease of the neuromuscular junction WORSENS with REST?
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Lambert Eaton
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The weakness in Myasthenia Gravis & Lambert Eaton is characteristically proximal or distal?
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PROXIMAL
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Which disease of the neuromuscular junction shows OVERDEVELOPMENT of the NMJ on MUSCLE Bx?
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Lambert Eaton
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Which disease of the neuromuscular junction shows loss of junctional folds & receptors on the POSTsynaptic membrane?
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Myasthenia Gravis
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What drug do you use to test for Myasthenia Gravis clinically?
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EDROPHONIUM (AChesterase inhibitor)
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Which diseases of the neuromuscular junction will show a 10% decrement on repetitive stim on NCS?
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ALL THREE OF THEM:
Myasthenia Gravis Lambert Eaton Botulism |
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What drug is used to TREAT Myasthenia Gravis?
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MESTINON (pyridostigmine) - AChesterase inhibitor
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What will diseases of the neuromuscular junction show on EMG exam? |
UNSTABLE MUAPs - The same MUAP will have VARYING AMPLITUDES - This occurs d/t NMJ BLOCKING - Could also see short duration small amplitude MUAPs |
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When performing REP STIM for evaluation of NMJ disease, the stimulus is:
A. Submax B. Supramax |
SUPRAMAX
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When performing REP STIM for evaluation of NMJ disease what rate do you stimulate at?
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3 Hz
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When performing REP STIM for evaluation of NMJ disease decrement of at least ___% must be observed between the ___ & ___ waveforms in order to be considered pathologic.
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10%
1st 4th |
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When performing REP STIM for evaluation of NMJ disease recordings should happen in a progressive proximal fashion, which muscle do you typically start at?
Name the subsequent muscles... |
1. Abductor Digit Minimi or Abductor Pollicis Brevis
2. Deltoid 3. Trapezius 4. NASALIS or ORIBICULARIS OCULI |
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What do you do if REP STIM shows no decrement but you still suspect a NMJ disorder?
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POST ACTIVATION EXHAUSTION
- Initial 10 second ISOMETRIC contraction - REP STIM every minute x5 minutes - Greatest decrement should be seen between rep stim recordings that are taken 2-5 minutes after |
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What do you do if your patient cannot perform a maximal isometric contraction when you are evaluating them for a NMJ disorder?
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HIGH RATE REP STIM
- 10-50 Hz - Painful |
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What is POST ACTIVATION FACILITATION (PAF)?
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After performing a rep stim & seeing decrement, a 10 SECOND ISOMETRIC CONTRACTION or HIGH RATE REP STIM is performed (50Hz):
- PAF is a a REPAIR in CMAP amplitude with an immediate follow up REP STIM d/t increase in CALCIUM in nerve terminal - Happens in both MG & LE (much more dramatic in LE though >200%) |
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How is Lambert Eaton distinguished from Myasthenia Gravis electrodiagnostically?
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Lambert Eaton will show >200% FACILITATION:
- Change in the 1st response of the baseline stimulus compared to 1st response of stimulus train AFTER exercise - MG would show partial decrement repair |
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What effect if any, does TEMPERATURE have on rep stim studies when evaluating for NMJ disorders?
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COLDER temperature (below 30-32 degrees C) causes more ACh to be released and less to be broken down
- May MASK decrement in otherwise diseased muscle (false negative study) |
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What is PSEUDOFACILITATION?
Is it a NORMAL or PATHOLOGIC response? |
A progressive INCREASE in CMAP amplitude after a period of exercise (or HRRS).
- Area under the curve remains the same -duration decreases as amplitude increases - represents improved synchronicity of muscle fiber contraction (less temporal dispersion) |
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What should you do if rep stim studies of at least three muscles are ALL NORMAL but you STILL suspect an NMJ disorder?
- What parameters does this measure? |
SINGLE FIBER EMG
- FIBER DENSITY - JITTER - BLOCKING |
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What is the MOST SENSITIVE test for NMJ disorders?
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SINGLE FIBER EMG
*LOW SPECIFICITY THOUGH (may be positive in motor neuron disorders & peripheral neuropathies as well) |
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What is FIBER DENSITY?
What is considered normal? |
Measured with SINGLE FIBER EMG:
- # of fibers that belong to a single motor unit - Normal = 1.5 - HIGHER = REINNERVATION of a denervated muscle has occurred |
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What is JITTER?
What is considered normal? |
Measured with SINGLE FIBER EMG:
- Variation between the discharges of muscle fibers belonging to the same motor unit - Normal = 10-60usec - INCREASED = evidence of reinnervation d/t COLLATERAL SPROUTING (immature nerve terminals are more out of synch) |
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What types of disease processes can show increased JITTER?
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- ALS
- NMJ disorders - Axonal neuropathies - collateral sprouting - myopathies |
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What is BLOCKING?
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Measured with SINGLE FIBER EMG:
- Single muscle fiber action potential fails to appear. - Basically EXTREME JITTER > 100usec - Normal jitter is 10-60usec |
