NEUROMUSCULAR JUNCTION DISORDER

Question 1

SNAP

Answer 1

NORMAL IN LEMS AND MG

Question 2

EMG

Answer 2

UNSTABLE MUAPs

Question 3

REPETITIVE NERVE STIMULATION
LOW REPETITION
HIGH REPETITION

Answer 3

LOW REPETITION (2-3 Hz)
MS: >10% DECREMENT FROM THE 1ST TO 5TH. TYPICAL “U” SHAPED SEEN.
LEMS: >10% DECREMENT FROM THE 1ST TO 5TH
BOTULISM: >10% DECREMENT

HIGH REPETITION DONE IF ISOMETRIC CONTRACTION CANNOT BE DONE.
MS: DECREMENT AND REPAIRED
LEMS: 200-200% INCREMENT
BOTULISM: MILD INCREMENT

Question 4

CMAP

Answer 4

MS: NORMAL
LEMS: LOW AMPLITUDE

Question 5

POST ACTIVATION FACILITATION

Answer 5

AFTER A DECREMENT IS NOTED WITH LRS AN ISOMETRIC CONTRACTION IS PERFORMED (50Hz) AND DEMONSTRATE REPAIR IN THE CMAP AMPLITUDE.
MG: 20-50% IMPROVEMENT
LEMS: >100% IMPROVEMENT
BOTULISM: >40% IMPROVEMENT

Question 6

SINGLE FIBER EMG

Answer 6

MOST SENSITIVE TEST BUT LOW SPECIFICITY. OTHER CONDITION WITH ABNORMALITIES ARE MND AND PERIPHERAL NEUROPATHIES AND MYOPATHIES.
EVALUATE SINGLE FIBERS FROM THE SAME MOTOR UNIT.
MEASURES:
-FIBER DENSITY: NORMAL 1.5, IF HIGHER REPRESENT DENNERVATION AND REINNERVATION.
- JITTER: DELAY TIME BETWEEN NEIGHBOR FIBERS. NORMAL LESS THAN 60micsec

Question 7

BLOCKING

Answer 7

ABNORMALITY WHEN A SINGLE MUSCLE FIBER ACTION FAILS TO APPEAR. OCCURS IF THE JITTER IS MORE THAN 100micsec