1. Repetitive Nerve Stimulation
Centre for converging technologies
UOR, Jaipur
Name: Mohit kumar pate
IX sem

2. PLAN OF THE TALK
 Physiology of Neuromuscular junction
 Procedure, technical aspects
 Interpretation
 Application in various conditions

3. RNS-TECHNIQUE
 RNS study is one of the most useful electro
diagnostic test for diagnosing pre- and postsynaptic
neuromuscular transmissions.

5. DEFINITIONS
 Quantum. A quantum is the amount of Ach
packaged in a single vesicle.
 Each quantum (vesicle) 1 mV change of
postsynaptic membrane potential.
 Rest, MEPP
 The number of quanta released after a
nerve action potential depends on the
number of quanta in the immediately
available (primary) store and calcium stores
 Normally 50-300(60) vesicles

6. DEFINITIONS
 End plate potential -EPP is the potential
generated at the postsynaptic membrane
following a nerve action potential and
neuromuscular transmission.
 60 mV change in the amplitude of the membrane
potential.
 Safety factor. The safety factor of neuromuscular
transmission is simply defined as the difference
between the EPP and the threshold potential for
initiating an action potential.
 MFAP
 CMAP

7. CALCIUM AND QUANTA DYNAMICS
 calcium :diffuses slowly out of the presynaptic terminal in
100–200 msec.
 Ach stores: immediately available (primary) store and
secondary (or mobilization) store
 Inter stimulus interval
 rapid RNS (more than every 100 msec, or stimulation
rate >10 Hz), calcium influx is greatly enhanced and the
probability of release of Ach quanta increases.

8. RNS-TECHNIQUE
 RNS is performed on selected motor nerves with
recording by surface electrodes.
 G1-motor point,G2-tendon
 Supramaximal stimulus
 Initial sharp negative deflection

9. MUSCLE SELECTION
 Clinically weak muscles should be selected.
 Usually facial and proximal limb muscles shows greater
abnormality than distal muscles.
 Cholinesterase inhibitors should be stopped 12-24 hrs
before.

10. MACHINE SETUP FOR RNS
Sensitivity (mV/div) 2-5
Sweep time (ms/div) 2
Low filter (Hz) 2-5
High filter (KHz) 2-3
Stimulus duration (msec) 0.1
Stimulus rate -low <5
Stimulus rate -high 30-50

11. IMPORTANT POINTS:
 Immobilization and isometric electrode position.
 Supramaximal stimulus
 Temperature must be controlled
 AchI withheld 4 hrs prior to study.
 Proximal site better than distal site
 Distal easy; proximal difficult.

12. STIMULUS TECHNIQUE
 Best at 3-5 hz
 Decrement increases with stimulus rates up to
10hz.
 Higher rates cause movement artifacts and painful
 Pseudo facilitation

13. LOW RATE RNS
 supra maximal CMAP
 3–5 stimuli to a mixed or motor nerve at a rate of
2–3 Hz.
 slow enough to prevent calcium accumulation,
high enough to deplete the quanta
 maximal decrease in Ach release occur after the
first four stimuli
 reproducible decrement
 exercises for 10 seconds to demonstrate repair
of the decrement (‘‘post-exercise facilitation’’)
 No decrement-1 minute max voluntary exercise –
post exercise exhaustion

14. LOW RATE RNS

15. HIGH RATE RNS
 optimal frequency is 20–50 Hz,for 2–10 seconds
 brief (10-second) period of maximal voluntary
isometric exercise has,the same effect as rapid
RNS
 Depletion of quanta vs calcium accumulation
 Incremental response in LEMS

16. HIGH RATE RNS

17. RNS IN PRE AND POST SYNAPTIC DISORDERS
Parameter Pre-synaptic Post-synaptic
CMAP amplitude Small Normal
Low rate RNS Decrement Decrement
High rate RNS Increment Decrement or
normal

18. MYASTHENIA GRAVIS

19. THANK YOU