ELECTROMYONEUROGRAPHY (EMNG)

SITI MARIAM BINTI MOHD HAMZAH

Electromyoneuronography (EMNG) is the combined use of electromyography (EMG) and

electroneuronography(ENoG). This technique allows for the measurement of a peripheral nerve’s conduction velocity upon stimulation (ENoG)

alongside electrical recording of muscular activity (EMG).

what is EMG?• is an investigation which the electrical of muscle is

recorded through a needle electrode inserted into the muscle .

• it is displayed on a cathode ray oscilloscope and played over a loud speaker for simultaneous visual and auditory analysis.

• surface EMG • intramuscular (needle and fine-wire) EMG.

types of EMG

• electrodes– Surface electrodes – Needle electrodes

• a high-gain amplifier (10-5000Hz) – connected to an oscilloscope – EMG signals may be fed to an audio unit for an on the spot

feel of the signals • an arrangement for recording the output

– EMG is best done in a specially constructed shielded room to prevent interference

equipment

principles of EMGmuscle activity (normal) results

Rest Electrically silentMinimal contraction voluntarily AP increaseMaximum contraction voluntarily Full recruitment pattern

muscle activity (weakness) results

Primary muscle disease

Rest Spontaneous electrical activity in form of fibrillation potentials

Minimal contraction voluntarily

AP will be of lower amplitude and shorter duration as compared to a normal muscle

Maximum contraction voluntarily

Recruitment potentials will be full

Neurogenic lesion

Rest Spontaneous electrical activity in form of fibrillation and fasciculation potentials

Minimal contraction voluntarily

AP will be of larger amplitude and longer duration as compared to a normal muscle

Maximum contraction voluntarily

Recruitment potentials will be less than normal

*in our case, right and left peroneal nerves cannot be stimulated, may conclude total damage of those nerve.

• is a non invasive, electro neurological diagnostic test to measure the conduction velocity and latency of peripheral nerves.

Electroneuronography

*AP are saltatory in nature.

In our case, right ulnar and median motor nerve conduction velocities are within normal limits. It may shows that there is no demyelination at the nerves and not affected.Any decrease in the NCV will indicate: • Extent of

demyelination of nerve

• Any Conduction Block

• Axonopathy (damage to the long portion of a nerve cell)

• Nerve Conduction Study • Sometimes combine with EMG and also

to do NCS, use the same equipment as EMG.

• useful for evaluating conduction problems in the proximal region of nerves

F waves

*in our case, right tibial F waves were absent and it might indicate, no conduction of the nerve and demyelination.

references• http://www.healthline.com/health/electromyography#Electromyog

raphyOverview1• http://myweb.wwu.edu/~chalmers/EMGfundamentals.pdf• http://www.slideshare.net/1choose1/electromyography-25196166• http://www.slideshare.net/RichardBaker12/emg-electrode-placeme

nta• http://

www.slideshare.net/sddq786/electroneurography-26918251?related=1

• https://www.aaet.info/files/documents/F-waves.pdf• Clinical Medicine (Clinical Methods and Lab. Investigations) (KV

Krishna Das)