ELECTROMYOGRAPHY ! Biomedical applications, risk factors & precautions !

                                               EMG TECHNIQUE..

"ELECTROMYOGRAPHY IS A PROCEDURE OF ACCESSES THE HEALTH OF MUSCLES" 

Electromyography (EMG) is an electrodiagnostic technique or electrodiagnostic medicine for diagnosing , evaluating electrical signals or an electrical activity which is produced within skeletal muscles . Instrument which is used in  EMG technique known as " Electromyograph"   which produced or record an electrical activity in skeletal muscles known "Electromyogram" . Electromyogram detects or records electrical impulses which is produced in muscle fibers or cell as a result of this EMG technique when these muscle fibers are electrically or neurologically stimulated by these electrical stimulation , these electrical signals are essential in detecting or diagnosing medical abnormalities , activation level of muscle fibers , recruitment level or analyzed the bio-mechanics of human as well as animal movements.An EMG translates these signals onto graph that helps doctor to diagnose.
  

                                           HISTORY OF EMG..

The very first documented experiment related with EMG started in Frances-co Redi's works in 1666. Redi discovered a highly specialized muscle of electrical rat fish (Electrical Eel)generated electricity.By 1773, Walsh had been capable to demonstrate or described that the eel fish's muscles have an ability to generate a spark of electricity .In 1792 , a publication entitled De Viribus Electricitiatis  in Motu Musculari Commentarius appeared,by LUIGI GALVANI in which author described that the electrical activity is capable to  initiate skeletal muscle contractions. The 1st actual recording of EMG was done by an "Oscilloscope"to demonstrated  electrical signals from skeletal muscles . From 1930's through 1950's the capability of detecting electromyographic signals improved and many researches which were engaged in EMG began to use improved or modified electrodes more widely for the proper and accurate study of muscles . In 1953 the AANEM was formed as in one of the several currently active medical societies with special interest in advancing or modifying the science and clinical practice of EMG. In 1960's , Clinical practice of surface EMG (sEMG) for the treatment of  specific abnormalities began . sEMG were first practitioned by Hardyck and his co-researchers. An EMG sensing device used by Cram and Steger which was introduced a clinical methodology for scanning , detecting and evaluating a variety of muscles .

At present , there are numbers of modified amplifiers are avalaible. Recent researches showed great results in  understanding appropriate features and characteristics of surface EMG recording. sEMG is highly demanding technique used for recording superficial skeletal muscles in kinesiological protocols. whereas, IM electrodes, used for evaluating deep muscles as well as localized ,muscular activity.

EMG used in hundreds of applications. Neurological and neuromuscular abnormalities now detects by EMG clinically. Gait laboratories and therapists , trained in the field of ergonomic assessment also used EMG . Biomechanics , voluntary control , neuromuscular physiology and anatomy , kinematic disorders , postural control and most important in all "PHYSIOTHERAPY" all of these medical fields used EMG technique.

       BIO-MEDICAL APPLICATIONS..

EMG is a diagnostic procedure in evaluating health of muscles and nerves that control them. These nerves cells are also called as MOTOR NEURONS that transmits electrical signals which causes muscle to contract or relax .

EMG test has several catagories of clinical and bio-medical applications. EMG used as a evaluating or treating tool for recognizing or demonstrating neuromuscular disorders , or as a research tool for  kinesiology , diseases related to voluntary or kinematic control. EMG's electrical impulses helps in different injection's pathway such as BOTULINUM TOXIN or PHENOL into muscles , it is also used as a controlled electrical impulse for "Prosthetic devices" such as prosthetic upper or lower extremity.

EMG also used in NM monitoring, general anesthesia with NM-blocking drugs in order to eliminate Postoperative residual curarization (PORC).

Some conditions are purely primary myopathic in nature. In these type cases EMG used in different manner . It is performed with another electronic diagnostic medicine treatment which basically involves in recording the conductive function of nerves this  procedure known as "Nerve conduction studies (NCS)".Pain in the upper and lower extremities , weakness due to compression of spinal or cranial nerves , some neurological injuries or pathologies treated by needles of EMG and NCS.

Injuries in spinal nerves dose not include neck , mid and lower back pain that's why research didn't prove the effectiveness of EMG or NCS in treating the causes of axial lumber , thoracic or cervical spine pain. Carpal tunnel syndrome is a nerve compression disorder in wrist region, Sciatica , and many other problem which are related to nerves and muscular pathologies can be treated with needle EMG. Amyotropic lateral sclerosis , Myasthenia gravis ,and Muscular dystrophy these are less or uncommon clinical pathologies which can be treated by EMG .

SYMPTOMS FOR EMG ..

Your doctor may perform EMG if you are going thorough these symptoms that actually a sign of any lesion or damage of muscle or nerve . Symptoms includes:

• Tingling 
• Muscular weakness
• Numbness 
• Paralysis 
• Involuntary muscular twisting ( tics)
• Muscular pain or cramping

PREPARATION OF SKIN..

Following steps are involves in EMG technique among in all these steps SKIN PREPARATION is most important . Now the question arises what is the reason behind this that we said that this step is very important  in EMG treatment ? 
So , the basic reason behind this is we actually  prepares skin for EMG treatment .

This is the initial and basic step of EMG before insertion of electrode needles in skin.

Q:How we prepares human skin for this treatment ?

A: Typically , preparation involves in simply cleaning the part of skin which is used in this treatment  with an ALCOHOL PAD.

                             

                            RISKS FACTORS..

Insertion of needle electrode can be difficult and it is depend upon the number of factors :

• Selection of specific muscle 
• Size of muscle 
• Perfect needling 
• Neat and New needle for each patient 
• Accurate representation of muscle insertion 

EMG treatment shows good and accurate results when it is done on SUPERFICIAL MUSCLES because it helps to generate the action potential in superficial muscles smoothly and easily and also capable to detects deep muscles which are difficult to detect.

In obese, the strength of EMG signals are weak due to poor penetration and poor detection of deep muscles.

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Human BELLY is the ideal location for EMG signals  ,present  in longitudinal mid line because belly's muscles are considered as the center of motor or voluntary muscles and center point for tendons insertion .

Implanted cardiac defibrillators (ICDs) & cardiac pacemaker devices are highly used in medical practices,on patients who suffered from myocardial infraction or they may passed through CABAG , there isn't any reported evidence which indicates there

 performance with electrodiagnostic tools on these patients , pose a safety hazards.

However, unintended inhibitions or triggering outcomes of electrical impulses are basically results of these treatments . Generally , as closer as stimulation to the site of pacemaker or pacing leads , greater the chance for inducing a voltage with sufficient

amplitude that inhibits the activity of  pacemaker .

CONTRADICTIONS..

No known contradictions as well as no complications reported are exists with these EMG or NCS for expected (pregnant) ladies  . 

• Lymphedema patients or patients are at risk to develop lymphedema  are extremely contradicted with EMG and NCS needling on the affected limb due to venipunture.
• Patients with gross edema and taut skin are also cautioned to avoid these EMG and NCS needling due to the high risk of developing worse CHRONIC WEEPING OF SEROUS FLUID .

MAXIMUM KINEMATIC CONTRACTION..

The basic function of EMG is to see "How well a muscle posses an ability to activates it self"

Most important or common procedure which help to determine this is : " MAX KINEMATIC OR VOLUNTARY CONTRACTIONS " 

Muscle force , which is mechanically calculated , correlates maximally with calculation of EMG activation of muscle this is assessed with surface electrode but these electrode only records the muscle fibers which are in contact with surface .

This is used to identifying :

• Analyzing peak force 
• force generated by target muscle 
  

CLINICAL NEUROPHYSIOLOGY includes :

• EEG
• Neurological Intaroperative monitoring (NIOM)
• Nerve conducting studies (NCS)
• EMG
• Evoked potentials 
• Polysomonography (PSG)
• Epilepsy monitoring

PATHOLOGICAL SIGNS FOR EMG..

There are various pathologies in which EMG and NCS techniques are apply.  Pathologies which are related to muscles are :   

MUSCLES DISORDERS..

• Inflammatory mayopathies 
• Polymyositis
• Dermatomyositis
• Inclusion body myopathy
• Myotonia Congentia 
• Muscular dystrohpies 
• Duchenne muscular dystrophy
• Becker muscular dystrophy
• Facioscapulohumeral dystrophy
• Limb girdle muscular dystrophy
• Centro-nuclear myotrophy 
•   Myotonic dystrophy 
• Mitochondrial myopathies
  
  

DISORDERS OF NEUROMUSCULAR JUNCTIONS..

• Myasthenia gravis
• Lambert-Eaton myasthenic syndrome 
• Botulism poisoning
• Organophosphate  poisoning
• Hypermegnesemia  
• Hypocalcemia 
  

DISORDERS RELATED TO NERVE INJURIES..

• Carpal tunnel syndrome 
• Diabetic neuropathy
• Amyloid neuropathy 
• Bell's palsy
• Tarsal tunnel syndrome
• Charcot-Marie-tooth syndrome
• Hemifascial spasm 

MOTOR NEURONS DISORDERS..

• Amyotropic lateral sclerosis 
• West Nile virus 
• Poliomyelitis 
• Kennedy's syndrome 
  

There are many more disorders which is related to plexus and root of nerves including :

• Neuralgic Amyotrophy 
• Lumbosacral radiculopathy 
• Hirayama diseases
• Traumaticobrachial plexopathy 
• Cervical , thoracic , lumber sacral  radiculopathy 
• Arachnoiditis 
• Spine stenosis
  
  

NORMAL RESULTS OF EMG..

EMG results can be calculated as :

1. Initially muscle is electrically in inactive state.
2. Needle insertion causes electrical irritability within the muscle. .
3. At this stage , electromyogram detects no abnormality within the muscle ( before electrical activity silent )
4. Muscle begin to contract maximally , action potential begin to appear.
5. Muscle contraction increased = more and more muscle fibers produced action potential .
6. Fully contracted muscle =  groups of action potential with varying rates and amplitudes ( complete recruitment and interference pattern)

LIMITATIONS OR PRECAUTIONS ..

Needle EMG has limitations :

• Less informative patients or unwilling to cooperate .
• Children and infants .
• paralytic individuals .
• Adipose tissue disorders 
• Deep muscles required intramuscular wires which is painful .

ABNORMAL RESULTS OF EMG..

Abnormal EMG reading results usually indicate nerve or muscle damage. 
EMG abnormal results found due to :

• EMG recordings vary with the type of disorders.
• Duration of problem.
• Age of patient.
• Patient's degree of cooperation .
• Type of electrode needle .
  

BY , RUBAB ALI..