Electromyography (EMG)

The referring doctor may order for the tests if you have signs or symptoms that may indicate a nerve or muscle disorder. Such symptoms may include:

• Tingling in hands or feet
• Numbness
• Muscle weakness
• Muscle pain or cramps
• Traumatic Injuries

The clinical conditions where the test is mostly indicated:

• Peripheral Neuropathies
• Muscle diseases: Myopathies
• Diseases of Nerve and Muscle junction-Myasthenia Gravis
• Diseases of Motor neurons of brain and spinal cord-Motor neurone disease

About the EMG/NCS Procedure:

These two studies go hand in hand and are required to differentiate Nerve from Muscle diseases.

It evaluates the site and severity of the nerve lesion and further differentiating into Demyelinating vs Axonal Neuropathy.

Hence helping the referring doctor to further evaluate and decide for the line of treatment.

Nerve Conduction Study

Some sticky pads will be placed on parts of your limbs, these are to record the responses from your nerves and tell us how well they are working.

To make your nerves work we need to stimulate them. This is done either with some clips on your finger or with a special probe. The shocks given are in Milli amperes and are quite bearable. The stimulus is local and does not travel all over the body. The Motor conduction stimulus feels like a tap and causes movement of the area being stimulated.

Needle EMG examination -

• It is done using fine Disposable Electrodes, which are thin solid pins
• No shocks are given .The Needle is inserted just into the muscle for few seconds
• The patient is asked to contract the muscle and the activity is picked up by the electrode and displayed on the monitor and over a loud speaker and diagnosis is made on-line.
• The number of muscles examined depends upon the working diagnosis.

Repetitive Nerve Stimulation (Decremental Study)

• Certain diseases with muscle weakness fall neither in the nerve or muscle problems but are due to pathology at the nerve and muscle junction called the neuromuscular junction.
• Special tests the Repetitive Nerve Stimulation (Decremental Study) and even more sophisticated tests like Single Fiber EMG (SFEMG) can evaluate these diseases.
• For this test please stop medication (if already started for Myasthenia Gravis) 24 hours prior with your referring doctors consent.
• Kindly carry the medication along so that it can be taken as soon as test is completed.
• During this test a continuous current stimuli (6-7 taps) are given to a nerve to be tested.

Evoked Potentials:

These are specialized tests which involve three major tests that measure responses to Visual, Auditory and Electrical stimuli

• Visual evoked potentials (VEP)
• Brainstem auditory evoked potentials (BAEP)
• Somatosensory evoked potentials (SSEP)

Test the Optic pathway (Visual evoked Potentials)

VEP : Visual evoked Potentials

This method currently provides the most sensitive means of detecting lesions of the Optic nerves.

• In order to stimulate the visual system you will be required to watch a checkerboard television screen.
• In the paediatric age group, the flash VEP may be used as a screening test for the visual pathway

Test the Auditory pathway (BAEP or BAER

BAEP : Brainstem Auditory Evoked Potentials

BERA : Brainstem Electric Response Audiometry

• We are recording the activity of ear and the auditory nerve in response to a sound.
• We attach 3 wires (forehead and behind each ear) and we give a headphone on both the ears to pick up this activity.
• It is a painless and non”invasive test.

• Many times children are unable to perform a standard hearing test.
• This can be due to the age of the child or their level of cooperation.
• Children will require sedation for the test.

SSEP (Somatosensory evoked potential)

A somatosensory evoked potential (SSEP) is an evoked potential caused by an electrical stimulus. This investigation therefore tests the pathway of the sensory nerves to the sensory areas of the brain.

A doctor may recommend you go for a SSEP test if you have been experiencing feelings of numbness or weakness in your arms or legs that may be due to problems affecting the spinal cord functioning

The SSEP procedure itself is safe and non-invasive.

• A small generator is used to create tiny electrical impulses that are used to stimulate nerves in the wrist or the ankle.
• While the impulses are usually not painful, they may cause your thumb or toe to twitch a little, which is normal.

Intraoperative Neuromonitoring

• This is a highly specialized technique offered at our centre.
• The nervous system can be monitored during the surgery to make it safer.
• It is used for complex spinal surgeries and for certain brain surgeries.