Nerve conduction studies (NCS)/ Electromyography (EMG)

Nerve conduction studies (NCS) examines the peripheral nerves by stimulating the nerves with safe tiny electrical pulses, like that of static shocks and recording the response. It is performed for multiple reasons and so is specific to the clinical presentation and the number of nerves being tested is dependent on this. It is usually performed on the limbs and with some of the study you can see the limb jerk similar to that of a tendon hammer. There is no side effects to the testing except for sweating.

  • No cream or oil on limbs or area to be tested.
  • Wear loose clothes so that sleeves or trousers can be pulled up above knee or elbow – depending on the required area of examination.

The test should take roughly 1hour.
On occasions further information is needed and so the neurologist may perform a Electromyography (EMG) study. EMG examines the muscle activity and the nerve supply to the muscles. The neurologist inserts a tiny recording pin into the muscles and listens to it at both rest and with activation. The neurologist does not draw or inject anything. Again the number of muscles sampled is dependent on the clinical presentation. On the rare occasion a person may receive a bruise from this test.

Preparation:

  • No cream or oil on limbs or area to be tested.
  • Wear loose clothes so that sleeves or trousers can be pulled up above knee or elbow – depending on the required area of examination.

Electroencephalography (EEG)

Electroencephalography (EEG) examines/records the brain activity. It is performed for multiple reasons such as epilepsy, headaches and memory/cognitive issues being the main reasons.

It is performed by placing 21 recording electrodes on the head for the brain activity and 2 on the chest for the heart beat. The electrodes are placed on by first abrading the skin (rubbing to reduce dead skin and natural oils) and then the electrodes are placed on with a special conductive paste and micropore where there is no hair to hold it in place. The test is performed with eyes closed and the patient is instructed when needed to do things like opening closing of eyes, hyperventilation and is shown a strobe light. There is usually no side effects to the test except for dirty hair.

Preparation:

    • Clean hair (no hair spray, gel, oil etc)
    • Do not drink coffee or other caffeine products
    • Always take medications as per normal unless indicated

The test should take 45 mins to an hour.

A sleep deprived EEG is also requested on occasion so that the doctor can get added information if needed. You will be instructed if this is the case and will be asked to stay up for 24 hours. The study is performed the same way as a routine EEG test just that one is expected to sleep during the recording.

Preparation:

    • Clean hair (no hair spray, gel, oil etc)
    • Do not drink coffee or other caffeine products
    • Always take medications as per normal unless indicated
    • 24 hours sleep deprived unless otherwise stated

A sleep deprived EEG takes 1.5 hours.

Visual Evoked Potentials (VEP)

VEP tests the optic nerve and is requested for things like optic neuritis or MS. It is performed by placing recording electrodes on with a conductive paste on the head and near the eyes. The patient has to stare at a red dot while the background of a checkerboard screen is shuffling. The hair will be dirty after the test.

Preparation:

    • Bring along reading glasses if you use it
    • Clean hair (no hair spray, gel, oil etc)
    • Avoid makeup

The test will take roughly 1 hour.

Somatosensory evoked potentials (SEP)

There are a few different types of SEPs and depending on the region of symptoms and possible cause your GP or specialist will request accordingly. Upper and Lower limb SEPs test the nerve path way through the cervical spine or whole spine to the brain. These tests can be requested for things like spinal pathology, demyelination, TOS, meralgia paraesthetica to name a few.

The test is performed by placing recording electrodes on the head, back, neck, shoulder or limbs, depending on the specific SEP test. The electrodes are placed on after abrading the skin with a special conductive paste. The nerve to be tested is stimulated with a tiny and continues electrical pulse for roughly 5 minutes – depending on patient relaxation and reproduction of response.

Preparation:

    • Clean hair (no hair spray, gel, oil etc)
    • Loose clothing if possible
    • No cream on body

The test will take roughly 1 hour per SEP.

Brain stem auditory evoked potentials (BAEP)/ Vestibular evoked myogenic responses (VEMP)

Brain stem auditory evoked potentials (BAEP)/ Vestibular evoked myogenic responses (VEMP)

BAEP tests the upper and lower brainstem pathways. It is performed for a number of reasons and may need to be performed in conjunction with other tests (e.g MRI or ENG) to clarify findings.

It is performed with loud auditory stimulation (as the name suggests) and recording electrodes placed on the head and ear lobes. These electrodes are prepped with an abrasive paste and applied with a conductive paste. The stimulation can go for roughly 5 minutes each side where the patient is required to relax and reduce any muscle artifact.

VEMP is an additional test performed with BAER if needed. The recording electrodes are placed on the neck (Sternocleidomastoid muscle) and base of neck. The patient is asked to activate the muscle by turning to the right or left and bring the head forward and auditory stimulation is once again applied to stimulate and record.

Preparation:

    • Clean hair (no hair spray, gel, oil etc)
    • No earrings

The test will take roughly 1 hour.