Faculty

The diagnostic tests carried out are listed below:-

• Electroencephalography (EEG)
• Video EEG
• Long Term Video EEG
• Bedside EEG Monitoring
• Electromyography (EMG)
• Nerve Conduction Studies (NCS)
• Repetitive Nerve Stimulation (RNST)
• Evoked potential
  1. Visual Evoked Potential (VEP)
  2. Brainstem Auditory Evoked Potential (BAER)
  3. Somatosensory (SSEP)
• Electroretinography (ERG)
• Intra-Operative Monitoring (IOM)

ELECTROENCEPHALOGRAPHY (EEG)

The electrical activity of brain is recorded by this test. The record is analysed for abnormalities in brain rhythm.

EEG is done in the following conditions:

• Epilepsy to confirm the diagnosis.
• In spells of unconsciousness/ fainting - EEG is useful in differentiating these disorders from epilepsy.
• Encephalitis (viral inflammation of brain e.g viral infections).
• Dementia.
• Stroke.
• Brain tumour.

The EEG is useful for diagnosis to decide about medication, in monitoring the response to treatment and in long term follow up to evaluate the course of the disease.

Details of Procedure

• The test is painless.
• The patient lies on the bed quietly.
• Electrodes (small metal discs) are placed on the head.
• During the test the patient may be asked to open and close the eyes on a few occasions, may be asked to breathe rapidly for few minutes. The patient is encouraged to relax with eyes closed and encouraged to sleep.
• The time required for preparation and actual recording may take approximately 40-60 minutes.
• There are no side effects.

Instructions

• Do not apply oil on the head.
• Take a light meal, avoid fasting.
• Take routine drugs.
• Small children and uncooperative patients may be given sedative medicine.
• This is an outpatient procedure. There is no need for admission to the hospital.

SPECIAL EEG PROCEDURE (Video-EEG/Long Term Recording)

Depends on the clinical disorders, seizure frequency and indication for primary video EEG. This can range from 1-3 hours in patients with frequent events (hourly) to

4-5 days in patients with infrequent events and evaluation prior to surgery. One attendant should accompany the patient during the procedure. The EEG along with video is recorded simultaneously to evaluate the nature of events.

ELECTROMYOGRAPHY (EMG)

The EMG test is used to evaluate the status of the muscles, nerves, roots and anterior horn cells. A number of neurological disorders present with weakness or atrophy (thinning) of muscles.

Some common disorders are:

• Muscular dystrophy.
• Myopathy.
• Neuropathy.
• Carpal tunnel syndrome.
• Nerve injuries.
• Cervical/lumbar radiculopathy.
• Motor neuron diseases.

The EMG may be done either alone or in combination with nerve conduction studies (NCS) depending on the neurological disorder.

Common symptoms of muscle involvement:

• Difficulty in climbing stairs.
• Difficulty in getting up from sitting/squatting position.
• Difficulty in performing movements like buttoning, breaking chapatis, mixing food, combing hair.
• Raising hands above the head.

Details of Procedure:

• A thin disposable EMG needle is inserted into the muscle to be examined. Depending on the type of disease one or more muscles may be required to be tested.
• You may experience mild pain during the procedure.
• There is no risk of transmitting the infection since disposable needles are used and they are destroyed after use.
• You can have your regular food and medication on the day of the test.
• You should wear loose clothes so that the test can be easily done.
• NERVE CONDUCTION STUDIES (NCS)
• Nerve conduction studies are used to evaluate the function of the nerves.
• There are mainly two types of nerves - motor and sensory. The nerve conduction studies are specially designed to perform motor nerve conduction and sensory nerve conduction.

Nerve conduction studies is recommend for following diseases: 

• Neuropathy in patients with diabetes mellitus.
• Connective tissue diseases
• Injury to the nerves
• Carpal tunnel syndrome
• Cervical/lumbar disc prolapse
• Intake of drugs, which may affect the nerves. (drugs taken for treatment of tuberculosis/ cancer)
• Guillain Barre Syndrome
• Hereditary Neuropathy
• Myasthenia.

Symptoms of nerve involvement :

• Tingling, numbness of hands/feet.
• Burning sensation / pain in the hands and feet.
• Decreased sensation in arms/legs.
• Weakness /thinning of arms and legs.

Details of Procedure

• Test usually takes 20-30minutes.
• Metal disc plates (electrodes) are placed on the skin over nerves
• and muscles and mild electrical stimulation is given and the response is recorded.
• Usually two nerves in upper limbs and two nerves in lower
• Limbs are tested. It may be necessary to test more nerves depending on the neurological disease.

Instructions

• Wear loose clothes, which will allow easy examination.
• Fasting not required.
• For children who are uncooperative sedation may be required.
• There is no after effect following the test.
• This is done as an outpatient procedure.

Repetitive Nerve Stimulation (RNST)

Repetitive nerve stimulation tests are a special type of nerve conduction study. Rather than a single electric shock, a brief series of shocks is applied to a motor nerve and responses are recorded from a muscle supplied by that nerve. The study is generally performed before and after brief exercise of the muscle. Serial response amplitudes are recorded. Repetitive nerve stimulation is useful for evaluating myasthenia gravis and other disorders of neuromuscular transmission.

EVOKED POTENTIAL (EP)

Evoked potential (EP) is the electrical response recorded from brain, spinal cord or peripheral nerve evoked by various external stimuli, such as visual, auditory or somatosensory stimulation. The recording electrodes are placed over the scalp, neck or spine which vary depending on the type of stimulus modality to be tested. The evoked potential provides valuable information about the functional status and diseases affecting vision, hearing and sensory pathways.

VISUAL EVOKED POTENTIAL (VEP)

VEP provides information regarding conduction in visual pathway from the retina to brain (occipital cortex).

VEP is recommended for following diseases:

Impairment of vision due to:

• a. Multiple Sclerosis
• b. Optic Neuritis
• c. Tumours of the brain (pituitary tumours)
• d. Head injuries
• e. Drugs which may cause visual impairment
• f. In children with mental retardation/ delayed development to assess visual status

Details of Procedure

• The test is performed in dark room.
• Each eye is tested separately.
• The patient is asked to focus on a point on the monitor, which shows
• checkerboard pattern.
• Small metals plates (electrodes) are applied to the head, which record the
• electrical potential.
• The procedure usually take approximately 30 minutes.

Instructions

• Hair should be washed, dried, with no oil, gel, spray etc.
• If the patient is using spectacles or contact lenses than he/she should wear them at the time of examination.
• For children who are uncooperative sedation may be required.

Electroretinography (ERG)

ERG is performed to evaluate the visual function particularly in the patients suspected to have retinal diseases. It can be performed independently or with VEP.

Brainstem Auditory Evoked Potential (BAER)

This test examines the integrity of auditory pathway through the brainstem. The sound enters ear canal and stimulates auditory nerve. The electrical impulse travels from auditory nerve through the brainstem to auditory cortex. During testing, the patient hears the repetitive click sound through the earphone.

BAER is recommended for following diseases:

• Hearing problem
• Dizziness/ Vertigo
• Multiple Sclerosis
• Tumours of the Brainstem
• Head Injuries
• Delayed development in children .
• Jaundice in children.

Details of Procedure

• The procedure is carried in a sound proof room.
• The stimulus is provided using headphone in one ear followed by second ear.
• The electrical response is recorded by small metal plates (electrodes).
• The test is not painful.

Instructions

• Hair should be washed, dried, with no oil, gel, spray etc.
• For children who are uncooperative sedation may be required.
• The procedure usually take approximately 30 minutes.

Somatosensory Evoked Potential (SSEP)

This test examines the sensory system from the peripheral nerve to the sensory cortex of brain. Weak electrical stimuli are applied to the peripheral nerve, for example median or ulnar nerve for upper extremity study and tibial nerve for lower extremity study.

SSEP is recommended for following diseases:

• Numbness/ weakness of arm or leg.
• Diseases of the spinal cord.
• Multiple Sclerosis.

Details of Procedure

• The electrical stimulation is applied to nerve in the arm or the leg.
• The response is recorded from the neck and the head by electrodes placed over the surface.
• Mild pain is experienced when electrical stimulation is applied.

Instructions

• Should wear loose clothes, which will allow easy examination.
• Fasting not required.
• For children who are uncooperative sedation may be required.
• There is no after effect following the test.
• This is done as an outpatient procedure.