ELECTROENCEPHALOGRAPHY (EEG)
The electrical activity of brain is recorded by this test. The record is analysed for abnormalities in brain rhythm.
1) EEG is done in the following conditions:-
a. Epilepsy to confirm the diagnosis.
b. In spells of unconsciousness / fainting – EEG is useful in differentiating these disorders from epilepsy.
c. Encephalitis (viral inflammation of brain e.g. viral infections).
d. Dementia.
e. Stroke.
f. 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.
2) Details of Procedure
a. The test is painless.
b. The patient lies on the bed quietly.
c. Electrodes (small metal discs) are placed on the head.
d. During the test the patient may be asked to breathe rapidly for few minutes. The patient is encouraged to relax with eyes closed and encouraged to sleep.
e. The time required for preparation and actual recording may take approximately 40-60 minutes.
f. There are no side effects.
3) Instructions
a. Hair should be washed, dried, with no oil, gel, spray etc.
b. Take a light meal, avoid fasting.
c. Take routine drugs.
d. Small children and uncooperative patients may be given sedative medicine.
This is an outpatient procedure. There is no need for admission to the hospital.
NERVE CONDUCTION STUDIES (NCS)
a. Nerve conduction studies are used to evaluate the function of nerves.
b. 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.
1) Nerve conduction studies are recommended for following diseases
a. Neuropathy in patients with diabetes mellitus.
b. Connective tissue diseases
c. Injury to the nerves
d. Carpal tunnel syndrome
e. Cervical / lumbar disc prolapse
f. Intake of drugs, which may affect the nerves (drugs taken for treatment of tuberculosis/cancer)
g. Guillain Barre Syndrome
h. Hereditary Neuropathy
i. Myasthenia
2) Symptoms of nerve involvement
a. Tingling, numbness of hands/feet.
b. Burning sensation / pain in the hands and feet.
c. Decreased sensation in arms/legs.
d. Weakness/thinning of arms and legs.
3) Details of Procedure
a. Wear loose clothes, which allow easy examination.
b. Fasting not required.
c. For children who are uncooperative sedation may be required.
d. There is no after effect following the test.
e. This is done as an outpatient procedure.
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.
1) Some common disorders are:
a. Muscular dystrophy
b. Myopathy
c. Neuropathy
d. Carpal tunnel syndrome
e. Nerve injuries
f. Cervical/lumbar radiculopathy
g. Motor neuron diseases.
EMG may be done either alone or in combination with nerve conduction studies (NCS) depending on the neurological disorder.
2) Common symptoms of muscle involvement:-
a. Difficulty in climbing stairs.
b. Difficulty in getting up from sitting/squatting position.
c. Difficulty in performing movements like buttoning, breaking chapatis, mixing food, combing hair.
d. Raising hands above head.
3) Details of Procedure
a. 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.
b. You may experience mild pain during the procedure.
c. There is no risk of transmitting the infection since disposable needles are used and they are destroyed after use.
d. You can have your regular food and medication on the day of the test.
e. You should wear loose clothes so that the test can be easily done.
f. This is done as an outpatient procedure.
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
1) Impairment of vision due to:-
a. Multiple sclerosis
b. Optic Neuritis
c. Tumors of the brain (pituitary tumors)
d. Head injuries
e. Drugs which may cause visual impairment
f. In children with mental retardation/delayed development to assess visual status.
2) Details of Procedure
a. The test is performed in dark room.
b. Each eye is tested separately.
c. The patient is asked to focus on a point on the monitor, which shows checkerboard pattern.
d. Small metal plates (electrodes) are applied to the head, which record the electrical potential.
e. The procedure takes approximately 30 minutes.
3) Instructions
a. Hair should be washed, dried, with no oil, gel, spray etc.
b. If the patient is using spectacles or contact lenses then he/she should wear them at the time of examination.
c. For children who are uncooperative, sedation may be required.
BRAINSTEM AUDITORY EVOKED POTENTIAL (BAEP)
This test examines the integrity of auditory pathway through the brainstem. The sound enters the 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.
1) BAEP is recommended for following diseases
a. Hearing problem
b. Dizziness/vertigo
c. Multiple sclerosis
d. Tumors of the brainstem
e. Head injuries
f. Delayed development in children
g. Jaundice in children.
2) Details of Procedure
a. The procedure is carried in a sound proof room.
b. The stimulus is provided using headphone in one ear followed by second ear.
c. The electrical response is recorded by small metal plates (electrodes).
d. The test is not painful.
3) Instructions
a. Hair should be washed, dried, with no oil, gel, spray etc.
b. For children who are uncooperative, sedation may be required.
c. The procedure usually takes approx. 30 minutes.