EEG and Nerve Conduction Tests: What to Expect and Why They Are Done

Your neurologist has recommended an EEG or a nerve conduction study and you are not quite sure what to expect. These are very common, routine investigations — and they are painless (or nearly so). Here is exactly what happens and why your doctor needs this information.

EEG (Electroencephalogram)

An EEG records the electrical activity of the brain through small sensors (electrodes) placed on the scalp. It is completely painless — no needles, no electricity passed into you. You sit or lie down while a technician applies the sensors with a gel, and the machine records brain wave patterns for about 30–45 minutes.

During the test, you may be asked to breathe deeply and rapidly (hyperventilation) and to look at a flashing light — these are activation procedures that help bring out any abnormal brain activity.

Why Is EEG Done?

• To diagnose epilepsy and classify the type of seizure
• To look for abnormal brain activity after a seizure or fainting episode
• To evaluate sleep disorders (sometimes done during sleep)
• To investigate unexplained changes in behaviour or consciousness
• To monitor brain activity in critically ill patients

How to Prepare for an EEG

• Wash your hair the night before — do NOT use oils, gels, or hairspray
• Sleep deprivation before the test is sometimes requested (the doctor will advise)
• Take your regular medications as usual, unless specifically told otherwise
• Eat normally — do not come fasting

Nerve Conduction Study (NCS) and EMG

A nerve conduction study measures how quickly electrical signals travel along your nerves. Small electrodes are placed on the skin, and very brief, mild electrical pulses are passed through the nerve — you feel a small tingling or muscle twitch. Most people find it mildly uncomfortable but not painful.

EMG (electromyography) goes one step further — a very thin needle electrode is inserted into muscles to record their electrical activity. This does sting briefly, similar to a blood test needle.

Why Is NCS/EMG Done?

• To diagnose peripheral neuropathy (nerve damage from diabetes, B12 deficiency etc.)
• To evaluate carpal tunnel syndrome or other nerve entrapments
• To assess muscle diseases (myopathies)
• To investigate weakness, numbness, or tingling in the limbs
• To evaluate Guillain-Barré syndrome or other nerve disorders

"EEG and nerve conduction studies are among the most important tools a neurologist has — they directly measure how your brain and nerves are functioning, in ways that no blood test or scan alone can reveal."

Sri Anand Child and Neuro Center, Chanda Nagar provides in-house EEG and nerve conduction studies. Same-visit results are available for most patients. Call +91 90633 66983 to schedule.