The electroencephalogram (EEG) is a medical test used to measure the electrical activity of the brain, via electrodes applied to your scalp. This procedure is completely painless and can be performed without shaving any of your hair. EEG can help diagnose a number of conditions, including epilepsy, sleep disorders and brain tumours. Another name for EEG is brain wave test.

Conditions diagnosed by EEG

Normal brain waves occur at a rate of up to 30 per second, but in someone with epilepsy, for example, the EEG may show bursts of abnormal discharges in the form of spikes and sharp wave patterns. Suspected epilepsy is the most common reason for an EEG.

Other conditions that may be diagnosed with the aid of an EEG include:

• Sleep disorders (such as narcolepsy)
• Head injuries
• Brain infection
• Brain haemorrhage
• Alzheimer's disease
• Degeneration of brain tissue
• Metabolic conditions that affect brain tissue
• Hormonal conditions that affect brain tissue
• Certain disorders of the central nervous system
• Stroke
• Brain tumour
• Brain death.