An electroencephalogram, or EEG for short, is a test that measures electrical activity in the brain. It is one of the most common methods of monitoring changes in brain activity and measuring the presence of abnormal activity. An EEG detects changes in electrical activity in the brain that may indicate potential problems such as a tumor, stroke, infection, or other medical condition. It also records the collective electrical signals produced by individual neurons in different brain regions.

These electrical impulses can be measured using electrodes placed on the scalp to detect voltage fluctuations at specific frequencies referred to as “brain waves.” However, it should be noted that an EEG cannot directly determine what a person is thinking or feeling. Instead, it provides information about how various brain parts respond to sensory stimuli or other mental tasks. Here, we will explain what EEGs measure and how it helps doctors diagnose brain disorders.

1. Head Injury

The most common reason for an EEG is to detect the effects of a head injury, such as a concussion. When injured, the brain’s electrical activity can cause abnormal brain waves that an EEG detects. These brain waves are called “spike waves” or “spike and wave complexes,” typically seen in patients who have suffered a head injury. According to WebMD, spike and wave complexes may indicate that the patient has suffered a mild traumatic brain injury. They can also be caused by stroke or other conditions that disrupt normal brain function. In some cases, spike and wave complexes may indicate that no trauma occurred and are only seen when there is increased electrical activity in the brain.

2. Sleep Disorders

An EEG may also diagnose sleep disorders such as narcolepsy or obstructive sleep apnea (OSA). During a sleep study, patients wear electrodes on their scalp to monitor their brain activity while they sleep. The test involves sleeping for at least 8 hours, during which the electrodes record electrical signals within their brains. If certain types of abnormal patterns appear in these recordings, it may indicate that someone suffers from one of these conditions. For example, irregular bursts of high-frequency waves associated with narcolepsy or low-frequency waves associated with OSA can often be detected on an EEG during regular sleeping cycles.

3. Brain Tumor

An EEG is also used to detect brain tumors in suspected cancer patients. The test involves placing electrodes on the scalp to monitor activity within the brain. If a patient has a tumor, these electrodes will pick up abnormal electrical activity caused by the tumor, which can be detected using an EEG. An EEG may also detect other tumors not involving the brain or spinal cord, such as those found in other body parts. These tumors are called “extracranial” or “paricranial” and are often more challenging to detect because they lie outside the skull and brain.

4. Mental Disorders

Many mental disorders can result in abnormal electrical activity within the brain that can be detected using an EEG. For example, certain types of epilepsy cause seizures, which may cause high levels of electrical activity within the brain. In some cases, this type of electrical activity may be detected on an EEG during regular sleeping cycles or when there is no apparent reason. Similarly, people with depression may experience abnormal patterns on an EEG if they are under stress or depressed at the time it is performed. An EEG headset will record brain activity and can be connected to a computer for analysis.

5. Cerebral Palsy

The EEG is used to detect cerebral palsy in children. Cerebral palsy is a type of brain damage that occurs when the brain does not develop correctly during pregnancy or shortly after birth. As a result, children with cerebral palsy may have slowed muscle movement, poor balance and coordination, and other neurological problems due to brain damage. Most children with cerebral palsy have abnormal brain waves, called slow waves on an EEG. The EEG is also used to detect other neurological disorders such as seizures in children.


These are just a few of the many uses for EEG. Many people use it to help diagnose certain brain disorders and monitor the brain for seizures. There are many commercial uses, such as detecting and measuring brain waves for use in music, video games, and other applications. Always consult a physician before using an EEG for non-medical purposes.

By Andy