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What Purpose Does an EEG Serve in Diagnosing Epilepsy?

An electroencephalogram, commonly known as an EEG, is a vital diagnostic tool used to help identify epilepsy. Epilepsy is a neurological condition characterised by recurrent seizures caused by abnormal electrical activity in the brain. The EEG records this electrical activity and provides valuable information to doctors when diagnosing epilepsy. This article explains the purpose of an EEG, how it is used in epilepsy diagnosis, and what patients can expect during the test, based on trusted UK health information.

How Does an EEG Work?

An EEG measures the electrical activity produced by brain cells using small sensors called electrodes placed on the scalp. These electrodes detect brain waves and transmit the data to a computer, creating a graphical record of brain activity. The test is painless, non-invasive and typically takes about 20 to 40 minutes, though longer monitoring may sometimes be required.

Role of EEG in Diagnosing Epilepsy

The primary purpose of an EEG in epilepsy diagnosis is to detect abnormal brain wave patterns associated with seizures. Specific changes such as spikes, sharp waves or spike-and-wave discharges suggest epileptic activity. These patterns help confirm the presence of epilepsy and identify the type of seizures a person experiences.

Supporting Diagnosis Alongside Clinical Assessment

An EEG is one component of the diagnostic process, complementing a detailed medical history and clinical examination. While a normal EEG does not rule out epilepsy, an abnormal EEG supports the diagnosis. Repeated or prolonged EEG monitoring increases the likelihood of detecting abnormalities.

Types of EEG Tests

There are different types of EEG tests. Routine EEG is performed during rest and may include activation procedures such as hyperventilation or flashing lights to provoke abnormalities. Ambulatory EEG involves recording brain activity over 24 to 72 hours during normal daily activities. Video EEG monitoring combines EEG with video recording to correlate seizures with brain activity.

Limitations of EEG

Not all people with epilepsy show abnormalities on EEG, especially if seizures are infrequent or deep within the brain. Conversely, some EEG abnormalities can occur in people without epilepsy. Therefore, EEG results must be interpreted in the context of clinical findings.

How to Prepare and What to Expect

Patients may be asked to avoid caffeine or get less sleep before the test to increase chances of detecting abnormalities. The procedure is safe and does not cause seizures, though activation techniques may trigger a seizure in some cases under controlled conditions.

Final Thought

An EEG serves a crucial role in diagnosing epilepsy by detecting abnormal brain electrical activity that underlies seizures. While it is not the sole diagnostic tool, EEG findings combined with clinical assessment guide accurate diagnosis and appropriate treatment planning.