From Diagnosis to Drug Trials: EEG in Epilepsy
How can an epilepsy drug’s effect on the brain be assessed when there are no seizures to count?
In Phase I clinical trials with healthy volunteers, seizure monitoring cannot provide that evidence. Development teams therefore need another way to determine whether a drug produces a measurable brain response consistent with its intended action.
Understanding Epilepsy and Why Awareness Matters
Electroencephalography (EEG) has been central to epilepsy care since the 1930s and now helps inform how the next generation of medicines is evaluated. Its role extends from diagnosis to clinical trials.
Epilepsy is a chronic neurological condition characterised by recurrent, unprovoked seizures arising from sudden surges of abnormal electrical activity in brain cells. These electrical surges may be associated with genetic factors, brain injuries or causes that remain unknown.
The condition can substantially affect quality of life, restricting participation in activities such as concerts and travel. The general misunderstanding of epilepsy can also contribute to stigma and isolation. Awareness therefore remains important for both people living with epilepsy and the wider community.
What is EEG and What Happens During a Recording?
EEG provides a safe, non-invasive way to record the brain’s electrical activity. Scalp electrodes detect small electrical signals from brain cells, which are displayed as wave patterns for clinical interpretation. EEG supports the diagnosis of epilepsy, sleep disorders and head injuries.
The procedure is straightforward and painless: a technician attaches small adhesive electrodes to the scalp without needles, while the participant sits or lies at rest. Deep breathing or photo-stimulation may be used to elicit brain activity during the assessment. Most recordings take between 20 minutes and an hour, with normal activities usually resumed immediately afterwards.
By detecting abnormal brain activity, EEG has contributed to diagnostic accuracy, public awareness and reduced stigma, supporting recognition of epilepsy as a treatable and better-understood medical condition.
EEG’s role in current clinical care and epilepsy research builds on discoveries dating to the 1930s, when scientists linked electrical brain patterns to brain function and behaviour. Frederic Gibbs and William Lennox identified distinctive EEG spikes during certain seizure types. In the 1940s, Penfield and Jasper showed that seizures often originate in areas surrounding injured brain tissue, rather than solely at the injury site. These findings established EEG’s value in classifying seizures and identifying their origin, providing a foundation for subsequent treatment and technology development.
EEG in Diagnosis
EEG’s diagnostic value must be considered alongside its limitations. Generalised epilepsy involves both sides of the brain, whereas focal epilepsy originates in a specific area. EEG can identify abnormal electrical patterns that indicate epilepsy risk, supporting timely detection and diagnosis.
However, abnormal patterns are detected in only about half of people with epilepsy, so a normal recording does not exclude the condition. Muscle activity and electrical devices can introduce interference, and post-seizure recordings may show slower activity during recovery. Clinicians therefore interpret EEG alongside other diagnostic assessments. Its ability to prompt early clinical suspicion nevertheless remains important for awareness and timely action.
Diagnostic differentiation is another important application. Conditions such as fainting, migraines and non-epileptic seizures can resemble epilepsy without producing the same changes in brain activity. EEG helps clinicians distinguish between these presentations, reducing the risk of misdiagnosis and supporting appropriate treatment and care. Communicating this role is an important part of building awareness of EEG.
Longitudinal EEG monitoring supports treatment decisions by showing whether abnormal electrical activity is increasing, decreasing or remaining stable. These observations can inform medication adjustments, consideration of alternative therapies and assessment of future seizure risk, supporting safer, more informed long-term management.
Advances in portable systems now enable recordings at home over several days or weeks, extending assessment beyond short hospital-based tests. At-home monitoring increases the opportunity to capture rare or unpredictable events and supports diagnostic accuracy. This is particularly valuable for infrequent events or ongoing assessment of seizure control.
At-home monitoring also offers greater convenience, less disruption and more complete data to inform treatment adjustments. EEG can identify characteristic electrical patterns, known as epileptiform discharges, that are often associated with epilepsy and are usually absent when symptoms have another cause. Recording and analysing activity during or between episodes supports clinical decisions on diagnosis, management and appropriate care.
EEG in Drug Development
In epilepsy drug development, EEG’s primary role is to measure the brain’s response to a medicine, rather than to deliver treatment. Early-phase studies use EEG to assess drug-related changes in brain activity in real time, sometimes before physical symptoms emerge. These assessments can show changes in epilepsy-associated electrical activity, effects related to seizure prevention or effects on healthy brain function.
Higher-density sensor systems improve localisation of abnormal activity, while computational methods and artificial intelligence can identify subtle signal changes relevant to seizure risk or treatment response. These advances support the development of safer, more effective epilepsy medicines. EEG remains central to research and clinical care, making awareness and support for its continued use important.
Non-Invasive Brain Stimulation Techniques
Non-Invasive Brain Stimulation (NIBS) comprises techniques designed to modulate brain activity externally, without surgery. It represents a potential option for people whose seizures remain uncontrolled with medication and who are not candidates for surgery.
Transcranial Magnetic Stimulation (TMS) uses magnetic pulses applied at the scalp to activate specific brain regions. Transcranial Direct Current Stimulation (tDCS) uses a mild electrical current to modulate brain cells, while the newer approach of Transcranial Ultrasound Stimulation (TUS) uses sound waves to reach deeper brain regions. These approaches remain largely experimental in epilepsy, although early studies suggest potential seizure reductions in some patients. Research also explores their use in pre-surgical brain mapping and guidance of permanent device placement.
Combining EEG and Brain Stimulation Techniques
Together, EEG and NIBS support evaluation of treatment approaches that combine medicines with brain stimulation. They help investigators assess whether responses differ by epilepsy type or patient group. EEG can also show whether a medicine changes brain activity in ways that may contribute to preventing future seizures. Communicating these advances builds understanding of, and support for, ongoing research. Greater public awareness of EEG and its role supports progress towards better treatments for people living with epilepsy.
How EEG Compares with Other Techniques
EEG’s principal advantage within the wider imaging and brain-monitoring toolkit is its ability to capture rapid changes in electrical activity during seizures and treatment assessment.
MRI and fMRI provide detailed information on brain structure and function but do not directly record electrical activity as it occurs. Magnetoencephalography (MEG) records magnetic rather than electrical signals and offers greater precision in localising seizure origins, although availability is more limited. Intracranial EEG (iEEG) provides more detailed recordings through electrodes placed directly on the brain but is reserved for selected situations such as epilepsy surgery planning.
Each approach has strengths and limitations; EEG’s accessibility and capacity for monitoring over time make it valuable in both research and clinical care. Early diagnosis and treatment remain important for outcomes and quality of life, reducing the likelihood of ongoing seizures, injury and social difficulties associated with delayed care.
EEG supports diagnostic confirmation and treatment selection. Continued research supports more accurate, accessible assessments, improved treatments and wider public awareness. Early intervention and sustained investigation remain central to improving safety, independence and quality of life for people living with epilepsy.
References
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