EEG- The Past, Present, and Future

From its first application a century ago to its widespread use in clinical studies and personal use, electroencephalograms (EEGs) are powerful diagnostic tools that provide a way to make sense of the most advanced part of the body, the brain. Without an EEG certain diseases and disorders cannot be diagnosed and treated, and we would be without considerable information regarding how the brain functions.

What is an EEG?

An EEG is a test that analyzes brain waves to detect any abnormalities in the brain’s electrical activity. Small metal discs called electrodes are stuck to the scalp to obtain the electrical activity readings, and the thin wires attached to the electrodes then transmit the electrical activity in the brain. The charges are amplified and appear on a computer screen or recorded printed on paper, and it is then the job of the healthcare professional to read and interpret the reading.

The Beginnings

The EEG dates back to the 1920s, when the German psychiatrist Hans Berger used the first EEG on July 6, 1924 during a neurosurgical operation on a 17-year-old boy. This advancement spearheaded a significant breakthrough in providing meaningful neurologic information and assisting in diagnosing neurological and psychiatric conditions. From this point, applications of the EEG continued to advance. In 1929 Berger reported on the EEG, citing the alpha and beta waves that appeared as spikes. Epileptiform spikes were first demonstrated in 1934, and clinical seizures with interictal epileptiform discharges and 3-Hz spike-wave patterns were first described in 1935. The first laboratories explicitly dedicated to EEGs were established in the United States in the 1930s and 40s.

What are EEGs Used for Now?

EEGs are currently used in various applications, including monitoring and diagnosing seizures and sleep disorders.

Epilepsy Monitoring Units

An epilepsy monitoring unit (EMU) is a specialized unit within a hospital where a patient spends 3-5 days. During this time, the patient has their brain activity continuously monitored using EEG and video recordings. The goal of the time spent in the EMU is to evaluate, diagnose, and treat seizures. One of the biggest challenges with diagnosing and treating seizures, epilepsy, and seizure-like disorders is determining what triggers the seizure or seizure-like activity and how the seizure affects the brain. Different types of seizures and epilepsy are triggered by different things and affect the brain in different ways, so determining the specific type is essential for selecting the best treatment.

Sleep Studies

EEGs are also used with other recording methods, including electrooculogram (EOG) and electromyography (EMG), for sleep studies, which diagnose sleep disorders such as sleep apnea, insomnia, narcolepsy, and restless legs syndrome. Utilizing EEGs allows technicians to record what activity is occurring in the unconscious brain, and comparing this information with that attained by the other tests can help diagnose sleep conditions. 

At-Home Usage

EEGs are used in more than the hospital and clinical settings; they can also be used in-home for usage by the general public. Their use at home allows the general public to analyze their brain activity. One example of this lies in “brain training” or neurofeedback, which uses the brain’s waves to train the brain to change its response. While these sessions can be completed in a clinic, technology has advanced to the point where they can also be completed in the comfort of the patient’s home.

Research Studies

EEGs are exceptionally important in clinical trials, especially for those regarding seizure activity. For example, EEGs allow the research team to determine if a certain treatment or medication is effective or what might trigger certain seizures. Other studies utilize EEGs to analyze sleep abnormalities and the factors and co-morbidities that might share a link.

The Future of EEGs

The future of the EEG is a promising field with the abilities of EEGs continuing to expand. Research is continually using EEGs to better understand current conditions, obtain more information, and find links that went previously undetected. EEGs are a diagnostic tool that will never fade in importance due to their ability to non-invasively monitor the most important aspect of the body. As research continues to utilize EEGs to understand how the brain works, the power of this test in diagnosing other conditions, and better understanding conditions such as epilepsy and seizures, will only increase.

References

Tudor, M., Tudor, L., & Tudor, K. I. (2005). Hans Berger (1873-1941)--povijest elektroencefalografije [Hans Berger (1873-1941)--the history of electroencephalography]. Acta medica Croatica : casopis Hravatske akademije medicinskih znanosti, 59(4), 307–313. 

Britton JW, Frey LC, Hopp JLet al., authors; St. Louis EK, Frey LC, editors. Electroencephalography (EEG): An Introductory Text and Atlas of Normal and Abnormal Findings in Adults, Children, and Infants [Internet]. Chicago: American Epilepsy Society; 2016. Appendix 6. A Brief History of EEG. Available from: https://www.ncbi.nlm.nih.gov/books/NBK390348/

Ciattei, J. (2022). Epilepsy Monitoring Units | The Johns Hopkins Epilepsy Center. Retrieved 7 April 2022, from https://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/epilepsy/emu.html

Sleep Study. (2022). Retrieved 7 April 2022, from https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/sleep-study

Gu, B., Zhu, M., Glass, M., Rougié, M., Nikolova, V., & Moy, S. et al. (2019). Cannabidiol attenuates seizures and EEG abnormalities in Angelman syndrome model mice. Journal Of Clinical Investigation, 129(12), 5462-5467. doi: 10.1172/jci130419

K. Lehnertz et al., "Seizure prediction by nonlinear EEG analysis," in IEEE Engineering in Medicine and Biology Magazine, vol. 22, no. 1, pp. 57-63, Jan.-Feb. 2003, doi: 10.1109/MEMB.2003.1191451.

Zangani, C., Casetta, C., Saunders, A., Donati, F., Maggioni, E., & D’Agostino, A. (2020). Sleep abnormalities across different clinical stages of Bipolar Disorder: A review of EEG studies. Neuroscience &Amp; Biobehavioral Reviews, 118, 247-257. doi: 10.1016/j.neubiorev.2020.07.031