By: Hiya Shaw

Focal Seizures

Seizures are a primary symptom of epilepsy, and they are classified into categories that are important to discern.

To understand focal seizures, it is important to first understand the foundations. Normally, neurons (brain cells) in the healthy brain fire in a sort of synchronized way. When neuronal firing turns abnormal by firing in extreme hypersynchrony, it suddenly changes brain activity. This triggers an epileptic seizure (Stafstrom & Carmant, 2015).

It is important to distinguish between an epileptic seizure and a non-epileptic seizure. To be brief, nonepileptic seizures are results of psychogenic events where there is no abnormal disturbance to the electric activity of the brain, whereas epileptic seizures are triggered in the brain due to such activity (Stafstrom & Carmant, 2015).

When an epileptic seizure is focal (previously known as partial), the abnormal electric activity is restricted to a specific region of the brain (Ighodaro et al., 2026).  Generalized seizures are another kind of epileptic seizure. The abnormal brain activity experienced during generalized seizures is more widespread, differentiating them from focal seizures (Ghulaxe et al., 2023). As Gupta et al. (2017) highlight, focal seizures are the most common type of seizure, more common than generalized seizures according to Ighodaro et al. (2026), affecting about 61% of individuals with epilepsy. This deeply impacts quality of life. Specifically, focal epileptic seizures risk injury and premature death. Additionally, epilepsy is often accompanied by depression, anxiety, and cognitive impairments, among other comorbidities (Ioannou et al., 2022).

Focal and generalized seizures are two of four seizure types. According to Beniczky et al. (2025), currently, the four main seizure classes are:

• Focal
• Generalized
• Unknown (whether the seizures are focal or generalized)
• Unclassified 

Within focal seizures, the presence of consciousness provides further classification. Unaffected consciousness during a focal seizure means an individual is experiencing a focal onset aware seizure. An altered conscious state means that an individual is experiencing focal onset impaired awareness seizures.

The specificity in classification is important and, consequently, diagnosing seizure types requires thorough attention and care. Ghulaxe et al. (2023) state that an accurate diagnosis requires examination of medical history, physical examinations, neuroimaging methods, and electroencephalography (EEG) tests. This examination also helps rule out other conditions with similar symptoms, particularly non-epileptic seizures.

EEGs are particularly useful as they map electrical brain activity, and their mapping allows differentiation between generalized and focal epilepsy (Stafstrom & Carmant, 2015). Further differentiation is provided by the classification of focal seizures and unknown origin, as they examine whether a patient was conscious during the seizure. This is done through clinical assessment (Ioannou et al., 2022). 

Focal seizures can be a result of many things. While Ioannou et al. (2022) provide some of the many specific reasons:

“Infections, head injuries, anatomical abnormalities of the brain (such as tumors or scars), genetic susceptibility, and cerebrovascular disease…”

Ighodaro et al. (2026) provide a more general list of the causes for a seizure based on the International League Against Epilepsy:

• Genetic
  • Structural
  • Metabolic
  • Immune
  • Infectious
  • Unknown

They also highlight that in children, perinatal hypoxic brain injury, in adolescents, head trauma and infections, and in adults, stroke is the most common cause for seizures.

Treatment for epilepsy follows one main goal: the elimination of the primary symptom—the seizures. The dependable option remains antiseizure medications (ASMs), though an unfortunate obstacle is drug resistance within the individuals who have epilepsy (Ioannou et al., 2022). Fortunately, new treatments such as responsive neurostimulation and deep brain stimulation may aid seizure control by controlling brain activity. There also exist surgical and lifestyle modification strategies that work towards the same goal.

Some of these treatments remain inaccessible due to costs, among other reasons, and these challenges are yet to be addressed. In researching this topic, the true burden of having focal seizures and epilepsy comes to light. It is important to acknowledge these systemic shortcomings and address them moving forward. I encourage reading The burden of epilepsy and unmet need in people with focal seizures (Ioannou et al., 2022) for further information, as it is open access and a credible source.

References

Beniczky, S., Trinka, E., Wirrell, E., Abdulla, F., Al Baradie, R., Alonso Vanegas, M., Auvin, S., Singh, M. B., Blumenfeld, H., Bogacz Fressola, A., Caraballo, R., Carreno, M., Cendes, F., Charway, A., Cook, M., Craiu, D., Ezeala‐Adikaibe, B., Frauscher, B., French, J., … Cross, J. H. (2025). Updated classification of epileptic seizures: Position paper of the international league against epilepsy. Epilepsia, 66(6), 1804–1823. https://doi.org/10.1111/epi.18338

Ghulaxe, Y., Joshi, A., Chavada, J., Huse, S., Kalbande, B., & Sarda, P. P. (2023). Understanding focal seizures in adults: A comprehensive review. Cureus. https://doi.org/10.7759/cureus.48173

Holmes, G. L. (2024). Generalized seizures. In Swaiman’s Pediatric Neurology (pp. 792-799.e1). Elsevier. https://doi.org/10.1016/B978-0-443-10944-7.00086-X

Ighodaro, E. T., Maini, K., Arya, K., & Sharma, S. (2026). Focal onset seizure. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK500005/

Ioannou, P., Foster, D. L., Sander, J. W., Dupont, S., Gil‐Nagel, A., Drogon O’Flaherty, E., Alvarez‐Baron, E., & Medjedovic, J. (2022). The burden of epilepsy and unmet need in people with focal seizures. Brain and Behavior, 12(9), e2589. https://doi.org/10.1002/brb3.2589

Stafstrom, C. E., & Carmant, L. (2015). Seizures and epilepsy: An overview for neuroscientists. Cold Spring Harbor Perspectives in Medicine, 5(6), a022426–a022426. https://doi.org/10.1101/cshperspect.a022426