The two main types of seizures are generalized seizures and focal onset seizures, previously called “partial onset.” Focal onset seizures are the most common type of seizures in adults with epilepsy. Focal seizures occur when there is abnormal electrical activity that begins on one side, or hemisphere, of the brain.
In 70 percent of people with epilepsy, the cause of seizures is unknown. However, in some cases, focal seizures are associated with scar tissue caused by a brain infection, birth injury, head injury, brain tumor, or other damage to a specific area of the brain.
While some antiepileptic drugs (AEDs) may be used to treat either focal or generalized seizures, other treatments are specifically effective in treating focal seizures. Treatment options depend on the exact epilepsy diagnosis, seizure type, and location of the seizure focus in the brain. With focal onset seizures, the seizure focus can sometimes be pinpointed as precisely as a single nerve network.
There are more than 30 different types of seizures. Focal onset seizures begin in a network of cells in only one hemisphere of the brain. Sometimes, a focal onset seizure can spread to affect both hemispheres — these are known as focal to bilateral seizures. Some people experience more than one type of seizure.
After establishing that seizures have a focal onset, neurologists further categorize focal seizures based on symptoms. Focal seizure symptoms may be motor (involving movement) or nonmotor. During focal seizures, a person’s awareness may be affected. For instance, if a person is aware of what is happening while they are having a focal seizure, this is known as a focal onset aware seizure, previously known as a “simple partial seizure.” If a person is not aware of their surroundings, it is called a focal impaired awareness seizure.
There’s no one-size-fits-all treatment regimen for focal seizures. Antiepileptic drugs (AEDs) are the mainstay of epilepsy treatment and often the first line for focal seizures. Second-line treatments for focal seizures include surgery, neuromodulation devices, and dietary therapy. These other therapies may be added to a person’s treatment regimen if they have tried at least two or more first-line AEDs and continued to experience breakthrough seizures.
The past 25 years have seen great progress in the development of AEDs. Today, there are more treatment options, antiseizure medications with fewer side effects, and more targeted AEDs to treat focal seizures than ever before.
In the last decade alone, several AEDs have been approved by the U.S. Food and Drug Administration (FDA) for use in treating focal onset seizures. These newer AEDs are sometimes called second- and third-generation AEDs. AEDs used to treat a specific type of seizure are referred to as narrow-spectrum AEDs, while those used to treat a wider variety of seizures are called broad spectrum.
Cannabis has been used to treat refractory seizures and severe epilepsy syndromes, such as Lennox-Gastaut syndrome. There is growing evidence that cannabis may be effective in treating other seizures, including focal onset seizures, as well. A recent study of cannabidiol (CBD), an active ingredient in cannabis, among 137 people, saw a 55 percent decrease of focal seizures.
Accurate diagnosis is an important part of choosing the right AED. Successful seizure control is more likely when treatment is started early, before recurrent seizures have established a pattern. Some AEDs are more effective at treating focal impaired awareness seizures, while others work best for focal aware seizures. Different medications work better for different people, depending on the level of seizure control, the ability to tolerate side effects, interactions with other medications, and personal needs (e.g., desiring pregnancy). Not all seizures will respond the same way to all medications.
For people with a new diagnosis of epilepsy, approximately 60 percent will become seizure-free when the first AED is tried. If the first AED works, but the side effects are intolerable, another AED can be prescribed with a decent possibility of success to achieve seizure control. Tailoring the dose of the AED for each person is critical.
If different medication trials fail, combination therapy of two AEDs can be tried, but the likelihood of efficacy decreases to approximately 10 percent at that point. After trying two different AEDs and failing to achieve seizure control, a person is considered to have drug-resistant, intractable, or refractory epilepsy.
Focal onset seizures originate only on one side of the brain. Often, the location of the seizures can be narrowed down to the exact focal point or group of nerves involved. The odds of becoming seizure-free after surgery are much higher if there is a small, well-defined seizure focus.
A person with refractory seizures may be a candidate for neurosurgery, if the following conditions apply:
Some people with hard-to-treat focal seizures have a good possibility of finding relief with neurosurgery. Surgery to treat focal seizures can be traditional open surgery, surgery that implants a neuromodulation device, or minimally invasive surgery, depending on a person’s case. Traditional open surgical procedures include:
Research shows surgery can be a very effective treatment for both adults and children with refractory focal seizures. In one clinical trial, 58 percent of participants reported greater relief from intractable focal seizures after surgery, while 8 percent reported that medication was more effective than surgery. In another clinical trial, surgery was the more successful focal-seizure treatment for 73 percent of participants. None of the people in the second trial found AEDs more effective than surgery.
Whether or not surgery curbs seizures entirely, it is important to continue taking AEDs as prescribed. The longer a person goes without having a seizure after surgery, the more likely it is that they will remain seizure-free.
Electrical brain stimulation, or neuromodulation, is a treatment option for some people with refractory focal onset seizures who are not good candidates for traditional open resection surgery — or who have already had the surgery and still have refractory seizures. Neurostimulation devices have shown success in controlling focal seizures by targeting the specific region or the focal point involved. Devices can also provide a great deal of customizability to fit the specific seizure diagnosis, characteristics, and symptoms. While these newer treatments are not in the same category as traditional open resection surgery, they are all still surgical procedures which require an incision in the skin, some type of anesthesia, and recovery. In almost all cases, people need to continue taking AEDs during treatment with neuromodulation.
Vagus nerve stimulation (VNS) is an option for people with drug-resistant focal seizures who are at least 4 years old, who are not candidates for surgery, or who have had surgery that has not worked. The VNS device is inserted under the skin on a person’s chest and attached to the vagus nerve in the lower neck. The device sends short electrical bursts to the brain, via the vagus nerve, to promote regular brain activity and prevent the misfires that cause seizures. The VNS device also includes a special magnet that can be worn on your belt or around your wrist. By passing this magnet over the VNS device, a person can prevent, shorten, or decrease the severity of an impending seizure.
Benefits of VNS therapy improve the longer a person continues it. Almost half of people using VNS saw their seizures decrease by at least 50 percent in the first two years. VNS may also reduce the length of time it takes a person to recover after having a focal onset seizure and lessen the severity of focal seizures. After a while of VNS success, some people may even be able to reduce their AED regimen.
Responsive nerve stimulation (RNS) is indicated for people ages 18 and older who have medication-refractory focal seizures and are not eligible for epilepsy surgery, or who have had epilepsy surgery but continue to experience seizures.
The RNS device is implanted within the skull. The wires of the RNS are connected to the surface of the brain where the seizure’s focal point has been identified. When possible seizure activity is picked up by the device, an electrical pulse is delivered within milliseconds to prevent or lessen the seizure.
RNS benefits increase over time. One study of 230 participants found that, on average, RNS cut seizures in half after two years of therapy. After seven years, two-thirds of people on RNS experienced a 50 percent reduction in seizures.
Deep brain stimulation (DBS) is approved for use in people 18 years or older with medication-refractory focal epilepsy. It is considered an appropriate option for people when traditional epilepsy surgery is not effective. DBS is a surgical procedure done by a neurosurgeon. Small wires, known as electrodes, transfer electrical signals from the DBS device straight to the brain to halt the impulses that are the source of the seizures. The DBS device is a programmable, battery-operated tool that delivers electric currents in a predetermined cycle. Approximately 50 percent of people who undergo DBS treatment have less seizures afterward, and some report that seizures are less severe. DBS is always used alongside antiseizure medications. If DBS makes a significant improvement in overall seizures, medication dosing can be lowered but not stopped.
There are two additional neuromodulation approaches under investigation: transcranial magnetic stimulation (TMS) and trigeminal nerve stimulation. While both use devices, they are not implanted in a surgical procedure and can be used in a doctor’s office. Both are strong magnets, typically placed on a person’s scalp, that induce an electrical current.
Stereotactic radiosurgery (SRS) is a noninvasive intervention sometimes used to treat focal epilepsy. SRS for epilepsy typically uses Gamma Knife, a radiosurgical treatment, to reach regions that cannot be accessed in traditional open surgery. Despite its name, no incisions in the skin are made. Computer software and MRI allow the surgeon to locate, plan, and irradiate seizure targets in the nervous system. Treatment involves focal, intense radiation to those specific areas while leaving nearby tissue intact.
SRS is also known to have a delayed therapeutic effect, which means that it may take a long time for it to become effective. This may be a consideration in treatment. One notable study of 20 people with medial temporal epilepsy reported that 65 percent were seizure-free two years after having SRS. However, results can be variable, depending on the type of epilepsy. Guidelines for SRS in focal epilepsy have not yet been formed.
Laser interstitial thermal therapy (LITT) is a minimally invasive surgery in which laser energy is used to target the specific brain regions responsible for causing seizures. A probe is put in these areas, which is guided by MRI. The probe can then destroy the region causing seizures with extreme accuracy. LITT is often best for people with mesial temporal lobe epilepsy.
Dietary therapies for epilepsy are low in carbohydrates (sugary, starchy foods) and high in fatty foods (meats, avocados, butter, and oils). These special diets are designed to change the way the body turns food into energy.
Dietary therapies should be medically supervised as part of a comprehensive epilepsy treatment plan. Always talk to your doctor before making changes to your diet.
The four diets commonly used in epilepsy treatment include:
In one study, the ketogenic diet reduced seizures by more than 50 percent in half of the children who tried it. Almost 15 percent of the participants saw their seizures stop entirely.
Among all the options to treat epilepsy, surgery is only one that is potentially curative. The rest of the treatment options, including medications and neurostimulation devices, may manage the symptoms extremely well and people may be seizure-free for years, but they do not provide a “cure” in the truest sense of the word. Children with epilepsy also have a good possibility of outgrowing their epilepsy.
Epilepsy is treatable and manageable, especially when it is promptly and accurately diagnosed, and treatment is begun as soon as possible. Finding the right combination of medication and therapies may take a little time and more than a couple of tries. Working closely with your neurologist and other specialists is the best way to get your epileptic seizures under control and hopefully achieve remission.
Have you found the right treatment regimen to control your focal epilepsy? Have you tried surgery or an implanted neuromodulation device? Comment below or post on MyEpilepsyTeam.