How a Comprehensive Epilepsy Diagnosis Can Help Drug-Resistant Seizures

Why EEG for epilepsy may only provide the first step for evaluation

If you have drug-resistant epilepsy (also called refractory or intractable epilepsy), you’re probably familiar with encephalography, or EEG. By measuring electrical patterns through electrodes placed on the scalp, doctors can get a basic sense of what’s happening in your brain.

Often, that testing comes with video observation and recording for a few hours, and sometimes over a few days. With a longer session, you may have done it during a hospital stay or brought equipment home to do it yourself.

A well-established test, EEG can provide valuable information. It’s typically where doctors start when diagnosing epilepsy. It also may provide the only testing you need to have a vagus nerve stimulator (VNS) implanted, one treatment option for drug-resistant epilepsy. (Some people who receive VNS may undergo additional testing.)

VNS has potential drawbacks, though, such as causing hoarseness.

To explore your full range of treatment options, you need additional expertise and further evaluation, beyond standard EEG. Doctors may be able to remove the source of seizures during surgery or implant a different type of device.

By working with epilepsy-focused specialists, you may be able to determine where the seizures start and get the answers you need.

Seeking other treatment options with an epileptologist and comprehensive epilepsy center

Comprehensive epilepsy centers offer the full range of services and potential treatments for drug-resistant seizures. Such centers also provide access to doctors called epileptologists — neurologists who have extra training in the diagnosis and treatment of epilepsy. (General neurologists treat a wider range of conditions.)

You can find this highly specialized care at Level 3 and Level 4 centers, as designated by the National Association of Epilepsy Centers (NAEC). If you’ve worked with a general neurologist for a year and still have uncontrolled seizures, the association recommends switching to a center with an epileptologist.

Treatments that only comprehensive centers can offer typically include resective epilepsy surgery to remove the source of seizures. They can also determine if additional devices for neuromodulation may work — such as deep brain stimulation (DBS) and responsive neurostimulation (RNS System).

The RNS System is also the only device to directly target the source of seizures and to respond in real time to prevent seizures before they start. It records EEG data about seizures and treatment activation, which allows your doctor to fine-tune therapy. (Learn more about the differences among VNS therapy, DBS and RNS System.)

For Tammey, a registered nurse, the RNS System greatly reduced the dangerous grand mal seizures she experienced and completely stopped her smaller seizures; however it is important to note that results will vary among individuals. She received the therapy while in the care of William Tatum, MD, medical director of the Mayo Clinic Comprehensive Epilepsy Center in Jacksonville, Florida.

“I tell everyone that he and the NeuroPace RNS System saved my life,” says Tammey, who finally felt confident enough to regularly venture out of her house.

How to tell where seizures come from: MRI for epilepsy, sEEG and other tests

To find the most effective therapy, you may need a thorough evaluation. Specialists at comprehensive centers work to confirm the type of seizures, pinpoint their source, safeguard critical brain functions and recommend appropriate therapy. They’ll explain what to expect and what comes next. You’ll have a chance to ask questions and express any concerns.

The first step — Phase 1 — involves initial testing, with Phase 2 reserved for times when doctors need more information for certain treatments. You may need one or more tests.

Phase 1:
In addition to video EEG, your evaluation will likely include neuropsychological testing to assess the various ways your brain functions, such as IQ and memory. You may also speak with a social worker, a psychologist or both.

Tests in Phase 1 are considered noninvasive. They may include:

• Scans: Evaluation typically involves some form of brain imaging. MRI shows brain structure, including any unusual features. (A functional MRI identifies which parts of the brain control critical functions, by looking at blood flow while you perform specific tasks such as moving your fingers or looking at pictures.) Single-photon emission computed tomography (SPECT) maps blood flow. And positron emission tomography (PET) shows the brain’s metabolism. Both SPECT and PET identify abnormal brain areas — possible seizure sources. All three scan types leave the scalp and skull untouched.
• Wada (intracarotid sodium amobarbital procedure, or ISAP): Usually an outpatient procedure, it evaluates brain areas responsible for language and memory. If seizures start in those areas, surgery targeting the source may pose too great a risk. During this minimally invasive test, doctors temporarily put one side of the brain asleep while they test the other side. They do so by asking you questions. They then switch sides.
• Magnetoencephalography (MEG): Like EEG, MEG measures the brain’s electrical patterns. But MEG uses a special scanner that surrounds the top of the head without touching it. The scanner senses the tiny magnetic fields given off by electrical currents. It’s done as an outpatient test, lasting about four hours. MEGs can provide detailed results without putting electrodes inside the brain, but not all epilepsy centers have these expensive machines.

Phase 2:
With standard EEG, the skull and the scalp can disrupt electrical pattern readings. Tests in phase 2 provide greater precision, when needed. (If doctors are confident they have identified the seizure source, you may not need Phase 2 evaluation to receive the RNS System.)

While there is a range of testing doctors can turn to in Phase 2, most involve some form of intracranial (inside the skull) monitoring. These tests temporarily place electrodes or other sensors in the brain. Should you need Phase 2 evaluation (and not everyone does), you can discuss the pros and cons of testing options with your doctors. Your epilepsy team will work to address any concerns you have and ensure you’re safe and comfortable during testing.

The most common forms of intracranial monitoring include:

• Stereoelectroencephalography (SEEG): This intracranial monitoring technique may show seizure sites deeper in the brain than standard EEG. You receive anesthesia, and surgeons make tiny holes in the skull and carefully place electrodes in select spots in the brain. After testing, they remove the electrodes. SEEG requires a 7- to 10-day hospital stay and is only available at Level 4 centers.
• Intraoperative neuromonitoring (IONM): Done during surgery, specially trained physicians use a variety of techniques such as electrocorticography (ECoG), electromyography (EMG), direct electrical stimulation (DES), motor evoked potential (MEP), and somatosensory evoked potential (SSEP) to maximize effectiveness of treatment while minimizing side effects, such as motor deficits.

It’s natural to feel nervous about any procedure that involves the brain. When Christine from Massachusetts was considering what to do, it gave her pause. But when further medication changes still didn’t help, she changed her mind — and benefited from the results.

A comprehensive evaluation and the RNS System helped her curtail the number of seizures and under her doctor’s guidance, reduce her medications. She also started traveling and driving again and went back to work.

“If someone living with epilepsy was considering whether to have the RNS System implanted, I would say, ‘Don’t hesitate,’” she says.