Epilepsy can be difficult to diagnose, in part because doctors rarely witness seizures firsthand. Epilepsy can also be challenging to distinguish from other conditions, including migraine, sleep disorders, heart problems, and transient ischemic attacks (temporary low blood flow to part of the brain, sometimes called a “mini-stroke”). It is possible to have one or more of these conditions in addition to epilepsy, further complicating diagnosis.
It is also important to note that not all seizures are caused by epilepsy. Epilepsy is defined as a neurological disorder that involves recurrent seizures caused by abnormal electrical activity in the brain. Nonepileptic seizures do not originate from abnormal electrical activity and may require different treatment than epileptic seizures.
Typically, a neurologist diagnoses epilepsy. It may also be diagnosed by a pediatrician, emergency room physician, or general practitioner.
There is no single test to diagnose epilepsy. Instead, a doctor will consider your medical history and may perform a variety of diagnostic tests.
The doctor will take a thorough history, asking detailed questions about what happens during your seizures, how long they last, and how often they occur. The physician may ask about a history of head injuries, infections, or other neurological symptoms. The doctor will likely ask about your family history of seizures. A clear picture may emerge from the medical history to help the doctor assess risk factors that strengthen the suspicion of epilepsy or rule out other conditions.
Electroencephalogram or EEG testing is used to visualize brain waves to monitor seizure activity. For an EEG, the technologist administering the test will place electrodes on your scalp. The electrodes pick up the tiny electrical charges resulting from brain activity. Most EEGs take one to 1.5 hours to set up and complete. Receiving an EEG is painless and cannot harm you.
Further complicating diagnostic processes, about half of EEGs performed on people who have seizures produce normal results. Even if you have frequent seizures, your EEG may be normal if you are not having a seizure during the test. You may be asked to rapidly blink your eyes, stare at blinking lights, or breathe deeply for several minutes to provoke seizure activity.
In addition to a standard EEG, your doctor may suggest an ambulatory or video EEG. Ambulatory EEGs record brain waves for a longer period of time, usually 24 hours to three days, to increase the chances of recording seizure activity. Ambulatory EEGs may be performed at home, at an outpatient clinic, or at a hospital. Electrodes will be placed on your scalp, and you’ll have a small recorder to wear on your waist.
During video EEGs, video and audio of your movement, behavior, and sounds are recorded along with the brain wave patterns recorded in an EEG. Video EEGs allow the neurologist to see what is happening in your brain during specific seizure behavior. Video EEGs can be done on an inpatient or outpatient basis.
When EEGs do capture seizure activity, they are very valuable tools. Some brain wave patterns are distinctive indicators of certain types of epilepsy, types of seizures, or other neurological disorders. Sometimes, EEG results can even indicate where in the brain the seizures originate.
If your EEG results are normal, it is not conclusive that you do or do not have epilepsy. Further tests will have to be performed.
Imaging tests are performed to evaluate brain function and structure. The most common neuroimaging procedures used to detect brain abnormalities associated with epilepsy are MRI, functional MRI, and CT scans. Single-photon enhanced computed tomography brain imaging and positron emission tomography imaging can also be used.
Neuroimaging scans can detect potential causes of seizures, including tumors, scar tissue, abnormal blood vessel formations, or hydrocephalus (an excess of spinal fluid).
Blood tests or saliva tests may be ordered to check for genetic causes of epilepsy. Blood tests can also screen for infections that may be the underlying cause of epilepsy.
Some people with epilepsy may have speech or auditory processing problems, so tests may be performed to measure processing ability. Assessment tests may be performed by audiologists (hearing specialists) or speech and language pathologists.
The doctor may order a neuropsychiatric test to quantify cognitive (related to thinking, memory, and reasoning) abilities in relation to normal or abnormal brain structures. Cognitive assessments may be performed by doctors, psychologists, educators, or other specialists.
As much as 70 percent of people diagnosed with epilepsy who receive appropriate treatment could become seizure-free within a few years. Some people never have another seizure, while others have sporadic seizures or uncontrolled seizures despite being on antiepileptic drugs (AEDs).
Some doctors define remission from epilepsy as 10 years without having a seizure and five years without AEDs. Other doctors consider someone in remission after two years without seizures (the last year off AEDs) or five years without seizures (the last two years off AEDs). The chances for remission are higher if the cause of epilepsy is unknown, seizures are few and far between, seizures are responsive to AEDs, and there are no underlying neurological problems.
The age at which a person receives an epilepsy diagnosis varies widely and is often correlated to the cause of epilepsy. Some forms of epilepsy, especially those that are caused by birth trauma or a genetic mutation, are diagnosed in infancy or early childhood. Other types of epilepsy don’t develop until adolescence or adulthood.