Diagnostic Tests

Diagnostic Tests

Diagnosing Epilepsy

Knowing if a person is having a seizure and diagnosing the type of seizure or epilepsy syndrome can be difficult. There are many other disorders that can cause changes in behavior and can be confused with epilepsy. Since the treatment of seizures depends on an accurate diagnosis, making sure that a person has epilepsy and knowing what kind is a critical first step.

What happens during a seizure is one of the most important pieces of information. And, since seizures rarely happen in a doctor’s office, the information given to the doctor and other health care professionals by you or other witnesses is extremely important. Yet, even with accurate descriptions of events, other tests are needed to learn more about the brain, what is causing the events and where the problem is located.

Here you’ll find information about diagnosing seizures and epilepsy. Start with the basics [following paragraphs], then move on to more detailed sections and advanced content. Share these pages with family and friends.

Authored by: Steven C. Schachter, MD | Patricia O. Shafer, RN, MN | Joseph I. Sirven, MD
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 8/2013
Source: Epilepsy Foundation of America

Why See A Doctor?

Diagnosing seizures and the type of epilepsy is like putting the pieces of a puzzle together and includes information from many people and different tests.

The first question is to find out if the person had a seizure, then the doctor will want to know the type of seizure or epilepsy syndrome that best explains the event. To do this, more information will be needed, including details of the medical history, blood tests, EEG tests, and brain imaging tests such as CT and MRI scans. This gives information about the electrical activity of the brain, what the brain looks like and possible causes of seizures. This information is put together with how the individual is feeling and how the seizures may be affecting the way the brain works.

  • This section takes you through each step in the diagnostic process.
  • The timing of each step will depend on what is going on with each person.
  • Sometimes tests will be repeated and give more accurate information at another time.
  • As new information is obtained, the initial diagnosis may be changed too.
  • It’s important to keep in touch with your doctors and health care team and let them know if new problems arise and if your seizures are not responding to treatment. If so, it’s time to take another look!
Authored by: Carl W. Bazil, MD, PhD | Joseph I. Sirven, MD
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 8/2013
Source: Epilepsy Foundation of America

What Kind of Doctor is Best?

  • A person who suspects a problem should go to a primary care doctor (pediatrician, internist, or family physician) first for evaluation. The primary care doctor may run some tests.
  • If the doctor suspects seizures, the person probably will be referred to a neurologist, a doctor with special training in disorders of the brain, including epilepsy.
  • Some neurologists have specific training in epilepsy and spend most of their time treating people with this disorder; they are called epileptologists. For routine treatment of epilepsy, it is usually not necessary to see an epileptologist. A consultation may be needed in certain circumstances, such as counseling about pregnancy and childbirth and when seizures are not controlled.
  • A person who has a seizure may be taken by ambulance to the Emergency Room. There they are seen by an emergency physician, or possibly a neurologist, and will be referred to a neurologist for follow-up.
Authored by: Carl W. Bazil, MD, PhD | Joseph I Sirven, MD
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 8/2013
Source: Epilepsy Foundation of America

What Will the Doctor Do?

The first and most important part of a visit to the doctor is an interview, called taking a history.

  • The doctor will ask for a complete description of what happened.
  • Often it is important to bring along a family member or someone else who saw the seizure and can tell the doctor what happened, since the person who had the spell may have been unconscious. Even if the person thinks that he or she was aware, there may be important aspects of the spell that are not recalled.
  • The doctor will want to hear not only a description of the seizure itself, but also the story of the events leading up to it and the after-effects that followed it.
  • The doctor then will thoroughly examine the person and probably will order several tests.
  • The doctor may have enough information on the first visit to recommend or start treatment, but sometimes this will happen only after further test results are reviewed.

Questions your doctor may ask:

  • Could the episode have been provoked by sleep deprivation, excessive use of alcohol or drugs, or some other factor?
  • What was the setting?
  • Did the episode occur shortly after standing?
  • Was there a warning?
  • Exactly what happened during the episode?
  • How long did it last?
  • Was the person tired or confused after the episode?
  • Has there been more than one episode? If so, were they all alike?
  • Has the person seen a doctor before about this kind of event?
  • If so, what tests were done?
  • Was any medication prescribed? What effect did it have?
Authored by: Carl W. Bazil, MD, PhD | Joseph I. Sirven, MD
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 8/2013
Source: Epilepsy Foundation of America

What Tests Are Needed?

The doctor usually orders a variety of tests to help make the diagnosis. These include:

  • A brain wave test, also called an EEG (electroencephalogram), to look for changes in the brain’s electrical patterns that are related to seizures.
  • Blood tests, to look for certain medical disorders.
  • Either a special x-ray of the brain, a CT scan (sometimes called a CAT scan), or an MRI scan (magnetic resonance imaging), to look for abnormal areas such as a tumor or infection.
  • Depending on the urgency of the situation, other tests also might be recommended, such as a lumbar puncture (also called a spinal tap), EKG (electrocardiogram, to check the heart), or a sleep test.

The results of these tests often appear completely normal in people with epilepsy. Normal test results do not mean that the seizures are not real or that epilepsy is not present.

Authored by: Carl W. Bazil, MD, PhD | Joseph I. Sirven, MD
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 8/201
Source: Epilepsy Foundation of America

Why Is My Doctor Ordering Other Tests to Evaluate My Seizures?

Not all events that appear to be seizures truly are epilepsy seizures, which occur due to abnormal surges of electrical activity in the brain. Some people that have been treated with seizure medication actually have a diagnosis other than epilepsy!

In fact, approximately 1 in 5 people who have not responded to medication and are admitted to an Epilepsy Monitoring Unit for evaluation of seizures are ultimately shown to have an alternative diagnosis.

While recording events with video EEG monitoring is considered the gold standard to diagnosis seizures and spells, other tests can be helpful as well.

Test: Cerebrovascular Imaging, such as

  • MR or CT angiogram of the head and neck
  • Carotid ultrasound
  • Conventional Angiography

Possible Alternative Diagnosis:

  • Transient Ischemic Attack
  • Stroke
  • Vasculitis
  • Vascular malformation

Test: Cardiac Holter Monitor

Possible Alternative Diagnosis:

  • Cardiac arrhythmia

Test: Tilt Table/Autonomic Reflex Study

Possible Alternative Diagnosis:

  • Syncope or convulsive syncope due to
    • Orthostatic Hypotension
    • Postural Orthostatic Tachycardia Syndrome (POTs)
    • Autonomic neuropathy

Test: Overnight Polysomnography (Sleep Study)

Possible Alternative Diagnosis:

  • Parasomnias (Sleep related abnormal movements)
  • Sleep apnea

Test: Movement Disorder Physiologic Study

Possible Alternative Diagnosis:

  • Myoclonus
  • Tremor
Authored by: Amy Crepeau, MD | Epilepsy.com Diagnostics editor
Source: Epilepsy Foundation of America

What If It’s Not Epilepsy?

After looking at the test results, the doctor (and perhaps some other specialists) may conclude that the person has a medical or psychological condition that causes events that look like epilepsy seizures. In that case, treating that condition (instead of giving seizure medicines) may prevent future incidents.

On the other hand, all the test results might be normal. Then the doctor has to determine whether treatment is needed. Some people have a single seizure and don’t have any more. But others go on to have more seizures later, leading to the diagnosis of epilepsy.

Authored by: Carl W. Bazil, MD, PhD | Joseph I. Sirven, MD
Reviewed by: Joseph I. Sirven, MD | Patricia O. Shafer, RN, MN on 8/2013
Source: Epilepsy Foundation of America

Genetic Testing

Genetic knowledge may be beneficial related to issues such as selection of optimal supportive care, informed medical decision-making, prognostic considerations, and avoidance of unnecessary testing.

What is genetics?

Genetics is the study of heredity or how different characteristics (traits) are passed from a parent to a child. A person inherits these traits from their parents. Each person has several thousand genes that are made up of DNA. Genes are packaged into larger structures called chromosomes. Chromosomes are present in almost every human body cell. Genetics play a part in many types of epilepsy.

The Role of Genetics in Epilepsy

Advances in science and technology can help identify molecular defects (for example, deletions or mutations) that contribute to the genetics of some types of epilepsy. Genetic testing helps scientists and physicians better understand how various genes may interact to produce a specific epilepsy syndrome. This genetic information may give people with epilepsy and their families more detail about their specific epilepsy syndrome. Several epilepsies have a genetic component and we know that epilepsy can run in families.

How is genetic testing done in people with epilepsy?

Usually, genetic testing requires a blood or saliva sample to be taken from the person with epilepsy. The sample is then sent to a laboratory for genetic testing. The test looks at the DNA in the person’s blood or saliva. The sample is analyzed for mutations or changes in a subset of genes that have a known association with different types of epilepsy.

What types of genetic disorders are there?

There are five types of genetic disorders:

  • single gene disordersthat result when a mutation causes a single gene to be altered or missing
  • multifactorial/complex disordersthat are related to mutations in a number of genes and are often also associated with an environmental influence
  • mitochondrial disordersthat result from mutations in DNA found in mitochondria; mitochondrial gene mutations cause a problem with how energy is produced in cells.
  • chromosomal disordersthat occur when entire chromosomes are missing or changed
  • epigenetic disordersthat are related to changes in the activity of genes, rather than a mutation in the structure of DNA

What are some examples of epilepsy syndromes where genetic testing may be helpful?

The inheritance of epilepsy is frequently complex. Genetic disorders can cause epilepsy alone or may cause a syndrome that affects various parts of the body as well as epilepsy. Some epilepsy syndromes are known to have a genetic basis, but the gene or genes that cause the syndrome have not yet been identified. Finally, some genetic disorders arise spontaneously through new gene mutations.

More than 20 different syndromes with epilepsy as a main feature have been mapped to specific genes. Many more single gene disorders that cause brain abnormalities or metabolic disorders have epilepsy as a primary symptom. Also, scientists have identified mutations in genes that control sodium, potassium, and calcium channels that can also cause epilepsy.

It’s important to note that genetic testing in some epilepsy syndromes has already played a significant role in clinical practice. This has been particularly true for people with epileptic encephalopathies that begin in infancy and early childhood. For example, this may include:

  • Dravet syndrome– more than 70% of people have mutations of SCN1A.
  • Epilepsy limited to females with mental retardation – involves the PCDH19

More challenging at this time are the subgroup of genetic generalized epilepsies (GGE) that include childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsyphotosensitive epilepsy, and generalized tonic-clonic seizures. GGE has a complex genetic inheritance pattern. This subset of epilepsies present a challenge, and currently we have little information about the genes that are implicated in GGE.

However, genetic testing still may have a key role to play. Over time, as more information is collected, the cause of these epilepsies will be better understood. Knowing the cause may improve testing, diagnosis, clinical treatment, and family counseling.

Some Epilepsy Syndromes Seen with Genetic Disorders

Below are listed some of the epilepsy syndromes that may result from genetic disorders. New genes involved in epilepsy are being identified regularly, and the genetics of epilepsy spectrum continues in a period of rapid growth.

Single Gene Epilepsy Syndromes

  • Autosomal dominant partial epilepsy with variable foci
  • Autosomal dominant nocturnal frontal lobe epilepsy
  • Benign familial neonatal convulsions
  • Benign infantile familial convulsions
  • Familial temporal lobe epilepsy
  • Generalized epilepsy with febrile seizures plus
  • Progressive myoclonus epilepsies
  • Epileptic encephalopathies (Dravet, PCDH19)

Other Single Gene Disorders that Can Manifest as Epilepsy

  • Neurofibromatosis 1
  • Tuberous sclerosis
  • Fragile X  syndrome
  • Rett syndrome
  • Acute intermittent porphyria
  • Leukodystrophies
  • Mucopolysaccharidoses (Sanfilippo syndrome)

Other Inherited Metabolic Conditions that May Cause Seizures

  • Phenylketonuria (PKU)
  • Galactosemia
  • Tay-Sachs disease
  • Pseudohypoparathyroidism
  • Pyridoxine dependency
  • Peroxisomal disorders

Multifactorial Disorders

  • Myoclonic-astatic epilepsy
  • Benign epilepsy of childhood with centrotemporal spikes
  • Benign myoclonic epilepsy of infancy
  • Juvenile myoclonic epilepsy
  • Childhood absence epilepsy
  • Juvenile absence epilepsy
  • Photosensitive epilepsy

Mitochondrial Disorders

  • Myoclonus epilepsy and ragged red fibers (MERRF)

Chromosomal Disorders

  • Down syndrome
  • Edwards syndrome
  • Patau syndrome
  • Wolf-Hirschhorn syndrome
  • Angelman syndrome
  • Ring chromosome abnormalities

How can genetic testing help people with epilepsy, their families, and their health care team? 

  • Genetic testing in a person with epilepsy can help confirm a specific diagnosis. It may also give information about other associated neurologic or medical conditions that may arise over time.
  • It may assist your neurologist with selecting an appropriate seizure medication and also with expectations regarding appropriate seizure control. Genetic information may also influence whether or not a specialized diet, such as the ketogenic diet, is recommended.
  • Genetic information may help to limit unnecessary or invasive testing.
  • Genetic testing may assist with understanding the prognosis or outlook of a person’s epilepsy and provides a basis for further genetic counseling for families.
Authored by: Elaine Kiriakopoulos MD | Drug Resistant and Rare Epilepsies Editor on 9/2015
Source: Epilepsy Foundation of America