Diagnosis of Seizure Disorder: Expert Evaluation and Testing

A seizure is characterized by a sudden, uncontrolled burst of electrical activity in the brain. This disruption can manifest in a variety of ways, from brief muscle twitches to loss of consciousness and convulsions. Understanding the cause and nature of seizures is crucial for effective management, and the first step is accurate diagnosis of a seizure disorder.

Seizure disorder is often used interchangeably with epilepsy. Epilepsy is diagnosed when a person experiences two or more unprovoked seizures occurring more than 24 hours apart. Unprovoked means these seizures are not triggered by immediate, reversible causes like alcohol withdrawal, heart problems, or severe low blood sugar (hypoglycemia). Seizures themselves can be a symptom of various underlying conditions, ranging from genetic predispositions to acquired conditions like brain trauma, tumors, dementia, or stroke. In many instances, the precise cause of seizures remains unknown.

Seizures can vary significantly in duration, lasting from mere seconds to several minutes. Some individuals experience an aura, a set of warning symptoms that precede a seizure. Auras can involve sensory changes like unusual smells, visual disturbances such as flashing lights or distorted vision, auditory hallucinations, or even emotional and cognitive experiences like déjà vu or out-of-body sensations.

Epilepsy and seizure disorders can affect anyone at any age, though they are more frequently diagnosed in young children and adults over the age of 55. In the United States alone, millions of people are living with epilepsy, highlighting the importance of effective diagnosis and management strategies.

The Diagnostic Process for Seizure Disorders

Diagnosing a seizure disorder requires a comprehensive approach, as doctors rarely witness seizures firsthand. Therefore, a detailed medical history is paramount in differentiating epilepsy from other conditions that may mimic seizure activity.

Medical History and Physical Examination

Epilepsy specialists rely heavily on patient history to understand the nature of events suspected to be seizures. During an initial consultation, expect detailed questions about the episodes, including:

Seizure Onset and Triggers: How did the seizure begin? Were there any identifiable triggers, such as stress, lack of sleep, or specific stimuli?
Seizure Duration: How long did the episode last?
Preceding Factors: Were there any unusual circumstances preceding the event, such as sleep deprivation or heightened stress?
Recent Illness: Has the individual experienced any recent illnesses or infections?
Medications and Substance Use: What medications are being taken, including over-the-counter drugs, alcohol, or illicit substances?
Activity Before Seizure: What was the person doing immediately before the event – lying down, standing, exercising, etc.?
Loss of Consciousness or Impairment: Did the person lose consciousness or experience any mental or physical impairment during the episode?
Seizure Manifestations: What specific movements were observed? This includes jerking, automatic movements (lip smacking), eye blinking, head turning, loss of bladder control, or tongue biting.
Post-Seizure State: Did the person experience confusion, drowsiness, or sleepiness after the episode?

Detailed observations from family members or witnesses are invaluable in confirming whether an event was indeed a seizure and in determining the seizure type. Recording a seizure on video, if possible and safe, can also provide crucial information for diagnosis.

A thorough physical examination is also essential. Seizures can sometimes be a symptom of an underlying medical condition. The physical exam, along with basic laboratory tests, helps to assess the function of major organ systems like the liver and kidneys, ruling out metabolic imbalances or systemic illnesses that could be contributing to seizures.

Neurological Examination

A neurological examination is a cornerstone of seizure disorder diagnosis. This exam assesses various aspects of brain function. A neurologist will evaluate:

Mental Status: Assessing memory, language, and orientation to person, place, and time. This may involve tasks like remembering words or naming objects.
Cognitive Function: Evaluating higher-level thinking skills, problem-solving, and reasoning.
Motor Strength and Coordination: Testing muscle strength, balance, gait, and fine motor skills.
Sensation and Reflexes: Assessing responses to touch, pain, vibration, and reflexes to identify any sensory or motor pathway abnormalities.

The neurological exam helps identify patterns of weakness, sensory loss, or subtle neurological deficits that may point towards an underlying brain disorder contributing to seizures.

Key Diagnostic Tests for Seizure Disorders

In addition to medical history and neurological exams, several diagnostic tests play a crucial role in confirming the diagnosis of a seizure disorder and identifying its cause and type.

Electroencephalography (EEG)

Electroencephalography (EEG) is the most specific diagnostic test for epilepsy and seizure disorders. It measures the electrical activity of the brain using electrodes placed on the scalp. EEG is a safe and painless procedure.

Routine EEG: Involves placing electrodes on the scalp with a paste or adhesive and recording brain activity for 20 to 40 minutes. The recording is typically done while the person is awake and sometimes while drowsy or asleep, as sleep can activate abnormal electrical patterns associated with epilepsy. Technicians may also employ activation procedures during a routine EEG, such as asking the person to hyperventilate (breathe rapidly) or look at flashing lights, as these can sometimes provoke abnormal electrical activity.
Ambulatory EEG: For individuals whose seizures are infrequent or occur outside of typical testing times, ambulatory EEG is used. This involves wearing a portable EEG recorder for an extended period, typically 24 to 72 hours, while going about daily activities. This increases the chance of capturing seizure-related electrical activity that might be missed in a routine EEG. Patients are often asked to keep a diary of their activities and any symptoms experienced during the recording period, and many devices have an “event” button to mark potential seizure occurrences.
Video EEG: Video EEG monitoring combines continuous EEG recording with synchronized video and audio recording. This allows doctors to correlate behavioral changes with brain electrical activity. It is particularly useful in differentiating epileptic seizures from non-epileptic events and in classifying seizure types. Video EEG can be performed in a hospital setting, where medication adjustments or sleep deprivation can be safely implemented to increase the likelihood of capturing seizure activity. Home video EEG monitoring is also an option in some cases.

Brain Imaging: MRI and CT Scans

Brain imaging techniques are essential to visualize the brain’s structure and identify any abnormalities that might be causing seizures.

MRI (Magnetic Resonance Imaging) Scan: MRI provides highly detailed images of the brain using magnetic fields and radio waves. It is superior to CT scans in visualizing soft tissues and is the preferred imaging modality for epilepsy diagnosis. MRI can detect subtle structural abnormalities such as:
- Hippocampal sclerosis: Scarring of the hippocampus, a common cause of temporal lobe epilepsy.
- Cortical dysplasia: Abnormal development of the brain’s outer layer.
- Brain tumors: Growths in the brain that can disrupt normal brain function.
- Vascular malformations: Abnormal blood vessels in the brain.
- Evidence of prior stroke or trauma: Structural changes indicating past brain injury.
CT (Computed Tomography) Scan: CT scans use X-rays to create cross-sectional images of the brain. While CT scans are less detailed than MRI in visualizing soft tissues, they are faster and readily available, making them useful in emergency situations, such as after a first-time seizure or to rule out acute structural problems like bleeding in the brain. CT scans are also used when MRI is contraindicated, such as in individuals with certain metallic implants.

Advanced Imaging Techniques: SPECT, PET, MRS, fMRI, MEG

In some cases, more specialized imaging techniques may be used to further investigate seizure disorders, particularly when considering epilepsy surgery or when routine imaging is non-diagnostic.

SPECT (Single-Photon Emission Computed Tomography) Scan: SPECT measures blood flow in the brain. A radioactive tracer is injected, and areas of increased blood flow, which may indicate seizure onset zones, are detected. ictal SPECT, performed during or immediately after a seizure, is compared to interictal SPECT, performed between seizures, to pinpoint seizure origin.
PET (Positron Emission Tomography) Scan: PET scans measure brain metabolism by using a radioactive glucose tracer. Areas of decreased glucose metabolism (hypometabolism) between seizures can indicate areas of brain dysfunction that may be the seizure onset zone. PET scans can be helpful in localizing the seizure focus, especially in focal epilepsies.
MRS (Magnetic Resonance Spectroscopy) Scan: MRS uses an MRI scanner to analyze the chemical composition of brain tissue. It can detect abnormalities in brain chemistry associated with seizures or differentiate seizures from other conditions like tumors or metabolic disorders.
fMRI (Functional MRI) Scan: fMRI measures brain activity by detecting changes in blood flow related to neural activity. During an fMRI, a person may be asked to perform specific tasks (e.g., language or motor tasks) to map brain functions. This is particularly useful in presurgical planning to identify eloquent cortex (brain areas responsible for critical functions like language and movement) and avoid damaging them during surgery.
MEG (Magnetoencephalography): MEG measures the magnetic fields produced by electrical activity in the brain. It has high temporal resolution, meaning it can detect rapid changes in brain activity. MEG can help localize seizure onset zones and map eloquent cortex, often providing complementary information to EEG and MRI, especially in surgical evaluations.

Accurate diagnosis of a seizure disorder is the first and most critical step towards effective management and improved quality of life. A comprehensive evaluation, including detailed medical history, neurological examination, and appropriate diagnostic testing, is essential for identifying the type of seizure disorder, underlying causes, and guiding the most effective treatment strategies. If you or someone you know is experiencing seizures, seeking evaluation from epilepsy specialists is crucial for receiving expert diagnosis and care.