Differential Diagnosis for Seizures
It is important to identify and treat any injury or disease process that may be producing seizures, such as:
- head trauma,
- infection (e.g., encephalitis, meningitis), and
- drug intoxication or withdrawal.
Conditions that produce symptoms similar to those that occur during seizures must be ruled out, such as the following:
- Breath-holding spells: bluish tint to the skin (cyanosis), loss of consciousness, loss of muscle tone
- Meniere's disease: vertigo, visual phenomena, speech impairment, altered consciousness
- Migraine: aura, loss of consciousness, nausea, photophobia, muscle weakness
- Movement disorder: tics, chorea, tremor
- Syncope: sudden loss of muscle tone and posture, loss of consciousness, vertigo, nausea, muscle spasm
Epilepsy and Electroencephalogram (EEG)
EEG is a diagnostic test used to investigate a seizure disorder. It identifies abnormal electrical activity in the brain, provides information about the type of seizure disorder, and locates the area of seizure focus.
Some of the findings on EEG are specific to particular disorders and subtypes of epilepsy. Activity during a seizure can be identified by a pattern on the graph, called epileptiform, which indicates epilepsy. Correlating this type of data with clinical symptoms of seizures often helps make an accurate diagnosis. Additionally, the EEG recording between seizures is often abnormal in patients with epilepsy.
The EEG measures electrical activity in the brain through small electrodes that are placed on the scalp on both sides of the head. If the results are normal, the test is repeated after the patient is subjected to seizure triggers, such as sleep deprivation, flashing light, and hyperventilation. Continuous, 24–72 hour EEG and video monitoring may be performed at home to obtain a record of seizure activity.
Epilepsy and Neuroimaging
Magnetic resonance imaging (MRI scan) or computed tomography (CT scan or CAT scan) are performed when a lesion or other structural cause, such as stroke or tumor, is suspected.