Lab Tests for Seizure Disorder

The Merck Manuals Online Medical Library defines a seizure as a periodic disturbance in the brain's electrical activity that results in some degree of temporary brain dysfunction. A seizure can be either a complex or a minor problem, depending upon the root cause of the seizure. In order to understand the origin and severity of a seizure, a number of laboratory tests can be conducted for diagnostic purposes.

• Laboratory tests are often used to diagnose the cause of seizures.

Blood Draws

• Typically, the first step of the diagnosis process is to conduct a series of blood tests to look for abnormalities. The most common tests performed are a complete blood count (CBC) and a glucose test. The CBC is used to evaluate red and white blood cell counts which can indicate whether or not an infection caused the seizure. The glucose test is used to evaluate abnormal sugar levels, which can cause a seizure, particularly when there is a sharp increase or decrease.

Other Lab Tests

• Additional laboratory tests to detect an infection can be used to determine the cause of a seizure. The most common of these tests include a cerebral spinal fluid (CSF) analysis, in which the fluid is drawn from the spine and analyzed. A blood culture may also be performed, which may detect septicemia or other bacterial infections of the blood. These types of serious infections can lead to seizures because of chemical imbalances which can cause electrical imbalances in the brain.

Electroencephalogram

• While blood tests may be effective in diagnosing the cause of a seizure, the primary test performed is an electroencephalogram, commonly known as an EEG. According to the National Institute of Health, an EEG measures faint electrical activity in the brain through the use of electrodes that are placed on the scalp. The test looks for changes or abnormal wave patterns in the brain that may be indicative of another health issue that can cause a seizure.

Imaging Scans

• Additional brain-imaging scans can be used to diagnose seizures. For example, a computerized tomography (CT) scan can be used to identify the presence of a brain abnormality or tumor. These abnormalities can also be detected through magnetic resonance imaging (MRI). If these tests are inconclusive, scans to evaluate the active areas of the brain are used. The most common scans are positron emission tomography (PET) scans and single-photon emission computerized tomography (SPECT) scans. Both scans use radioactive materials to evaluate active regions of the brain and to determine the region of the brain where a seizure originates.

Diagnosis of seizure disorders

• Since seizures can be caused by a number of different factors, it is important that the treatment options are in alignment with the diagnostic findings. For example, if the laboratory tests reveal that the seizure was caused by sharp fluctuations in glucose levels, the person may be treated for diabetes or other glucose-related diseases. More commonly, however, seizures are one-time events that do not require a specific treatment program.