Evaluation and Diagnosis
Seizure diagnosis in very young children initially focuses on whether the behavior in question is indeed a seizure. Since the doctor often is not present when the suspect behavior or symptoms occur, the reported observations of parents or guardians are an important factor in the diagnosis. Additional evaluation and testing will likely be necessary to identify characteristics that, together with the doctor’s examination and parents’ report, will lead to an accurate diagnosis of the seizure syndrome, if the infant does, in fact, have a seizure syndrome.
Seizures are marked by a disturbance of electrical activity in the brain. The EEG (electroencephalogram) records such abnormal activity and is the most commonly used diagnostic tool. Often the child’s seizures are confirmed and the syndrome identified with this procedure alone. However, diagnosis may require several EEG s taken while the child is asleep, awake and very tired.
The sleep EEG is especially valuable as it enhances the seizure detection rate of the routine (awake) EEG from 60 percent to 90 percent. A normal EEG does not exclude the possibility of epilepsy when there are other convincing clinical signs. Syndrome diagnosis in some children may require hospitalization for video-EEG monitoring. This procedure provides a simultaneous, split-screen visual record of the child’s movements and the corresponding brain wave pattern .
Neuroimaging procedures (CT, MRI, PET, SPECT) are used when brain damage is suspected or when the electrical disturbance is localized within specific areas of the brain. MRI is most often the imaging procedure of choice; however, each procedure has its special use.
- CT (computed axial tomography) is valuable in detecting small calcified lesions and in assessing head injury when seizures are present
- MRI (magnetic resonance imaging) helps identify abnormalities of brain structure
- PET (positron emission tomography) helps identify subtle changes in area that generate seizures
- SPECT (single photon emission computed tomography) images blood flow in the brain
- MEG (magnetoencephalography) records magnetic activity produced by the brain’s electrical activity—that is, identifies areas of seizure activity and pinpoints sites of normal sensory function
- fMRI (functional MRI) helps identify areas of seizure activity and sites of normal brain activity
Laboratory analysis of blood and urine are used to detect possible infections or errors of metabolism and nutrition that might be the underlying cause of the child’s seizures. Appropriate studies will be dictated by the medical history and doctor’s examination. A spinal-fluid analysis is almost always conducted if the cause of the seizures remains unknown.
The laboratory evaluation might include tests for the following:
- Blood cell count
- Blood gases
- Liver function
- Serum amino acids
- Urine organic acids