Epilepsy Diagnosis

When epilepsy is suspected, a patient is evaluated with a complete physical and neurological examination and a thorough seizure history. Most of the tests are to identify the precise location and extent of the seizure focus, the character of the seizures, and the relationship of the seizure focus to other brain functions, such as speech. How many tests have to be done depends on the type of treatment being planned and how much information each test produces.

MRI forms the mainstay of imaging for epilepsy, and increasingly functional MRI and magnetic resonance spectroscopy are utilized for structural lesions, but may often fail to localize the seizure focus.

Seizures are the result of abnormal "synchronized firing" of a cluster of brain cells. These cells become very metabolically active during the seizure, and in most patients remain less active than normal brain tissue between seizures. How the seizures present in symptoms differs depending on which part of the brain is involved. During a seizure, the PET/CT scan shows the area responsible for the seizure as an area of increased glucose use. Between the seizures, PET/CT shows a characteristic pattern of reduced need for glucose. PET/CT imaging, especially when performed concurrently with surface EEG measurements, may be useful for localizing all of the seizure foci for surgical resection.

Accurate localization of the focus of the seizure activity is critically important to determine treatment options.

Source: Atlas of Clinical Positron Emission Tomography by Sallie F. Barrington, Michael N. Maisey and Richard R. Wahl. Oxford University Press, Inc. New York, NY. 2006.