Frontiers in Imaging Markers for Epileptogenesis

November 1, 2007

Contributing to the problem is the relative unreliability of EEG tracings recorded from patients during the interictal period. Although these tracings can reveal certain abnormalities that are characteristic of epilepsy, such as spikes, they tend to be relatively nonspecific. Interictal spikes, for instance, occur inconsistently; they are present in some persons who do not have epilepsy and absent in others who do.

Solid information about the causes and underlyingmechanisms of epilepsy is as jumbled asthe disorder itself. This is partially becauseso many diverse events can cause localizedor diffuse clusters of nerve cells to fireabnormally, triggering an epileptic seizure.

Contributing to the problem is the relative unreliability of EEG tracings recorded from patients during the interictal period. Although these tracings can reveal certain abnormalities that are characteristic of epilepsy, such as spikes, they tend to be relatively nonspecific. Interictal spikes, for instance, occur inconsistently; they are present in some persons who do not have epilepsy and absent in others who do. For this reason, they have no value for predicting the onset of a seizure. Furthermore, the magnitude of these spikes does not necessarily correlate with the severity of the patient's epilepsy.1

A noninvasive, accurate electrophysiological or neuroimaging marker would be of tremendous value for profiling a patient's risk, diagnosing epilepsy, developing new treatments, planning treatment, and monitoring the response to that treatment. A clinically accessible surrogate marker that reliably predicted seizures also could help a patient manage his or her life to minimize the impact and potential damage of epileptic episodes or, better yet, thwart or blunt an impending attack.

EPILEPSY

Epilepsy can develop in any person at any stage of life. Children appear to be at greatest risk for developing new-onset epilepsy until about the age of 10 years.2 After that, the potential for epilepsy stabilizes until it increases again around the age of 55 to 60, when the incidence of strokes, brain tumors, and Alzheimer disease starts to escalate. Risk factors for epilepsy are summarized in Table 1.2,3

 Table 1- Risk factors for epilepsy
Low birth weight 
Occurrence of seizures within the firstmonth of life 
Presence of brain abnormalities at birth 
Intracranial bleeding 
Vascular abnormalities 
Brain trauma 
Anoxia 
Brain tumors 
Infections of the brain: abscess, meningitis,encephalitis
Stroke related to arterial blockage 
Cerebral palsy 
Seizures occurring within the first few daysof head trauma 
Family history of epilepsy or febrile seizures 
Alzheimer disease 
Drug abuse