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Differentiating Temporal Lobe Epilepsy through Functional Neuroimaging

The human brainEpilepsy is a brain disorder in which the normal pattern of neuronal activity becomes disturbed, causing changes in behavior, sensation or awareness and sometimes convulsions, muscle spasms and loss of consciousness. These symptoms, which go under the umbrella of seizures, may last from a few seconds to a few minutes.

This disorder may result from events that compromise the brain’s natural circuitry, such as severe head injury, brain infection or disease, stroke, or oxygen deprivation. However, a specific cause for this condition is hardly ever found.

Epilepsy can be differentiated according to the region of the brain where focal seizures originate. In temporal lobe epilepsy, the most common form of localized epilepsy in adults, the area of seizures onset is the temporal lobe, a structure that has a pivotal role in processing emotions and storing short-term memory. This particular epilepsy can be further classified as lateral, mesial and mesio-lateral temporal lobe epilepsy.

Whenever surgery to the temporal lobe is necessary in order to remove seizure focus, being able to discern these types of temporal lobe epilepsy is a critical requirement for good surgical outcome. In a recent study, researchers from Samsung Medical Center, Korea, forged ahead in investigating these differences using functional neuroimaging.

Temporal lobe epilepsy patients underwent brain PET studies between seizures activity and SPECT both during and between seizures. From these scans Analyze software was used to perform SISCOM (Subtraction Ictal SPECT CO-registered to MRI) analysis. Through the combination of SPECT and MRI, SISCOM allows the assessment of regional activation in the brain. Merging the critical functional information from the SPECT scans with the structural detail of the MRI, SISCOM provides an important synergistic visualization which allows direct functional to structural analysis.

In their study, the investigators showed that hypometabolism and hyperperfusion were circumscribed to the temporal region in mesio-lateral patients and to extratemporal regions in lateral subjects. These results highlight that through the use of SISCOM, researchers will be able to differentiate between mesio-lateral and lateral temporal lobe epilepsy and acquire the essential clinical information necessary in their pre-surgical decision-making process.

Download our Guide to SISCOM Processing

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