When multiple anatomic lesions are seen on MRI and the identification of an offending epileptogenic focus could help limit the extent of surgery.
Also, with FDG, activation of secondary and tertiary seizure foci may result in decreased FDG accumulation, whereas SPECT regional CBF agents create a "snapshot" of blood flow focused only on the primary epileptogenic focus.
In 7 out of 9 clinical seizures recorded from Patient 1, at the beginning of the seizures (0-30sec), there was a comparatively higher number of incoming and a lower number of outgoing connections at the epileptogenic focus than the other brain sites (Fig.
In this work, the generalized partial directed coherence (GPDC) measure of directed connectivity between brain regions was used in conjunction with statistically significant in-degree and out-degree measures of graph connectivity to quantify the connectivity over time of the epileptogenic focus during seizures.
Epileptogenic focus localization using ictal rCBF SPECT
Several articles characterize the brain propagation patterns of the epileptogenic electrocortical discharge and resultant rCBF hyperemia to allow for more accurate localization of the epileptogenic focus in cases where [greater than or equal to]2 cortical areas are seen to be hyperemic on the brain SPECT scan.
The result of the ictal brain SPECT scan was subsequently coregistered with the MRI scan, and the placement of subdural grid electrodes confirmed the epileptogenic focus location.