Abstracts

Rationale: Temporal lobe epilepsy in general, is divided in mesial and neocortical, however; fusiform gyrus or basal temporal lobe epilepsy has not been clearly described. Fusiform gyrus epilepsy is an entity that is under recognized with no clear stereotypical features, that may have a challenging interpretation on scalp-EEG due to poor localizing value. Fusiform gyrus should be considered as a possible epileptogenic region in the surgical evaluation of intractable epilepsy in order to avoid biases that may lead to poor outcomes due to misinterpretation of the data. Our aim is to describe and characterize right fusiform gyrus epilepsy as a unique entity. Methods: The first patient’s semiology consisted of visual like auras as “objects coming towards him”, followed by unresponsiveness, manual automatisms and repetitive vocalization. The seizure duration would last 1-2 minutes, occurring twice per week. MRI demonstrated a ganglioglioma in the right basal temporal lobe involving the mid to posterior region of the fusiform gyrus with normal hippocampal structures. He had previously failed 4 antiepileptic drugs (AED). The second patient presented with episodes of intermittent aphasia and confusion, loss of awareness and generalized tonic clonic seizures occurring once per week. MRI demonstrated a right fusiform gyrus cavernoma with normal hippocampus. She had failed a total of 8 AEDs. Results: Patient 1 demonstrated inter-ictal EEG sharp waves from left fronto-temporal (90%), right frontotemporal (5%), and bi-frontal region (5%). Ictal findings demonstrated seizures predominantly from left fronto-temporal (>70%), non-localizable regions, and right frontocentral region. Ictal SPECT showed tracer uptake in the right anterior lateral temporal, left insular, and possible temporal spread. Given a clear lesion in the right basal temporal lobe and ictal SPECT findings, right temporal lobe resection was performed with complete resolution of his seizures for the last five months. Patient 2 also demonstrated inter ictal sharp waves from the right frontotemporal and left fronto-temporal regions. Ictal findings demonstrated seizures arising from the left more than right frontotemporal regions. Conclusions: Rapid propagation of temporal lobe epilepsy has been well known in mesial and neocortical epilepsy. Networks involved may differ when compared to left and right temporal lobes. In fact, the fusiform region on the left side may have different manifestations clinically and on EEG when compared to the right. In our cases, the right fusiform epileptic lesions presented with predominantly contralateral ictal and inter-ictal findings. This may be explained by the spread from a “hidden” or difficult area to evaluate on scalp EEG, given its discrete location. Our case not only helps to understand right fusiform lesional cases, but may also assist in the planning of non-lesional, bitemporal, or left temporal epilepsies, where the right fusiform gyrus may be the true epileptogenic zone.