The emissary veins of the foramen ovale: an anatomical study using magnetic resonance imaging.

PURPOSE: The emissary veins (EVs) passing through the foramen ovale (FO) are not well understood. The aim of this study was to characterize these veins using contrast magnetic resonance imaging (MRI). METHODS: In total, 85 patients underwent thin-sliced, contrast MRI. Coronal and sagittal images were used for the analysis. RESULTS: The EVs of the FO were well delineated in 100% on sagittal and 97% on coronal images. On the sagittal images, these veins could be classified into the lateral, medial, and perineural types in association with the mandibular division of the trigeminal nerve (V3) segment in the FO. In 22% of the slides, the medial EV was more predominant than lateral one, while in 64% of the slides, the latter was more predominant. On the coronal images, the identified EVs of the FO coursed medially to the V3 in 68% and laterally in 72% of 165 sides. The perineural EVs most frequently coursed along both the lateral and medial surfaces of the V3. On the sagittal images, the angles formed by the midline of the V3 segment in the FO and lower margin of the FO were 81.5 ± 11.9° on the left side and 80.0 ± 12.2° on the right, while on the coronal images, they were 61.5 ± 12.1° on the left side and 64.8 ± 11.3° on the right. CONCLUSIONS: The EVs of the FO are structures that may be characterized by a well-developed venous channel in the lateral aspect of the V3 and nearly symmetrical orientation of both V3s lying in the FO.

Network Analysis of Foramen Ovale Electrode Recordings in Drug-resistant Temporal Lobe Epilepsy Patients.

Approximately 30% of epilepsy patients are refractory to antiepileptic drugs. In these cases, surgery is the only alternative to eliminate/control seizures. However, a significant minority of patients continues to exhibit post-operative seizures, even in those cases in which the suspected source of seizures has been correctly localized and resected. The protocol presented here combines a clinical procedure routinely employed during the pre-operative evaluation of temporal lobe epilepsy (TLE) patients with a novel technique for network analysis. The method allows for the evaluation of the temporal evolution of mesial network parameters. The bilateral insertion of foramen ovale electrodes (FOE) into the ambient cistern simultaneously records electrocortical activity at several mesial areas in the temporal lobe. Furthermore, network methodology applied to the recorded time series tracks the temporal evolution of the mesial networks both interictally and during the seizures. In this way, the presented protocol offers a unique way to visualize and quantify measures that considers the relationships between several mesial areas instead of a single area.