Can developmental venous anomalies cause seizures?

[Neuroradiological and pathohistological markers of the main epileptogenic substrates in children. Other cerebral disorders]

High-resolution MRI is an important tool in the diagnosis of structural epilepsy |in determining the seizure initiation zones, identification of the mechanisms of epileptogenesis in predicting outcomes and preventing postoperative complications in patients. In this article we have tried to demonstrate the neuroradiological and pathohistological characteristics of the main epileptogenic substrates in children using modern classification. The second part of the article is devoted to the spectrum of epileptogenic cerebral disorders, in addition to cortical malformations.

Temporal encephaloceles and coexisting epileptogenic lesions

OBJECTIVE

This study was performed to identify coexisting structural lesions in patients with epilepsy and known temporal encephaloceles (TEs).

METHODS

Forty-seven structural magnetic resonance imaging (MRI) scans of patients with epilepsy and radiologically diagnosed TEs were retrospectively reviewed visually and using an automated postprocessing software, the Morphometric Analysis Program v2018 (MAP18), to depict additional subtle, potentially epileptogenic lesions in the 3D T1-weighted MRI data. All imaging findings were evaluated in the context of clinical and electroencephalographical findings.

RESULTS

The study population consisted of 47 epilepsy patients (38.3% female, n = 18). The median age at the time of the scan was 40 years (range 12-81 years). Twenty-one out of 47 MRI scans (44.7%) showed coexisting lesions in the initial MRI evaluation; in 38.3% (n = 18) of patients, those lesions were considered probably epileptogenic. After postprocessing, probable epileptogenic lesions were identified in 53.2% (n = 25) of patients. Malformations of cortical development had initially been reported in 17.0% (n = 8) of patients with TEs, which increased to 38.3% (n = 18) after postprocessing. TEs and other epileptogenic lesions were considered equally epileptogenic in 21.3% (n = 10) of the cases in the initial MR reports and 25.5% (n = 12) of the cases after postprocessing.

SIGNIFICANCE

Temporal encephaloceles are a potential cause of MRI-negative temporal lobe epilepsy. According to our data, TEs can occur with other lesions, suggesting that increased awareness is also required in patients with lesional epilepsy. TEs may not always be epileptogenic; hence, their occurrence with other structural pathologies may influence the presurgical evaluation and surgical approach. Finally, TEs can be associated with malformations of cortical development, which may indicate a common developmental etiology of those lesions.

Prevalence and anatomical characteristics of developmental venous anomalies: an MRI study

PURPOSE

Developmental venous anomalies (DVAs) are extreme anatomical venous variations formed by multiple radiating medullary veins, which converge centripetally into a single collecting vein. Their coexistence with symptomatic cavernous malformations (CMs) has been reported in the literature. The aim of this study was to assess the characteristics of DVAs using MRI.

METHODS

A total of 6948 head MRIs of adult Caucasian patients were retrospectively analyzed to determine the number and locations of DVAs. We collected the data on the termination of the collecting vein, the prevalence of DVA-related CMs, and MRI FLAIR signal-hyperintensity corresponding to the location of the DVA.

RESULTS

At least one DVA was identified in 7.46% of the patients. The prevalence decreased with age, with a Pearson correlation coefficient of - 0.7328. A total of 599 DVAs were identified. Multiple DVAs were found in 10.92% of the patients with DVAs. The DVAs were identified more often in the supratentorial region (73.12%, p < 0.0001), and the most common location was the frontal lobe (35.23%). The collecting vein usually drained into the superficial cerebral veins (68.78%). CMs were observed in 4.14% of the patients with DVAs, and the prevalence showed a positive correlation with age. Signal-intensity abnormalities were identified in the vicinity of 5.18% DVAs.

CONCLUSION

Knowledge about characteristics of DVAs and associated anomalies is essential for neuroradiologists and neurosurgeons. The large number of currently available diagnostic studies enables us to assess anatomical variants on a great number of subjects.

Epilepsy Lesion Localization is not Predicted by Developmental Venous Anomaly Location or its FDG-PET Metabolic Activity

BACKGROUND AND PURPOSE

This study's purpose is to correlate location and metabolic activity of developmental venous anomalies (DVAs) in epilepsy patients to the seizure focus as determined by ictal/interictal encephaloelectrogram (EEG).

METHODS

A retrospective search was performed for epilepsy patients with DVAs who underwent brain ¹⁸ F-fluorodeoxyglucose positron emission tomography (¹⁸ F-FDG-PET) and magnetic resonance imaging (MRI). MRI exams were analyzed to characterize DVA location and associated structural findings. MRI and PET images were co-registered and assessment of ¹⁸ F-FDG uptake in the DVA territory was performed. The electronic medical record was reviewed for each subject to determine seizure semiology and site of seizure focus by ictal/interictal EEG.

RESULTS

Twenty-eight DVAs in 25 patients were included. Twelve DVAs demonstrated regional metabolic abnormality on ¹⁸ F-FDG-PET. There was no significant correlation between DVA site and seizure focus on EEG. DVA location was concordant with EEG seizure focus in three subjects, and all three demonstrated hypometabolism on ¹⁸ F-FDG-PET. This significance remains indeterminate, as one of these DVAs was associated with cavernoma, which could serve as the true seizure focus, and one of the patients underwent resection of the DVA without decrease in seizure frequency. Furthermore, there was no statistically significant relationship between DVA metabolic activity and DVA-EEG lobar or laterality concordance.

CONCLUSIONS

In this sample, there is no significant correlation between location of DVA and seizure focus, and hypometabolism within the DVA territory is not predictive of EEG/DVA co-localization. As use of ¹⁸ F-FDG-PET for evaluation of epilepsy increases, knowledge of this poor correlation is important to avoid diagnostic confusion and potentially unnecessary surgery in epilepsy patients.

The Imaging of Localization Related Symptomatic Epilepsies: The Value of Arterial Spin Labelling Based Magnetic Resonance Perfusion

Accurate identification of the epileptogenic zone is an important prerequisite in presurgical evaluation of refractory epilepsy since it affects seizure-free outcomes. Apart from structural magnetic resonance imaging (sMRI), delineation has been traditionally done with electroencephalography and nuclear imaging modalities. Arterial spin labelling (ASL) sequence is a non-contrast magnetic resonance perfusion technique capable of providing similar information. Similar to single-photon emission computed tomography, its utility in epilepsy is based on alterations in perfusion linked to seizure activity by neurovascular coupling. In this article, we discuss complementary value that ASL can provide in the evaluation and characterization of some basic substrates underlying epilepsy. We also discuss the role that ASL may play in sMRI negative epilepsy and acute scenarios such as status epilepticus.