Structural and physiological MRI correlates of occult cerebrovascular disease in late-onset epilepsy

Abstract

Late-onset epilepsy (LOE), with onset after 50 years of age, is often attributed to underlying occult cerebrovascular disease. LOE is associated with a three-fold increase in subsequent stroke risk, therefore it is important to improve our understanding of pathophysiology. In this exploratory study, we aimed to determine whether established structural magnetic resonance imaging markers and novel physiological imaging markers of occult cerebrovascular disease were more common in patients with LOE than age-matched controls.Sixteen patients with LOE (mean age ± SD: 67.6 ± 6.5 years) and 15 age-matched control subjects (mean age: 65.1 ± 3.9 years) underwent a 3 T MRI scan protocol. T1-weighted images and T2-weighted fluid attenuated inversion recovery (FLAIR) images were used to determine cortical grey matter volume and white matter hyperintensity (WMH) volume respectively, whilst multiple delay time arterial spin labelling (ASL) images were collected at rest and during a hypercapnic challenge. Cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from ASL data under both normocapnic and hypercapnic conditions. Cerebrovascular reactivity was also calculated for both CBF and AAT relative to the change in end-tidal CO2.Patients with LOE were found to have significantly lower cortical volume than control subjects (33.8 ± 3.8% of intracranial volume vs. 38.0 ± 5.5%, p = 0.02) and significantly higher WMH volume (1339 ± 1408 mm3 vs. 514 ± 481 mm3, p = 0.047). Baseline whole brain AAT was found to be significantly prolonged in patients with LOE in comparison to control subjects (1539 ± 129 ms vs. 1363 ± 167 ms, p = 0.005). Voxel-based analysis showed the significant prolongation of AAT to be predominantly distributed in the frontal and temporal lobes. Voxel-based morphometry showed the lower cortical volume to be localised primarily to temporal lobes. No significant differences in CBF or cerebrovascular reactivity were found between the two groups. Baseline whole brain AAT and cortical volume differences persisted upon further analysis to take account of differences in smoking history between patients and control subjects.These findings suggest that occult cerebrovascular disease is relevant to the pathophysiology of LOE.

Patterns of postictal cerebral perfusion in idiopathic generalized epilepsy: a multi-delay multi-parametric arterial spin labelling perfusion MRI study

“…Our results revealed that IGE patients with absence seizures showed prolonged ATT in the left superior temporal gyrus. This finding is consistent with a recently published study that found that patients with late-onset epilepsy have significantly prolonged ATT in widespread brain regions, but the greatest prolongation is predominantly distributed in the temporal and frontal lobes 20 . The authors considered that the prolongation of ATT may be attributable to the recruitment of secondary collaterals induced by seizure activity.…”

“…The technique has been employed successfully in cerebrovascular diseases, such as acute ischemic stroke 18 and moyamoya disease 15 , which demonstrates significant correlations between multi-delay ASL and dynamic susceptibility contrast (DSC) as well as computed tomography (CT) perfusion CBF measurements. In addition, a recent study using this protocol found no significant differences in CBF and significantly prolonged ATT between patients with late-onset epilepsy and control subjects 20 . The authors considered that the prolonged ATT may be attributable to the recruitment of secondary collaterals induced by seizure activity.…”

Delayed seizures after intracerebral haemorrhage

“…haematoma size) does not support this hypothesis. Alternatively, injury secondary to CSVD (both micro-and macro-structural) may act independently on delayed seizure risk (Gibson et al, 2014;Hanby et al, 2015). Finally, a combination of the two mechanisms described above cannot be ruled out.…”

A Rare Cause of Late-Onset Epilepsy: Linear Scleroderma en Coup de Sabre

“…Late-Onset Epilepsy (LOE), with onset in adult life, is often attributed to cerebrovascular disease and intracranial tumor [1]. While our patient indicated a rare cause, which is the Linear Scleroderma en Coup de Sabre (LScs).…”