Prevalence and subtypes of radiological cerebrovascular disease in late-onset isolated seizures and epilepsy.

BACKGROUND: Late-onset epilepsy (LOE), onset over 60, is often attributed to cerebrovascular disease (CVD), and is associated with increased stroke risk. We investigated the radiological prevalence of CVD in LOE. METHODS: We undertook a retrospective case-control study of patients with LOE and age and sex-matched controls, also matched for imaging modality. Radiological CVD was recorded, with radiological findings by an experienced consultant neuroradiologist usi a structured proforma. RESULTS: 105 cases and 105 controls were studied, comprising 61 (58.1%) males, mean (±SD) age (years) 72.7±7.48 (cases), 72.4±7.02 (controls). 9 cases had isolated seizures rather than LOE. Imaging modality (in cases and controls) was CT in 59 and MRI in 46. Radiological CVD was more prevalent amongst cases (65.7%) than controls (33.3%) (p<0.0001, Chi-square), odds ratio 3.83 (95% CI 2.16-6.79). Large vessel disease (LVD) (single or multiple cortical or subcortical infarcts>1.5 cm) was present in 23 (21.9%) cases and 2 (1.9%) (p<0.001) controls, with small vessel disease (SVD) (periventricular or subcortical white matter lesions (WMLs), including leukoaraiosis (LA)) present in 52 (49.5%) cases (LA in 4) and 34 (32.3%) controls (LA in 0) (p<0.05). When WMLs were rated using a semiquantitative visual rating scale, a trend towards greater severity was observed amongst cases compared to controls. CONCLUSIONS: Radiological CVD is significantly more prevalent in patients with LOE than controls, including signs of both LVD and SVD. SVD also appears to be of greater severity. Further studies are needed in this area.

Dynamic contrast-enhanced imaging techniques: CT and MRI.

Over the last few decades there has been considerable research into quantifying the cerebral microvasculature with imaging, for use in studies of the human brain and various pathologies including cerebral tumours. This review highlights key issues in dynamic contrast-enhanced CT, dynamic contrast-enhanced MRI and arterial spin labelling, the various applications of which are considered elsewhere in this special issue of the British Journal of Radiology.

Abnormalities of cerebral perfusion in multiple sclerosis.

BACKGROUND: Measuring perfusion provides a potential indication of metabolic activity in brain tissue. Studies in multiple sclerosis (MS) have identified areas of decreased perfusion in grey matter (GM) and white matter (WM), but the pattern in clinical subgroups is unclear. OBJECTIVES: This study investigated perfusion changes in differing MS clinical subgroups on or off beta-interferon therapy using a non-invasive MRI technique (continuous arterial spin labelling) to investigate whether different clinical MS subtypes displayed perfusion changes and whether this could give a further insight into the pathological mechanisms involved. METHODS: Sixty patients (21 relapsing remitting, 14 secondary progressive, 12 primary progressive, 13 benign) and 34 healthy controls were compared. Statistical parametric mapping (SPM '99) was used to investigate regional variations in perfusion in both GM and WM. Global WM perfusion was derived by segmenting WM from images using T(1) relaxation times. RESULTS: Regions of lower perfusion in predominantly GM were observed in the primary and secondary progressive cohorts, particularly in the thalamus. Increased WM perfusion was seen in relapsing remitting and secondary progressive cohorts. CONCLUSIONS: Low GM perfusion could reflect decreased metabolism secondary to neuronal and axonal loss or dysfunction with a predilection for progressive forms of MS. Increased WM perfusion may indicate increased metabolic activity possibly due to increased cellularity and inflammation. Improved methodology and longitudinal studies may enable further investigation of regional and temporal changes, and their relationship with physical and cognitive impairment.