Small vessel disease

Vascular white matter lesions are age-related, asymptomatic foci of ischaemic demyelination (unidentified bright objects or ‘UBOs’), myelin pallor or gliosis. They are uncommon in those below age 40 years (figure 1), thereafter, increasing in frequency with age. These white matter changes occur in 5–10% of those aged 20–40 years. Most patients are neurologically normal. At all ages, the incidence and lesion load increase with cardiovascular risk factors (figure 2). The white matter lesions are small and have high T2 signal but differ from MS plaques because of their irregular shape, poor definition and peripheral location and are most common in the frontal and parietal lobes. Posterior fossa lesions are uncommon, and callosal lesions are rare because of a dual blood supply.