Sarcoidosis, more frequently, affects African-Americans as well as individuals of Scandinavian origin. The estimated incidence of neurosarcoidosis in these ethnic groups is 15-20 and 35-80 cases per 100,000, correspondingly. However, a review of a number of retrospective case series reports indicates that 5-10 % of patients with sarcoidosis suffer from neurological complications and in 50-70 % of these individuals neurologic abnormalities are the initial clinical presentations. These neurologic abnormalities commonly develop during the first 2 years of systemic involvement. Isolated neurosarcoidosis, which means exclusive involvement of the
Fig. 5.2 0x10XX: Medium-power photomicrograph showing meningeal granulomas containing a few giant cells and a surrounding lymphocytic infiltrate (H&E, original magnification x 100)
nervous system without systemic involvement, is uncommon and its prevalence differs among various studies between 1-3 % and 10-17 % [4, 5]. Usually, sarcoidosis peaks in the third to fifth decades for most individuals, and neurologic symptoms commonly manifest during the first 2 years of disease. Women often have been reported to have a later age of onset and are more frequently affected compared to men. Various genetic, infectious, and environmental causes have been associated with sarcoidosis but without any proven cause and effect relationship.