Is “unilateral” moyamoya disease different from moyamoya disease?

Whether a diagnosis of moyamoya disease is justified in patients with typical angiographic evidence of moyamoya disease unilaterally and normal angiographic findings contralaterally remains controversial. In this study the authors analyzed longitudinal angiographic change, familial occurrence, and basic fibroblast growth factor (bFGF) concentration in the cerebrospinal fluid (CSF) of patients with "unilateral" moyamoya disease. Over a 10-year period, 10 cases of unilateral moyamoya disease were followed using conventional angiography or magnetic resonance angiography. Basic FGF in CSF, obtained from the subarachnoid space of the cerebral cortex during revascularization surgery, was measured in five cases. Among the 10 cases of unilateral moyamoya disease, only one pediatric case showed obvious signs of progression to typical bilateral disease. The other nine cases (including six adults and three children) remained stable throughout follow-up radiological examinations (magnetic resonance angiography) with a mean observation period of 3.5 years. There was no familial occurrence in these cases of unilateral moyamoya disease. Levels of bFGF, which are high in typical moyamoya disease, were low in these patients. The progression from unilateral moyamoya disease to the typical bilateral form of the disease appears to be infrequent. The low levels of bFGF in the CSF of these patients and the lack of familial occurrence strongly suggest that most cases of unilateral moyamoya disease, especially those found in adults, are distinct from typical bilateral moyamoya disease.