The first 3-D volumetric analysis of mesencephalothalamic giant perivascular spaces showing steady and slow growth over 17 years

Background: Giant perivascular spaces (PVSs) are very rare condition in the brain and can be associated with neurological symptoms. It often enlarges and causes obstructive hydrocephalus which requires surgical intervention. However, the growth velocity has never been investigated. Case Description: Here, we report a woman in her early eighties with giant PVSs eventually followed up 17 years. She presented with dizziness and mild headache for a week and her neurological examination showed no abnormality. Her brain magnetic resonance imaging (MRI) showed a multiple cystic lesion, 28 mm in maximum diameter as a whole, in the left mesencephalothalamic region. There were no solid part, rim enhancement, or perilesional intensity change suggesting edema or gliosis. Smaller PVSs were also seen in bilateral-hippocampi, basal ganglia, white matter, and left frontal operculum. Retrospectively, five MRI studies over 17 years were analyzed using a 3-D volumetric software and found a very slow growth of the lesion, from 6.54 ml to 9.83 ml indicating gain of 0.1752 ml (2.68%) per year. Conclusion: This is the first report verifying a gradual enlargement of giant PVSs in a natural course. The prospective 3-D volumetric analysis on PVSs may elucidate the true nature of these lesions.