Enlarged perivascular spaces serve as marker for progression in Parkinson’s disease

A greater number of enlarged perivascular spaces within the basal ganglia correlated with indicators of motor disability progression among patients with Parkinson’s disease, according to findings published in Neurology.

As a result, visible perivascular spaces in the basal ganglia represent potential markers for progression of motor disability in patients with PD, the researchers noted.

“Perivascular spaces [PVSs] are commonly invisible in conventional brain MRI in young brains; however, enlarged PVSs, which appear as linear or ovoid structures with a signal intensity similar to that of cerebrospinal fluid, become more numerous in specific brain regions ... with increasing age,” the researchers wrote. “The clinical implications of enlarged PVSs remain controversial: Some studies suggest that enlarged PVSs are a normal phenomenon in the elderly, while others have noted that visible PVSs, particularly in the basal ganglia, are closely linked to cerebral small vessel diseases, inflammatory conditions and cognitive impairment.”

However, clinical relevance of enlarged PVSs in the basal ganglia in PD is not well-established, according to Young H. Sohn, MD, PhD, of Yonsei University College of Medicine, and colleagues.

For this reason, Sohn and colleagues sought to examine the association between enlarged PVSs within the basal ganglia at baseline and long-term motor outcomes, including levodopa-induced dyskinesia, wearing-off, freezing of gait and a longitudinal increase in the doses for dopaminergic drugs.

The study included 248 patients (mean age, 67.4 years; 130 women) with drug-naïve, early-stage PD. Patients underwent brain MRI and dopamine transporter scans at baseline assessment. The researchers reviewed medical records and calculated the number of baseline enlarged basal ganglia PVSs using axial T2-weighted images.

Sohn and colleagues then divided patients into two groups, including those with a low number of enlarged PVSs (n = 156) and those with a high number of enlarged PVSs (n = 92). They used Cox regression models to compare the levodopa-induced dyskinesia, wearing-off and freezing of gait-free times between the two groups and a linear mixed model to compare longitudinal increases in levodopa-equivalent dose per body weight between the two groups.

The study results demonstrated that patients with a high number of enlarged PVSs had higher small vessel disease burden and were aged older than those with a low number of enlarged PVSs (72.28 years vs. 64.58 years).

In addition, those with a higher number of enlarged PVSs experienced higher decreases in dopamine transporter availability across all striatal sub-regions, except for the ventral striatum.

Although the risk for levodopa-induced dyskinesia or wearing-off was comparable between the two groups, the researchers observed greater risk for freezing of gait among those with high numbers of enlarged PVSs. They also found that the doses of dopaminergic medications needed for effective symptom control were higher among those with greater numbers of enlarged PVSs.

“These findings suggest that visible PVSs in the basal ganglia, which can be easily rated on T2-weighted images, [have] the potential to serve as a prognostic marker for the progression of motor disability in patients with [PD],” the researchers wrote.