Resting State Functional Connectivity Signatures of MRgFUS Vim Thalamotomy in Parkinson's Disease: A Preliminary Study

Abstract

Magnetic Resonance-guided high-intensity Focused Ultrasound (MRgFUS) of the thalamic ventral intermediate nucleus (Vim) for tremor has increasingly gained interest as a new non-invasive alternative to standard neurosurgery. Resting state functional connectivity (rs-FC) correlates of MRgFUS have not been extensively investigated yet. A region of interest (ROI)-to-ROI rs-FC MRI “connectomic” analysis focusing on brain regions relevant for tremor was conducted on 15 tremor-dominant patients with Parkinson's disease who underwent MRgFUS. We tested whether rs-FC between tremor-related areas was modulated by MRgFUS at 1 and 3 months post-operatively, and whether such changes correlated with individual clinical outcomes assessed by the MDS-UPDRS-III sub items for tremor. Significant increase in FC was detected within bilateral primary motor (M1) cortices, as well as between bilateral M1 and crossed primary somatosensory cortices, and also between pallidum and the dentate nucleus of the untreated hemisphere. Correlation between disease duration and FC increase at 3 months was found between the putamen of both cerebral hemispheres and the Lobe VI of both cerebellar hemispheres, as well as between the Lobe VI of untreated cerebellar hemisphere with bilateral supplementary motor area (SMA). Drop-points value of MDS-UPDRS at 3 months correlated with post-treatment decrease in FC, between the anterior cingulate cortex and bilateral SMA, as well as between the Lobe VI of treated cerebellar hemisphere and the interpositus nucleus of untreated cerebellum. Tremor improvement at 3 months, expressed as percentage of intra-subject MDS-UPDRS changes, correlated with FC decrease between bilateral occipital fusiform gyrus and crossed Lobe VI and Vermis VI. Good responders (≥50% of baseline tremor improvement) showed reduced FC between bilateral SMA, between the interpositus nucleus of untreated cerebellum and the Lobe VI of treated cerebellum, as well as between the untreated SMA and the contralateral putamen. Good responders were characterized at baseline by crossed hypoconnectivity between bilateral putamen and M1, as well as between the putamen of the treated hemisphere and the contralateral SMA. We conclude that MRgFUS can effectively modulate brain FC within the tremor network. Such changes are associated with clinical outcome. The shifting mode of integration among the constituents of this network is, therefore, susceptible to external redirection despite the chronic nature of PD.

Evaluation of Cerebral Volume Changes in Patients with Tremor Treated by MRgFUS Thalamotomy

“…Numerous studies have used imaging techniques to demonstrate the presence of structural and functional brain alterations in patients with TE and PD [ 8 , 9 , 10 ]. Some previous reports in the literature also explored the possible prognostic value of imaging finding, using standard and advanced imaging techniques, in patients submitted to pharmacological, surgical, and less invasive treatments for tremor [ 11 , 12 , 13 , 14 , 15 ].…”

Profiling functional networks identify activation of corticostriatal connectivity in ET patient after MRgFUS thalamotomy

“…Our previous study also found no significant change in the neural spontaneous activity of the Vim lesion site, while decreased in the left occipital cortex after MRgFUS thalamotomy [33]. The rs-fMRI study from Jang et al and Mario et al indicated a significant perturbation in the cortical network rather than the thalamus as well [4, 34]. This may be a manifestation of neuro-dynamics compensation or brain structure remodeling; another possible explanation for this phenomenon is that our 3T MRI-based imaging scans have relatively limited capabilities for subcortical tissue, restricting us to capture more subtle changes.…”

Topological patterns of motor networks in Parkinson’s disease with different sides of onset: A resting-state-informed structural connectome study

“…Local efficiency is defined by evaluating which of a node’s neighbors are neighbors of each other and is a measure of network segregation. The accumulation and dissemination of α-synuclein aggregates in the brain in the early stages of PD has been demonstrated to be associated with alterations in resting-state FC in the basal ganglia, intercortical, and intracortical networks ( Stanziano et al, 2021 ). It has also been demonstrated that brain structural and functional connections are damaged in the early stages of PD.…”