Objective: To ascertain whether the implementation of an extensive battery of neurophysiological tests may contribute to ameliorating the long-lasting success rate and of Magnetic resonance-guided high-intensity focused ultrasound (MRgFUS) unilateral therapy, focusing VIM, in Parkinson’s disease (PD) patients.

Background: MRgFUS represents a renewed approach capable to provide, by unilateral VIM lesions, an opportunity to handle the contralateral motor spectrum in PD patients manifesting intolerance to elevated drug titration or drug adverse events. Moreover, pioneering protocols are showing that MRgFUS may induce “focal temporary BBB opening as a therapeutic tool for neuro-restorative therapies” (Gasca-Salac C et al., 2021). It is matter of debate whether lesioning VIM might be proposed even in earlier disease stages and/or bilaterally. To this aim, it appears crucial to gather information on the integrity of the thalamo-cortical pathways before and after lesioning.

Method: Despite COVID-19, whose impact was deleterious on the enrollment pace, the team directed by Prof Marini (in L’Aquila) has completed, asides from routine work, a cohort of 11 PD patients specifically obeying to the dedicated protocol. The latter includes, asides from a comprehensive neuropsychological examination and all the routine motor and non-motor scoring of an academic center, a battery of Neurophysiological tests, such as bilateral sensory evoked potentials (SEP), Neurovegetative tests, EEG and Blink reflex (any test is repeated at 1 mo to weigh the transient edema-linked response, hence at 3 and 6 mo).

Results: So far, the limited number of patients is discouraging any conclusion. SEP parameters (i.e. N30), in presence of tremor, may reveal inconsistent. However, a more complex time-consuming protocol, which compares OFF-THER versus ON-levodopa SEP (before and after FUS) is underway. Moreover, an homemade algorithm (developed in Matlab, utilizing commercial software fieldtrip toolbox) is allowing to cut electrical artifacts and promises to monitor basic and spectral EEG during the post-lesioning follow-up.

Conclusion: Complex procedure, as here described, are founded on a multi-disciplinary team, comprising clinical neurophysiologists, blind raters and paramedics. Hopefully, the optimization of this or similar protocols might concur to a better patient’s selection and a validation of experimental trials.

References: Gasca-Salac C et alNat Commun. 2021 Feb 3;12(1):779. doi: 10.1038/s41467-021-21022-9. Blood-brain barrier opening with focused ultrasound in Parkinson’s disease dementia

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