Objective: To examined whether multifractal properties of pallidal activity correlate with dystonic symptom severity across patients.

Background: The internal segment of globus pallidus (GPi) is the most common target for surgical treatment of dystonia. Contemporary hypotheses suggest the role of altered pallidal neuronal activity for pathophysiology of dystonic movements. The main focus aims to study pathological synchronization and its association with dystonic symptoms. However, there is another framework to study brain dynamics using fractal geometry. In this study we assume, that decreased complexity, as measured with multifractal analysis, may be a marker of motor control impairment in dystonia.

Method: We recorded local field potentials (LFP) from the globus pallidus in 19 patients undergoing lead implantation for deep brain stimulation (DBS). Patients with cervical, segmental and generalized dystonias (BFMDRS=22.55+-15.33; TWSTRS=21.52+-7.09) were included in this study. Multifractal spectrum was estimated based on wavelet leaders.

Results: We found that dystonic BFMDRS symptom severity significantly correlated with the width of the multifractal spectrum (-0.5817, p=0.008). We also observed that with an increase of severity score, the shape of the spectrum becomes more asymmetric, which means a change in the sensitivity of the signal to the local fluctuations with high and low magnitudes. No significant correlations were found for the TWSTRS.

Conclusion: Multifractal analysis could be used to improve our understanding of movement disorders and enhance placement precision of deep brain stimulators needed for dystonia treatment.
This study was supported by Russian Foundation for Basic Research (20-015-00438) and Russian Science Foundation (18-15-00009)

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MDS Abstracts - https://www.mdsabstracts.org/abstract/multifractal-spectrum-width-of-pallidal-activity-correlates-with-dystonic-severity/