Abnormal patterns of theta frequency oscillations during the temporal evolution of freezing of gait in Parkinson’s disease

• Electrophysiology can offer novel insights into the spatiotemporal dynamics underlying episodes of freezing of gait.
• Episodes of freezing of gait display a unique signature of abnormal oscillatory activity in theta band power spectral density.
• The results provide a potential means for therapeutic prediction and alleviation of freezing episodes in susceptible patients.

ObjectiveWe sought to characterize the electrophysiological signature of Freezing of gait in Parkinson’s disease.MethodsWe examined 24 patients with idiopathic Parkinson’s disease and significant freezing of gait as they performed a series of timed up-and-go tasks in their ‘off’ state while electroencephalographic data was collected from four scalp leads. Fast Fourier Transformation was utilized to explore the power spectral density between periods of normal walking and periods of freezing, as well as during the transition between the two states. In addition, Cross Spectrum and Cross Frequency analyses were used to explore the role of impaired temporal and spatial connectivity.ResultsWhen compared to walking, episodes of freezing were associated with a significant increase in theta band power within the central and frontal leads. The transition from normal walking to freezing of gait was also associated with increased theta frequency coupling between the central and frontal leads, along with an increase in cross-frequency coupling in the central lead.ConclusionsEpisodes of freezing of gait in Parkinson’s disease are associated with abnormal oscillatory activity in the brain.SignificanceThese results provide novel insights into the pattern of spatiotemporal dynamics underlying freezing of gait and may provide a potential means for therapeutic prediction and alleviation of freezing episodes in susceptible patients.