The Clinical Significance Of Oscillatory Activity In Globus Pallidus Internus In Primary Dystonia

BackgroundDystonia is a kind of movement disorders caused by active and antagonistic muscle incoordination or excessive contractions,resulting in twisting,repetitive movements or abnormal postures.Primary dystonia ranks third in the incidence of movement disorders after essential tremor and Parkinson's disease.Primary dystonia has a wide spectrum of causes and manifestations that can lead to irreversible fixation of skeletal deformities and disability,which can even lead to a sudden death.Deep brain stimulation(DBS)is the therapeutic use of chronic electrical stimulation in the deep brain nucleus to achieve the goal of treating or alleviating the nerve system diseases.The pathogenesis of dystonia is not clear,and the DBS electrode can record the information of local field potential nerve activities in deep brain,which provides a unique method for exploring the pathogenesis of dystonia.ObjectivesIn order to explore the neural oscillation of dystonia and neurobiological marker of dystonia,we designed this study to explore the oscillation from the perspective of deep brain activity.Thus to achieve a more accurate stimulation model and improve the efficacy of DBS.We recorded EMG signals of the affected muscle surface to differentiate the patients' different states.At the same time,the DBS electrode was used to record oscillatory activity of local field potentials in globus pallidus internus(GPi).The oscillatory activity over theta(?,4~8 Hz),alpha(?,8~13 Hz),low beta(l?,13~23 Hz),high beta(h?,23 ~ 38)and gamma(?,55 ~ 90Hz)bands in childhood-onset and adult-onset dystonia was to analyze.The result should to promote the reveal neurobiological marker of dystonia and further study of dystonia's characteristics and mechanism of DBS treatment,which provides a theoretical basis for studying the pathogenesis of dystonia and achieving closed-loop DBS.MethodsRetrospective inclusion of eight patients with childhood-onset dystonia and ten patients with adult-onset dystonia bilateral implantation of DBS electrode targeting the GPi in Radcliffe Infirmary,Oxford.The patients were scored before and after DBS.After DBS,the local field potentials and muscle EMG signals under resting and involuntary movement conditions were recorded and power spectral density analysis and statistical tests were performed.Thus further analysis of local field potential characteristics in dystonia was performed.Results1.Normalized power spectral density of GPi local field potentials was significantly enhanced in theta and alpha frequency band in dystonia patients.2.In childhood-onset group,the state of involuntary movement had higher power over the 4~10Hz frequency band than the resting state,while it had lower power than the resting state over the 10~25Hz and 27~38Hz frequency bands.There was a significance over 14~16.5Hz and 20~22Hz(P?0.05).3.In adult-onset group,involuntary movement had higher power over the 4~6Hz than the resting state,while it had lower power than the resting state over the 6.5~20Hz.There was a significance over 9~11Hz and 13~4.5Hz(P?0.05).4.In voluntary movement,childhood-onset dystonia patients had higher beta band(29~37Hz)and lower beta band(13.5~16Hz)compared with adult-onset dystonia(P?0.05).5.In resting,childhood-onset dystonia patients had lower power over low frequency bands and higher power over 30~38Hz compared with adult-onset dystonia.(P?0.05)6.In normalized involuntary movement state,childhood-onset dystonia had higher ?-band power and high ?-band power than adult-onset dystonia(P?0.05).7.In resting-state,adult-onset dystonic symptom severity significantly correlated with the ?-band power.In involuntary movement state,childhood-onset normalized dystonic symptom severity significantly correlated with the high ?-band power.Childhood-onset clinical improvement negatively correlated with low ?-band power.ConclusionThis result provided that dystonia was characterized by low-frequency(4 ~ 10Hz).And the result suggested that childhood-onset dystonia had higher high ? power than adult-onset dystonia,while adult-onset dystonia had higher power over ? low frequency band.LFPs correlated with DBS clinical improvement.It suggested that different types of dystonia exhibit different characteristics of oscillation activities and has different biomarker during closed-loop DBS.Our finding suggested that beta oscillation may be a useful biomarker of child-onset dystonia and theta and alpha oscillation may be a useful biomarker of adult-onset dystonia,which may require different stimulation strategies for close-loop DBS treatment.