Category: Choreas (Non-Huntington's Disease)
Objective: To investigate the physiological mechanisms of neurons in the basal ganglia motor circuit underlying choreic movements.
Background: Synchronized burst discharges and the low discharge rates of the internal globus pallidus (GPi) have been estimated to be major alterations of neurons which drive choreic movements; however, little is known about the physiological mechanisms underlying burst discharges.
Method: Five patients with choreic movements (striatal lacunar infarction, dentatorubral-pallidoluysian atrophy, diabetic hemichorea-hemiballism, Huntington’s disease, tardive dyskinesia) were treated with either pallidotomy or GPi DBS. During intra-operative mapping, we recorded spontaneous neuronal activity from single neurons in the GPi and the external globus pallidus (GPe). Neuronal discharge rates and patterns were analyzed and compared with those collected from patients with Parkinson’s disease (PD).
Results: Choreic movements were abolished after pallidal surgery in all patients. We analyzed 49 GPi and 44 GPe neurons from the chorea patients, along with 183 GPi and 176 GPe neurons from 28 patients with PD. The discharge frequencies of the GPi (mean±SD, 50.0±31.7Hz) and GPe (32.6±21.4Hz) in choreic disorders were significantly lower (p<0.005) than those of the GPi (86.6±31.7Hz) and GPe (60.3±26.3Hz) in PD, and the discharge patterns of the GPi were more bursty in choreic disorders. The correlations between the percentage of spikes in bursts and the discharge rate in GPi showed a different distribution in PD vs chorea; however, analysis of co-variance revealed that the discharge rate is the sole determinant for differentiating chorea from PD.
Conclusion: Pallidal surgery was highly effective for the treatment of chorea, suggesting a common neural mechanism underlying chorea with various etiologies. Compared to PD, lower rate and higher burstiness in discharges of pallidal neurons were characteristic of chorea. The discharge burstiness was determined by the discharge rate through chorea and PD. The discharge rate may be the major determinant for transition from non-choreic state to choreic state, and choreic movement may occur when a certain threshold of the discharge rate is exceeded.
To cite this abstract in AMA style:T. Hashimoto, T. Goto, K. Yoshida, L. Johnson, J. Vitek. Discharge rate dependency of bursting of pallidal neurons underlying choreic movements [abstract]. Mov Disord. 2020; 35 (suppl 1). https://www.mdsabstracts.org/abstract/discharge-rate-dependency-of-bursting-of-pallidal-neurons-underlying-choreic-movements/. Accessed December 5, 2023.
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MDS Abstracts - https://www.mdsabstracts.org/abstract/discharge-rate-dependency-of-bursting-of-pallidal-neurons-underlying-choreic-movements/