Background Although thalamotomy could dramatically improve both parkinsonian resting tremor and essential tremor （ET）, the mechanisms are obviously different. This study aimed to investigate the neuronal activities in the ventrolateral thalamus of Parkinson＇s disease （PD） and ET. Methods Thirty-six patients （PD： 20, ET： 16） were studied. Microelectrode recordings in the ventral oral posterior （Vop）and the ventral intermediate nucleus （Vim） of thalamus was performed on these patients who underwent thalamotomy.Electromyography （EMG） was recorded simultaneously on the contralateral limbs to surgery. Single unit analysis and the interspike intervals （ISIs） were measured for each neuronal type. ISI histogram and auto-correlograms were constructed to estimate the pattern of neuronal firing. Mann-Whitney test and Kruskal-Wallis （K-W） test were used to compare the mean spontaneous firing rate （MSFR） of neurons of PD and ET patients. Results Three hundred and twenty-three neurons were obtained from 20 PD trajectories, including 151 （46.7%） tremor related neuronal activity, 74 neurons （22.9%） with tonic firing, and 98 （30.4%） neurons with irregular discharge. One hundred and eighty-seven neurons were identified from 16 ET trajectories including 46 （24.6%） tremor-related neuronal activity, 77 （41.2%） neurons with tonic firing, and 64 neurons （34.2%） with irregular discharge. The analysis of MSFR of neurons with tonic firing was 26.7 （3.4-68.3） Hz （n=74） and that of neurons with irregular discharge （n=98） was 13.9 （3.0-58.1） Hz in PD; whereas MSFR of neurons with tonic firing （n=77） was 48.8 （19.0-135.5） Hz and that of neurons with irregular discharge （n=64） was 26.3 （8.7-84.7） Hz in ET. There were significant differences in the MSFR of two types of neuron for PD and ET （K-W test, both P〈0.05）. Significant differences in the MSFR of neuron were also obtained from Vop and Vim of PD and ET （16.3 Hz vs. 34.8 Hz, 28.0 Hz vs.
CHEN Hai ZHUANG Ping MIAO Su-hua YUAN Gao ZHANG Yu-qing LI Jian-yu LI Yong-jie
Background It has been proposed that parkinsonian motor signs result from hyperactivity in the output nucleus of the basal ganglia, which suppress the motor thalamus and cortical areas. This study aimed to explore the neuronal activity in the globus pallidus internus （GPi） and the ventrolateral thalamic nuclear group （ventral oral posterior/ventral intermediate, Vop/Vim） in patients with Parkinson＇s disease （PD）. Methods Twenty patients with PD who underwent neurosurgery were studied. Microelectrode recording was performed in the GPi （n=10） and the Vop/Vim （n=10） intraoperatively. Electromyography （EMG） contralateral to the surgery was simultaneously performed. Single unit analysis was carried out. The interspike intervals （ISI） and coefficient of variation （CV） of ISI were calculated. Histograms of ISI were constructed. A unified Parkinson＇s disease rating scale （UPDRS） was used to assess the clinical outcome of surgery. Results Three hundred and sixty-three neurons were obtained from 20 trajectories. Of 175 GPi neurons, there were 15.4% with tremor frequency, 69.2% with tonic firing, and 15.4% with irregular discharge. Of 188 thalamic neurons, there were 46.8% with tremor frequency, 22.9% with tonic firing, and 30.3% with irregular discharge. The numbers of three patterns of neuron in GPi and Vop/Vim were significantly different （P 〈0.001）. ISI analysis revealed that mean firing rate of the three patterns of GPi neurons was （80.9±63.9） Hz （n=78）, which was higher than similar neurons with 62.9 Hz in a normal primate. For the Vop/Vim group, ISI revealed that mean firing rate of the three patterns of neurons （n=95） was （23.2±17.1） Hz which was lower than similar neurons with 30 Hz in the motor thalamus of normal primates. UPDRS indicated that the clinical outcome of pallidotomy was （64.3±29.5）%, （83.4±19.1）% and （63.4±36.3）%, and clinical outcome of thalamotomy was （92.2±12.9）%, （68.0±25.2）% and （44.3±7.2）% for tremor, r
CHEN Hai ZHUANG Ping ZHANG Yu-qing LI Jian-yu LI Yong-jie
