Trigeminal somatosensory-evoked potential: A neurophysiological tool to monitor the extent of lesion of ganglion radiofrequency thermocoagulation in idiopathic trigeminal neuralgia: A case-control study.

To reflect the extent of thermolesion of ganglion by testing the change of trigeminal somatosensory-evoked potential (TSEP) before and after ganglion radiofrequency thermocoagulation surgery (GRT), and evaluate long-term clinic effect by follow-up visiting of 1 year.Patients with idiopathic trigeminal neuralgia (TN) in the second division were enrolled between October 2014 and October 2015. They were treated with computed tomography-guided GRT and a follow-up visiting of 1 year. Bilateral TSEP measurements were performed 1 day before and 2 days after the GRT surgery. The latency and peak-to-peak amplitude of W2 and W3 were recorded.Immediate postprocedure pain relief (grades I-III) was 100% and 92.5% 1 year later. Facial numbness rate of grades III and IV was 70%, 40%, and 12.5%, respectively, at immediate, 2 days, and 1 year after GRT. No sever complications happened. The latency of W2 and W3 of patients who had no pain no numbness after 1 year of GRT was 1.74 ±â€Š0.24 and 3.84 ±â€Š0.66 ms, respectively, of TN side, and 1.71 ±â€Š0.39 and 3.63 ±â€Š0.85 ms of the healthy side before GRT. The amplitude of W2 and W3 was 1.13 ±â€Š0.50 and 1.99 ±â€Š1.09 uv, respectively, of TN side and 1.24 ±â€Š0.40 and 1.89 ±â€Š0.81 uv of the healthy side before GRT. There was no statistical difference of the latency and amplitude between 2 sides of W2 and W3 before surgery (P > 0.05). The latency of W2 and W3 delayed and the amplitude reduced especially in TN side after surgery comparing before (P < 0.001). And, comparisons of the latency and amplitude of W2 and W3 between TN side and the healthy side after surgery showed the latency of W2 and W3 delayed (W2: P = 0.02; W3: P = 0.01) and the amplitude of W2 reduced (P = 0.003), but the amplitude of W3 had no statistical difference (P = 0.22). The mean delayed latency and 95% confident interval of W2 and W3 were 0.22 ±â€Š0.35 (0.1-0.34) ms and 0.35 ±â€Š0.64 (0.14-0.57) ms, respectively. The mean decreased amplitude and 95% confident interval of W2 and W3 were 22 ±â€Š24 (14-30)% and 23 ±â€Š32 (12-34)%, respectively.GRT can make the latency delay and the amplitude decrease of TSEP. And the latency and amplitude of W2 and W3 can be considered reliable and safe reference for monitoring the extent of thermolesion.

Neuronal firing in the ventrolateral thalamus of patients with Parkinson's disease differs from that with essential tremor.

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. 49.9 Hz) (K-W test, both P < 0.05), respectively. CONCLUSION: In consistent with recent findings, the decreased MSFR of neurons observed in the Vop is likely to be involved in PD whereas the increased MSFR of neurons seen in the Vim may be a cause of ET.

[Neuronal activity of ventrolateral thalamus in patients with essential tremor].

OBJECTIVE: To investigate the neuronal activity in the ventrolateral thalamus in relation to essential tremor (ET). METHODS: Microelectrode recording in the ventral oral posterior (Vop) and ventral intermediate nucleus (Vim) of thalamus was performed on 10 patients with ET and 10 patients with Parkinson's disease (PD) who underwent thalamotomy for tremor during operation. Electromyography (EMG) was carried out on the contralateral limbs simultaneously. Single unit analysis was performed to measure the interspike interval (ISI) and histogram was constructed to evaluate the pattern of neuronal activity. Student t-test was employed to compare the mean spontaneous firing rate (MSFR) and ISI of neuronal firing in Vop/Vim between the ET patients and PD patients. and correlation test. RESULTS: Two hundred and sixty-six neurons were identified from 20 trajectories, 38.0% being neurons with tremor-related neuronal activity Tremor cells, 31.9% of neurons related to tonic firing, and 30.1% of neurons related to irregular discharge. 131 of these thalamic neurons, were obtained from 10 ET patients. 38 of these 131 neurons (29.0%) were related to tremor-related neuronal activity, 54 (41.2%) neurons were related to tonic firing with a mean spontaneous firing rate (MSFR) of (55+/-21) Hz, and 39 neurons (29.8%) were related to irregular discharge with a MSFR of (32+/-17) Hz. In the meantime, 135 neurons were obtained from 10 PD patients. Of these 135 neurons 63 (46.7%) were related to tremor, 31 neurons (23.0%) related to tonic firing with a MSFR of (39+/-15) Hz, and 41 (30.3%) were related to irregular discharge with a MSFR of (21+/-8) Hz. The MSFR levels of pooled neurons in Vop/Vim with tonic firing and irregular discharge of the ET patients were significantly higher than those of the PD patents (t=2.74 and 2.99, both P<0.05). And the MSFR levels in Vop and Vim of the ET patients were significantly higher than those of the PD patients (both P<0.05). CONCLUSION: Vim receives the projection from cerebellum. The increase of neuronal firing frequency observed in Vim suggests that the pathophysiology of ET may be correlated with excessive activity of cerebellum.