Jianyu Li

Stimulation-Induced Dyskinesia in the Early Stage after Subthalamic Deep Brain Stimulation

Background: Deep brain stimulation of the subthalamic nucleus (STN-DBS) is a very effective surgical procedure for Parkinson’s disease. It significantly improves cardinal parkinsonian symptoms as well as levodopa-induced dyskinesia. Interestingly, STN-DBS can also provoke or exacerbate dyskinesia. In the present study, stimulation-induced dyskinesia (SID) was found in the early stage (less than 1 month) after STN-DBS in some patients. The aim was to discuss this interesting phenomenon. Methods: Side effects of each electrode contact were tested at 9.0 ± 3.8 days (range, 3–16 days) after STN-DBS, and 40 contacts of 16 electrodes (15 patients) were found to induce dyskinesia. The location of these contacts was calculated in the postoperative magnetic resonance imaging, and was compared to the positions of active contacts and dorsal margin of the subthalamic nucleus (STN). Results: Most SID at the threshold manifested as repetitively dystonic involuntary movement, and the most common site was the contralateral lower limb (27/40, 67.5%). The mean location of the 40 contacts with SID was 11.9 ± 0.9 mm lateral, 0.4 ± 1.7 mm anterior, and 1.8 ± 1.9 mm inferior to the midcommissural point. The point was located inferior to the dorsal margin of the STN (p = 0.01, t tests), and no significant difference was found between this point and the location of active contacts (p > 0.05, t tests). Conclusion: In the early stage after STN-DBS, dyskinesia is easily induced by high-frequency stimulation of the upper portion of the STN, which may predict the best site for chronic stimulation.

Subthalamic deep brain stimulation for Parkinson's disease: correlation between locations of oscillatory activity and optimal site of stimulation.

Subthalamic nucleus deep brain stimulation (STN DBS) is an effective surgical treatment for Parkinsons disease (PD). Recent studies demonstrated that pathological oscillations are seen largely within the dorsolateral portion of the STN, which is the same location that predicts optimal therapeutic benefit with DBS; however, the precise nature of the relationship between these two phenomena remains unclear. The purpose of this study was to explore localization of oscillatory activity in relation to the optimal contacts of DBS which results in the best motor improvement. We studied 23 PD patients who underwent electrode implantation into the STN for motor symptoms. Microelectrode recordings were taken from the STN during surgery and neuronal activity was analyzed offline. Spectral characteristics were calculated. Clinical outcomes were evaluated pre- and post-STN DBS implantation using the Unified Parkinsons Disease Rating Scale (UPDRS III). The position of optimal electrode contacts was assessed by postoperative magnetic resonance imaging (MRI) and was compared to the location of oscillatory activity within the STN as well as its dorsal margin (where STN neuronal activity was first detected). Of the total 188 neurons obtained, 51 (27.1%) neurons showed significant oscillatory activity. Of those, 47 (92.2%) were localized in the dorsal portion of the STN. Furthermore, there was no significant difference between the averaged coordinates of the position of 40 optimal contacts and the coordinates of the dorsal margin of the STN. The data indicate that the positions of the best contacts correlate with the locations of the oscillatory neurons supporting the prediction that stimulation of the dorsolateral oscillatory region leads to an effective clinical outcome for STN DBS surgery.

Characteristics of subthalamic oscillatory activity in parkinsonian akinetic-rigid type and mixed type.

Objective: To explore neurons with β oscillatory activity in the subthalamic nucleus (STN) in relation to parkinsonian motor signs. Methods: We studied 27 patients with Parkinsons disease (PD) who underwent electrode implantation for STN deep brain stimulation. Thirteen patients were classified as akinetic-rigid (AR) type and 14 patients were classified as mixed type. Microelectrode recording was performed in the STN and the electromyogram (EMG) was simultaneously recorded. Single-unit and spectral analyses were performed. Coherence analysis was used to explore the relationship between β oscillatory activity and EMG activity. Unpaired t-test and chi-square were used to compare the differences between the two PD types. Results: Of 130 neurons identified in the AR type, 43.8% were β oscillatory neurons (mean: 21.3 ± 6.87 Hz, βFB) and 0.8% were tremor frequency oscillatory neurons (4–6 Hz, TFB). Of 102 neurons identified in the mixed type, 19.6% were β oscillatory neurons and 26.5% were TFB oscillatory neurons. There was a significant difference in proportion of neurons with βFB and TFB oscillations between the two PD groups. Additionally, 12% of the βFB oscillatory neurons were coherent with limb EMG of the AR type, but there was no coherence in the mixed type. Most oscillatory neurons were localized in the dorsal portion of the STN. Conclusion: The STN βFB oscillatory neurons correlate with parkinsonian rigidity-bradykinesia. The high proportion of βFB oscillatory neurons found in the AR type of PD is indirect evidence for their importance in generating motor impairment.

Deep Brain Stimulation of the Globus Pallidus Internus in Patients with Intractable Tourette Syndrome: A 1-year Follow-up Study.

Background:Deep brain stimulation (DBS) has been a promising treatment for patients with refractory Tourette syndrome (TS) for more than a decade. Despite successful DBS treatment of TS in more than 100 patients worldwide, studies with a large patient sample and long-term follow-up assessments are still scarce. Accordingly, we investigated the clinical efficacy and safety of globus pallidus internus (GPi) DBS in the treatment of intractable TS in 24 patients with a 1-year follow-up assessment. Methods:Bilateral/unilateral GPi-DBS was performed in 24 patients with TS. We evaluated symptoms of tics and obsessive-compulsive disorder (OCD) through the Yale Global Tic Severity Scale (YGTSS) and Yale-Brown Obsessive-compulsive Scale (Y-BOCS). We used the Wechsler Adult Intelligence Scale-Revised in China (WAIS-RC) to evaluate the safety of the treatment. We conducted follow-up assessments of all patients for at least 12 months (12–99 months). Results:Symptoms of tics and OCD were significantly relieved at a 12-month follow-up assessment. The mean YGTSS score was 74.04 ± 11.52, 49.83 ± 10.91, 32.58 ± 7.97, and 31.21 ± 8.87 at baseline, 3, 6, and 12 months, respectively. The mean YGTSS scores obtained at the follow-up assessments were significantly different from the baseline (P < 0.05). The improvement in motor tics was superior to that in phonic tics. The mean Y-BOCS scores were 21.61 ± 4.97, 18 ± 4.58, 14.39 ± 3.99, and 13.78 ± 4.56 at baseline, 3, 6, and 12 months, respectively (P < 0.05). We observed a remarkable improvement in psychiatric comorbidities, such as OCD and attention-deficit hyperactivity disorder, after the procedure. WAIS-RC scores were comparable before and after the operation. There were no severe postoperative complications. Conclusion:GPi-DBS appears to comprehensively alleviate tic symptoms and psychiatric comorbidities in patients with TS, thus significantly improving patients’ quality of life.

Neuronal firing patterns in the subthalamic nucleus in patients with akinetic-rigid-type Parkinson’s disease

Recent studies suggest that Parkinsons disease (PD) is associated with pathological synchronous oscillatory activity in the basal ganglia. Beta frequency band (β-FB) oscillations likely contribute to bradykinesia and rigidity in PD; however, details of the relationship between these two phenomena remain unclear. To explore β-FB oscillatory activity in relation to motor signs of bradykinesia and rigidity, we studied 17 patients with akinetic-rigid type PD who had electrodes implanted into the subthalamic nucleus (STN) for deep brain stimulation therapy. Microelectrode recordings were obtained in the STN during surgery and neuronal activity was analyzed offline. The spectral characteristics were calculated. Of 155 neurons from 30 STN, 56 (36.1%) had β-FB oscillatory activity. Neurons with oscillatory activity were localized in the dorsal two-thirds of the STN. These data indicate that β-FB oscillatory activity may be of particular importance in the generation of motor deficits in PD.