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Summary: The rate model of basal ganglia function predicts that muscle activity in dystonia is due to disinhibition of thalamus resulting from decreased inhibitory input from pallidum. We seek to test this hypothesis in children with dyskinetic cerebral palsy undergoing evaluation for deep brain stimulation (DBS) to analyze movement-related activity in different brain regions. The results revealed prominent beta-band frequency peaks in the globus pallidus interna (GPi), ventral oralis anterior/posterior (VoaVop) subnuclei of the thalamus, and subthalamic nucleus (STN) during movement but not at rest. Connectivity analysis indicated stronger coupling between STN-VoaVop and STN-GPi compared to GPi-STN. These findings contradict the hypothesis of decreased thalamic inhibition in dystonia, suggesting that abnormal patterns of inhibition and disinhibition, rather than reduced GPi activity, contribute to the disorder. Additionally, the study implies that correcting abnormalities in GPi function may explain the effectiveness of DBS targeting the STN and GPi in treating dystonia.

Objectives: To investigate the use of SPECT/CT imaging in patients who had postoperative neck pain after cervical fusion procedures and to devise an appropriate treatment strategy for this patient population. Methods: 23 patients (8 male, 15 female) with postoperative neck pain were included in this study. Average age of patient was 60 ± 2.11 years. All patients underwent prior cervical fusion surgery and after at least 1 year of postoperative observation continue to suffer unremitting and debilitating neck pain with or without non-dermatomal arm pain. All patients underwent postoperative imaging studies including MRI and CT scan. If no clear origin of pain was detected, SPECT/CT imaging was obtained. Average number of years from prior surgery to SPECT/CT scanning was 5.5 ± 1.1 years. Preoperative VAS score averaged 8.39 ± 0.29 for this patient cohort. Results: Of the 23 patients who underwent SPECT/CT due to inadequacy of diagnosis based on anatomic studies, 15 patients underwent cervical spine surgery. Eight patients were referred to pain management based on SPECT/CT imaging and clinical symptomatology. 6 surgeries were anterior and 9 were posterior. Last follow-up evaluation after revision surgery was at 12 months. Average VAS scores declined after revision surgery to 4.74 ± 0.5. Conclusion: Identification of postoperative spinal surgery pain is necessary to design the appropriate intervention. Patients seen in our practice suffering from failed cervical spinal surgery syndrome and offered SPECT/CT imaging leading to the identification of a focus of surgical treatment experienced significant reduction in VAS scores after revision surgery.

The contribution of different brain regions to movement abnormalities in children with dystonia is unknown. Three awake subjects undergoing depth electrode implantation for assessments of potential deep brain recording targets performed a rhythmic figure-8 drawing task. Two subjects had dystonia, one was undergoing testing for treatment of Tourette Syndrome and had neither dystonia nor abnormal movements during testing. Movement-related signals were evaluated by determining the magnitude of task-related frequency components. Brain signals were recorded in globus pallidus internus (GPi), the ventral oralis anterior/posterior (VoaVop) and the ventral intermediate (Vim) nuclei of the thalamus. In comparison to the subject without dystonia, both children with dystonia showed increased task-related activity in GPi and Vim. This finding is consistent with a role of both basal ganglia and cerebellar outputs in the pathogenesis of dystonia. Our results further suggest that frequency analysis of brain recordings during cyclic movements may be a useful tool for analysis of the presence of movement-related signals in various brain regions.

Background: There is significant evidence for cognitive decline following deep brain stimulation (DBS). Current stimulation paradigms utilize gamma frequency stimulation for optimal motor benefits; however, little has been done to optimize stimulation parameters for cognition. Recent evidence implicates subthalamic nucleus (STN) theta oscillations in executive function, and theta oscillations are well-known to relate to episodic memory, suggesting that theta frequency stimulation could potentially improve cognition in Parkinson’s disease (PD). Objective: To evaluate the acute effects of theta frequency bilateral STN stimulation on executive function in PD versus gamma frequency and off, as well as investigate the differential effects on episodic versus nonepisodic verbal fluency. Methods: Twelve patients (all males, mean age 60.8) with bilateral STN DBS for PD underwent a double-blinded, randomized cognitive testing during stimulation at (1) 130–135 Hz (gamma), (2) 10 Hz (theta) and (3) off. Executive functions and processing speed were evaluated using verbal fluency tasks (letter, episodic category, nonepisodic category, and category switching), color-word interference task, and random number generation task. Performance at each stimulation frequency was compared within subjects. Results: Theta frequency significantly improved episodic category fluency compared to gamma, but not compared to off. There were no significant differences between stimulation frequencies in other tests. Conclusion: In this pilot trial, our results corroborate the role of theta oscillations in episodic retrieval, although it is unclear whether this reflects direct modulation of the medial temporal lobe and whether similar effects can be found with more canonical memory paradigms. Further work is necessary to corroborate our findings and investigate the possibility of interleaving theta and gamma frequency stimulation for concomitant motor and cognitive effects.

Deep brain stimulation (DBS) for secondary (acquired, combined) dystonia does not reach the high degree of efficacy achieved in primary (genetic, isolated) dystonia. We hypothesize that this may be due to variability in the underlying injury, so that different children may require placement of electrodes in different regions of basal ganglia and thalamus. We describe a new targeting procedure in which temporary depth electrodes are placed at multiple possible targets in basal ganglia and thalamus, and probing for efficacy is performed using test stimulation and recording while children remain for one week in an inpatient Neuromodulation Monitoring Unit (NMU). Nine Children with severe secondary dystonia underwent the NMU targeting procedure. In all cases, 4 electrodes were implanted. We compared the results to 6 children who had previously had 4 electrodes implanted using standard intraoperative microelectrode targeting techniques. Results showed a significant benefit, with 80% of children with NMU targeting achieving greater than 5-point improvement on the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS), compared with 50% of children using intraoperative targeting. NMU targeting improved BFMDRS by an average of 17.1 whereas intraoperative targeting improved by an average of 10.3. These preliminary results support the use of test stimulation and recording in a Neuromodulation Monitoring Unit (NMU) as a new technique with the potential to improve outcomes following DBS in children with secondary (acquired) dystonia. A larger sample size will be needed to confirm these results.