MRI directed bilateral stimulation of the subthalamic nucleus in patients with Parkinson's disease

Deep Brain Stimulation in the Treatment of Tardive Dyskinesia

Tardive dyskinesia (TD) is a phenomenon observed following the predominantly long-term use of dopamine receptor blockers (antipsychotics) widely used in psychiatry. TD is a group of involuntary, irregular hyperkinetic movements, mainly in the muscles of the face, eyelid, lips, tongue, and cheeks, and less frequently in the limbs, neck, pelvis, and trunk. In some patients, TD takes on an extremely severe form, massively disrupting functioning and, moreover, causing stigmatization and suffering. Deep brain stimulation (DBS), a method used, among others, in Parkinson's disease, is also an effective treatment for TD and often becomes a method of last resort, especially in severe, drug-resistant forms. The group of TD patients who have undergone DBS is still very limited. The procedure is relatively new in TD, so the available reliable clinical studies are few and consist mainly of case reports. Unilateral and bilateral stimulation of two sites has proven efficacy in TD treatment. Most authors describe stimulation of the globus pallidus internus (GPi); less frequent descriptions involve the subthalamic nucleus (STN). In the present paper, we provide up-to-date information on the stimulation of both mentioned brain areas. We also compare the efficacy of the two methods by comparing the two available studies that included the largest groups of patients. Although GPi stimulation is more frequently described in literature, our analysis indicates comparable results (reduction of involuntary movements) with STN DBS.

Present and future of subthalamotomy in the management of Parkinson´s disease: a systematic review

Introduction: The subthalamic nucleus (STN) is known to be involved in the pathophysiology of Parkinson´s disease and by reducing its abnormal activity, normal output of basal ganglia can be restored along with improvement in PD cardinal motor features. Deep brain stimulation of the STN is currently the main surgical procedure for PD with motor complications, but lesioning can be an alternative.Areas covered: Here, the authors systematically review the current evidence regarding subthalamotomy both with radiofrequency and, more recently, with focused ultrasound (FUS) for the treatment of PD.Expert opinion: Unilateral subthalamotomy for the treatment of PD motor features can be considered a viable option in asymmetric patients, particularly with FUS which allows a minimally invasive safe and effective ablation of the STN. Risk of inducing dyskinesia (i.e., hemichorea/ballism) may be strikingly reduced when lesions enlarge dorsally to impinge on pallidothalamic fibers.

Machine Learning's Application in Deep Brain Stimulation for Parkinson's Disease: A Review

Deep brain stimulation (DBS) is a surgical treatment for advanced Parkinson's disease (PD) that has undergone technological evolution that parallels an expansion in clinical phenotyping, neurophysiology, and neuroimaging of the disease state. Machine learning (ML) has been successfully used in a wide range of healthcare problems, including DBS. As computational power increases and more data become available, the application of ML in DBS is expected to grow. We review the literature of ML in DBS and discuss future opportunities for such applications. Specifically, we perform a comprehensive review of the literature from PubMed, the Institute for Scientific Information's Web of Science, Cochrane Database of Systematic Reviews, and Institute of Electrical and Electronics Engineers' (IEEE) Xplore Digital Library for ML applications in DBS. These studies are broadly placed in the following categories: (1) DBS candidate selection; (2) programming optimization; (3) surgical targeting; and (4) insights into DBS mechanisms. For each category, we provide and contextualize the current body of research and discuss potential future directions for the application of ML in DBS.

Assessment of Deep Brain Stimulation Implantation Surgery: A Practical Scale

BACKGROUND

Patients requiring deep brain stimulation (DBS) will undergo extensive preoperative and postoperative evaluations. However, the field lacks a robust scoring system for quantifying the outcomes of DBS surgery. We sought to determine whether a practical scale could assess the outcomes of DBS surgery and the clinical significance.

METHODS

A retrospective study was performed of the data from 150 patients who had undergone DBS from February 2017 to February 2019. An independence analysis and multivariate testing were used to identify significant independent predictors. The scale scores were computed by summing across the weighted predictors. The correlation between the scale scores and the intraoperative electrophysiological signal length (IESL), DBS power-on voltage, improvement rate in the unified Parkinson disease rating scale (UPDRS) and UPDRS part III (UPDRS III) scores was analyzed. Receiver operating characteristics curve analysis was used to quantify the discriminative capacity of the scale for predicting the prognosis.

RESULTS

Listwise exclusion of patients with incomplete data sets yielded a final sample of 130 patients with Parkinson disease who had undergone bilateral DBS. Multivariate testing identified 3 independent predictors of the prognosis, including electrode implantation duration, postoperative pneumocephalus volume, and electrode fusion error. The scale scores correlated significantly with the subthalamic nucleus DBS power-on voltage (r = -0.4063; P < 0.0001), globus pallidus internus DBS power-on voltage (r = -0.4723; P = 0.0014), and improvement rate of the UPDRS (r = 0.3490; P < 0.0001) and UPDRS III (r = 0.6623; P < 0.0001) scores. However, the scale scores did not significantly correlate with the subthalamic nucleus IESL and globus pallidus internus IESL. Receiver operating characteristics curve analysis revealed impressive outcome discrimination for the UPDRS and UPDRS III scores (UPDRS: area under the curve, 0.62, P = 0.0219; UPDRS III: area under the curve, 0.85, P < 0.0001).

CONCLUSIONS

We have introduced a novel practical scale capable of assessing the outcomes of DBS surgery and predicting the prognosis of patients after DBS surgery.

Deep Brain Stimulation Programming for Movement Disorders: Current Concepts and Evidence-Based Strategies

Deep brain stimulation (DBS) has become the treatment of choice for advanced stages of Parkinson's disease, medically intractable essential tremor, and complicated segmental and generalized dystonia. In addition to accurate electrode placement in the target area, effective programming of DBS devices is considered the most important factor for the individual outcome after DBS. Programming of the implanted pulse generator (IPG) is the only modifiable factor once DBS leads have been implanted and it becomes even more relevant in cases in which the electrodes are located at the border of the intended target structure and when side effects become challenging. At present, adjusting stimulation parameters depends to a large extent on personal experience. Based on a comprehensive literature search, we here summarize previous studies that examined the significance of distinct stimulation strategies for ameliorating disease signs and symptoms. We assess the effect of adjusting the stimulus amplitude (A), frequency (f), and pulse width (pw) on clinical symptoms and examine more recent techniques for modulating neuronal elements by electrical stimulation, such as interleaving (Medtronic®) or directional current steering (Boston Scientific®, Abbott®). We thus provide an evidence-based strategy for achieving the best clinical effect with different disorders and avoiding adverse effects in DBS of the subthalamic nucleus (STN), the ventro-intermedius nucleus (VIM), and the globus pallidus internus (GPi).

Efficacy of Dural Sealant System for Preventing Brain Shift and Improving Accuracy in Deep Brain Stimulation Surgery

The success of deep brain stimulation (DBS) depends heavily on surgical accuracy, and brain shift is recognized as a significant factor influencing accuracy. We investigated the factors associated with surgical accuracy and showed the effectiveness of a dural sealant system for preventing brain shift in 32 consecutive cases receiving DBS. Thirty-two patients receiving DBS between March 2014 and May 2015 were included in this study. We employed conventional burr hole techniques for the first 18 cases (Group I) and a dural sealant system (DuraSeal) for the subsequent 14 cases (Group II). We measured gaps between the actual positions of electrodes and the predetermined target positions. We then retrospectively evaluated the factors involved in surgical accuracy. The average gap between an electrode’s actual and target positions was 1.55 ± 0.83 mm in all cases. Postoperative subdural air volume e, the only factor associated with surgical accuracy (r = 0.536, P < 0.0001), was significantly smaller in Group II (Group I: 43.9 ± 27.7, Group II: 12.1 ± 12.5 ml, P = 0.0006). The average electrode position gap was also significantly smaller in Group II (Group I: 1.77 ± 0.91, Group II: 1.27 ± 0.59 mm, P = 0.035). Use of a dural sealant system could significantly reduce intracranial air volume, which should improve surgical accuracy.

Decreased Power but Preserved Bursting Features of Subthalamic Neuronal Signals in Advanced Parkinson's Patients under Controlled Desflurane Inhalation Anesthesia

Deep brain stimulation (DBS) surgery of the subthalamic nucleus (STN) under general anesthesia (GA) had been used in Parkinson's disease (PD) patients who are unable tolerate awake surgery. The effect of anesthetics on intraoperative microelectrode recording (MER) remains unclear. Understanding the effect of anesthetics on MER is important in performing STN DBS surgery with general anesthesia. In this study, we retrospectively performed qualitive and quantitative analysis of STN MER in PD patients received STN DBS with controlled desflurane anesthesia or LA and compared their clinical outcome. From January 2005 to March 2006, 19 consecutive PD patients received bilateral STN DBS surgery in Hualien Tzu-Chi hospital under either desflurane GA (n = 10) or LA (n = 9). We used spike analysis (frequency and modified burst index [MBI]) and the Hilbert transform to obtain signal power measurements for background and spikes, and compared the characterizations of intraoperative microelectrode signals between the two groups. Additionally, STN firing pattern characteristics were determined using a combined approach based on the autocorrelogram and power spectral analysis, which was employed to investigate differences in the oscillatory activities between the groups. Clinical outcomes were assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) before and after surgery. The results revealed burst firing was observed in both groups. The firing frequencies were greater in the LA group and MBI was comparable in both groups. Both the background and spikes were of significantly greater power in the LA group. The power spectra of the autocorrelograms were significantly higher in the GA group between 4 and 8 Hz. Clinical outcomes based on the UPDRS were comparable in both groups before and after DBS surgery. Under controlled light desflurane GA, burst features of the neuronal firing patterns are preserved in the STN, but power is reduced. Enhanced low-frequency (4–8 Hz) oscillations in the MERs for the GA group could be a characteristic signature of desflurane's effect on neurons in the STN.

Treatment of the ventral intermediate nucleus for medically refractory tremor: A cost-analysis of stereotactic radiosurgery versus deep brain stimulation

INTRODUCTION

Medically refractory tremor treatment has evolved over the past half-century from intraoperative thalamotomy to deep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (VIM). Within the past 15years, unilateral radiosurgical VIM thalamotomy has emerged as a comparably efficacious treatment modality.

METHODS

An extensive literature search of VIM DBS series was performed; the total cost of VIM DBS was calculated from hospitals geographically representative of the entire United States using current procedural terminology and work relative value unit (RVU) codes. The 2016 Medicare Ambulatory Payment Classification for stereotactic radiosurgery (SRS) was added to the work RVU to determine the total cost of VIM SRS for both Gamma Knife and linear accelerator SRS. Cost estimates assumed that VIM DBS was performed without intraoperative microelectrode recording.

RESULT

The mean unilateral VIM DBS cost was $17,932.41 per patient. For SRS VIM, the total costs for Gamma Knife ($10,811.77) and linear accelerator ($10,726.40) were 40% less expensive than for unilateral VIM DBS.

CONCLUSION

Radiosurgery of the VIM is 40% less expensive than unilateral VIM DBS in treatment of medically refractory tremor, regardless of radiosurgical modality. This finding argues for increased radiation oncology involvement in the management of medically refractory tremor patients.

The Insertion of Electrodes in the Brain for Electrophysiological Recording or Chronic Stimulation Is Not Associated With Any Biochemically Detectable Neuronal Injury

OBJECTIVE

The aim of this study was to evaluate the degree of brain tissue injury that could be potentially induced by the introduction of a) microrecording electrodes, b) macrostimulation electrodes, or c) chronic stimulation electrodes. We aimed to evaluate whether the use of five simultaneous microrecording tracks is associated with any brain injury not detectable by conventional imaging such as CT or MRI.

MATERIALS AND METHODS

The study included 61 patients who underwent surgery for implantation of 121 DBS leads. In all cases, five simultaneous tracts were utilized for microelectrode recordings. All patients underwent measurements of serum S-100b at specific time points as follows: a) prior to the operation, and b) intraoperatively at specific stages of the procedure: 1) after opening the burr hole, 2) after the insertion of microrecording electrodes, 3) during macrostimulation, 4) at the end of the operation, and 5) on the first postoperative day.

RESULTS

The levels of serum S-100B protein remained within the normal range during the entire period of investigation in all patients with the exception of two cases. In both patients, the procedure was complicated by intraparenchymal hemorrhage visible in neuro-imaging. The first patient developed a small intraparenchymal hemorrhage, visible on the postoperative MRI, with no neurological deficit. The second patient experienced a focal epileptic seizure after the insertion of the right DBS chronic lead and the postoperative CT scan revealed a right frontal lobe hemorrhage.

CONCLUSION

These results strongly indicate that the insertion of either multiple recording electrodes or the implantation of chronic electrodes in DBS does not increase the risk of brain hemorrhage or of other intracranial complications, and furthermore it does not cause any biochemically detectable brain tissue damage.

STN DBS for Parkinson's disease: results from a series of ten consecutive patients implanted under general anaesthesia with intraoperative use of 3D fluoroscopy to control lead placement

BACKGROUND

Deep brain stimulation (DBS) of the sub-thalamic nucleus (STN) is a recognised treatment for advanced Parkinson's disease (PD). We present our results of 10 consecutive patients implanted under general anaesthesia (GA) using intraoperative robotic three-dimensional (3D) fluoroscopy (Artis Zeego; Siemens, Erlangen, Germany).

METHOD

Ten patients (nine men, one woman) with a mean age of 57.6 (range, 41-67) years underwent surgery between October 2013 and January 2015. The mean duration of PD was 9.2 [1-10] year. The procedure was performed under GA: placement of the stereotactic frame, implantation of the electrodes (Lead 3389; Medtronic, Minnesota, MN, USA) and 3D intraoperative fluoroscopic control (Artis Zeego) with image fusion with the preoperative MRI scans. All patients were evaluated preoperatively and 6 months postoperatively.

RESULTS

The mean operative time was 240.1 (185-325) min. The mean Unified Parkinson's Disease Rating Scale (UPDRS) II OFF medication decreased from 23.9 preoperatively to 15.7 postoperatively. The mean OFF medication UPDRS III decreased from 41 to 11.6 and the UPDRS IV decreased from 10.6 to 7. The mean preoperative and postoperative L-Dopa doses were 1,178.5 and 696.5 mg, respectively. Two complications were recorded: one episode of transient confusion (24 h) and one internal pulse generator (IPG) infection.

CONCLUSIONS

With improvement in preoperative magnetic resonance imaging (MRI) and the ability to control the position of the leads intraoperatively using Artis Zeego, we now perform this procedure under GA. Our results are comparable to others reported. The significant decrease in the duration of surgery could be associated with a reduced rate of complications (infection, loss of patient collaboration). However, this observation needs to be confirmed.

Spatial distance between anatomically- and physiologically-identified targets in subthalamic nucleus deep brain stimulation in Parkinson's disease

BACKGROUND

Subthalamic nucleus (STN) stimulation is the treatment of choice for carefully chosen patients with idiopathic Parkinson's disease (PD) and refractory motor fluctuations. We evaluated the value of intraoperative electrophysiology during STN deep brain stimulation (DBS) procedures in refining the anatomically-defined target.

METHODS

We determined the spatial distance between the anatomical and physiological targets along x, y and z axes in 50 patients with PD who underwent bilateral subthalamic nucleus DBS surgery.

RESULTS

The mean spatial distance between anatomical and functional targets was 1.84 ± 0.88 mm and the least distances in different methods were 0.66 mm [standard error (SE): 0.07], 1.07 mm (SE: 0.08) and 1.01 mm (SE: 0.08) on x, y and z axes, respectively, for the combined method.

CONCLUSION

The most physiologically-accurate anatomical targeting was achieved via a combination of multiple independent methods. There was a statistically significant difference between the anatomical and functional targets in all methods (even the combined) on the y coordinate, emphasizing the need for intra-operative electrophysiological monitoring to refine the anatomico-radiologically-defined target.

Intraoperative MRI for optimizing electrode placement for deep brain stimulation of the subthalamic nucleus in Parkinson disease

OBJECT

The degree of clinical improvement achieved by deep brain stimulation (DBS) is largely dependent on the accuracy of lead placement. This study reports on the evaluation of intraoperative MRI (iMRI) for adjusting deviated electrodes to the accurate anatomical position during DBS surgery and acute intracranial changes.

METHODS

Two hundred and six DBS electrodes were implanted in the subthalamic nucleus (STN) in 110 patients with Parkinson disease. All patients underwent iMRI after implantation to define the accuracy of lead placement. Fifty-six DBS electrode positions in 35 patients deviated from the center of the STN, according to the result of the initial postplacement iMRI scans. Thus, we adjusted the electrode positions for placement in the center of the STN and verified this by means of second or third iMRI scans. Recording was performed in adjusted parameters in the x-, y-, and z-axes.

RESULTS

Fifty-six (27%) of 206 DBS electrodes were adjusted as guided by iMRI. Electrode position was adjusted on the basis of iMRI 62 times. The sum of target coordinate adjustment was −0.5 mm in the x-axis, −4 mm in the y-axis, and 15.5 mm in the z-axis; the total of distance adjustment was 74.5 mm in the x-axis, 88 mm in the y-axis, and 42.5 mm in the z-axis. After adjustment with the help of iMRI, all electrodes were located in the center of the STN. Intraoperative MRI revealed 2 intraparenchymal hemorrhages in 2 patients, brain shift in all patients, and leads penetrating the lateral ventricle in 3 patients.

CONCLUSIONS

The iMRI technique can guide surgeons as they adjust deviated electrodes to improve the accuracy of implanting the electrodes into the correct anatomical position. The iMRI technique can also immediately demonstrate acute changes such as hemorrhage and brain shift during DBS surgery.

Three-dimensional fluid-attenuated inversion recovery sequence for visualisation of subthalamic nucleus for deep brain stimulation in Parkinson's disease

INTRODUCTION

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an accepted treatment for advanced Parkinson's disease (PD). However, targeting the STN is difficult due to its relatively small size and variable location. The purpose of this study was to assess which of the following sequences obtained with the 3.0 T MR system can accurately delineate the STN: coronal 3D fluid-attenuated inversion recovery (FLAIR), 2D T2*-weighted fast-field echo (T2*-FFE) and 2D T2-weighted turbo spin-echo (TSE) sequences.

METHODS

We included 20 consecutive patients with PD who underwent 3.0 T MR for DBS targeting. 3D FLAIR, 2D T2*-FFE and T2-TSE images were obtained for all study patients. Image quality and demarcation of the STN were analysed using 4-point scales, and contrast ratio (CR) of the STN and normal white matter was calculated. The Friedman test was used to compare the three sequences.

RESULTS

In qualitative analysis, the 2D T2*-FFE image showed more artefacts than 3D FLAIR or 2D T2-TSE, but the difference did not reach statistical significance. 3D FLAIR images showed significantly superior demarcation of the STN compared with 2D T2*-FFE and T2-TSE images (P < 0.001, respectively). The CR of 3D FLAIR was significantly higher than that of 2D T2*-FFE or T2-TSE images in multiple comparison correction (P < 0.001), but there was no significant difference in the CR between 2D T2*-FFE and T2-TSE images.

CONCLUSION

Coronal 3D FLAIR images showed the most accurate demarcation of the STN for DBS targeting among coronal 3D FLAIR, 2D T2*-FFE and T2-TSE images.

Anesthesiologic regimen and intraoperative delirium in deep brain stimulation surgery for Parkinson's disease

BACKGROUND

In many centers the standard anesthesiological care for deep brain stimulation (DBS) surgery in Parkinson's disease patients is an asleep-awake-asleep procedure. However, sedative drugs and anesthetics can compromise ventilation and hemodynamic stability during the operation and some patients develop a delirious mental state after the initial asleep phase. Further, these drugs interfere with the patient's alertness and cooperativeness, the quality of microelectrode recordings, and the recognition of undesired stimulation effects. In this study, we correlated the incidence of intraoperative delirium with the amount of anesthetics used intraoperatively.

METHODS

The anesthesiologic approach is based on continuous presence and care, avoidance of negative suggestions, use of positive suggestions, and utilization of the patient's own resources. Clinical data from the operations were analyzed retrospectively, the occurrence of intraoperative delirium was extracted from patients' charts. The last 16 patients undergoing the standard conscious sedation procedure (group I) were compared to the first 22 (group II) psychologically-guided patients.

RESULTS

The median amount of propofol decreased from 146 mg (group I) to 0mg (group II), remifentanyl from 0.70 mg to 0.00 mg, respectively (P<0.001 for propofol and remifentanyl). Using the new procedure, 12 of 22 patients (55%) in group II required no anesthetics. Intraoperative delirium was significantly less frequent in group II (P=0.03).

CONCLUSIONS

The occurrence of intraoperative delirium correlates with the amount of intraoperative sedative and anesthetic drugs. Sedation and powerful analgesia are not prerequisites for patients' comfort during awake-DBS-surgery.

The effects of brain stimulation of subthalamic nucleus surgery on gait and balance performance in Parkinson disease. A pilot study

INTRODUCTION

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by tremor, rigidity and bradykinesia. Gait and postural difficulties supersede tremor, rigidity and bradykinesia as drivers of disease burden in patients with advanced PD. The aim of this study was to describe the effects of deep brain stimulation of the subthalamic nucleus on gait ability and balance performance in patients with PD.

MATERIAL AND METHODS

We studied 19 consecutive patients who underwent bilateral stimulation of the subthalamic nucleus. Patients were evaluated preoperatively and at the 5(th) day and 6(th) month after surgery. Timed Up and Go Test, 12 m Walking Test, Chair Stand Test and Berg Balance Scale (BBS) were used to assess mobility and balance performance. Unified Parkinson's Disease Rating Scale (UPDRS III) and Hoehn and Yahr Scale were also used.

RESULTS

All the patients' mobility ability and balance performance improved after surgery (p < 0.05). At the 6th month after surgery, the Timed Up and Go Test scores were decreased from 56.05 ±42.52 to 21.47 ±20.36, the 12 m Walking Test scores were decreased from 100.44 ±66.44 to 28.84 ±19.79, the Chair Stand Test scores were increased from 4.00 ±4.66 to 11.68 ±4.43 and the BBS score was increased from 12.84 ±6.89 to 38.89 ±8.79. UPDRS total scores were significantly improved 6 months after surgery (p < 0.001). UPDRS total scores were decreased from 98.26 ±37.69 to 39.36 ±18.85. The Hoehn and Yahr Scale score was significantly decreased after surgery (p < 0.05).

CONCLUSIONS

Surgical therapy is an effective treatment to improve gait ability and balance performance in Parkinson's patients.

Brain shift during bur hole–based procedures using interventional MRI

Object

Brain shift during minimally invasive, bur hole–based procedures such as deep brain stimulation (DBS) electrode implantation and stereotactic brain biopsy is not well characterized or understood. We examine shift in various regions of the brain during a novel paradigm of DBS electrode implantation using interventional imaging throughout the procedure with high-field interventional MRI.

Methods

Serial MR images were obtained and analyzed using a 1.5-T magnet prior to, during, and after the placement of DBS electrodes via frontal bur holes in 44 procedures. Three-dimensional coordinates in MR space of unique superficial and deep brain structures were recorded, and the magnitude, direction, and rate of shift were calculated. Measurements were recorded to the nearest 0.1 mm.

Results

Shift ranged from 0.0 to 10.1 mm throughout all structures in the brain. The greatest shift was seen in the frontal lobe, followed by the temporal and occipital lobes. Shift was also observed in deep structures such as the anterior and posterior commissures and basal ganglia; shift in the pallidum and subthalamic region ipsilateral to the bur hole averaged 0.6 mm, with 9% of patients having over 2 mm of shift in deep brain structures. Small amounts of shift were observed during all procedures; however, the initial degree of shift and its direction were unpredictable.

Conclusions

Brain shift is continual and unpredictable and can render traditional stereotactic targeting based on preoperative imaging inaccurate even in deep brain structures such as those used for DBS.

Patients' expectations in subthalamic nucleus deep brain stimulation surgery for Parkinson disease

OBJECTIVE

Subthalamic nucleus (STN) deep brain stimulation (DBS) is an established treatment for patients with advanced Parkinson disease. However, some patients feel less satisfied with the outcome of surgery. We sought to study the relationship between expectations, satisfaction, and outcome in STN DBS for Parkinson disease.

METHODS

Twenty-two consecutive patients undergoing STN DBS completed a modified 39-item Parkinson disease questionnaire (PDQ-39) preoperatively and 6 months postoperatively. A satisfaction questionnaire accompanied the postoperative questionnaire.

RESULTS

Patients expected a significant improvement from surgery preoperatively: preoperative score (median PDQ-39 summary score [interquartile range]): 37.0 (9.5), expected postoperative score: 13.0 (8.0), P < 0.001. Patients improved after surgery (preoperative score 39.0 [11.5], postoperative score 25.0 [14.3], P = 0.003), although there was a substantial disparity between the expected change (24.0 [15.0]) and actual change (14.0 [22.5]), P = 0.008. However, most patients felt that surgery fulfilled their expectations (mean score on a 0%-100% visual analog scale); (75.3 ± 17.8) and were satisfied (73.3 ± 25.3). Satisfaction correlated with fulfillment of expectations (r = 0.910, P < 0.001) but not with quantitative changes in PDQ-39 scores.

CONCLUSIONS

Addressing patients' expectations both preoperatively and postoperatively may play an important role in patient satisfaction, and therefore overall success, of STN DBS surgery for Parkinson disease.

Microelectrode targeting of the subthalamic nucleus for deep brain stimulation surgery

Though microelectrode recordings likely increase the risks and costs of DBS, incremental improvement in accuracy may translate into improved outcomes that justify these risks and costs. Clinically based, controlled studies to resolve these issues are problematic. Until such studies are reported, physicians must rely on indirect evidence. The spatial variability of physiologically defined optimal targets, as determined by microelectrode recording (MER), necessary for targeting the STN was calculated. Study of the effectiveness of a MER algorithm was based on the number of penetrations required. The radius of the volume with a 99% chance of including the physiologically defined optimal target, based on 108 cases, was 4.5 mm. This is larger than the estimated radius of the DBS effect, which is variously estimated to be 2 to 3.9 mm. The 99% confidence radius in the plane orthogonal to the lead was 3.2 mm. In 70% of cases, the imaging-based trajectories corresponded to the physiologically defined optimal target. For the remaining 30% of cases, 70% required only a single additional MER tract. The radii of the 99% confidence volume and area may be larger than the effective radius of stimulation. Surveying within those volumes or areas is therefore necessary to assure that at least 99% of cases will cover the physiologically defined target. The MER algorithm was robust in detecting the physiologically defined optimal target. However, there are significant caveats in interpretation of the data.

Pitfalls in precision stereotactic surgery

Precision is the ultimate aim of stereotactic technique. Demands on stereotactic precision reach a pinnacle in stereotactic functional neurosurgery. Pitfalls are best avoided by possessing in-depth knowledge of the techniques employed and the equipment used. The engineering principles of arc-centered stereotactic frames maximize surgical precision at the target, irrespective of the surgical trajectory, and provide the greatest degree of surgical precision in current clinical practice. Stereotactic magnetic resonance imaging (MRI) provides a method of visualizing intracranial structures and fiducial markers on the same image without introducing significant errors during an image fusion process. Although image distortion may potentially limit the utility of stereotactic MRI, near-complete distortion correction can be reliably achieved with modern machines. Precision is dependent on minimizing errors at every step of the stereotactic procedure. These steps are considered in turn and include frame application, image acquisition, image manipulation, surgical planning of target and trajectory, patient positioning and the surgical procedure itself. Audit is essential to monitor and improve performance in clinical practice. The level of stereotactic precision is best analyzed by routine postoperative stereotactic MRI. This allows the stereotactic and anatomical location of the intervention to be compared with the anatomy and coordinates of the intended target, avoiding significant image fusion errors.

Reducing hemorrhagic complications in functional neurosurgery: a large case series and systematic literature review

Object

Hemorrhagic complications carry by far the highest risk of devastating neurological outcome in functional neurosurgery. Literature published over the past 10 years suggests that hemorrhage, although relatively rare, remains a significant problem. Estimating the true incidence of and risk factors for hemorrhage in functional neurosurgery is a challenging issue.

Methods

The authors analyzed the hemorrhage rate in a consecutive series of 214 patients undergoing imageguided deep brain stimulation (DBS) lead placement without microelectrode recording (MER) and with routine postoperative MR imaging lead verification. They also conducted a systematic review of the literature on stereotactic ablative surgery and DBS over a 10-year period to determine the incidence and risk factors for hemorrhage as a complication of functional neurosurgery.

Results

The total incidence of hemorrhage in our series of image-guided DBS was 0.9%: asymptomatic in 0.5%, symptomatic in 0.5%, and causing permanent deficit in 0.0% of patients. Weighted means calculated from the literature review suggest that the overall incidence of hemorrhage in functional neurosurgery is 5.0%, with asymptomatic hemorrhage occurring in 1.9% of patients, symptomatic hemorrhage in 2.1% and hemorrhage resulting in permanent deficit or death in 1.1%. Hypertension and age were the most important patient-related factors associated with an increased risk of hemorrhage. Risk factors related to surgical technique included use of MER, number of MER penetrations, as well as sulcal or ventricular involvement by the trajectory. The incidence of hemorrhage in studies adopting an image-guided and image-verified approach without MER was significantly lower than that reported with other operative techniques (p < 0.001 for total number of hemorrhages, p < 0.001 for asymptomatic hemorrhage, p < 0.004 for symptomatic hemorrhage, and p = 0.001 for hemorrhage leading to permanent deficit; Fisher exact test).

Conclusions

Age and a history of hypertension are associated with an increased risk of hemorrhage in functional neurosurgery. Surgical factors that increase the risk of hemorrhage include the use of MER and sulcal or ventricular incursion. The meticulous use of neuroimaging—both in planning the trajectory and for target verification—can avoid all of these surgery-related risk factors and appears to carry a significantly lower risk of hemorrhage and associated permanent deficit.

Clinical safety of brain magnetic resonance imaging with implanted deep brain stimulation hardware: large case series and review of the literature

BACKGROUND

Over 75,000 patients have undergone deep brain stimulation (DBS) procedures worldwide. Magnetic resonance imaging (MRI) is an important clinical and research tool in analyzing electrode location, documenting postoperative complications, and investigating novel symptoms in DBS patients. Functional MRI may shed light on the mechanism of action of DBS. MRI safety in DBS patients is therefore an important consideration.

METHODS

We report our experience with MRI in patients with implanted DBS hardware and examine the literature for clinical reports on MRI safety with implanted DBS hardware.

RESULTS

A total of 262 MRI examinations were performed in 223 patients with intracranial DBS hardware, including 45 in patients with an implanted pulse generator. Only 1 temporary adverse event occurred related to patient agitation and movement during immediate postoperative MR imaging. Agitation resolved after a few hours, and an MRI obtained before implanted pulse generator implantation revealed edema around both electrodes. Over 4000 MRI examinations in patients with implanted DBS hardware have been reported in the literature. Only 4 led to adverse events, including 2 hardware failures, 1 temporary and 1 permanent neurological deficit. Adverse neurological events occurred in a unique set of circumstances where appropriate safety protocols were not followed. MRI guidelines provided by DBS hardware manufacturers are inconsistent and vary among devices.

CONCLUSIONS

The importance of MRI in modern medicine places pressure on industry to develop fully MRI-compatible DBS devices. Until then, the literature suggests that, when observing certain precautions, cranial MR images can be obtained with an extremely low risk in patients with implanted DBS hardware.

Magnetic resonance imaging techniques for visualization of the subthalamic nucleus

The authors reviewed 70 publications on MR imaging-based targeting techniques for identifying the subthalamic nucleus (STN) for deep brain stimulation in patients with Parkinson disease. Of these 70 publications, 33 presented quantitatively validated results. There is still no consensus on which targeting technique to use for surgery planning; methods vary greatly between centers. Some groups apply indirect methods involving anatomical landmarks, or atlases incorporating anatomical or functional data. Others perform direct visualization on MR imaging, using T2-weighted spin echo or inversion recovery protocols. The combined studies do not offer a straightforward conclusion on the best targeting protocol. Indirect methods are not patient specific, leading to varying results between cases. On the other hand, direct targeting on MR imaging suffers from lack of contrast within the subthalamic region, resulting in a poor delineation of the STN. These deficiencies result in a need for intraoperative adaptation of the original target based on test stimulation with or without microelectrode recording. It is expected that future advances in MR imaging technology will lead to improvements in direct targeting. The use of new MR imaging modalities such as diffusion MR imaging might even lead to the specific identification of the different functional parts of the STN, such as the dorsolateral sensorimotor part, the target for deep brain stimulation.

A cost analysis of intraoperative microelectrode recording during subthalamic stimulation for Parkinson's disease

Deep brain stimulation of the subthalamic nucleus is the standard of care for treating medically intractable Parkinson's disease. Although the adjunct of microelectrode recording improves the targeting accuracy of subthalamic nucleus deep brain stimulation in comparison with image guidance alone, there has been no investigation of the financial cost of intraoperative microelectrode recording. This study was performed to address this issue. A comprehensive literature search of large subthalamic nucleus deep brain stimulation series (minimum, 75 patients) was performed, revealing a mean operating room time of 223.83 minutes for unilateral and 279.79 minutes for simultaneous bilateral implantation. The baseline operating room time was derived from the published operating room time for subthalamic nucleus deep brain stimulation without microelectrode recording. The total cost (operating room, anesthesia, neurosurgery) was then calculated based on hospitals geographically representative of the entire United States. The average cost for subthalamic nucleus deep brain stimulation implantation with microelectrode recording per patient is $26,764.79 for unilateral, $33,481.43 for simultaneous bilateral, and $53,529.58 for staged bilateral. For unilateral implantation, the cost of microelectrode recording is $19,461.75, increasing the total cost by 267%. For simultaneous bilateral implantation, microelectrode recording costs $20,535.98, increasing the total cost by 159%. For staged bilateral implantation, microelectrode recording costs $38,923.49, increasing the total cost by 267%. Microelectrode recording more than doubles the cost of subthalamic nucleus deep brain stimulation for Parkinson's disease and more than triples the cost for unilateral and staged bilateral procedures. The cost burden of microelectrode recording to subthalamic nucleus deep brain stimulation requires the clinical efficacy of microelectrode recording to be proven in a prospective evidence-based manner in order to curtail the potential for excessive financial burden to the health care system.

An assessment of current brain targets for deep brain stimulation surgery with susceptibility-weighted imaging at 7 tesla

BACKGROUND

Deep brain stimulation (DBS) surgery is used for treating movement disorders, including Parkinson disease, essential tremor, and dystonia. Successful DBS surgery is critically dependent on precise placement of DBS electrodes into target structures. Frequently, DBS surgery relies on normalized atlas-derived diagrams that are superimposed on patient brain magnetic resonance imaging (MRI) scans, followed by microelectrode recording and macrostimulation to refine the ultimate electrode position. Microelectrode recording carries a risk of hemorrhage and requires active patient participation during surgery.

OBJECTIVE

To enhance anatomic imaging for DBS surgery using high-field MRI with the ultimate goal of improving the accuracy of anatomic target selection.

METHODS

Using a 7-T MRI scanner combined with an array of acquisition schemes using multiple image contrasts, we obtained high-resolution images of human deep nuclei in healthy subjects.

RESULTS

Superior image resolution and contrast obtained at 7 T in vivo using susceptibility-weighted imaging dramatically improved anatomic delineation of DBS targets and allowed the identification of internal architecture within these targets. A patient-specific, 3-dimensional model of each target area was generated on the basis of the acquired images.

CONCLUSION

Technical developments in MRI at 7 T have yielded improved anatomic resolution of deep brain structures, thereby holding the promise of improving anatomic-based targeting for DBS surgery. Future study is needed to validate this technique in improving the accuracy of targeting in DBS surgery.

Minimizing brain shift in stereotactic functional neurosurgery

BACKGROUND

Stereotactic functional neurosurgical interventions depend on precise anatomic targeting before lesioning or deep brain stimulation (DBS) electrode placement.

OBJECTIVE

To examine the degree of subcortical brain shift observed when adopting an image-guided approach to stereotactic functional neurosurgery.

METHODS

Coordinates for the anterior and posterior commissural points (AC and PC) were recorded on thin-slice stereotactic magnetic resonance imaging (MRI) scans performed before and immediately after DBS electrode implantation in 136 procedures. The changes in length of AC-PC and in stereotactic coordinates for AC and PC were calculated for each intervention. In patients with Parkinson disease undergoing bilateral subthalamic nucleus (STN) DBS with at least 6 months of follow-up, pre- and postoperative scores of the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS-III) were reviewed.

RESULTS

Mean (SD) change in AC-PC length (DeltaAC-PC) was 0.6 (0.4) mm. There was no statistically significant difference in DeltaAC-PC between groups when examining anatomic target subgroups (P =.95), age subgroups (P = .63), sex (P = .59), and unilateral versus bilateral implantation (P =.15). The mean (SD) vector changes for the commissural points were: -0.1 (0.3) mm in X, -0.4 (0.6) mm in Y, and -0.1 (0.7) mm in Z for the AC; and -0.1 (0.3) mm in X, -0.2 (0.7) mm in Y, and 0.0 (0.7) mm in Z for the PC. There was a negligible correlation between the magnitude of brain shift and percentage improvement in UPDRS-III off-medication in patients undergoing STN DBS for PD (R <0.01).

CONCLUSION

Brain shift has long been considered an issue in stereotactic targeting during DBS procedures. However, with the image-guided approach and surgical technique used in this study, subcortical brain shift was extremely limited and did not appear to adversely affect clinical outcome.

A new MRI approach for accurately implanting microelectrodes into deep brain structures of the rhesus monkey (Macaca mulatta)

The accurate implantation of microelectrodes is a significant difficulty facing many neurophysiologists. This paper reports on a new method used to promote the precise positioning of electrode implantation through magnetic resonance imaging (MRI), allowing both the relevant brain structure and the MRI-visible external markers anchored on the skull (in this case rigid glass tubes with a 0.5mm internal diameter) to be displayed. By referencing these markers, the coordinates of the brain target were calculated. Using this novel approach, recording electrodes were successfully implanted into the superior colliculus (SC) of rhesus monkeys, with an error <1mm, and its neuronal discharge signals were obtained. This new method allows neurophysiologists to precisely target the small deep brain structures of monkeys and study their electrophysiological characteristics in detail.

Deep brain stimulation compared with bariatric surgery for the treatment of morbid obesity: a decision analysis study

Object

Roux-en-Y gastric bypass is the gold standard treatment for morbid obesity, although failure rates may be high, particularly in patients with a BMI > 50 kg/m2. With improved understanding of the neuropsychiatric basis of obesity, deep brain stimulation (DBS) offers a less invasive and reversible alternative to available surgical treatments. In this decision analysis, the authors determined the success rate at which DBS would be equivalent to the two most common bariatric surgeries.

Methods

Medline searches were performed for studies of laparoscopic adjustable gastric banding (LAGB), laparoscopic Roux-en-Y gastric bypass (LRYGB), and DBS for movement disorders. Bariatric surgery was considered successful if postoperative excess weight loss exceeded 45% at 1-year follow-up. Using complication and success rates from the literature, the authors constructed a decision analysis model for treatment by LAGB, LRYGB, DBS, or no surgical treatment. A sensitivity analysis in which major parameters were systematically varied within their 95% CIs was used.

Results

Fifteen studies involving 3489 and 3306 cases of LAGB and LRYGB, respectively, and 45 studies involving 2937 cases treated with DBS were included. The operative successes were 0.30 (95% CI 0.247–0.358) for LAGB and 0.968 (95% CI 0.967–0.969) for LRYGB. Sensitivity analysis revealed utility of surgical complications in LRYGB, probability of surgical complications in DBS, and success rate of DBS as having the greatest influence on outcomes. At no values did LAGB result in superior outcomes compared with other treatments.

Conclusions

Deep brain stimulation must achieve a success rate of 83% to be equivalent to bariatric surgery. This high-threshold success rate is probably due to the reported success rate of LRYGB, despite its higher complication rate (33.4%) compared with DBS (19.4%). The results support further research into the role of DBS for the treatment of obesity.

Therapy for dyskinesias in Parkinson’s disease patients

Dyskinesia hampers the quality of life for most Parkinson’s disease patients following several years of therapy. However, the severity of L-Dopa-induced dyskinesia (LID) varies between patients, being quite tolerable in late-onset patients. Understanding the pathogenesis of LID has contributed to the development of a set of therapeutic strategies, including the choice, in early stages, of the least pulsatile regimen of dopamine-receptor activation. In cases where LIDs are already disabling, there is only a limited number of options: the optimization of ongoing DOPA-centered treatment, the utilization of glutamate antagonists and the exploration of the benefits of antipsychotic agents. More radical solutions are provided by deep brain stimulation in the subthalamic nucleus (or internal pallidus). This approach has proved efficacious in reducing LID, largely because it allows a reduction in dopaminergic daily doses. Stereotactic neurosurgery has fuelled several lines of investigation regarding the crosstalk between the basal ganglia and motor cortex. Here, we will present interesting evidence highlighting the potential for repetitive transcranial stimulation in reducing the occurrence of LID. The future may disclose important new avenues for the treatment of LIDs, given the current development of promising agents that might target different facets of dyskinesia, such as the impairment of striatal plasticity and non-Dopaminergic contributors such as adenosine, nitric oxide and the nucleotide cascade.

Subthalamic deep brain stimulation after anesthetic inhalation in Parkinson disease: a preliminary study

OBJECT

The authors of this preliminary study investigated the outcome and feasibility of intraoperative microelectrode recording (MER) in patients with Parkinson disease (PD) undergoing deep brain stimulation of the subthalamic nucleus (STN) after anesthetic inhalation.

METHODS

The authors conducted a retrospective analysis of 10 patients with PD who received a desflurane anesthetic during bilateral STN electrode implantation. The MERs were obtained as an intraoperative guide for final electrode implantation and the data were analyzed offline. The functional target coordinates of the electrodes were compared preoperatively with estimated target coordinates.

RESULTS

Outcomes were evaluated using the Unified Parkinson's Disease Rating Scale 6 months after surgery. The mean improvement in total and motor Unified Parkinson's Disease Rating Scale scores was 54.27 +/- 17.96% and 48.85 +/- 16.97%, respectively. The mean STN neuronal firing rate was 29.7 +/- 14.6 Hz. Typical neuronal firing patterns of the STN and substantia pars nigra reticulata were observed in each patient during surgery. Comparing the functional target coordinates, the z axis coordinates were noted to be significantly different between the pre- and postoperative coordinates.

CONCLUSIONS

The authors found that MER can be adequately performed while the patient receives a desflurane anesthetic, and the results can serve as a guide for STN electrode implantation. This may be a good alternative surgical method in patients with PD who are unable to tolerate deep brain stimulation surgery with local anesthesia.

Globus pallidus stimulation improves both motor and nonmotor aspects of quality of life in advanced Parkinson's disease

Our purpose was to measure the change in quality of life (QoL) following deep brain stimulation of the globus pallidus interna (GPi-DBS) in advanced Parkinson 's disease (PD), and identifies any associations with changes in motor features of the disease. Eleven patients (age range 54-69 years, 2 women) underwent GPi-DBS (4 unilateral, 7 bilateral). Outcome measures included assessment of PD-specific QoL (mean 8 months postsurgery) using the PDQ-39 questionnaire, and standard motor assessments. Off-period UPDRS III motor scores fell by (43 +/- 8)% (mean +/- SEM). Dyskinesia severity was reduced on the abnormal involuntary movement scale by (80 +/- 3)% and UPDRS IVa by (58 +/- 8)%. QoL as assessed by the PDQ39SI improved by (30 +/- 5)%, with significant improvements in mobility, activities of daily living, bodily discomfort, emotional wellbeing, communication, and cognitions subscales. Bilateral and unilateral groups demonstrated equivalent PDQ39SI improvement. QoL improvement was highly correlated with dyskinesia reduction but not reduction in UPDRS score or age at surgery. GPi-DBS markedly improves QoL in advanced PD. The impacts are broad and improve QoL domains not directly affected by the motor symptoms of the disease. Reduced dyskinesia plays a major role in the improvement of QoL in GPi-DBS treated patients.

L-DOPA-INDUCED DYSKINESIA AND STEREOTACTIC SURGERY FOR PARKINSON'S DISEASE

OBJECTIVE

To assess the impact of different surgical targets and techniques, such as ablation and deep brain stimulation, to treat patients with L-dopa-induced dyskinesia (LID), a major therapeutic complication of Parkinson's disease.

METHODS

This review analyzes the effects of early surgical procedures to treat hyperkinesia and the current methods and targets used to combat LID in Parkinson's disease, which are mainly thalamotomy, pallidotomy, and deep brain stimulation of the globus pallidus internus and the subthalamic nucleus.

RESULTS

Available information indicates that surgery of the globus pallidus internus and thalamus (the pallidal receiving area) and of the subthalamic nucleus has a pronounced antidyskinetic effect. This effect is associated with a concomitant improvement in the parkinsonian (“off”-medication) state. Although it is more profound with pallidal and subthalamic surgery, such an effect can also be observed to some extent with thalamic surgery. The latter is attributable to the fact that surgery of the ventralis intermedius is primarily effective for treating tremor. An integral pallidothalamic pathway is needed for dyskinesia to be expressed. Thus, LID is less frequent after subthalamotomy or deep brain stimulation of the subthalamic nucleus through a functional effect mediated by the physiological normalization of the motor system and by an indirect effect associated with a reduction in the daily dose of L-dopa.

CONCLUSION

Surgery is the only treatment available for Parkinson's disease that can predictably improve both the parkinsonian motor syndrome and LID. The exact mechanisms involved in these effects are not well understood. Pallidal and thalamic surgery affecting pallidal relays reduce LID frequency by disrupting the pallidothalamic circuit, probably eliminating the neuronal activity associated with dyskinesia. Alternatively, the antidyskinetic effect of subthalamic nucleus surgery may in part be attributable to a reduction in the L-dopa dose as well as to the stabilization of the basal ganglia circuits after the surgical procedure.

Safety of Anterior Commissure-Posterior Commissure-Based Target Calculation of the Subthalamic Nucleus in Functional Stereotactic Procedures

The subthalamic nucleus (STN) is a common target of functional stereotactic surgeries. High-field magnetic resonance imaging and sophisticated computer systems provide precise identification of the nucleus location in stereotactic space. However, it is unclear what additional benefit these techniques provide over traditional anterior commissure-posterior commissure (AC-PC)-based standard atlas coordinate calculation methods based on the AC-PC plane. The accuracy of AC-PC-based standard atlas coordinate targeting of the STN using 1.5-tesla images compared with direct visualization of the nucleus on fused 3-tesla images was examined. A retrospective examination of stereotactic images from 20 patients (40 STN targets) who underwent deep brain stimulation for Parkinson's disease was undertaken at our institution. Two methods were used to identify the STN stereotactic coordinates: (1) an AC-PC-based standard atlas coordinate calculation obtained by a series of measurements using 1.5-tesla images, and (2) a computer workstation calculation using fused 3-tesla and 1.5-tesla images. Euclidean distances between two sets of coordinates of the same target were calculated in three dimensions. Differences along individual X, Y, and Z axes were analyzed to determine whether there was a greater difference in one direction than in another. Data from the right and left sides were pooled to increase the sample power. The anterior-posterior and lateral frame tilts were compared to X, Y, and Z differences to find a correlation using linear regression. Statistical analyses were performed. The accuracy of the position of the STN calculated with state-of-the-art imaging systems was not significantly better than that obtained using traditional AC-PC-based standard atlas coordinate calculation if the frame was aligned with the AC-PC plane. The mean difference was 0.45 mm, 0.72 mm, and 0.98 mm in the X, Y, and Z axes, respectively. Therefore, it is possible to effectively target the STN for stereotactic treatment of Parkinson's disease, for instance in a situation where expensive advanced technology is unavailable.

Brain mapping in stereotactic surgery: a brief overview from the probabilistic targeting to the patient-based anatomic mapping

In this article, we briefly review the concept of brain mapping in stereotactic surgery taking into account recent advances in stereotactic imaging. The gold standard continues to rely on probabilistic and indirect targeting, relative to a stereotactic reference, i.e., mostly the anterior (AC) and the posterior (PC) commissures. The theoretical position of a target defined on an atlas is transposed into the stereotactic space of a patient's brain; final positioning depends on electrophysiological analysis. The method is also used to analyze final electrode or lesion position for a patient or group of patients, by projection on an atlas. Limitations are precision of definition of the AC-PC line, probabilistic location and reliability of the electrophysiological guidance. Advances in MR imaging, as from 1.5-T machines, make stereotactic references no longer mandatory and allow an anatomic mapping based on an individual patient's brain. Direct targeting is enabled by high-quality images, an advanced anatomic knowledge and dedicated surgical software. Labeling associated with manual segmentation can help for the position analysis along non-conventional, interpolated planes. Analysis of final electrode or lesion position, for a patient or group of patients, could benefit from the concept of membership, the attribution of a weighted membership degree to a contact or a structure according to its level of involvement. In the future, more powerful MRI machines, diffusion tensor imaging, tractography and computational modeling will further the understanding of anatomy and deep brain stimulation effects.

Effect of medical and surgical interventions on health-related quality of life in Parkinson's disease

Motor-related parameters are the standard outcome parameters for treatment interventions. Nonetheless, subjective appraisals about the consequences of treatment on health-related quality of life (HRQoL) are meanwhile established and may uncover important aspects of interventions. We have reviewed the literature with a defined search strategy and collected 61 clinical trials, which have used HRQoL as a planned outcome parameter. The articles were rated similarly as for the Task Force report of the Movement Disorder Society on interventions for Parkinson's disease (PD), but the relevant outcome parameter was HRQoL. We found that unilateral pallidotomy, deep brain stimulation of the subthalamic nucleus, and rasagiline are efficacious to improve the HRQoL of PD patients. For many other interventions, the efficacy to improve HRQoL in the PD setting cannot be considered to be proven so far. HRQoL should be part of future trial designs and more research is necessary to understand the determinants of QoL in PD.

COMPARISON OF TWO TECHNIQUES TO POSTOPERATIVELY LOCALIZE THE ELECTRODE CONTACTS USED FOR SUBTHALAMIC NUCLEUS STIMULATION

OBJECTIVE

Cerebral ventriculography (Vg) and magnetic resonance imaging (MRI) scanning are routine procedures to determine the implanted electrode placement into the subthalamic nucleus (STN) and are used in several centers that provide deep brain stimulation for Parkinson's disease patients. However, because of image distortion, MRI scan accuracy in determining electrode placement is still matter of debate. The objectives of this study were to verify the expected localization of the electrode contacts within the STN and to compare the stereotactic coordinates of these contacts determined intraoperatively by Vg with those calculated postoperatively by MRI scans. To our knowledge, this is the first study attempting to compare the "gold standard" of stereotactic accuracy (Vg) with the anatomic resolution provided by MRI scans.

METHODS

Images from 18 patients with Parkinson's disease who underwent bilateral operation were used in this study. Among the 36 chronically stimulated contacts, 28 contacts (78%) were localized in the dorsolateral part of the STN. The remaining eight contacts (22%) were located more dorsally in the zona incerta, close to the upper border of the STN.

RESULTS

Significant differences were found between Vg and MRI scans regarding the mediolateral x coordinate of the contacts for both left and right electrodes and regarding the right-sided anteroposterior y coordinate. No statistical difference was found for the left-sided y coordinate and the dorsoventral z coordinate for both sides.

CONCLUSION

If we assume that Vg is an imaging gold standard, our results suggest that postoperative MRI scanning may induce a slight image translation compared with Vg. However, MRI scans allowed localization of most of the contacts within the STN.

Deep brain stimulation in neurologic disorders

Deep brain stimulation (DBS) is an effective surgical therapy for well-selected patients with medically intractable Parkinson's disease (PD) and essential tremor (ET). The purpose of this review is to describe the success of DBS in these two disorders and its promising application in dystonia, Tourette Syndrome (TS) and epilepsy. In the last 10 years, numerous short- and intermediate-term outcome studies have demonstrated significant relief to patients with PD and ET. A few long-term follow-up studies have also reported sustained benefits. When successful, DBS greatly reduces most of parkinsonian motor symptoms and drug-induced dyskinesia, and it frequently improves patients' ability to perform activities of daily living with less encumbrance from motor fluctuations. Quality of life is enhanced and many patients are able to significantly reduce the amount of antiparkinsonian medications required to still get good pharmacological benefit. Overall, adverse effects associated with DBS tend to be transient, although device-related and other postoperative complications do occur. DBS should be considered the surgical procedure of choice for patients who meet strict criteria with medically intractable PD, ET and selected cases of dystonia.

Deep brain stimulation for Parkinson's disease

Indications for the treatment of Parkinson's disease (PD) with deep brain stimulation (DBS) are severe, therapy refractory tremor and complications of long-term levodopa uptake. Since its first application DBS has become a standard therapy for these patients. Theoretically, the ventrolateral part of the internal pallidum (GPI) or the subthalamic nucleus (STN) are suitable targets in order to treat all cardinal symptoms of patients in an advanced stage of PD stereotactically. Although clinical efficacy of both GPI or STN stimulation is obviously comparable, it has become widely accepted to prefer STN over GPI DBS. If PD-associated, medically intractable tremor is the most disabling symptom, stimulation of the ventrolateral motor thalamus can be an alternative. Anatomical targets for DBS are small and located in critical brain areas. Furthermore, this type of surgery is highly elective. As a consequence, high resolution multiplanar imaging and adequate treatment planning software are indispensable prerequisites for DBS surgery. Currently, commercially available impulse generators deliver a permanent high frequency periodic pulse train stimulation that interacts rather unspecifically with the firing pattern of both normal and pathological neurons. Prospectively, the development of more specific stimulation paradigms may help to improve the efficacy of this treatment modality.