Deep brain stimulation of the subthalamic nucleus: clinical effectiveness and safety

Long term follow-up in advanced Parkinson's disease treated with DBS of the subthalamic nucleus

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting both motor and non-motor systems. Deep brain stimulation of the subthalamic nucleus (STN-DBS) has been an approved treatment for PD for more than 30 years, but few data are available regarding its long-term effectiveness.

OBJECTIVE

The aim of this study is to evaluate patients' outcome, both from a motor and non-motor perspective, 9 to 14 years after DBS implantation. We have investigated patients with advanced PD and treated with STN-DBS, in relation to key clinical features of PD.

METHODS

18 patients were assessed both retrospectively and prospectively. They underwent motor examination, neuropsychological evaluation and questionnaires on the quality of life, preoperatively, as well as 1, 9 and 14 years after DBS surgery. All patients were implanted with STN-DBS at San Raffaele Hospital between 2004 and 2010.

RESULTS

13 males and five females underwent DBS implantation with a mean PD duration of 11 years. Stimulation significantly improved med-off/stim-on condition up to 9 years, compared to the preoperative off state, and med-on/stim-on condition at 14 years, compared to med-on/stim-off state. Long term improvement specifically involved tremor and rigidity, as well as dopaminergic daily dose. At the same time, STN-DBS had no long-lasting effect on axial symptoms and cognitive functions.

CONCLUSIONS

STN-DBS remains an effective therapy for advanced PD, also over the years. Despite the underlying progression of the disease, this treatment extends the period in which the overall quality of life is still acceptable.

Long-term Results for Single Channel-Guided Deep Brain Stimulation Used to Treat Parkinson's Disease

Introduction

The optimal method for targeting the subthalamic nucleus (STN) and positioning the deep brain stimulation (DBS) electrode is still controversial. In this study, single channel-guided stimulations were used in order to determine the most proper way to target the STN. Findings were synthesised for use in clinical situations. This paper presents the long-term results of DBS applied using single-channel guidance.

Methods

We retrospectively reviewed 15 patients who had undergone STN-DBS to treat Parkinson's disease in-between 2010 and 2017. All patients were examined preoperatively, and they were routinely followed-up 2-7 years postoperatively.

Results

The use of single-channel guidance resulted in better outcomes of motor complaints of Parkinson's patients. Moreover, a significantly greater improvement in Unified Parkinson's Disease Rating Scale Score (UPDRS) was achieved in either ON or OFF periods of patients.

Conclusion

Single channel-guided STN-DBS is a safe procedure and it results in improved motor outcomes in advanced Parkinson's Disease.

Initial Results of Bilateral Subthalamic Nucleus Stimulation for Parkinson Disease in a Newly Established Center in a Developing Country: Shiraz, Southern Iran

OBJECTIVE

To report the establishment of a new center for deep brain stimulation (DBS) as a surgical treatment for Parkinson disease and the surgical outcomes, from 2014 to 2017 in Shiraz, Southern Iran.

METHODS

A new treatment program was established in Shiraz through a multidisciplinary team in 2014. Thirty-four patients underwent implantation of subthalamic nucleus (STN) electrodes during the last 3 years. Twenty-five patients fulfilled the minimum 6-month follow-up criteria. The baseline Unified Parkinson Disease Rating Scale (UPDRS) was assessed 1 month before surgery in both off-medication and on-medication states by a movement disorder neurologist. To evaluate the outcomes, subscores of the UPDRS were assessed in all patients before surgery and at least 6 months after the operation.

RESULTS

All 25 patients had advanced Parkinson disease categorized as stage 3 or 4 using the Hoehn and Yahr scale. STN DBS resulted in a dramatic improvement in motor function of most patients. A reduction in dopaminergic medication dosage (average 60% reduction) was observed. The mean improvement was 40% in UPDRS II and 67% in UPDRS III. No surgical or hardware complications were observed. Stimulation-related adverse effects, including increased falling and worsening of speech, occurred in a few patients after surgery. Most of the patients experienced weight gain after surgery.

CONCLUSIONS

Bilateral STN DBS is a satisfactory and safe treatment for carefully selected patients with advanced Parkinson disease. According to the results, the procedure can be performed safely and with comparable results in developing countries around the world.

Neuropsychological performance changes following subthalamic versus pallidal deep brain stimulation in Parkinson's disease: a systematic review and metaanalysis

BACKGROUND

Studies comparing subthalamus (STN) and globus pallidus internus (GPi) deep brain stimulation (DBS) for the management of Parkinson's disease in terms of neuropsychological performance are scarce and heterogeneous. Therefore, we performed a systematic review and metaanalysis to compare neuropsychological outcomes following STN DBS versus GPi DBS.

METHODS

A computer literature search of PubMed, the Web of Science, and Cochrane Central was conducted. Records were screened for eligible studies, and data were extracted and synthesized using Review Manager (v. 5.3 for Windows).

RESULTS

Seven studies were included in the qualitative synthesis. Of them, four randomized controlled trials (n=345 patients) were pooled in the metaanalysis models. The standardized mean difference (SMD) of change in the Stroop color-naming test favored the GPi DBS group (SMD=-0.31, p=0.009). However, other neuropsychological outcomes did not favor either of the two groups (Stroop word-reading: SMD=-0.21, p=0.08; the Wechsler Adult Intelligence Scale (WAIS) digits forward: SMD=0.08, p=0.47; Trail Making Test Part A: SMD=-0.05, p=0.65; WAIS-R digit symbol: SMD=-0.16, p=0.29; Trail Making Test Part B: SMD=-0.14, p=0.23; Stroop color-word interference: SMD=-0.16, p=0.18; phonemic verbal fluency: bilateral DBS SMD=-0.04, p=0.73, and unilateral DBS SMD=-0.05, p=0.83; semantic verbal fluency: bilateral DBS SMD=-0.09, p=0.37, and unilateral DBS SMD=-0.29, p=0.22; Boston Naming Test: SMD=-0.11, p=0.33; Beck Depression Inventory: bilateral DBS SMD=0.15, p=0.31, and unilateral DBS SMD=0.36, p=0.11).

CONCLUSIONS

There was no statistically significant difference in most of the neuropsychological outcomes. The present evidence does not favor any of the targets in terms of neuropsychological performance.

The Dominant-Subthalamic Nucleus Phenomenon in Bilateral Deep Brain Stimulation for Parkinson's Disease: Evidence from a Gait Analysis Study

Background

It has been suggested that parkinsonian [Parkinson’s disease (PD)] patients might have a “dominant” (DOM) subthalamic nucleus (STN), whose unilateral electrical stimulation [deep brain stimulation (DBS)] could lead to an improvement in PD symptoms similar to bilateral STN-DBS.

Objectives

Since disability in PD patients is often related to gait problems, in this study, we wanted to investigate in a group of patients bilaterally implanted for STN-DBS: (1) if it was possible to identify a subgroup of subjects with a dominant STN; (2) in the case, if the unilateral stimulation of the dominant STN was capable to improve gait abnormalities, as assessed by instrumented multifactorial gait analysis, similarly to what observed with bilateral stimulation.

Methods

We studied 10 PD patients with bilateral STN-DBS. A clinical evaluation and a kinematic, kinetic, and electromyographic (EMG) analysis of overground walking were performed—off medication—in four conditions: without stimulation, with bilateral stimulation, with unilateral right or left STN-DBS. Through a hierarchical agglomerative cluster analysis based on motor Unified Parkinson’s Disease Rating Scale scores, it was possible to separate patients into two groups, based on the presence (six patients, DOM group) or absence (four patients, NDOM group) of a dominant STN.

Results

In the DOM group, both bilateral and unilateral stimulation of the dominant STN significantly increased gait speed, stride length, range of motion of lower limb joints, and peaks of moment and power at the ankle joint; moreover, the EMG activation pattern of distal leg muscles was improved. The unilateral stimulation of the non-dominant STN did not produce any significant effect. In the NDOM group, only bilateral stimulation determined a significant improvement of gait parameters.

Conclusion

In the DOM group, the effect of unilateral stimulation of the dominant STN determined an improvement of gait parameters similar to bilateral stimulation. The pre-surgical identification of these patients, if possible, could allow to reduce the surgical risks and side effects of DBS adopting a unilateral approach.

The added value of semimicroelectrode recording in deep brain stimulation of the subthalamic nucleus for Parkinson disease

Object

Accurate placement of the leads is crucial in deep brain stimulation (DBS). To optimize the surgical positioning of the lead, a combination of anatomical targeting on MRI, electrophysiological mapping, and clinical testing is applied during the procedure. Electrophysiological mapping is usually done with microelectrode recording (MER), but the relatively undocumented semimicroelectrode recording (SMER) is a competing alternative. In this study the added value and safety of SMER for optimal lead insertion in the subthalamic nucleus (STN) in a consecutive cohort of patients with Parkinson disease (PD) was assessed.

Methods

Between 2001 and 2010, a consecutive single-center cohort of 46 patients with PD underwent DBS of the STN (85 lead insertions). After exclusion of 11 lead insertions for mostly technical reasons, 74 insertions were included for the assessment. Anatomical target localization was based on either 1.5-T MRI or fused 3-T MRI with CT, with reference to anterior commissure–posterior commissure coordinates. Electrophysiological mapping was performed with SMER. Intraoperative clinical testing was dominant in determining the final lead position. The target error was defined as the absolute distance between the anatomical or electrophysiological target and the final lead position. The effect of SMER on anatomical target error reduction and final target selection was analyzed. Also, the anatomical and electrophysiological target error was judged against the different imaging strategies. For safety evaluation, the adverse events related to all lead insertions were assessed.

Results

The use of SMER significantly reduced the anatomical target error from 1.7 (SD 1.6) mm to 0.8 (SD 1.3) mm (p < 0.0001). In particular, the anatomical target error based on 1.5-T MRI was significantly reduced by SMER, from 2.3 (SD 1.5) mm to 0.1 (SD 0.5) mm (p < 0.001). Anatomical target error reduction based on 3-T MRI fused with CT was not significantly influenced by SMER (p = 0.2), because the 3-T MRI-CT combination already significantly reduced the anatomical target error from 2.3 (SD 1.5) mm to 1.5 (SD 1.5) mm compared with 1.5-T MRI (p = 0.03). No symptomatic intracerebral hemorrhage was reported. Intracerebral infection was encountered in 1 patient following lead insertion.

Conclusions

Semimicroelectrode recording has added value in targeting the STN in DBS for patients with PD based on 1.5-T MRI. The use of SMER does not significantly reduce the anatomical target error in procedures with fused 3-T MRI-CT studies and therefore might be omitted. With the absence of hemorrhagic complications, SMER-guided lead implantation should be considered a safe alternative to MER.

Subthalamic nucleus deep brain stimulation does not improve visuo-motor impairment in Parkinson's disease

OBJECTIVE

To evaluate how bilateral subthalamic nucleus deep brain stimulation (STN-DBS) affects visuo-motor coordination (VMC) in patients with Parkinson's disease (PD).

BACKGROUND

VMC involves multi-sensory integration, motor planning, executive function and attention. VMC deficits are well-described in PD. STN-DBS conveys marked motor benefit in PD, but pyscho-cognitive complications are recognized and the effect on VMC is not known.

METHODS

Thirteen PD patients with bilateral STN-DBS underwent neurological, cognitive, and mood assessment before VMC testing with optimal DBS stimulation parameters ('on-stimulation') and then, on the same day without any medication changes, after DBS silencing and establishing motor function deterioration ('off-stimulation'). Twelve age-matched healthy controls performed 2 successive VMC testing sessions, with a break of similar duration to that of the PD group. The computer cursor was controlled with a dome-shaped 'mouse' hidden from view that minimized tremor effects. Movement duration, hand velocity, tracking continuity, directional control variables, and feedback utilization variables were measured. MANOVA was performed on (1) clinically measured motor function, (2) VMC performance and (3) mood and attention, looking for main and interaction effects of: (1) group (controls/PD), (2) test-order (controls: first/second, PD: on-stimulation/off-stimulation), (3) path (sine/square/circle) and (4) hand (dominant/non-dominant).

RESULTS

Unified PD Rating Scale (UPDRS) Part III worsened off-stimulation versus on-stimulation (mean: 42.3 versus 21.6, p = 0.02), as did finger tapping (p = 0.02), posture-gait (p = 0.01), upper limb function (p<0.001) and backwards digit span (p = 0.02). Stimulation state did not affect mood. PD patients performed worse in non-velocity related VMC variables than controls (F(5,18) = 8.5, p<0.001). In the control group there were significant main effects of hand (dominant/non-dominant), path (sine/square/circle) and test-order (Test_1/Test_2). In the PD group, hand and path effects, but no test-order (on-stimulation/off-stimulation), were found.

CONCLUSIONS

'Low-level' clinically-measured motor function responds to STN-DBS but 'high-level' motor and cognitive functions relating to VMC may be unresponsive to STN-DBS.

Perfusion brain SPECT in assessing motor improvement after deep brain stimulation in Parkinson's disease

BACKGROUND

High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become an established therapeutic approach for the management of patients with late-stage idiopathic Parkinson's disease (PD). The aim of the present study was to assess regional cerebral blood flow (rCBF) changes related to motor improvement.

METHODS

Twenty-one PD patients underwent two rCBF SPECT studies at rest, once preoperatively in the off-meds state and the other postoperatively (at 6 ± 2 months) in the off medication/on stimulation state. Patients were classified according to the UPDRS and H&Y scale. NeuroGam software was used to register, quantify, and compare two sequential brain SPECT studies of the same patient in order to investigate rCBF changes during STN stimulation in comparison with preoperative rCBF. The relationship between rCBF and UPDRS scores was used as a covariate of interest.

RESULTS

Twenty patients showed clinical improvement during the first months after surgery, resulting in a 44 % reduction of the UPDRS motor score. The administered mean daily levodopa dose significantly decreased from 850 ± 108 mg before surgery to 446 ± 188 mg during the off-meds state (p < 0.001, paired t test). At the 6-month postoperative assessment, we noticed rCBF increases in the pre-supplementary motor area (pre-SMA) and the premotor cortex (PMC) (mean rCBF increase = 10.2 %, p < 0.05), the dorsolateral prefrontal cortex and in associative and limbic territories of the frontal cortex (mean rCBF increase = 8.2 %, p > 0.05). A correlation was detected between the improvement in motor scores and the rCBF increase in the pre-SMA and PMC (r = 0.89, p < 0.001).

CONCLUSIONS

Our study suggests that STN stimulation leads to improvement in neural activity and rCBF increase in higher-order motor cortical areas.

200-300Hz movement modulated oscillations in the internal globus pallidus of patients with Parkinson's Disease

Symptoms in Parkinson's Disease (PD) have been linked to oscillatory activity within the basal ganglia. In humans, such activity has been detected mainly in the local field potentials (LFPs) recorded from electrode contacts used for deep brain stimulation. Although most studies have focused on activity within the subthalamic nucleus (STN), the internal part of the globus pallidus (GPi) is considered an equally efficacious site for therapeutic neuromodulation. Moreover, while most investigations have evaluated changes in oscillatory activity in the beta (12-35Hz) and gamma (35-100Hz) bands, our preliminary spectral analysis of LFP signals in the GPi suggested distinct activity at higher frequencies as well. We hypothesized there is a unique LFP signature in the GPi that consists of movement modulated spectral power increases above 100Hz. Using invasive recordings from the GPi of patients undergoing DBS, in addition to confirming increased beta band activity within the GPi of patients with PD, we have identified and characterized a previously undescribed peak between 200 and 300Hz centered at approximately 235Hz, whose height and width but not center frequency are movement modulated. An increase in peak height is not transient, but rather persists for the duration of movement. The 200-300Hz rhythms in the GPi could have a functional role in the basal ganglia reentrant circuits by encoding output information entering the thalamo-cortical network or by organizing downstream activity for the successful execution of tasks.

Deep brain stimulation and cognitive decline in Parkinson's disease: a clinical review

Parkinson’s disease is a common and often debilitating disorder, with a growing prevalence accompanying global population aging. Current drug therapy is not satisfactory enough for many patients, especially after a few years of symptom progression. This is mainly due to the motor complications that frequently emerge as disease progresses. Deep brain stimulation (DBS) is a useful therapeutic option in carefully selected patients that significantly improves motor symptoms, functional status, and quality of life. However, cognitive impairment may limit patient selection for DBS, as patients need to have sufficient mental capabilities in order to understand the procedure, as well as its benefits and limitations, and cooperate with the medical team throughout the process of selection, surgery, and postsurgical follow-up. On the other hand it has been observed that certain aspects of cognitive performance may decline after DBS, namely when the therapeutic target is the widely used subthalamic nucleus. These are important pieces of information for patients, their families, and health care professionals. This manuscript reviews these aspects and their clinical implications.

Effects of subthalamic nucleus stimulation on emotional prosody comprehension in Parkinson's disease

BACKGROUND

Although impaired decoding of emotional prosody has frequently been associated with Parkinson's disease (PD), to date only few reports have sought to explore the effect of Parkinson's treatment on disturbances of prosody decoding. In particular, little is known about how surgical treatment approaches such as high frequency deep brain stimulation (DBS) affect emotional speech perception in patients with PD. Accordingly, the objective of this study was to evaluate the effect of subthalamic nucleus (STN) stimulation on prosody processing.

METHODOLOGY/PRINCIPAL FINDINGS

To this end the performance of 13 PD patients on three tasks requiring the decoding of emotional speech was assessed and subsequently compared to the performance of healthy control individuals. To delineate the effect of STN-DBS, all patients were tested with stimulators turned on as well as with stimulators turned off. Results revealed that irrespective of whether assessments were made "on" or "off" stimulation, patients' performance was less accurate as compared to healthy control participants on all tasks employed in this study. However, while accuracy appeared to be unaffected by stimulator status, a facilitation of reactions specific to highly conflicting emotional stimulus material (i.e. stimulus material presenting contradicting emotional messages on a verbal and non-verbal prosodic level) was observed during "on" stimulation assessments.

CONCLUSION

In sum, presented results suggest that the processing of emotional speech is indeed modulated by STN-DBS. Observed alterations might, on the one hand, reflect a more efficient processing of highly conflicting stimulus material following DBS. However, on the other hand, given the lack of an improvement in accuracy, increased impulsivity associated with STN stimulation needs to be taken into consideration.

The effect of deep brain stimulation surgery on repetitive behavior in Parkinson patients: A case series

Repetitive behavior has been increasingly reported in Parkinson's disease (PD) patients. This study evaluates the effect of Deep Brain Stimulation (DBS) treatment on existing repetitive behavior in three PD patients who underwent unilateral STN DBS surgery at the University of Florida Movement Disorders Center. No significant change in repetitive behavior was noted acutely post-surgery; however, all cases were participating less in their repetitive behavior over time. In this series, DBS surgery seemed to have no acute effect on repetitive behavior. It is difficult to ascertain whether DBS improves repetitive behavior chronically because of confounding factors in our three cases.

Functional surgery for Parkinson's disease treatment: a structured analysis of a decade of published literature

The aim of this study was to analyse and compare published data during the last decade on the different approaches to Parkinson's disease surgery. Eighty-eight papers published between 1990 and 2001 fulfilled the inclusion criteria. Full-text and prospective papers on lesion and stimulation of GPi or STN were assessed. Descriptive analysis of surgery procedure and population under study was performed, as well as a meta-analysis of the most consistently reported variables. A total of 1702 patients underwent surgery with a mean age of 58.75 years (range 46.5 - 72.5), mean duration of illness 13.6 years (8.1 - 18.1) and a male:female ratio 1.5:1. Mean postoperative follow-up was 9 months (1 - 52). Single blind assessment was performed in two papers, while double blind evaluation was used in 6. In the GPi group, no difference was found between the pre- and postoperative levodopa equivalent daily dose (960.39 v. 943.13; p > 0.05), while the STN group showed a marked reduction (1104.8 v. 483.04; p < 0.05) of this dosage. Meta-analysis of the most consistently reported variables (UPDRS total score, UPDRS motor score, UPDRS ADL score and Schwab & England score showed that Nucleus, Bilaterality of Approach and Surgical Procedure were the best moderators for defining outcome. Bilateral DBS STN procedures proved to be associated with better outcome. Microelectrode recording was not found to be a moderator that influenced outcome. Although there was a significant improvement of dyskinesias among the different approaches described in the papers, the heterogeneity of data makes it impossible to perform a structured analysis on this item.

Anxiety rating scales in Parkinson's disease: critique and recommendations

Anxiety syndromes are common in patients with Parkinson's disease (PD) with up to 30% suffering from panic disorder, and up to 11% from generalized anxiety disorder (GAD). Anxiety is associated with increased subjective motor symptoms, more severe gait problems, dyskinesias, freezing, and on/off fluctuations. Anxiety has a negative impact on health related quality of life and is strongly associated with depressive syndromes. Since a variety of anxiety scales have been used in PD patients, the Movement Disorder Society commissioned a task force to assess the clinimetric properties of these scales in PD. A systematic review was conducted to identify anxiety scales that have either been validated or used in patients with PD. Six anxiety rating scales were identified. These were the Beck anxiety inventory, the hospital anxiety and depression scale, the Zung self-rating anxiety scale and anxiety status inventory, the Spielberger state trait anxiety inventory, and the Hamilton anxiety rating scale. In addition, Item 5 (anxiety) of the neuropsychiatric inventory was included in the review. No scales met the criteria to be "recommended," and all scales were classified as "suggested." Essential clinimetric information is missing for all scales. Because several scales exist and have been used in PD, the task force recommends further studies of these instruments. If these studies show that the clinimetric properties of existing scales are inadequate, development of a new scale to assess anxiety in PD should be considered.

Bilateral subthalamic nucleus stimulation in advanced Parkinson's disease: five year follow-up

OBJECTIVE

To assess the long-term efficacy and safety of bilateral subthalamic nucleus (STN) stimulation in patients with advanced Parkinson's disease (PD).

METHODS

42 consecutive patients with idiopathic PD treated with bilateral STN stimulation were enrolled. Parkinsonian status, medication intake and neuropsychological evaluation were assessed preoperatively and at 1 and 5 years postoperatively in on and off medication/on and off stimulation conditions.

RESULTS

23 patients could be followed-up 5 years after surgery. In the remaining cases, 5 died, 1 could not be assessed because of device removal for infection, 1 decided not to be stimulated, and 11 were lost of follow-up (one because of a liver carcinoma and the others because they refused the formal four conditions of assessment). STN stimulation reduced the UPDRS motor score by 55 % compared to baseline in the off-medication conditions. Tremor, rigidity, bradykinesia, postural stability, and gait improved by 74 %, 66 %, 59 %, 17 % and 37 %, respectively. UPDRS part II scores were reduced by 38 %. The dopaminergic treatment daily dose was reduced by 54.4 % after surgery. Axial dopa-unresponsive signs worsened in some patients. Among the 42 initial patients we observed the following: 2 brain hemorrhages, 3 infections of the device, 2 phlebitis and 1 pulmonary embolism. In addition, 2 patients needed a repositioning of the electrode. Among the 23 patients followed at 5 years, long lasting side effects consisted in dysarthria (56 %), depression (39 %), eyelid opening apraxia (30.4 %) and apathy (4.3 %).

CONCLUSIONS

Our data confirm that bilateral STN stimulation is beneficial in the long-term for PD patients but does not prevent disease progression and the occurence of axial levodopa unresponsive signs in some patients.

Deep brain stimulation of the subthalamic nucleus for the treatment of Parkinson's disease

High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN-HFS) is the preferred surgical treatment for advanced Parkinson's disease. In the 15 years since its introduction into clinical practice, many studies have reported on its benefits, drawbacks, and insufficiencies. Despite limited evidence-based data, STN-HFS has been shown to be surgically safe, and improvements in dopaminergic drug-sensitive symptoms and reductions in subsequent drug dose and dyskinesias are well documented. However, the procedure is associated with adverse effects, mainly neurocognitive, and with side-effects created by spread of stimulation to surrounding structures, depending on the precise location of electrodes. Quality of life improves substantially, inducing sudden global changes in patients' lives, often requiring societal readaptation. STN-HFS is a powerful method that is currently unchallenged in the management of Parkinson's disease, but its long-term effects must be thoroughly assessed. Further improvements, through basic research and methodological innovations, should make it applicable to earlier stages of the disease and increase its availability to patients in developing countries.

Long-term effects of STN DBS on mood: psychosocial profiles remain stable in a 3-year follow-up

BACKGROUND

Deep brain stimulation of the subthalamic nucleus significantly improves motor function in patients with severe Parkinson's disease. However, the effects on nonmotor aspects remain uncertain. The present study investigated the effects of subthalamic nucleus deep brain stimulation on mood and psychosocial functions in 33 patients with advanced Parkinson's disease in a three year follow-up.

METHODS

Self-rating questionnaires were administered to 33 patients prior to surgery as well as three, six, twelve and 36 months after surgery.

RESULTS

In the long run, motor function significantly improved after surgery. Mood and psychosocial functions transiently improved at one year but returned to baseline at 36 months after surgery. In addition, we performed cluster and discriminant function analyses and revealed four distinct psychosocial profiles, which remained relatively stable in the course of time. Two profiles featured impaired psychosocial functioning while the other two of them were characterized by greater psychosocial stability.

CONCLUSION

Compared to baseline no worsening in mood and psychosocial functions was found three years after electrode implantation. Moreover, patients can be assigned to four distinct psychosocial profiles that are relatively stable in the time course. Since these subtypes already exist preoperatively the extent of psychosocial support can be anticipatory adjusted to the patients' needs in order to enhance coping strategies and compliance. This would allow early detection and even prevention of potential psychiatric adverse events after surgery. Given adequate psychosocial support, these findings imply that patients with mild psychiatric disturbances should not be excluded from surgery.

Deep brain stimulation for Parkinson's disease: prevalence of adverse events and need for standardized reporting

Deep brain stimulation (DBS) has assumed a prominent role in the treatment of Parkinson's disease (PD). In this manuscript, we attempt to estimate the prevalence and categorize adverse events (AEs) of DBS in PD, based on efficacy studies published over the last decade. We conclude that reliable categorization and quantification of AEs based on available data poses many challenges and argue that a standardized scheme for reporting AEs should be created. This would provide a foundation for a meaningful risk/benefit analysis, for comparison of results between centers and, ultimately, for a well informed decision by physicians and patients as to whether surgery should be pursued.

Single electrode and multiple electrode guided electrical stimulation of the subthalamic nucleus in advanced Parkinson's disease

OBJECTIVE

It is still debated to what extent intraoperative electrophysiological techniques contribute to the outcome of subthalamic nucleus (STN) deep brain stimulation (DBS). Intraoperative electrophysiological recordings for identification of the STN can be made with one electrode or with multiple, simultaneously implanted electrodes. The latter provide more detailed information about the electrophysiological boundaries of the STN; however, implantation of several electrodes at one time might increase the risk of bleeding. Here we report the results of a study of patients with advanced Parkinson's disease, in which one group of patients underwent bilateral STN DBS with electrophysiological recordings from a single electrode, and the other group received STN DBS with multiple (five or fewer) simultaneously implanted electrodes.

PATIENTS AND METHODS

Fifty-five patients suffering from advanced Parkinson's disease who underwent bilateral STN stimulation were included in this study. Thirty-two patients underwent STN DBS guided by a single semi-microelectrode, and 23 patients underwent STN DBS guided with simultaneously implanted multiple microelectrodes. All patients were examined preoperatively and 3 and 12 months postoperatively with regard to activities of daily living, motor functions, and neuropsychological functions.

RESULTS

We found that the simultaneous implantation of multiple electrodes does not increase the risk of bleeding or any other major intracranial complication. The use of multiple electrodes resulted in better motor results when compared with patients who underwent STN DBS guided with a single recording electrode. There were significantly more improvements in patients' tremor and rigidity, and as a consequence, a better total Unified Parkinson Disease Rating Scale, Part III score was identified during the medication-off phase. Despite better motor effects, patients treated with multiple electrodes showed subtle deterioration in neuropsychological functions, particularly in memory function.

CONCLUSION

STN DBS performed with multiple electrophysiological recording electrodes resulted in better motor outcome but induced specific mild declines in neuropsychological functions.

Prosthetic systems for therapeutic optical activation and silencing of genetically-targeted neurons

Many neural disorders are associated with aberrant activity in specific cell types or neural projection pathways embedded within the densely-wired, heterogeneous matter of the brain. An ideal therapy would permit correction of activity just in specific target neurons, while leaving other neurons unaltered. Recently our lab revealed that the naturally-occurring light-activated proteins channelrhodopsin-2 (ChR2) and halorhodopsin (Halo/NpHR) can, when genetically expressed in neurons, enable them to be safely, precisely, and reversibly activated and silenced by pulses of blue and yellow light, respectively. We here describe the ability to make specific neurons in the brain light-sensitive, using a viral approach. We also reveal the design and construction of a scalable, fully-implantable optical prosthetic capable of delivering light of appropriate intensity and wavelength to targeted neurons at arbitrary 3-D locations within the brain, enabling activation and silencing of specific neuron types at multiple locations. Finally, we demonstrate control of neural activity in the cortex of the non-human primate, a key step in the translation of such technology for human clinical use. Systems for optical targeting of specific neural circuit elements may enable a new generation of high-precision therapies for brain disorders.

Assessment of the effects of subthalamic stimulation in Parkinson disease patients by artificial neural network

This study aims at applying an artificial neural network for the evaluation of the effects of deep brain stimulation (DBS) of the subthalamic nucleus (STN) on Parkinson disease (PD) patients with and without medication. A sample of 15 PD patients who have undergone STN DBS were evaluated under four test conditions: medication off and stimulation off (mof-sof), medication off and stimulation on (mof-son), medication on and stimulation off (mon-sof) and medication on and stimulation on (mon-son). A control group with 30 subjects was also evaluated. Principal component analysis (PCA) was applied on vertical ground reaction force (vGRF) and the first six principal component scores (PC score) were obtained in both groups. Those PCs scores were used as input in a probabilistic neural network (PNN). PNN presented satisfactory classification performance in the separation of controls and PD with 90.1% accuracy, 69.2% sensitivity and 100% specificity. The stimulation mof-son and mon-son conditions presented better results compared to mon-sof. In the mof-son condition, 41.7% were classified as normal, while further enhancement (63.3%) was given by the mon-son condition. These results indicated the potentiality of PNN to quantitatively evaluate treatment effects. Furthermore, STN DBS shows improvement on vGRF pattern in PD patients, most substantially when used with medication.

Exhaustive, one-year follow-up of subthalamic nucleus deep brain stimulation in a large, single-center cohort of parkinsonian patients

OBJECTIVE

To prospectively assess the impact of subthalamic nucleus (STN) deep brain stimulation (DBS) at 12 months after surgery in a series of 100 consecutive patients treated in a single center. The primary objective was to describe the clinical outcome in terms of efficacy and tolerance in STN-DBS patients. A secondary objective was to discuss presurgery clinical characteristics a posteriori as a function of outcome.

METHODS

One hundred and three consecutive patients with severe Parkinson's disease received bilateral STN-DBS in our clinic between May 1998 and March 2003. Clinical assessment was performed before and 12 months after surgery and was based on the Unified Parkinson's Disease Rating Scale, Parts II, III, and IV A; the Schwab and England Scale; and cognitive evaluation. Patient-rated overall improvement was also evaluated.

RESULTS

Twelve months after surgery, the Unified Parkinson's Disease Rating Scale Part III score decreased by 43%, the Unified Parkinson's Disease Rating Scale Part II score (activities of daily living) fell by 34%, and the severity of dyskinesia-related disability decreased by 61%. The main surgical complications after STN-DBS were as follows: infection (n = 7), intracerebral hematoma (n = 5), electrode fracture (n = 4), and incorrect lead placement (n = 8). We observed cognitive decline and depression in 7.7 and 18% of the patients, respectively. The mean patient-rated overall improvement score was 70.7%.

CONCLUSION

The efficacy and safety of STN-DBS in our center's large cohort of Parkinsonian patients are generally similar to the results obtained by other groups, albeit at the lower limit of the range of reported values. In contrast to efficacy, the occurrence of adverse events cannot be predicted. Younger patients with Parkinson's disease (i.e., those younger than 60 yr) often show an excellent response to levodopa. However, in view of our data on overall patient satisfaction and the occurrence of adverse events, we suggest that older patients (but not those older than 70 yr) and less dopa-sensitive patients (but not those with a response <50%) should still be offered the option of STN-DBS.

High-frequency stimulation of the subthalamic nucleus prolongs the increase in striatal dopamine induced by acute l-3,4-dihydroxyphenylalanine in dopaminergic denervated rats

High-frequency stimulation of the subthalamic nucleus (STN-HFS) is a powerful approach for treating the motor symptoms of Parkinson's disease (PD). It results in clinical improvement in patients with PD, further reducing the l-3,4-dihydroxyphenylalanine (L-DOPA) requirement and thus L-DOPA-induced dyskinesia. However, it remains unclear how STN-HFS modifies the response to L-DOPA. We investigated the effect of STN-HFS on striatal extracellular concentrations of dopamine and its metabolites following acute L-DOPA administration in intact or partially dopaminergic denervated (DA-PL) rats. L-DOPA treatment significantly increased striatal dopamine levels in intact and DA-PL animals, with the maximal effect observed 1 h after L-DOPA injection. This increase was more pronounced in DA-PL rats (ipsilateral to the lesion) than in intact animals. It remained fairly stable 1 h after the maximal effect of L-DOPA and then decreased towards basal values. STN-HFS in intact rats had no effect on the maximal L-DOPA-induced increase in striatal extracellular dopamine concentration or the return to basal values, the profiles observed being similar to those for non-stimulated intact animals. Conversely, STN-HFS amplified the L-DOPA-induced increase in striatal dopamine levels during the stimulation period (1 h) in DA-PL rats and this increase was sustained throughout the post-stimulation period (2.5 h), without the return to basal levels observed in stimulated intact and non-stimulated rats. These new neurochemical data suggest that STN-HFS interferes with L-DOPA effects, probably synergically, by stabilizing dopamine levels in the striatum and shed light on the mechanisms of STN-HFS in PD.

Apathy and verbal fluency in STN-stimulated PD patients

OBJECTIVE

To evaluate apathy and its relation to verbal fluency tasks in a consecutive series of 19 patients with Parkinson's disease (PD) submitted to deep brain stimulation of the subthalamic nucleus (DBS of STN).

METHODS

19 consecutive PD patients submitted to bilateral DBS of STN were studied for apathy pre-operatively and 17 months after surgery. The PD patients underwent a battery of cognitive tests assessing reasoning, memory and frontal executive functions, including phonemic and categorial fluency tasks. The Beck Depression Inventory (BDI) was used for depression. Apathy was assessed by means of the Apathy Scale (AS). In order to quantify changes among individual patients, the clinical criterion of more or less than 1 SD (standard z-score) was used to register a patient as improved or worsened, respectively.

RESULTS

After surgery, apathy scores did not change and mood improved (p < 0.02), while a significant worsening was found in the phonemic fluency (p < 0.001). The percentage of patients with an apathy score above the recommended cut-off value (14) was 42% both before and after DBS of STN. Individual outcomes on the apathy scale (1 SD criterion) evidenced that 53% of the patients remained stable, 16% improved, while 31% worsened. This last percentage reduced to 21% (4/19) when considering only the PD patients with an apathy score > or =14 after surgery. No significant correlation was found between the apathy scores variation and any of the neurological variables considered, and, in particular, no correlation was found between apathy and verbal fluency.

CONCLUSIONS

The results of the present study suggest that DBS of STN does not necessarily induce apathy even if individual patients show a moderate post-operative worsening of apathetic symptoms.

Subthalamic nucleus deep brain stimulation in elderly patients--analysis of outcome and complications

Background

There is an ongoing discussion about age limits for deep brain stimulation (DBS). Current indications for DBS are tremor-dominant disorders, Parkinson's disease, and dystonia. Electrode implantation for DBS with analgesia and sedation makes surgery more comfortable, especially for elderly patients. However, the value of DBS in terms of benefit-risk ratio in this patient population is still uncertain.

Methods

Bilateral electrode implantation into the subthalamic nucleus (STN) was performed in a total of 73 patients suffering from Parkinson's disease. Patients were analyzed retrospectively. For this study they were divided into two age groups: group I (age <65 years, n = 37) and group II (age ≥ 65 years, n = 36). Examinations were performed preoperatively and at 6-month follow-up intervals for 24 months postoperatively. Age, UPDRS motor score (part III) on/off, Hoehn & Yahr score, Activity of Daily Living (ADL), L-dopa medication, and complications were determined.

Results

Significant differences were found in overall performance determined as ADL scores (group I: 48/71 points, group II: 41/62 points [preoperatively/6-month postoperatively]) and in the rate of complications (group I: 4 transient psychosis, 4 infections in a total of 8 patients, group II: 2 deaths [unrelated to surgery], 1 intracerebral hemorrhage, 7 transient psychosis, 3 infections, 2 pneumonia in a total of 13 patients), (p < 0.05). Interestingly, changes in UPDRS scores, Hoehn & Yahr scores, and L-dopa medication were not statistically different between the two groups.

Conclusion

DBS of the STN is clinically as effective in elderly patients as it is in younger ones. However, a more careful selection and follow-up of the elderly patients are required because elderly patients have a higher risk of surgery-related complications and a higher morbidity rate.

Effects of subthalamic nucleus deep brain stimulation and levodopa on energy production rate and substrate oxidation in Parkinson's disease

Patients with Parkinson's disease (PD) often lose weight, but after subthalamic nucleus deep brain stimulation (STN-DBS), they gain weight. We compared daily energy intake (DEI), resting energy expenditure (REE) and substrate oxidation rates (measured by indirect calorimetry) in nineteen STN-DBS-treated patients (Group S), thirteen others on pharmacologic treatment by levodopa (Group L) and eight control subjects. We also determined the acute effects of STN-DBS and levodopa on REE and substrate oxidation rates. STN-DBS treated patients gained 9·7 (sem 7·1) kg after surgery, whereas patients on pharmacologic treatment lost 3·8 (sem 10·0) kg since diagnosis. In STN-DBS-treated patients, REE (−16·5 %;P<0·001), lipid oxidation (−27 %;P<0·05) and protein oxidation (−46 %;P<0·05) were decreased, whereas glucose oxidation was elevated (+81 %;P<0·05) as compared to patients on pharmacologic treatment. Levodopa acutely reduced REE (−8·3 %;P<0·05) and glucose oxidation (−37 %;P<0·01) with a slight hyperglycaemic effect (after levodopa challenge: 5·6 (sem 0·8)v.before levodopa challenge: 5·3 (sem 0·6) mmol/l;P<0·01). Switching ‘on’ STN-DBS acutely reduced REE (−17·5 %;P<0·01) and lipid oxidation (−24 %;P<0·001) 30 min after starting stimulation. Fasting glycaemia was slightly but significantly reduced (5·4 (sem 1·4)v.5·5 (sem 1·3) mmol/l;P<0·01). After STN-DBS, the normalization of REE and the reduction in lipid and protein oxidation contribute to the restoration of weight. As levodopa decreases glucose oxidation, the reduction in daily dose of levodopa in STN-DBS-treated patients helps prevent the effect of weight gain on glycaemia.

Bilateral subthalamic nucleus stimulation in advanced Parkinson's disease: three years follow-up

OBJECTIVE

To assess the long-term efficacy and safety of chronic bilateral stimulation of the subthalamic nucleus (STN) in patients with advanced Parkinson's disease (PD).

METHODS

36 consecutive patients with idiopathic Parkinson's disease treated with bilateral stimulation of the STN were studied. Parkinsonian status was assessed preoperatively and at 1 and 3 years postoperatively using the Unified Parkinson's Disease Rating Scale (UPDRS) and neuropsychological evaluation in on and off-medication / on and off stimulation conditions.

RESULTS

At 3 years follow-up, STN stimulation reduced the UPDRS motor score by 54.2 % compared to baseline in the off-medication conditions. Tremor, rigidity, bradykinesia, postural stability, and gait improved by 72.2 %, 62.4 %, 56.8 %, 40.5 % and 45.3 %, respectively. UPDRS part II scores were reduced by 41.4 %. The overall dopaminergic drugs dose was reduced by 48.6 % after surgery and four patients were no longer taking antiparkinsonian medication at three years. However, axial dopa-unresponsive signs worsened in some patients. The most frequent transient adverse event consisted in mood disorders in 23 patients.

CONCLUSIONS

Our data demonstrate that: 1) bilateral STN stimulation is relatively safe, improves the motor symptoms and drug-related motor complications of PD, and reduces the daily dosage of medication; 2) this benefit is sustained over time despite the occurrence of axial doparesistant signs in some patients.

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.

Neuropsychological performance following staged bilateral pallidal or subthalamic nucleus deep brain stimulation for Parkinson's disease

Deep brain stimulation (DBS) has the potential to significantly reduce motor symptoms in advanced Parkinson's disease (PD). Controversy remains about non-motor effects of DBS and the relative advantages of treatment at two brain targets, the globus pallidus internus (GPi) and the subthalamic nucleus (STN). We investigated effects of DBS on neuropsychological functioning in 42 patients with advanced PD randomly assigned to receive staged bilateral DBS surgery of either the GPi or STN. Patients underwent neuropsychological assessment prior to and 6 months after unilateral surgery. Twenty-nine subsequently underwent surgery to the contralateral side and completed a second follow-up neuropsychological evaluation 15 months later. Unilateral treatment resulted in small but statistically significant reductions in performance on several measures, including verbal fluency and working memory. A similar pattern was observed after bilateral treatment. Reductions in verbal associative fluency were significant only after left-sided treatment. There were few significant differences related to treatment at the two surgical targets. Supplementary analyses suggested that decrements in select neuropsychological domains following DBS are unrelated to age or post-surgical reduction in dopaminergic medication dose. Findings are discussed with reference to possible causes of neuropsychological decline and the need for further controlled studies of specific neuropsychological effects of DBS.

Gait Changes in Response to Subthalamic Nucleus Stimulation in People with Parkinson Disease

BACKGROUND AND PURPOSE

For individuals with advanced Parkinson disease (PD), stimulation of the subthalamic nucleus (STN) reduces tremor, rigidity, and bradykinesia, but the effects of stimulation on gait and mobility are not fully understood. The purpose of this paper is to describe the effects of unilateral and bilateral STN stimulation on gait following staged stimulator implantations in a series of individuals with PD.

CASE DESCRIPTIONS

Participants were 6 individuals with PD who underwent staged stimulator implantation surgeries. The effects of stimulation on gait were assessed in the optimally medicated state using items from the Unified Parkinson's Disease Rating Scale (UPDRS) related to gait and self-reported mobility, time to complete the Timed Up and Go (TUG) test, and quantitative gait analysis. Gait was evaluated with stimulation turned off and with stimulation turned on after unilateral stimulator implantation and again after implantation of the second stimulator.

OUTCOMES

Variable effects of unilateral and bilateral STN stimulation on gait were observed on UPDRS self-reported mobility, TUG time, and gait velocity, but changes were not detected using the UPDRS gait item. Minimal gait changes, either positive or negative, were detected with unilateral stimulation. With bilateral stimulation, gait improved for 3 individuals but worsened for the other 3 individuals.

DISCUSSION

The ability to detect changes in gait after STN stimulation using the UPDRS gait item was limited, but variable effects were detected by self-report, TUG time, and gait velocity. For half of the individuals studied, bilateral stimulation improved these measures, but gait worsened for the remaining individuals. Future research is needed to better understand factors that influence the effect of STN stimulation on walking, and assessment of gait changes in people with PD should include self-report and performance-based measures, such as the TUG test or gait velocity.

Targets for deep brain stimulation in Parkinson's disease

The use of stimulation electrodes implanted in the brain to control severely disabling neurological and psychiatric conditions is an exciting and fast emerging area of neuroscience. An excellent example is Parkinson's disease (PD), in which tens of thousands of patients have now been implanted with stimulation electrodes. Patients with PD underwent deep brain stimulation (DBS) at the level of the thalamus, globus pallidus internus, subthalamic nucleus, pedunculopontine nucleus and prelemniscal radiation. The results of these interventions revealed that each target has its own specific stimulation-related positive and negative effects. Clinicians can choose their DBS target based on the situation of their individual PD patients. In the authors' opinion, patient-specific targeting should be preferred over disease-specific targeting. In this review, the authors give an overview of the targets that have been used for DBS in PD and discuss patient-specific targeting.

Lessons learned in deep brain stimulation for movement and neuropsychiatric disorders

The introduction of deep brain stimulation (DBS) as a treatment for medication-refractory essential tremor in the late 1980s revealed, for the first time, that "chronically" implanted brain hardware had the potential to modulate neurologic function with surprisingly low morbidity. Over time, the therapeutic promise of DBS has become evident in Parkinson's disease and dystonia. In some experienced centers, complex tremor disorders, such as posttraumatic Holmes tremor and the tremor of multiple sclerosis, are being increasingly targeted. More recently, other indications, including obsessive-compulsive disorder, Tourette's syndrome, major depression, and chronic pain, have been proposed. As the field has expanded, our knowledge about potential cognitive side effects of DBS has also expanded. This article reviews the current knowledge regarding the impact of stimulation of the subthalamic nucleus, globus pallidus internus, and ventralis intermedius nucleus of the thalamus on symptoms in essential tremor, Parkinson's disease, and dystonia. Also discussed are the emerging targets, what is known about the cognitive sequelae of DBS, and what has been learned about the complications and therapeutic failures.

Bilateral subthalamic stimulation improves gait initiation in patients with Parkinson's disease

Impaired gait initiation is one of the typical sign of advanced Parkinson's disease (PD). This is the first study to examine quantitatively the effect of deep brain stimulation of the subthalamic nucleus on the performance of gait initiation for patients with advanced PD. A total of 11 patients after surgery of bilateral deep brain stimulation of the subthalamic nucleus (STN) were tested in both the deep brain stimulation (DBS) ON and OFF conditions and/or in both the medication ON (i.e., with the usual dosage of antiparkinsonian medications administered) and OFF (i.e., with the usual dosage of antiparkinsonian medications withheld) conditions. DBS had no effect on the onset of anticipatory postural adjustment (APA). The effect of DBS approached significant level for the onset of swing foot lifting, but reached significant level for the delay of swing foot lifting. DBS significantly increased the amplitude of the APA, amplitude of reactive shear forces on both feet, and amplitude of COP in both anterior-posterior and medial-lateral directions. It is concluded that DBS significantly improved the performance of patients with advanced PD in gait initiation.

Chronic deep brain stimulation of the subthalamic nucleus for Parkinson's disease: effects on cognition, mood, anxiety and personality traits

OBJECTIVE

To evaluate modifications occurring in cognitive functions and behavioural aspects in a group of 72 consecutive patients with Parkinson's disease (PD) 15 months after bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN).

METHODS

72 consecutive PD patients bilaterally implanted for DBS of the STN were evaluated before and after surgery with a mean follow-up of 15 months. A neuropsychological assessment was performed to evaluate reasoning (Raven Colour Matrices), memory (Bisyllabic Word Repetition Test, Corsi's Block-Tapping Test, Paired-Associate Learning) and frontal executive functions (Trail Making Test Part B, Nelson Modified Card Sorting Test, phonemic and category verbal fluency tasks). Mood and suicidal ideation were evaluated using the Beck Depression Inventory (BDI). Anxiety was measured by means of the State-Trait Anxiety Inventory and personality traits were evaluated with the Structured Clinical Interview for the DSM-III-R Axis II Disorders (SCID-II). Assessment of thought disorders and apathy was based on subitems of the Unified Parkinson's Disease Rating Scale.

RESULTS

The comparisons between pre- and postoperative neuropsychological test scores showed a significant worsening only in phonemic and semantic verbal fluency tasks, while fewer errors were found in the Nelson Modified Card Sorting Test. Globally, behavioural assessment evidenced a small improvement in mood, as assessed by the BDI, in obsessive-compulsive and paranoid personality traits (SCID-II). Thought disorders worsened while suicidal ideation, anxiety and apathy showed no postoperative modifications. The analysis of individual outcomes (+/-1 SD criterion) evidenced a relevant postoperative cognitive decline in 3 patients out of 65 (4.5%). Moreover, following implantation, 1 patients exhibited psychosis (1.5%), 2 patients experienced a clinically relevant worsening of depressive symptoms (3%), 7 patients showed an increase in anxiety (12%) and 3 patients a worsening in depression and anxiety symptoms (3%). On the contrary, 12 patients (20%) showed a relevant improvement in mood and 14 patients (23%) a relevant reduction of anxiety symptoms after the surgery.

CONCLUSIONS

The present study confirms that STN DBS is cognitively safe since the only relevant change observed was a mild decrease in verbal fluency tasks. Globally, a small postoperative improvement was found in the BDI, and in two SCID-II subscales concerning obsessive-compulsive and paranoid personality traits, even though postoperative behavioural disturbances can occur in individual patients.

Behavioural changes after bilateral subthalamic stimulation in advanced Parkinson disease: a systematic review

INTRODUCTION

The long-lasting beneficial effects of subthalamic nucleus (STN) deep brain stimulation (DBS) on motor function have now largely been acknowledged. Whereas behavioural changes have been demonstrated in certain case reports and small case series, some authors have not observed behavioural changes at all. The extent to which these changes occur has not yet been established. The aim of the present study was to systematically analyse behavioural changes of bilateral STN DBS.

MATERIALS AND METHODS

A structured Medline search was conducted using previously described methods. Studies were selected according to specific in- and exclusion criteria. Data on patients, surgical technique, outcome and complications were collected and pooled.

RESULTS

In total 1,398 patients who underwent bilateral STN DBS were included. The total cumulative follow-up period was 1,480 patient-years. Cognitive problems were seen in 41%, depression in 8%, and (hypo)mania in 4% of the patients. Anxiety disorders were observed in less than 2%, and personality changes, hypersexuality, apathy, anxiety, and aggressiveness were observed in less than 0.5% of the group studied. About half of the patients did not experience behavioural changes.

CONCLUSION

Caregivers should be aware of the extent of these behavioural changes and a risk/benefit evaluation should be performed for individual patients.

Efficacy of bilateral subthalamic nucleus (STN) stimulation in Parkinson's disease

BACKGROUND

Deep brain stimulation (DBS) has, for the most part, replaced irreversible stereotactic coagulations in the surgical treatment of advanced Parkinson's disease. This study was undertaken to evaluate the benefits of bilateral STN stimulation related to its potential risks and side effects.

METHOD

Twenty-nine consecutive Parkinsonian patients treated with STN-DBS were prospectively followed-up. Effects on Parkinsonian symptoms were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS). The evaluation was performed preoperatively and included postoperative follow-up evaluations at one and twelve months. All evaluations were made during the patient's best on-medication phase and postoperative follow-ups were conducted under both stimulator-on and stimulator-off conditions by a blinded neurologist. A neuropsychologist also evaluated the patients at every visit.

FINDINGS

Two patients were excluded from the analysis because of severe surgical complications and three for an infection demanding the removal of the stimulator material. Other complications and side effects were clearly milder and temporary. At twelve months after surgery dyskinesia scores in the UPDRS were 53% lower than preoperative values. The results of the UPDRS motor scores improved 31.4% and activities of daily living (ADL) scores increased 19% compared with the preoperative situation. Also, the daily levodopa dose was 22% lower. Neuropsychological changes were minor, except for some deterioration in verbal fluency.

CONCLUSION

The majority of Parkinsonian patients experienced significant and long lasting relief from their motor symptoms and an improvement in ADL functions due to DBS-STN therapy when evaluated at the best on-medication phase.

Impact of subthalamic nucleus stimulation on the initiation of gait in Parkinson’s disease

The effects of subthalamic nucleus (STN) stimulation on the anticipatory postural actions associated with the initiation of gait were studied in ten patients with idiopathic Parkinson's disease undergoing therapeutic deep brain stimulation. Kinematic, dynamic and electromyographic analysis was performed before and while subjects were starting gait in response to an external cue. Effects of STN stimulation on the standing posture preceding the go signal included significant improvement of the vertical alignment of the trunk and shank, decrease of the hip joint moment, backward shift of the center of pressure (CoP) and reduction of abnormal tonic and/or rhythmic activity in the thigh and leg muscles. Responses to bilateral STN stimulation were more consistent than those evoked by unilateral stimulation. Moreover, comparison between postural changes induced by STN stimulation applied prior to the gait initiation cue and during simple quiet standing revealed more significant responses in the former condition. Effects on the actual gait initiation process included shortening of the imbalance phase, larger backward/lateral displacement of CoP and more physiological expression of the underlying anticipatory muscular synergy. Additional changes were shortening of the unloading phase, shortening of the first-swing phase and increase in the length of the first step. Results demonstrate substantial influence of STN stimulation on functionally basic motor control mechanisms. In particular, the evidence of more significant responses upon attention-demanding conditions and the remarkable effects on postural programmes sub-serving feed-forward regulation of the onset of complex multijoint movements, suggests a consistent action on postural sub-systems relying on cognitive data processing and internal models of body mechanics.