Medication dose reductions after pallidal versus subthalamic stimulation in patients with Parkinson's disease

Evidente VGH, Premkumar AP, Adler CH, Caviness JN, Driver‐Dunckley E, Lyons MK. Medication dose reductions after pallidal versus subthalamic stimulation in patients with Parkinson’s disease.
Acta Neurol Scand: 2011: 124: 211–214.
© 2010 John Wiley & Sons A/S. Objective – To compare the medication dose reduction between deep brain stimulation (DBS) of the globus pallidus interna (GPi) vs subthalamic nucleus (STN) in matched patients with Parkinson’s disease (PD). Materials and methods – Records of 12 patients with PD who underwent GPi‐DBS at our institution from 2002 to 2008 were matched by pre‐operative PD medication doses and pre‐operative motor Unified Parkinson’s Disease Rating Scale (UPDRS) scores to 12 cases of STN‐DBS. PD medication doses were converted to levodopa equivalent doses (LEDs). Results – GPi and STN groups had similar mean pre‐operative LEDs and motor UPDRS scores. At 6 months post‐DBS, there was no significant difference in percent reduction in LEDs between the GPi (47.95%) and STN (37.47%) groups (P = 0.52). The mean post‐operative ‘medication off/stimulation on’ motor UPDRS scores did not differ significantly between GPi (15.33) and STN (16.25) groups (P = 0.74). The mean percent reduction in motor UPDRS scores was also similar between GPi (58.44%) and STN (58.98%) patients (P = 0.94). Conclusions – We conclude that in disease‐matched patients with PD undergoing DBS, both GPi and STN may result in similar reduction in PD medication doses.     

Long‐term results of a multicenter study on subthalamic and pallidal stimulation in Parkinson's disease

We report the 5 to 6 year follow‐up of a multicenter study of bilateral subthalamic nucleus (STN) and globus pallidus internus (GPi) deep brain stimulation (DBS) in advanced Parkinson's disease (PD) patients. Thirty‐five STN patients and 16 GPi patients were assessed at 5 to 6 years after DBS surgery. Primary outcome measure was the stimulation effect on the motor Unified Parkinson's Disease Rating Scale (UPDRS) assessed with a prospective cross‐over double‐blind assessment without medications (stimulation was randomly switched on or off). Secondary outcomes were motor UPDRS changes with unblinded assessments in off‐ and on‐medication states with and without stimulation, activities of daily living (ADL), anti‐PD medications, and dyskinesias. In double‐blind assessment, both STN and GPi DBS were significantly effective in improving the motor UPDRS scores (STN, P < 0.0001, 45.4%; GPi, P = 0.008, 20.0%) compared with off‐stimulation, regardless of the sequence of stimulation. In open assessment, both STN‐ and GPi‐DBS significantly improved the off‐medication motor UPDRS when compared with before surgery (STN, P < 0.001, 50.5%; GPi, P = 0.002, 35.6%). Dyskinesias and ADL were significantly improved in both groups. Anti‐PD medications were significantly reduced only in the STN group. Adverse events were more frequent in the STN group. These results confirm the long‐term efficacy of STN and GPi DBS in advanced PD. Although the surgical targets were not randomized, there was a trend to a better outcome of motor signs in the STN‐DBS patients and fewer adverse events in the GPi‐DBS group. © 2010 Movement Disorder Society     

Neuropsychological changes between "off" and "on" STN or GPi stimulation in Parkinson's disease

BACKGROUND: In a previous study on a consecutive series of 62 patients with PD, the authors showed that bilateral subthalamic or pallidal continuous high-frequency deep brain stimulation (DBS) affects neither memory nor executive functions 3 to 6 months after surgery. OBJECTIVE: To investigate the specific effects of DBS by comparing the performance of patients with the stimulator turned "on" and "off." METHODS: The performance of 56 patients on clinical tests of executive function was compared after 3 and 12 months of DBS of the subthalamic nucleus (STN; n = 48) or the internal globus pallidus (GPi; n = 8) with the stimulator "on" or "off." Global intellectual efficiency, verbal learning, and mood were also evaluated with the stimulator "on." The performance of another group of 20 patients was compared after 6 months of DBS of the STN (n = 15) or the GPi (n = 5) with the stimulator "on" or "off" on more experimental tests recently shown to be more sensitive to l-dopa therapy. RESULTS: When the stimulator was "on," STN patients showed a mild but significant improvement in psychomotor speed and working memory. In comparison with the presurgical state, STN patients had no cognitive deficit at 12 months, except for lexical fluency. There was no differential effect of STN or GPi stimulation. CONCLUSIONS: 1) The specific effect of DBS seems to mimic the action of l-dopa treatment in the cognitive as in the motor domain; 2) the surgery associated with DBS does not appear to affect the cognitive performance of patients with PD 12 months later, except for a mild deficit in lexical fluency.     

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.     

Pallidal vs subthalamic nucleus deep brain stimulation in Parkinson disease

BACKGROUND: Deep brain stimulation (DBS) of the globus pallidus interna (GPi) and subthalamic nucleus (STN) has been reported to relieve motor symptoms and levodopa-induced dyskinesia in patients with advanced Parkinson disease (PD). Although it has been suggested that stimulation of the STN may be superior to stimulation of the GPi, comparative trials are limited. OBJECTIVE: To extend our randomized, blinded pilot comparison of the safety and efficacy of STN and GPi stimulation in patients with advanced PD. DESIGN: This study represents the combined results from our previously published, randomized, blinded, parallel-group pilot study and additional patients enrolled in our single-center extension study. SETTING: Oregon Health and Science University in Portland.Patients Twenty-three patients with idiopathic PD, levodopa-induced dyskinesia, and response fluctuations were randomized to implantation of bilateral GPi or STN stimulators. Patients and evaluating clinicians were blinded to stimulation site. All patients were tested preoperatively while taking and not taking medications and after 3, 6, and 12 months of DBS. MAIN OUTCOME MEASURES: Postoperatively, response of symptoms to DBS, medication, and combined medication and DBS was evaluated. Twenty patients (10 in the GPi group and 10 in the STN group) completed 12-month follow-up. RESULTS: Off-medication Unified Parkinson's Disease Rating Scale motor scores were improved after 12 months of both GPi and STN stimulation (39% vs 48%). Bradykinesia tended to improve more with STN than GPi stimulation. No improvement in on-medication function was observed in either group. Levodopa dose was reduced by 38% in STN stimulation patients compared with 3% in GPi stimulation patients (P = .08). Dyskinesia was reduced by stimulation at both GPi and STN (89% vs 62%). Cognitive and behavioral complications were observed only in combination with STN stimulation. CONCLUSION: Stimulation of either the GPi or STN improves many features of advanced PD. It is premature to exclude GPi as an appropriate target for DBS in patients with advanced disease.     

Deep brain stimulation in the management of Parkinson's disease

Deep brain stimulation (DBS) is a neurosurgical treatment of Parkinson's disease and other movement disorders. This surgical technique is applied to three brain targets: the ventral intermediate nucleus of the thalamus (Vim), the globus pallidus internus (Gpi) and the subthalamic nucleus (STN). Vim DBS improves contralateral parkinsonian tremor. STN and GPi DBS improve contralateral bradykinesia, rigidity, parkinsonian tremor and also levodopa-induced dyskinesia. There is little comparative data between bilateral STN and bilateral GPi procedures but the improvement with bilateral STN DBS seems more pronounced than with bilateral GPi DBS. Moreover, only STN BDS allows a significant decrease of antiparkinsonian medication. The other advantage of STN over GPi DBS is the lower consumption of current. The DBS procedure contrary to ablative surgery has the unique advantage of reversibility and adjustability over time. Patients with no behavioral, mood and cognitive impairments benefit the most from bilateral STN DBS. The stimulation-induced adverse effects related to DBS are reversible and adjustable. More specific adverse effects related do hardware are: disconnection, lead breaking, erosion or infection. The disadvantage of DBS is a relatively high cost. The setting of stimulation parameters to achieve the best clinical result may be very time-consuming. Most authors agree that DBS is a safer and more favorable procedure than ablative surgery.     

Bilateral Implantation in Globus Pallidus Internus and in Subthalamic Nucleus in Parkinson's Disease

Introduction . Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and of the pars interna of Globus Pallidus (GPi) is used to improve parkinsonian symptoms and attenuate levodopa‐induced motor complications in Parkinson's disease (PD) (DBS for PD study group, 2001). It is still not clear what the best anatomic structures to stimulate are or what the physiologic effects of DBS are. Most of the studies regarding DBS for parkinsonian symptoms have been conducted in patients with STN implantation, and these studies reported significant improvement in motor function with a relatively low rate of complication. The large experience of ablative surgery associated with the DBS experience of some groups worldwide indicate that GPi is a possible and very promising target for the management of parkinsonian symptoms. Surgical procedures have become safer and it is now possible, in selected cases, to target both structures in the same patient by means of the stereotactic system, “3P Maranello” (CLS‐SRL, Italy). Using this system we were able to evaluate the clinical effects of simultaneous stimulation of both STN and GPi as well as evaluate the effects of isolated stimulation of each target. As it is known that there is a high intersubject variability of DBS, it seems relevant to test all different combinations of DBS in the same patient. Methods . We assessed the effects of DBS in 13 cases of PD, immediately after (30 min) stimulation and during chronic stimulation (weeks or months). Patients fell into two groups. The first (n = 7) responded to both GPi and STN stimulation equally. The second group (n = 6) was preferentially stimulated with only one target (STN = 5, GPi = 1). Results . There was a good reduction in levodopa treatment following surgery. Most patients remained were chronically treated with bilateral stimulation of both targets. Conclusion . We conclude that DBS of STN and GPi was effective, with most patients treated chronically with both targets stimulated.     

Change in fatigue after bilateral subthalamic nucleus deep brain stimulation for Parkinson's disease

BackgroundBilateral subthalamic nucleus (STN) deep brain stimulation (DBS) improves motor function in patients with medically intractable Parkinson’s disease (PD), but the effects of STN DBS on fatigue are unknown. The purpose of this study was to examine the effects of STN DBS on fatigue scores in patients with PD.MethodsTwenty PD patients underwent bilateral STN DBS surgery at our institution from 2007 to 2009. Only data from the 17 patients who completed the Parkinson Fatigue Scale (PFS) and Unified PD Rating Scale (UPDRS) before and approximately 6 months after surgery were analyzed. Other evaluations included the Geriatric Depression Scale (GDS), Apathy Evaluation Scale (AES), and Epworth Sleepiness Scale (ESS).ResultsWhen the cohort was analyzed as a whole, there was no significant change in the mean or binary PFS score from baseline to the 6 month evaluation. However, the fatigue response of individual subjects was variable. Six of 12 subjects with fatigue before surgery were not fatigued post-operatively, while 3/5 subjects without fatigue before surgery became fatigued after DBS surgery. Fatigue in 8 subjects remained unchanged. Change in fatigue scores correlated significantly with change in the motor UPDRS, GDS and AES. Improvement in PFS also correlated with a higher PFS baseline score and higher baseline UPDRS motor off score.ConclusionsChanges in fatigue severity were not observed in our cohort as a whole, but there were changes in fatigue on an individual level. These changes appear to be related to the effects of STN DBS on motor improvement and mood.     

Acute psychotropic effects of bilateral subthalamic nucleus stimulation and levodopa in Parkinson's disease.

High-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves the motor symptoms of Parkinson's disease (PD). Opposite changes in mood, such as mania or depression, have been reported after surgery, but it is not known whether these side effects are specifically related to STN DBS. To learn whether STN DBS also influences the limbic loop, we investigated acute subjective psychotropic effects related to levodopa or bilateral STN DBS. After a median postoperative follow-up of 12 months, 50 PD patients completed the Addiction Research Center Inventory (ARCI), assessing subjective psychotropic effects in four conditions: off-drug/on-stimulation; off-drug/off-stimulation; on-drug/off-stimulation; and on-drug/on-stimulation. Both levodopa and STN DBS improved all the ARCI subscales, indicating subjective feelings of well being, euphoria, increase in motivation, and decrease in fatigue, anxiety, and tension. A suprathreshold dose of levodopa was significantly more effective than STN DBS, using the same electrical parameters as for chronic stimulation, on four of the five ARCI subscales. We concluded that 1) both STN DBS and levodopa have synergistic acute beneficial psychotropic effects in PD, 2) the psychotropic effects of both treatments need to be considered in the long-term management of chronic STN DBS, and 3) the results indicate an involvement of the limbic STN in mood disorders of PD.     

STN vs. Pallidal Stimulation in Parkinson Disease: Improvement With Experience and Better Patient Selection

Objectives. This is a prospective study to determine the outcomes of subthalamic nucleus (STN) vs. globus pallidus internus (GPi) deep brain stimulation (DBS) at our institution. Materials and Methods. We studied a total of 39 patients — 29 with STN and 10 with GPi DBS over a period of up to 6 years. Mean ages in the two groups were similar (59 and 60 years, respectively) and disease duration prior to implantation was similar (9.6 and 11.7 years, respectively). Unified Parkinson Disease Rating Scale (UPDRS) was recorded preoperatively and at follow‐up (at least at 6‐month intervals). Medications also were recorded, and each patient's levodopa equivalent units (LEU) were calculated. Results were analyzed using a paired Student's t‐test. Results. LEU reduced significantly (p < 0.05) in the STN group (5.7 to 3.7) but not the GPi group. Both targets significantly improved part 3 and part 4 scores of the UPDRS but GPi DBS did not improve part 2 scores (activities of daily living). STN DBS had much better outcome on the motor “off” scores of the UPDRS, whereas GPi only improved tremor. A comparison of the “earliest 10” and “most recent 10” STN patients showed a significant improvement in outcome in the most recent cases. Conclusions. In our group, STN was more effective for alleviating the symptoms of Parkinson disease, even in older patients with significant dyskinesias. Better patient selection and greater experience have led to more improvement in the more recent patients.     

The latest evidence on target selection in deep brain stimulation for Parkinson’s disease

Deep brain stimulation (DBS) is one of the most promising neuromodulatory techniques to gain momentum over the last 20 years, with significant evidence showing the benefit of DBS for Parkinson’s disease (PD). However, many questions still exist pertaining to the optimal placement of stimulation contacts. This paper aims to review the latest and most relevant studies evaluating subthalamic nucleus (STN) and globus pallidus interna (GPi) stimulation. Additionally, it aims to shine a light on several of the lesser-known targets with mounting evidence of efficacy. Referenced literature for the main body of the article was gathered from Medline and PubMed databases. Results were limited to “full text”, “English language” and publications from 1999 onwards. Case reports were excluded. The current evidence irrefutably demonstrates the benefits of both STN and GPi DBS on Unified Parkinson’s Disease Rating Scale (UPDRS) III motor scores, with very similar outcomes seen after 1–2 years. Currently, it appears the greatest differences lie in the associated adverse effects. STN DBS was associated with a greater reduction in dopamine replacement therapy, but also appeared to have more negative effects on speech and mood. Meanwhile, in regards to alternative targets, the pedunculopontine nucleus has shown promising improvement in axial symptoms, while the ventral intermediate nucleus has demonstrated significant efficacy at suppressing tremor, and the caudal zona incerta may be superior to the STN and GPi in improving UPDRS-III scores. Due to the complexity of Parkinson’s disease, an individual disease profile must be determined in a patient-by-patient fashion such that appropriate targets can be selected accordingly.     

Stimulation Region Within the Globus Pallidus Does Not Affect Verbal Fluency Performance

BackgroundSubthalamic (STN) and globus pallidus (GP) deep brain stimulation (DBS) have been previously shown to be efficacious in the treatment of selected Parkinson patients with medication resistant motor fluctuations and/or tremor. Deep brain stimulation of the STN has been implicated with more cognitive and mood side effects as compared to GP DBS; however, more studies are needed to better understand possible target differences. Previously, Mikos et al. [1] reported worsening of verbal fluency depending on the stimulation location within the STN region.Objective/hypothesisThe current study applied the methods used by Mikos et al. (2011) to a different sample of Parkinson patients who underwent GP DBS. Based on differences in the size and functional somatotopy between structures (GP 412 mm³ vs. STN 167 mm³), we hypothesized that there would be a less robust relationship between volume of tissue activated, fluency performance, and stimulation contact within the GP compared to what was reported in the STN.MethodsPatient-specific DBS models were created and the volume of tissue activated within the GP was calculated. These data were correlated with patients' verbal fluency performance at dorsal, optimal, and ventral stimulation contacts.ResultsIn contrast to STN findings, there was no significant relationship between stimulation location and fluency performance in patients who received GP DBS.Conclusion(s)These results suggest that fluency may be less sensitive to stimulation location in the globus pallidus and thus there may be more flexibility in terms of DBS programming with GP DBS patients.     

Deep Brain Stimulation (DBS) attentional effects parallel those of l-dopa treatment

Summary. Aim of our study was to investigate the different effects on attentional capacity of deep brain stimulation DBS (STN or GPi) and of l-dopa in PD patients. Patients were evaluated on-DBS/off-l-dopa, on-l-dopa/off-DBS, on-l-dopa/on-DBS and off-l-dopa/off-DBS. Our results indicate that DBS effects on attentional functions parallel those of l-dopa. A site independent (both STN and GPi) worsening of verbal fluency was observed, possibly connected to the stimulus effect on the cortico-subcortical-cortical loop. Received December 11, 2000; accepted March 1, 2001     

Pallidal stimulation in advanced Parkinson's patients with contraindications for subthalamic stimulation

The aim of this study was to evaluate the efficacy and safety of bilateral pallidal (GPi) deep brain stimulation (DBS) 6 months after surgery in advanced parkinsonian patients whose dopa‐resistant axial motor signs or cognitive decline constituted contraindications for subthalamic nucleus (STN) DBS. Seventeen patients with a mean age of 59.3 ± 7.1 years (range, 45–70), mean disease duration of 12.5 ± 4.3 years (range, 7–20), and contraindications for STN DBS, underwent bilateral GPi DBS. They were evaluated before surgery and 6 months afterward, in accordance with Core Assessment Program for Intracerebral Transplantation recommendations. There were mean improvements of 41.1% in the UPDRS III motor score in the off‐dopa condition and 20.3% in the activities of daily living score. Motor fluctuations were reduced by 22.9% and dyskinesias by 68.6%. Axial motor signs improved in the off‐dopa condition by 34.2%. Neuropsychological performances remained unchanged at the 6‐month assessment. Bilateral GPi DBS is both safe and effective in advanced parkinsonian patients with untreatable motor fluctuations, for whom STN DBS is contraindicated due to dopa‐resistant axial motor signs or cognitive decline. As such, it should be regarded as a viable option for these patients. © 2010 Movement Disorder Society     

Long‐term effects of pallidal or subthalamic deep brain stimulation on quality of life in Parkinson's disease

We assessed the effects of deep brain stimulation of the subthalamic nucleus (STN‐DBS) or internal pallidum (GPi‐DBS) on health‐related quality of life (HrQoL) in patients with advanced Parkinson's disease participating in a previously reported multicenter trial. Sickness Impact Profile (SIP) questionnaires were available for analysis in a subgroup of n = 20/20 patients with GPi‐DBS and n = 45/49 patients with STN‐DBS at baseline, 6 and 36 months. The SIP provides a physical dimension and a psychosocial dimension sum score and 12 category scores: Alertness/Intellectual Behavior (AIB), Ambulation (A), Body Care and Movement (BCM), Communication (C), Eating (E), Emotional Behavior (EB), Home Management (HM), Mobility (M), Recreation and Pastimes (RP), Sleep and Rest (SR), Social Interaction (SI), and Work (W). Motor functioning was assessed by means of the Unified Parkinson's Disease Rating Scale and diaries. At 6 months significant improvements in off‐period motor symptoms and activities of daily living were paralleled by significant reductions in the total, physical, and psychosocial SIP score in both treatment groups. At 3 years, sustained improvements were observed in the physical dimension score, BCM, E, M, RP after STN‐DBS and M, SI after GPi‐DBS. All other SIP subscores approached baseline values, but were still the same or better (except C) whereas motor functioning remained stable after 36 months. STN‐DBS and GPi‐DBS led to significant early improvements in HrQoL. Despite sustained motor improvements many of these initial benefits were lost after 3 years. This may reflect either progression of the disease or adaptive changes in the subjective perception of health‐related wellbeing over time. © 2009 Movement Disorder Society     

Which target for DBS in Parkinson's disease? Subthalamic nucleus versus globus pallidus internus

We selected 14 patients with advanced idiopathic Parkinson's disease (PD) and examined the clinical effects of STN DBS versus GPi DBS. Nine patients underwent bilateral STN DBS and five underwent bilateral GPi patients. All patients were followed for at least 12 months. The evaluation was performed on and off drug before surgery; on-drug/on-DBS and off-drug/on-DBS at 1, 2, 6 and 12 months after stereotactic surgery. At 1 and 3 months after surgery in off-drug/on-DBS condition, both groups showed an improvement in motor score (UPDRS II). Nevertheless, the results changed after long-term stimulation in the two groups. Chronic STN DBS is superior to GPi DBS in the amelioration of the clinical features and in the decrease of time spent in the off state. The efficacy in reduction of LID was comparable at 1 and 3 months after surgery, but the results were better in STN DBS after chronic stimulation. The L-dopa dose was reduced only in the STN group.     

Comparison of weight gain and energy intake after subthalamic versus pallidal stimulation in Parkinson's disease

To compare body mass index (BMI) and daily energy intake (DEI) after subthalamic versus pallidal deep brain stimulation (DBS). Weight gain following DBS in Parkinson's disease patients remains largely unexplained and no comparison of subthalamic and pallidal (GPi) stimulation has yet been performed. BMI and DEI, dopaminergic drug administration and motor scores were recorded in 46 patients with PD before STN (n = 32) or GPi (n = 14) DBS and 3 and 6 months after. At M6, BMI had increased by an average of 8.4% in the STN group and 3.2% in the GPi group. BMI increased in 28 STN and 9 GPi patients. This increase was significantly higher in the STN group (P < 0.048) and the difference remained significant after adjustment for reduced dopaminergic medication; 28.6% of GPi patients were overweight at 6 months (14.3% preoperatively) versus 37.5% of STN patients (21.9% preoperatively). Changes in BMI were negatively correlated with changes in dyskinesia in the GPi–DBS group. Food intake did not change in the two groups, either quantitatively or qualitatively. Frequent weight gain, inadequately explained by motor improvement or reduced dopaminergic drug dosage, occurred in subthalamic DBS patients. The difference between groups suggests additional factors in the STN group, such as homeostatic control center involvement. © 2009 Movement Disorder Society     

Acute Changes in Mood Induced by Subthalamic Deep Brain Stimulation in Parkinson Disease Are Modulated by Psychiatric Diagnosis

BackgroundDeep brain stimulation of the subthalamic nucleus (STN DBS) reduces Parkinson disease (PD) motor symptoms but has unexplained, variable effects on mood.ObjectiveThe study tested the hypothesis that pre-existing mood and/or anxiety disorders or increased symptom severity negatively affects mood response to STN DBS.MethodsThirty-eight PD participants with bilateral STN DBS and on PD medications were interviewed with Structured Clinical Interview for DSM-IV-TR Axis I Disorders (SCID) and completed Beck Depression Inventory (BDI) and Spielberger State Anxiety Inventory (SSAI) self-reports. Subsequently, during OFF and optimal ON (clinical settings) STN DBS conditions and while off PD medications, motor function was assessed with the United Parkinson Disease Rating Scale (UPDRS, part III), and participants rated their mood with Visual Analogue Scales (VAS), and again completed SSAI. VAS mood variables included anxiety, apathy, valence and emotional arousal.ResultsSTN DBS improved UPDRS scores and mood. Unexpectedly, PD participants diagnosed with current anxiety or mood disorders experienced greater STN DBS-induced improvement in mood than those diagnosed with remitted disorders or who were deemed as having never met threshold criteria for diagnosis. BDI and SSAI scores did not modulate mood response to STN DBS, indicating that clinical categorical diagnosis better differentiates mood response to STN DBS than self-rated symptom severity. SCID diagnosis, BDI and SSAI scores did not modulate motor response to STN DBS.ConclusionsPD participants diagnosed with current mood or anxiety disorders are more sensitive to STN DBS-induced effects on mood, possibly indicating altered basal ganglia circuitry in this group.     

Deep brain stimulation in the treatment of Parkinson's disease: a review and update

Deep brain stimulation (DBS) is a neurosurgical treatment of severe forms of Parkinson's disease, already applied to three targets, the thalamus, the internal pallidum (GPi) and the subthalamic nucleus (STN). Thalamic DBS mainly improves contralateral tremor and is therefore restricted to a small group of patients with tremor dominant disease. STN and GPi DBS improve off-motor periods and dyskinesias. The magnitude of the improvement seems more constant with STN DBS than with GPi, but there is very little comparative data between these procedures. The DBS procedure has the unique advantage of reversibility and adjustability over time. Most authors agree that bilateral DBS is reasonably safe, which is not the case of ablation. In any event, surgery is restricted to patients disabled by their condition but still responding well at times to levodopa, who are generally fit with no behavioural, mood or cognitive impairment. DBS can have side effects. Side effects more specific to the DBS procedure are infection, disconnection and hardware failure. DBS, like ablative surgery can induce an intracranial lesion like a hematoma or a stroke. There are side effects more specific to the target like postural instability, dysarthria or paresthesia in the thalamus and dyskinesias or eyelid opening apraxia in the STN. The mechanism by which high frequency DBS mimics the effect of ablation is not fully understood.     

Changes in cognitive‐emotional and physiological symptoms of depression following STN‐DBS for the treatment of Parkinson’s disease

Background and purpose: Subthalamic nucleus deep brain stimulation (STN‐DBS) has been shown to have beneficial effects on the motor features of Parkinson’s disease (PD), but its impact on non‐motor symptoms, most notably mood, has not been fully explored. Methods: In the first study to independently compare the emotional‐cognitive and somatic/physiological symptoms of depression, we examined mood differences in 17 bilateral STN‐DBS and 22 matched non‐surgical PD patients at baseline and 6 months. Results: The STN‐DBS group reported higher levels of depression at baseline with significant endorsement of physical symptomatology. Postoperatively, no significant between‐group differences in physical symptoms of depression were found. In contrast, a significant group by time interaction for cognitive‐emotional symptoms of depression was found, with the STN‐DBS group reporting an increase in psychological symptoms of distress. The STN‐DBS group also reported an increase in anxiety following surgery. The suicide rate of 5% found in our study is consistent with other postoperative studies in PD. The impact of changes in levodopa and psychotropic medication are also explored. Conclusions: Preliminary results suggest that the motor improvement often observed in patients with PD following bilateral STN‐DBS may be partially offset by an increase in affective‐cognitive symptoms of depression.