Bilateral Subthalamic Nucleus Stimulation Research Articles

Bilateral subthalamic nucleus stimulation for generalized dystonia after bilateral pallidotomy

Thalamotomies and pallidotomies were commonly performed before the deep brain stimulation (DBS) era. Although ablative procedures can lead to significant dystonia improvement, longer periods of analysis reveal disease progression and functional deterioration. Today, the same patients seek additional treatment possibilities. Four patients with generalized dystonia who previously had undergone bilateral pallidotomy came to our service seeking additional treatment because of dystonic symptom progression. Bilateral subthalamic nucleus DBS (B-STN-DBS) was the treatment of choice. The patients were evaluated with the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and the Unified Dystonia Rating Scale (UDRS) before and 2 years after surgery. All patients showed significant functional improvement, averaging 65.3% in BFMDRS (P = .014) and 69.2% in UDRS (P = .025). These results suggest that B-STN-DBS may be an interesting treatment option for generalized dystonia, even for patients who have already undergone bilateral pallidotomy.

Effects of Simultaneous Bilateral Subthalamic Nucleus and Pedunculopontine Nucleus Deep Brain Stimulation on Saccades in Advanced Parkinson Disease

Effects of Simultaneous Bilateral Subthalamic Nucleus and Pedunculopontine Nucleus Deep Brain Stimulation on Saccades in Advanced Parkinson Disease

Somatomotor mu rhythm amplitude correlates with rigidity during deep brain stimulation in Parkinsonian patients

ObjectiveParkinsonian patients have abnormal oscillatory activity within the basal ganglia-thalamocortical circuitry. Particularly, excessive beta band oscillations are thought to be associated with akinesia. We studied whether cortical spontaneous activity is modified by deep brain stimulation (DBS) in advanced Parkinson’s disease and if the modifications are related to the clinical symptoms. MethodsWe studied the effects of bilateral electrical stimulation of subthalamic nucleus (STN) on cortical spontaneous activity by magnetoencephalography (MEG) in 11 Parkinsonian patients. The artifacts produced by DBS were suppressed by tSSS algorithm. ResultsDuring DBS, UPDRS (Unified Parkinson’s Disease Rating Scale) rigidity scores correlated with 6–10Hz and 12–20Hz somatomotor source strengths when eyes were open. When DBS was off UPDRS action tremor scores correlated with pericentral 6–10Hz and 21–30Hz and occipital alpha source strengths when eyes open.Occipital alpha strength decreased during DBS when eyes closed. The peak frequency of occipital alpha rhythm correlated negatively with total UPDRS motor scores and with rigidity subscores, when eyes closed. ConclusionSTN DBS modulates brain oscillations both in alpha and beta bands and these oscillations reflect the clinical condition during DBS. SignificanceMEG combined with an appropriate artifact rejection method enables studies of DBS effects in Parkinson’s disease and presumably also in the other emerging DBS indications.

Effects of varying subthalamic nucleus stimulation on apraxia of lid opening in Parkinson’s disease

Apraxia of lid opening (ALO) is a non-paralytic inability to open the eyes or sustain lid elevation at will. The exact pathophysiological mechanisms underlying the syndrome are still unknown. ALO has been reported in patients with Parkinson's disease (PD) after subthalamic nucleus (STN) deep brain stimulation (DBS), suggesting a possible involvement of the basal ganglia. We aimed to assess the effects of varying STN stimulation voltage on ALO in PD patients. Seven out of 14 PD patients with bilateral STN stimulation consecutively seen in our centre presented with ALO. We progressively increased voltage on each STN, using either 130 Hz (high-frequency stimulation, HFS) or 2 or 3 Hz (low-frequency stimulation, LFS). In five patients, HFS induced ALO time-locked to stimulation in 7 out of 10 STNs at a voltage higher than that used for chronic stimulation. LFS induced myoclonus in the pretarsal orbicularis oculi muscle (pOOm) with a rhythm synchronous to the frequency. In the other two patients with ALO already present at the time of the study, HFS improved ALO in 3 out of 4 STNs. ALO recurred within minutes of stimulation arrest. Our findings show that STN-DBS can have opposite effects on ALO. On the one hand, ALO is thought to be a corticobulbar side effect due to lateral current spreading from the STN, in which case it is necessary to use voltages below the ALO-inducing threshold. On the other hand, ALO may be considered a form of off-phase focal dystonia possibly improved by increasing the stimulation voltages.

Chronic bilateral subthalamic stimulation after anterior callosotomy in drug-resistant epilepsy: Long-term clinical and functional outcome of two cases

We explored the efficacy and safety of bilateral SubThalamic Nucleus (STN) stimulation in two subjects suffering from drug-resistant epilepsy even after anterior callosotomy. Case 1 had about 65% decrease of partial motor seizures and the complete disappearance of tonic-clonic generalized attacks. Case 2, with sudden drop (atonic) attacks, partial complex seizures, atypical absences and rare tonic-clonic seizures, showed no meaningful reduction of fits and a stimulation associated atypical absence rate increase.

Combined pallidal and subthalamic nucleus stimulation in sporadic dystonia-parkinsonism

Multifocal deep brain stimulation (DBS) is a new technique that has been introduced recently. A 39-year-old man with dystonia-parkinsonism underwent the simultaneous implantation of subthalamic nucleus (STN) and globus pallidus internus (GPi) DBS electrodes. While bilateral STN DBS controlled the parkinsonian symptoms well and allowed for a reduction in levodopa, the improvement of dystonia was only temporary. Additional GPi DBS also alleviated dystonic symptoms. Formal assessment at the 1-year follow-up showed that both the parkinsonian symptoms and the dystonia were markedly improved via continuous bilateral combined STN and GPi stimulation. Sustained benefit was achieved at 3 years postoperatively.

Familial Aggregation of Panic Disturbances in Parkinson's Disease

Familial Aggregation of Panic Disturbances in Parkinson's Disease

Deep Brain Stimulation of Subthalamic Nuclei Affects Arm Response Inhibition In Parkinson's Patients

The precise localizations of the neural substrates of voluntary inhibition are still debated. It has been hypothesized that, in humans, this executive function relies upon a right-lateralized pathway comprising the inferior frontal gyrus and the presupplementary motor area, which would control the neural processes for movement inhibition acting through the right subthalamic nucleus (STN). We assessed the role of the right STN, via a countermanding reaching task, in 10 Parkinson's patients receiving high-frequency electrical stimulation of the STN of both hemispheres (deep brain stimulation, DBS) and in 13 healthy subjects. We compared the performance of Parkinson's patients in 4 experimental conditions: DBS-ON, DBS-OFF, DBS-OFF right, and DBS-OFF left. We found that 1) inhibitory control is improved only when both DBS are active, that is, the reaction time to the stop signal is significantly shorter in the DBS-ON condition than in all the others, 2) bilateral stimulation of STN restores the inhibitory control to a near-normal level, and 3) DBS does not cause a general improvement in task-related motor function as it does not affect the length of the reaction times of arm movements, that is, in our experimental context, STN seems to play a selective role in response inhibition.

Pain due to osteoarthritis may impair the early outcome of deep brain stimulation in Parkinson's disease

Objective To analyse postoperative pain due to osteoarthritis in patients with Parkinson's disease submitted to bilateral subthalamic nucleus stimulation. Methods Fifty-three parkinsonian patients (mean age, 59.9 ± 8.3 years; mean disease duration, 11.5 ± 4.2 years) referred for subthalamic nucleus stimulation were enrolled. Patients were prospectively asked to refer and describe any pain due to osteoarthritis they experienced at any time during the preoperative period and within the 6 postoperative months. Pre-existing pain due to osteoarthritis, therapeutic changes, parkinsonian motor disability and weight gain were assessed as explanatory factors for occurrence pain due to osteoarthritis after surgery. Results After surgery, thirty patients (57%) complained of pain due to osteoarthritis whereas all demonstrated great functional improvement. Twenty (67%) among the 30 experienced similar pain sensation before surgery. Symptoms occurred rapidly, between 4 and 26 postoperative weeks. Multiple stepwise regression analysis showed that pre-existing pain due to osteoarthritis, 6-month postoperative UPDRS III motor score and axial sub-score improvements in the off-drug/ on-stimulation condition were accurate independent predictors of pain due to osteoarthritis after surgery ( F(8, 41) = 2.20, p < 0.047). Conclusion Our results highlight the high prevalence of pain due to osteoarthritis arising shortly after subthalamic implantation. An accurate pain and osteo-articular assessment should be performed preoperatively in parkinsonian candidates for subthalamic nucleus stimulation in order to limit occurrence of complications in the early postoperative period.

The Need for a Multifactorial Approach to Raise the Standard in Deep Brain Stimulation Reporting

Deep brain stimulation (DBS) has been demonstrated to be an effective therapeutic strategy for the treatment of pharmacologically refractory Parkinson disease (PD) ( 1. Kleiner-Fisman G Herzog J Fisman DN et al. Subthalamic nucleus deep brain stimulation: summary and meta-analysis of outcomes. Mov Disord. 2006; 21: S290-S304 Crossref Scopus (761) Google Scholar ). Since its renaissance in 1987 ( 2. Benabid AL Pollak P Louveau A Henry S de Rougemont J Combined (thalamotomy and stimulation) stereotactic surgery of the VIM thalamic nucleus for bilateral Parkinson disease. Appl Neurophysiol. 1987; 50: 344-346 PubMed Google Scholar , 3. Hariz MI Blomstedt P Zrinzo L Deep brain stimulation between 1947 and 1987: the untold story. Neurosurg Focus. 2010; 29: E1 Crossref Scopus (150) Google Scholar ), it has become widely accepted in the movement disorders community with more than 33,000 patients currently implanted. Targets have evolved from the ventral intermediate nucleus of the thalamus ( 2. Benabid AL Pollak P Louveau A Henry S de Rougemont J Combined (thalamotomy and stimulation) stereotactic surgery of the VIM thalamic nucleus for bilateral Parkinson disease. Appl Neurophysiol. 1987; 50: 344-346 PubMed Google Scholar , 4. Benabid AL Pollak P Gervason C et al. Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus. Lancet. 1991; 337: 403-406 Abstract PubMed Scopus (1393) Google Scholar ) to the globus pallidus internus ( 5. Siegfried J Lippitz B Bilateral chronic electrostimulation of ventroposterolateral pallidum: a new therapeutic approach for alleviating all parkinsonian symptoms. Neurosurgery. 1994; 35 (discussion 1129–1130): 1126-1129 Crossref PubMed Scopus (409) Google Scholar ), subsequently to the subthalamic nucleus (STN) ( 6. Pollak P Benabid AL Gross C et al. [Effects of the stimulation of the subthalamic nucleus in Parkinson disease]. Rev Neurol (Paris). 1993; 149: 175-176 PubMed Google Scholar ), and recently to the pedunculopontine nucleus ( 7. Stefani A Lozano AM Peppe A et al. Bilateral deep brain stimulation of the pedunculopontine and subthalamic nuclei in severe Parkinson’s disease. Brain. 2007; 130: 1596-1607 Crossref PubMed Scopus (636) Google Scholar ). While debate exists with respect to the optimal therapeutic target ( 8. Okun MS Foote KD Subthalamic nucleus vs globus pallidus interna deep brain stimulation, the rematch: will pallidal deep brain stimulation make a triumphant return?. Arch Neurol. 2005; 62: 533-536 Crossref PubMed Scopus (64) Google Scholar , 9. Minguez-Castellanos A Escamilla-Sevilla F Pallidal vs subthalamic deep brain stimulation for Parkinson disease: winner and loser or a sharing of honors?. Arch Neurol. 2005; 62 (author reply 1643): 1642-1643 Crossref Google Scholar ), DBS of STN is the most common surgical intervention for PD ( 10. Benabid AL Chabardes S Mitrofanis J Pollak P Deep brain stimulation of the subthalamic nucleus for the treatment of Parkinson’s disease. Lancet Neurol. 2009; 8: 67-81 Abstract Full Text Full Text PDF PubMed Scopus (971) Google Scholar ). DBS of the STN has resulted in substantial motor improvements and often leads to a significant reduction in levodopa administration ( 11. Molinuevo JL Valldeoriola F Tolosa E et al. Levodopa withdrawal after bilateral subthalamic nucleus stimulation in advanced Parkinson disease. Arch Neurol. 2000; 57: 983-988 Crossref PubMed Scopus (191) Google Scholar ). Now that these major advances in motor function have been achieved, the apparent limbic side-effects of DBS have come into greater focus ( 12. Okun MS Green J Saben R Gross R Foote KD Vitek JL Mood changes with deep brain stimulation of STN and GPi: results of a pilot study. J Neurol Neurosurg Psychiatry. 2003; 74: 1584-1586 Crossref PubMed Scopus (93) Google Scholar ).

Changes in Speech Characters of Patients With Parkinson’s Disease After Bilateral Subthalamic Nucleus Stimulation

To investigate the effects of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on acoustic characteristics of speech in Chinese patients with Parkinson's disease (PD). Eleven patients (five men and six women) diagnosed with PD participated in this study. Motor disabilities and speech samples were evaluated and recorded under six different conditions according to the states of medication and stimulation. Motor disabilities were evaluated with the Unified Parkinson's Disease Rating Scale (UPDRS). Acoustic signals were recorded from the subjects during production of sustained vowels /a/, /i/, and/u/; repetitions of /pataka/; and sentence production tasks. Acoustic analysis was performed with the Multidimensional Voice Program (MDVP), the Motor Speech Profile (MSP), and Computerized Speech Lab (CSL) (Kay Elemetrics, Lincoln Park, NJ). Based on the UPDRS III scores, the motor ability of the patients improved. There was almost no change in the speech score, which was also supported by the instrumental analysis of PD speech. This indicated that bilateral STN-DBS was associated with a significant improvement in the patients' motor disabilities but did not have much influence on speech performance during the short time after the stimulation switch was turned on. Furthermore, gender-related differences for speech performance were demonstrated, with the vowel /i/ being more sensitive. These results are consistent with previous studies that have reported disparity between limb and speech improvements after neurosurgical intervention for PD, such as STN-DBS. The long-term effects of STN-DBS on Parkinsonian speech of Chinese patients should be studied further.

Change of the melanocortin system caused by bilateral subthalamic nucleus stimulation in Parkinson’s disease

OBJECTIVES - Determine whether bilateral subthalamic nucleus stimulation (STN-DBS) in Parkinson's disease (PD) is associated with an increase in neuropeptide Y (NPY) and/or resistance to inhibition by leptin in relation to post-surgery weight gain. MATERIALS AND METHODS - This prospective study included 20 patients who underwent bilateral STN-DBS and 17 who refused surgery. Data were obtained at baseline, 3 and 6 months on neurological and nutritional status, including determination of body mass index (BMI) and serum NPY and leptin levels. RESULTS - NPY and leptin levels changed over time, with a distinct pattern. The BMI increase at 6 months was greater in the surgical group (5.5 ± 6.3% vs 0.5 ± 3.5%; P = 0.035). Medical group exhibited a reduction in leptin level (-2.0 ± 4.3 ng/ml) and a consequent increase in NPY level (72.4 ± 58.7 pmol/ml). However, STN-DBS patients showed an increase in leptin (3.1 ± 5.0 ng/ml; P = 0.001 vs medical group) and also in NPY (12.1 ± 53.6 pmol/ml; P = 0.022 vs medical group) levels, which suggests resistance to inhibition by leptin. Rise in NPY level correlated with higher stimulation voltages. CONCLUSIONS - Bilateral STN-DBS causes disruption of the melanocortin system, probably related to diffusion of the electric current to the hypothalamus. This mechanism may in part explain the weight gain of patients with PD after surgery.

Electrode Position and the Clinical Outcome after Bilateral Subthalamic Nucleus Stimulation

We compared the surgical outcome with electrode positions after bilateral subthalamic nucleus (STN) stimulation surgery for Parkinson's disease. Fifty-seven patients treated with bilateral STN stimulations were included in this study. Electrode positions were determined in the fused images of preoperative MRI and postoperative CT taken at six months after surgery. The patients were divided into three groups: group I, both electrodes in the STN; group II, only one electrode in the STN; group III, neither electrode in the STN. Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn and Yahr stage, and activities of daily living scores significantly improved at 6 and 12 months after STN stimulation in both group I and II. The off-time UPDRS III speech subscore significantly improved (1.6 ± 0.7 at baseline vs 1.3 ± 0.8 at 6 and 12 months, P < 0.01) with least L-dopa equivalent daily dose (LEDD) (844.6 ± 364.1 mg/day at baseline; 279.4 ± 274.6 mg/day at 6 months; and 276.0 ± 301.6 mg/day at 12 months, P < 0.001) at 6 and 12 months after STN deep brain stimulation (DBS) in the group I. Our findings suggest that the better symptom relief including speech with a reduced LEDD is expected in the patients whose electrodes are accurately positioned in both STN.

The relevance of age and disease duration for intervention with subthalamic nucleus deep brain stimulation surgery in Parkinson disease

The optimal age and disease duration for consideration of deep brain stimulation (DBS) surgery are not well characterized in patients with Parkinson disease. The aim of this study was to assess variation in motor response to surgery among subgroups stratified by age and disease duration. A total of 46 patients referred for DBS were recruited for the study. Preoperative dyskinesia and rigidity scores were recorded, and then patients received bilateral subthalamic nucleus stimulation. Preoperative motor scores were then compared with postoperative scores over 1 year. At 1 year postoperatively, patients with ≤ 10 years' disease duration showed a significant (45%) reduction in rigidity and a significant (64%) reduction in dyskinesia. Patients with > 10 years disease also showed a significant (70%) reduction in dyskinesia at 1 year postoperatively, but failed to show significant improvement in rigidity (31% reduction). Patients < 70 years old showed a significant (58%) improvement in rigidity and a significant (53%) improvement in dyskinesia. Finally, patients ≥ 70 years old showed a significant (90%) improvement in dyskinesia, but failed to show any significant change in rigidity at 1 year postoperatively. The postoperative improvement in rigidity for younger patients with shorter disease duration may indicate that performing early surgery maximizes the benefit of DBS. However, older patients with primarily dyskinesia symptoms also appear to have significant clinical improvement, and DBS can offer relief from this common consequence of long-term levodopa use.

POD06 Human pedunculopontine nucleus displays vestibular reactivity

We recorded local field potentials (LFPs) in a patient with implanted bilateral subthalamic nucleus (STN) and pedunculopontine nucleus (PPN) deep brain stimulation (DBS) electrodes at 2 kHz and filtered at...

Long-term follow-up of deep brain stimulation for Meige syndrome

Meige syndrome is characterized by blepharospasm, cervical dystonia, and facial oromandibular dystonia. The medical treatment of this condition is largely unsuccessful over time and is a major source of decreased quality of life in those patients suffering from this disease. Recent advances in the application of deep brain stimulation (DBS) surgery techniques for many disorders have prompted several recent reports of DBS for medically refractory cases of Meige syndrome. While the etiology for this disorder is unknown, it is considered by many investigators to be a form of idiopathic torsion dystonia. Pallidal stimulation is widely considered to be effective for dystonia. The authors report the long-term results of bilateral globus pallidus internus (GPi) or subthalamic nucleus (STN) stimulation in 3 patients with Meige syndrome and 1 patient with Parkinson disease and associated craniofacial dystonia treated at their center. Initial 12-month and long-term follow-up Burke-Fahn-Marsden scores were substantially improved in all 4 patients compared with preoperative scores. Bilateral GPi DBS may be an effective and safe treatment for medically refractory Meige syndrome. The results are comparable with those reported in the literature. Sustained and long-term improvement in symptoms does appear to be reproducible across reports. The authors' patient with Parkinson disease and associated craniofacial dystonia syndrome undergoing bilateral STN DBS noted immediate and sustained improvement in his symptoms. Further study is required, but these results, along with the other reports, suggest that bilateral GPi DBS is an effective treatment for medically refractory Meige syndrome.

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.

Do the effects measured by intraoperative and postoperative STN macrostimulation in Parkinson’s disease match?

The aim of our study was to compare the results obtained by intraoperative and postoperative subthalamic nucleus (STN) macrostimulation in Parkinson's disease (PD). One hundred three PD patients implanted with bilateral STN stimulation were included. The thresholds for efficacy and side effects (motor contraction; paresthesias; oculomotor signs) observed on the same trajectory and at the same depth during the intraoperative evaluation and the first postoperative setting of STN stimulation parameters were collected. The level of improvement was divided into four categories depending on the degree of rigidity reduction: 0: no effect, A (mediocre efficacy): 20-50%, B (good efficacy): 60-100%, LL: lesion-like effect (disappearance of rigidity after implantation). Efficacy of STN stimulation was analyzed in 83 patients for a total of 664 contacts. For the best effects (B, LL), the results obtained in the operative room were concordant with those of the postoperative evaluation for 81% of the contacts. For the mediocre effects (A) and absence of efficacy, the results were only concordant in 20%. Side effects were analyzed in 103 patients for a total of 824 contacts. In 35% of the tested contacts paresthesias that were absent during surgery were observed postoperatively. This discrepancy was of 17% for the motor and of 10% for oculomotor side effects. Differences between the type of electrodes used, the stimulation parameters employed and the conditions of the assessment could explain these discrepancies.

Complex repetitive behavior: Punding after bilateral subthalamic nucleus stimulation in Parkinson's disease

“Punding” is the term used to describe a stereotyped motor behavior characterized by an intense fascination with repetitive purposeless movements, such as taking apart mechanical objects, handling common objects as if they were new and entertaining, constantly picking at oneself, etc. As a phenomenon with both impulsive and compulsive features, the phenomenology of punding is currently being questioned. In order to investigate the pathophysiology of this phenomenon, we screened a population of Parkinson's disease (PD) outpatients who underwent subthalamic nucleus deep brain stimulation (STN DBS). We conducted a patient-and-relative-completed survey with 24 consecutive patients in an academic outpatient care center, using a modified version of a structured interview. Patients were administered the Unified Parkinson's Disease Rating Scale (UPDRS), the Obsessive–Compulsive Inventory and the Sheehan Disability Scale. Five (20.8%) of the 24 subjects were identified as punders, including three men (60%) and two women. The punders were comparable to the non-punders in terms of clinical and demographic factors. The punder and non-punder groups only differed statistically with regard to the length of time from DBS implantation. Those findings suggest that punding might be induced by STN DBS, and its rate of occurrence in DBS population seems to be more common than previously suspected.

Bilateral subthalamic nucleus stimulation in the treatment of advanced Parkinson's disease. Five years' personal experience

Background and purposeThe objective of the study was to assess bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) for patients with advanced Parkinson disease (PD). Material and methodsThe study population included 5 patients with bilateral STN DBS who completed a 5-year postoperative follow-up period. In all patients electrodes (Model 3387 or 3389) were stereotactically bilaterally inserted into the STN using a Leksell stereotactic G frame. The clinical rating tests included Unified Parkinson's Disease Rating Scale (UPDRS) and two motor-timed tests derived from CAPIT (rapid movements between two points and stand-walk-sit test). All patients were assessed in off and on condition before implantation and 1, 3 and 5 years in medication on and off condition and stimulation on condition and stimulation off condition. To compare preoperative to postoperative UPDRS scores, only mean values and standard deviations are presented because of the small study population. ResultsThe stimulation effect was noted in the off state, resulting in a 59% improvement in motor scores of UPDRS at 5-year follow-up, when compared to preoperative scores. In the on state the stimulation improved motor scores by 17%. At 5-year follow-up, reduction of daily levodopa dose was 50%. ConclusionsBilateral STN DBS is an effective and safe treatment for patients with advanced PD. Bilateral STN DBS contributes to improvement of parkinsonian symptoms in the off state and levodopa-induced dyskinesia. This can be correlated with a 50% reduction of daily levodopa dose 5 years postoperatively.