Pallidal surgery for the treatment of primary generalized dystonia: long-term follow-up

OBJECTIVE: To describe the results and long-term follow-up after functional surgery of the internal segment of the globus pallidus (GPi) in 10 patients with primary generalized dystonia. PATIENTS AND METHODS: Nine of the 10 patients were positive for the DYT1 gene mutation. Bilateral deep brain stimulation (DBS) of the GPi was performed in three cases, bilateral pallidotomy in two, and combined surgery (unilateral GPi lesion with contralateral stimulation) in the remaining five. All patients were evaluated with the Burke-Fahn-Marsden dystonia scale (BFMDS) before, immediately after surgery, at 3 weeks, 3 and 6 months and then yearly. Follow up time ranged from 15 to 105 months (mean: 66.1 months) with six patients having more than 6 years follow up. RESULTS: All patients improved after surgery. All patients with unilateral or bilateral DBS experienced an immediate improvement before starting stimulation. The magnitude of this initial micro lesion effect did not predict the magnitude of the long-term benefit of DBS. The mean decrease in the in the BFMDS was 34%, 55%, and 65% in the movement scale; and 32%, 48%, and 49% in the disability scale for patients with bilateral pallidal DBS, combined unilateral DBS and contralateral pallidotomy, and bilateral pallidotomy, respectively. Worsening of dystonia after a plateau of sustained benefit was observed in three patients. Two patients required multiple pallidal surgeries. Adverse events included: permanent anarthria (1), misplacement of the electrode requiring further surgery (2), scalp infection (1), and hardware related problems (3). CONCLUSIONS: This long-term follow up study confirms the beneficial effect of pallidal DBS or pallidotomy in primary generalized dystonia. In addition, our results extent previous observations by showing that, in these patients, (1) the microlesion effect of DBS is not predictive of long-term benefit; (2) combined DBS with contralateral pallidotomy appears to be more effective than bilateral pallidal DBS; and (3) dystonia can reappear after an initial good response during long term follow up.     

The Influence of Deep Brain Stimulation Intensity and Duration on Symptoms Evolution in an OFF Stimulation Dystonia Study

BackgroundDeep brain stimulation (DBS) of the internal globus pallidus (GPi) is an established therapy for primary generalized dystonia. However, the evolution of dystonia symptoms after DBS discontinuation after years of therapy has only rarely been reported. We therefore longitudinally studied the main physiological measurements known to be impaired in dystonia, with DBS ON and then again after termination of DBS, after at least five years of continuous DBS.ObjectiveWe studied whether dystonia evolution after DBS discontinuation in patients benefiting from long-term GPi DBS is different from that observed in earlier stages of the therapy.MethodsIn eleven DYT1 patients treated with bilateral GPi DBS for at least 5 years, dystonia was assessed ON-DBS, immediately after switch-off (OFF-DBS1) and 48 h after DBS termination (OFF-DBS2). We studied the influence of DBS intensity on dystonia when DBS was discontinued.ResultsOn average a significant difference in symptoms was measured only between ON-DBS and OFF-DBS1 conditions. Importantly, none of the patients returned to their preoperative dystonia severity, even 48 h after discontinuation. The amount of clinical deterioration in the OFF conditions positively correlated with higher stimulation current in the chronic ON-DBS condition.ConclusionsThe duration of DBS application influences symptom evolution after DBS termination. DBS intensity seems to have a prominent role on evolution of dystonic symptoms when DBS is discontinued. In conclusion, DBS induces changing modulation of the motor network with less worsening of symptoms after long term stimulation, when DBS is stopped.     

DYT6 dystonia: Mutation screening,phenotype, and response to deep brain stimulation

Mutations in THAP1, a gene encoding a nuclear pro‐apoptotic protein, have been associated with DYT6 dystonia. First reports on the phenotype of DYT6 dystonia show an early onset dystonia with predominant cranio‐cervical and laryngeal involvement. Here we assessed the frequency and phenotype of THAP1 mutation carriers in a large Dutch cohort of adult‐onset (≥26 years) dystonia (n = 388) and early‐onset dystonia (n = 67) patients. We describe the phenotype of DYT6 dystonia patients and their response on GPi DBS. Overall, 3 nonsynonymous heterozygous mutations were detected in the early‐onset group (4.5%). Two DYT6 families were identified, showing a heterozygous phenotype. All patients had segmental or generalized dystonia, often associated with profound oromandibular and laryngeal involvement. No nonsynonymous mutations were found in patients with adult‐onset focal dystonia. Rare synonymous variants were identified in conserved regions of THAP1, two in the adult‐onset cervical dystonia group and one in the control group. Four DYT6 dystonia patients were treated with GPi DBS with moderate to good response on motor function but marginal benefit on speech. © 2010 Movement Disorder Society     

Bilateral deep brain stimulation of the globus pallidus internus in tardive dystonia

Tardive dystonia is a disabling movement disorder as a consequence of exposure to neuroleptic drugs. We followed 6 patients with medically refractory tardive dystonia treated by bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) for 21 ± 18 months. At last follow‐up, the Burke‐Fahn‐Marsden Dystonia Rating Scale (BFMDRS) motor score improved by 86% ± 14%, and the BFMDRS disability score improved by 80% ± 12%. Bilateral GPi‐DBS is a beneficial therapeutic option for the long‐term relief of tardive dystonia. © 2008 Movement Disorder Society     

Pallidal and thalamic deep brain stimulation in myoclonus‐dystonia

Deep brain stimulation (DBS) of the internal globus pallidus (GPi) and ventral intermediate thalamic nucleus (VIM) are established treatment options in primary dystonia and tremor syndromes and have been reported anecdotally to be efficacious in myoclonus‐dystonia (MD). We investigated short‐ and long‐term effects on motor function, cognition, affective state, and quality of life (QoL) of GPi‐ and VIM‐DBS in MD. Ten MD‐patients (nine ε‐sarcoglycan‐mutation‐positive) were evaluated pre‐ and post‐surgically following continuous bilateral GPi‐ and VIM‐DBS at four time points: presurgical, 6, 12, and as a last follow‐up at a mean of 62.3 months postsurgically, and in OFF‐, GPi‐, VIM‐, and GPi‐VIM‐DBS conditions by validated motor [unified myoclonus rating scale (UMRS), TSUI Score, Burke‐Fahn‐Marsden dystonia rating scale (BFMDRS)], cognitive, affective, and QoL‐scores. MD‐symptoms significantly improved at 6 months post‐surgery (UMRS: 61.5%, TSUI Score: 36.5%, BFMDRS: 47.3%). Beneficial effects were sustained at long‐term evaluation post‐surgery (UMRS: 65.5%, TSUI Score: 35.1%, BFMDRS: 48.2%). QoL was significantly ameliorated; affective status and cognition remained unchanged postsurgically irrespective of the stimulation conditions. No serious long‐lasting stimulation‐related adverse events (AEs) were observed. Both GPi‐ and VIM‐DBS offer equally effective and safe treatment options for MD. With respect to fewer adverse, stimulation‐induced events of GPi‐DBS in comparison with VIM‐DBS, GPi‐DBS seems to be preferable. Combined GPi‐VIM‐DBS can be useful in cases of incapaciting myoclonus, refractory to GPi‐DBS alone. © 2010 Movement Disorder Society     

Long‐term clinical outcome in meige syndrome treated with internal pallidum deep brain stimulation

Deep brain stimulation of the globus pallidus internus (GPi DBS) is effective in the treatment of primary segmental and generalized dystonia. Although limb, neck, or truncal dystonia are markedly improved, orofacial dystonia is ameliorated to a lesser extent. Nevertheless, several case reports and small cohort studies have described favorable short‐term results of GPi DBS in patients with severe Meige syndrome. Here, we extend this preliminary experience by reporting long‐term outcome in a multicenter case series, following 12 patients (6 women, 6 men) with Meige syndrome for up to 78 months after bilateral GPi DBS. We retrospectively assessed dystonia severity based on preoperative and postoperative video documentation. Mean age of patients at surgery was 64.5 ± 4.4 years, and mean disease duration 8.3 ± 4.4 years. Dystonia severity as assessed by the Burke–Fahn–Marsden Dystonia Rating Scale showed a mean improvement of 45% at short‐term follow‐up (4.4 ± 1.5 months; P < 0.001) and of 53% at long‐term follow‐up (38.8 ± 21.7 months; P < 0.001). Subscores for eyes were improved by 38% (P = 0.004) and 47% (P < 0.001), for mouth by 50% (P < 0.001) and 56% (P < 0.001), and for speech/swallowing by 44% (P = 0.058) and 64% (P = 0.004). Mean improvements were 25% (P = 0.006) and 38% (P < 0.001) on the Blepharospasm Movement Scale and 44% (P < 0.001) and 49% (P < 0.001) on the Abnormal Involuntary Movement Scale. This series, which is the first to demonstrate a long‐term follow‐up in a large number of patients, shows that GPi DBS is a safe and highly effective therapy for Meige syndrome. The benefit is preserved for up to 6 years. © 2011 Movement Disorder Society     

Deep Brain Stimulation for Dystonia: A Meta‐Analysis

Objective. To use a meta‐analysis on all reported cases of deep brain stimulation (DBS) for dystonia to determine which factors significantly influence outcome. The Burke‐Fahn‐Marsden (BFM) movement scale, the most reported measure, was chosen as the primary outcome measure for this analysis. Methods. A MEDLINE search identified 137 patients who underwent DBS for dystonia in 24 studies that had individual BFM scores. Individual patient data, including age at onset of dystonia, age at surgery, gender, distribution of dystonia, etiology of dystonia, presence of associated features, abnormality of preoperative imaging, prior stereotactic surgeries, nucleus stimulated, type of anesthesia used, use of physiologic monitoring, type of imaging used for localization, stimulation parameters used, time of response to stimulation, and timing of outcome assessment were entered into an SPSS database for statistical analysis. Results. The mean BFM percentage change (improvement in postoperative score from baseline) was 51.8% (range ?34% to 100%). Significantly better outcomes were achieved with stimulation of the globus pallidus internus (GPi) than with stimulation of the posterior portion of the ventral lateral (VLp) nucleus of the thalamus (p = 0.0001). The etiology of the dystonia also had a significant effect on outcomes. Statistically significant improvements in outcomes were seen for all etiologic categories, except encephalitis. Dystonia due to birth injury and encephalitis had significantly worse outcomes when compared to other etiologies. However, there were no significant differences in the outcomes of patients who were DYT1 (DYT1 is the gene associated with the disorder Dystonia Musculorum Deformans) gene positive, DYT1 gene negative, or had pantothenate kinase‐associated neurodegeneration (PKAN), tardive dyskinesia, and idiopathic and posttraumatic dystonias. Longer duration of dystonia symptoms correlated negatively with surgical outcome. A regression model using the three variables—stimulation site, etiology of dystonia, and duration of dystonia symptoms—explained 51% of the variance in outcomes. Conclusion. Deep brain stimulation of the GPi provides significant improvement in BFM scores in a variety of dystonic conditions.     

Deep brain stimulation in the treatment of severe dystonia

A retrospective study of a consecutive series of 19 patients with medically intractable dystonia treated with uni- or bilateral deep brain stimulation (DBS) is reported. A minimal follow-up of 6 months was available, up to eleven years in one patient. The first twelve consecutive patients (4 with primary and 8 with secondary dystonia) were treated with chronic stimulation of the posterior part of the ventrolateral thalamic nucleus (VLp). In this group global functional outcome was improved in 8 patients, although dystonia movement and disability scale scores did not show significant improvement. Of the 12 patients treated first by VLp DBS, three (1 primary and 2 secondary dystonia) underwent pallidal (GPi) DBS after the VLp DBS failed to improve their symptoms. The last seven consecutive patients (5 primary and 2 secondary dystonia) were treated directly with GPi DBS. Extracranial infection prevented chronic GPi DBS in one patient. In another GPi patient, preliminary negative tests with the electrodes discouraged implantation of the stimulators, and the patient was not treated with chronic DBS. In the remaining group of eight patients including those previously treated with VLp DBS, chronic GPi DBS resulted in a significant improvement in the dystonia movement scale and disability scores. Although this is a retrospective study dealing with dystonia of heterogeneous etiology, the results strongly suggest that GPi DBS has a better outcome than VLp DBS Received: 22 January 2001 / Received in revised form: 28 February 2001 / Accepted: 1 March 2001     

A family with a hereditary form of torsion dystonia from Northern Sweden treated with bilateral pallidal deep brain stimulation

To evaluate pallidal DBS in a non‐DYT1 form of hereditary dystonia. We present the results of pallidal DBS in a family with non‐DYT1 dystonia where DYT5 to 17 was excluded. The dystonia is following an autosomal dominant pattern. Ten members had definite dystonia and five had dystonia with minor symptoms. Four patients received bilateral pallidal DBS. Mean age was 47 years. The patients were evaluated before surgery, and “on” stimulation after a mean of 2.5 years (range 1–3) using the Burke‐Fahn‐Marsden scale (BFM). Mean BFM score decreased by 79 % on stimulation, from 42.5 ± 24 to 9 ± 6.5 at the last evaluation. Cervical involvement improved by 89%. The 2 patients with oromandibular dystonia and blepharospasm demonstrated a reduction of 95% regarding these symptoms. The present study confirms the effectiveness of pallidal DBS in a new family with hereditary primary segmental and generalized dystonia. © 2009 Movement Disorder Society     

Exacerbation of blepharospasm associated with craniocervical dystonia after placement of bilateral globus pallidus internus deep brain stimulator

To report a case of exacerbation of blepharospasm after bilateral globus pallidus internus (GPi) deep brain stimulator (DBS) placement. A 69‐year‐old male presented after bilateral GPi DBS placement for blepharospasm and craniocervical dystonia with worsening eyelid spasms and associated apraxia of lid opening (ALO). Numerous attempts to adjust DBS parameters were ineffective. Consequently, bilateral upper eyelid myectomy was performed. Myectomy surgery was free of complications. The patient had significant improvement of blepharospasm and ALO. Although early success has been reported with DBS placement in a small number of patients with focal dystonias, further studies and longer follow‐up are needed to demonstrate whether this will prove to be a useful approach in the treatment of blepharospasm. Upper eyelid myectomy can provide an effective means for treating blepharospasm and associated ALO. © 2008 Movement Disorder Society     

Pallidal deep brain stimulation in patients with cranial-cervical dystonia (Meige syndrome).

Idiopathic cranial-cervical dystonia (ICCD) is an adult-onset dystonia syndrome affecting orbicularis oculi, facial, oromandibular, and cervical musculature. ICCD is frequently difficult to treat medically. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a highly effective treatment for idiopathic generalized dystonia, however less is known about the effect of GPi DBS on ICCD. In this article, we present the results from a pilot study assessing the effect of GPi DBS in a series of patients with ICCD. Six patients underwent bilateral stereotactic implantation of DBS leads into the sensorimotor GPi. Patients were evaluated with the Burke-Fahn-Marsden dystonia rating scale (BFMDRS) and Toronto western spamodic torticollis rating scale (TWSTRS) before surgery and 6 months postoperatively. At 6 months, patients showed a 72% mean improvement in the BFMDRS total movement score (P < 0.028, Wilcoxin signed rank test). The mean BFMDRS disability score showed a trend toward improvement (P < 0.06). The total TWSTRS score improved 54% (P < 0.043). Despite improvement in dystonia, mild worsening of motor function was reported in previously nondystonic body regions with stimulation in 4 patients. Although GPi DBS was effective in these patients, the influence of GPi DBS on nondystonic body regions deserves further investigation.     

Sustained quality‐of‐life improvements over 10 years after deep brain stimulation for dystonia

Background : Little is known about the quality of life of people with dystonia and DBS beyond 5 years. The objectives of this study were (1) to examine the long‐term quality‐of‐life outcomes in a large cohort of people with dystonia and DBS, (2) to determine the incidence of stimulation‐induced parkinsonism, and (3) to elucidate the potential long‐term cognitive impact of DBS in this cohort. Methods : Fifty‐four subjects with dystonia and DBS for more than 5 years were contacted via social media and were offered to complete a quality‐of‐life survey comparing current‐day life and life prior to DBS. The primary study outcomes were the Short Form survey, a parkinsonian symptoms questionnaire, the Telephone Montreal Cognitive Assessment, and the Measurement of Every Day Cognition. Results : Thirty‐seven of 54 subjects consented to the study. Average age was 39.7 ± 16.6 years, 16 were female, and 23 were DYT1+. Average time from implantation was 10.5 years. Average total Short Form survey scores improved, from 43.7 pre‐DBS to 69.5 current day (P < 0.0005). Mean total self‐reported parkinsonian symptom score was 13.8 ± 14.7, with worsening balance and hypophonia the most common. Average Telephone Montreal Cognitive Assessment was 20.1 ± 1.6, with 3 of 29 scores (10.3%) in the impaired range (score of 18 or less). Average total Every Day Cognition score was 1.25 ± 0.35, with 3 subjects (10.3%) scoring in the range of impaired cognition (>1.81). Conclusions : DBS for dystonia results in long‐term quality‐of‐life improvements that persist on average 10 years or more after surgery. The prevalence of stimulation‐induced parkinsonism and cognitive impairment is low. © 2018 International Parkinson and Movement Disorder Society     

Long Disease Duration Interferes With Therapeutic Effect of Globus Pallidus Internus Pallidal Stimulation in Primary Cervical Dystonia

Objectives: We retrospectively investigated the correlation between disease duration and the therapeutic effect of globus pallidus internus (GPi) stimulation in patients with primary cervical dystonia (CD). Materials and Methods: Eight patients with CD unresponsive to medical treatments underwent bilateral GPi deep brain stimulation (DBS). They were followed for 63.5 ± 38.2 months (mean ± standard deviation) and were assessed before and at 1, 12, 24, and 36 months after surgery and at their final visit to our outpatient clinic using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Univariate analysis was performed to identify factors that affected their postoperative TWSTRS score. Results: At last follow‐up, disease severity and the degree of disability and pain on the TWSTRS were significantly improved by 70.2%, 76.1%, and 87.1%, respectively (p < 0.05, Wilcoxon signed‐rank test). Neither age nor preoperative CD severity was predictive of postoperative improvement; however, the disease duration affected their reduction rate of TWSTRS severity score at each time point investigated (p < 0.05). Conclusions: Bilateral GPi‐DBS is an effective long‐term therapy in patients with CD. The delivery of GPi stimulation in the earlier course of CD may yield greater postoperative improvement.     

Good long-term efficacy of pallidal stimulation in cervical dystonia: a prospective, observer-blinded study

Background and purpose: Deep brain stimulation of the internal globus pallidus (GPi‐DBS) is established as an effective treatment of primary generalised dystonia in controlled studies. In cervical dystonia (CD), only one previous study has reported observer‐blinded outcome assessment of long‐term GPi‐DBS, with 1‐year follow‐up. Methods: In this prospective, single‐centre study, eight patients with CD (7 women:1 man, 4 focal:4 segmental) treated with bilateral GPi‐DBS for median (range) 30 (12–48) months, were evaluated by the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS; Severity, Disability and Pain scores), the Short‐Form Health Survey‐36 (SF‐36), and the Becks Depression Index in an open design. In addition, a blinded rater assessed the TWSTRS Severity score from videos obtained preoperatively and at the last follow‐up. Results: In the blinded evaluation, median (range) TWSTRS Severity score improved from 25 (19–30) to 8 (4–23) (P = 0.028), thus a 70% (23–82) score reduction. In the open evaluation, median Severity score improvement at the last follow‐up was 73%, representing a significant further improvement from 50% at 6 months. The Disability and Pain scores improved by median 91% and 92%, respectively, and the SF‐36 subdomain scores improved significantly. A reversible right hemiparesis and aphasia occured in one patient 4 days postoperatively, because of reversible oedema around the left electrode. No other serious adverse effects and no permanent morbidity were observed. Conclusions: This single‐blinded study shows good long‐term efficacy of GPi‐DBS in CD patients and supports using this treatment in those who have insufficient response to medical treatment.     

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     

Chronic deep brain stimulation in patients with tardive dystonia without a history of major psychosis

Tardive dystonia usually occurs with a delay after neuroleptic exposure in patients with major psychosis. A subgroup of patients, however, is given such medication for “mild depression” or “neurasthenia.” Tardive dystonia, in general, may respond favorably to pallidal deep brain stimulation (DBS). Nevertheless, it remains unclear thus far whether or not similar beneficial outcome is achieved with pallidal DBS in different subgroups of patients with tardive dystonia. Four women (mean age 59 years at surgery) underwent stereotactic pallidal DBS in the frame of an observational study. Tardive dystonia occurred secondary to medication with fluspirilene and haloperidol, and injection of long‐acting depot neuroleptics prescribed for mild depression or “nervousness.” Assessment included the Burke‐Fahn‐Marsden (BFM) scale preoperatively and at 12 months follow‐up. Extended follow‐up was available at a mean of 27.3 months postoperatively (range 16–36 months). There were no surgically related complications. All 4 patients experienced sustained statistically significant benefit from pallidal DBS. Mean improvement at 12 months was 77% for the BFM motor score (range, 45–91%; P = 0.043), and 84% at the last available follow‐up (range, 70–91%; P = 0.03). This was paralleled by improvement of the BFM disability score. Chronic pallidal DBS in patients with tardive dystonia without a history of major psychosis provides sustained improvement which is similar to that in other subgroups of patients with tardive dystonia. This effect is stable on extended follow‐up for up to 3 years. © 2010 Movement Disorder Society     

Deep Brain Stimulation of the Globus Pallidus in a 7-Year-Old Girl with DYT1 Generalized Dystonia

The experience of pediatric deep brain stimulation (DBS) of the globus pallidus internus (GPi) in the treatment of early-onset DYT1 generalized dystonia is still limited. Here, we report the surgical experience of bilateral GPi-DBS under general anesthesia by using microelectrode recording in a 7-year-old girl with early-onset DYT1 generalized dystonia. Excellent improvement of her dystonia without neurological complications was achieved. This case report demonstrates that GPi-DBS is an effective and safe method for the treatment of medically refractory early-onset DYT1 generalized dystonia in children.     

Micro lesion effect of the globus pallidus internus and outcome with deep brain stimulation in patients with Parkinson disease and dystonia

To determine whether the immediate response to electrode implantation (micro lesion effect, MLE) in the internal segment of the globus pallidus (GPi) predicts symptom improvement with deep brain stimulation (DBS) at 6 months in patients with Parkinson's disease (PD) or generalized dystonia. Electrode implantation in the subthalamic nucleus (STN) prior to electrical stimulation has been reported to predict a beneficial effect of DBS in patients with PD, but whether this is also the case for the GPi in either PD or dystonia patients has not been established. We studied 20 patients (11 with PD and 9 with dystonia) who underwent electrode implantation in the GPi. Effects were assessed using standardized scales after 24 hours, weekly for 3 weeks prior to starting DBS, and after 6 months of DBS. 10 of 11 PD and 8 of 9 dystonia cases who benefited from electrode implantation also showed improvement in all motor and disability scores after 6 months of DBS of the GPi. One dystonia patient who did not show MLE benefited from DBS. The presence of MLE after electrode implantation in the GPi may help predict motor benefit from DBS in PD and generalized dystonia patients. © 2009 Movement Disorder Society     

Review of the functional surgical treatment of dystonia

A review of functional surgery for dystonia is presented. Recently renewed interest in stereotaxy for dystonia has followed the resurgence of pallidotomy and the introduction of deep brain stimulation (DBS) in Parkinson's disease (PD) in the early 1990s. However, even since the 1950s, small series of patients treated with ablative surgery have been carefully studied, providing useful information, notably regarding the tolerability of surgery. In the setting of dystonia, thalamotomy was first performed with substantial benefits, but some authors outlined the great variability in outcome, and the high incidence of operative side-effects. In the 'modern' era of functional surgery for movement disorders, the globus pallidus internus (GPi) has emerged to be currently the best target for dystonia, based on small series of patients published in the last few years. Both bilateral posteroventral pallidotomy (PVP) and bilateral pallidal stimulation, performed by several teams, have benefited a variety of patients with severe dystonia, the most dramatic improvements being seen in primary dystonia with a mutation in the DYT1 gene. Whereas patients with secondary dystonia have often shown a lesser degree of improvement, some publications have nevertheless reported major benefit. There is today a strong need for carefully controlled studies comparing secondary and primary dystonia, DYT1 and non-DYT1 dystonia, ablative surgery and DBS, with additional assessment of neuropsychological changes, especially in children treated with bilateral pallidal procedures.