Deep Brain Stimulation in Rare Inherited Dystonias.

BACKGROUND: Rare causes of inherited movement disorders often present with a debilitating phenotype of dystonia, sometimes combined with parkinsonism and other neurological signs. Since these disorders are often resistant to medications, DBS may be considered as a possible treatment. METHODS: Patients with identified genetic diseases (ataxia-telangiectasia, chorea-achantocytosis, dopa-responsive dystonia, congenital nemaline myopathy, methylmalonic aciduria, neuronal ceroid lipofuscinosis, spinocerebellar ataxia types 2 and 3, Wilson's disease, Woodhouse-Sakati syndrome, methylmalonic aciduria, and X trisomy) and disabling dystonia underwent bilateral GPi DBS (bilateral thalamic Vim nucleus in 1 case). The primary outcome was the difference in the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) between baseline, 1 year and last available follow-up. Preoperative factors such as age at surgery, disease duration at surgery, proportion of life lived with dystonia and severity of dystonia were correlated to the primary outcome. RESULTS: Eleven patients were operated between February 2003 and December 2013. Age and duration of disease at time of surgery were 30 ± 19 and 12.5 ± 15.7 years, respectively. DBS effects on dystonia severity were variable but overall marginally effective, with a mean improvement of 7.9% (p = 0.39) at 1-year follow-up and 16.7% (p = 0.46) at last follow-up (mean 47.3 ± 19.9 months after surgery). No preoperative factors were identified to predict the surgical outcome. CONCLUSION: Our findings support the current knowledge that DBS is modestly effective in treating rare inherited dystonias with a combined phenotype. However, the BFMDRS might not be the best tool to measure outcome in these severely affected patients.

Long-term neuropsychiatric outcomes after pallidal stimulation in primary and secondary dystonia.

OBJECTIVE: To evaluate changes in the diagnosis of Axis I psychiatric disorders in patients with primary and secondary dystonia after deep brain stimulation (DBS) of the globus pallidus internus (GPi). METHODS: Structured Clinical Interviews for the DSM-IV, Axis I psychiatric disorders, were prospectively performed before and after surgery. Diagnoses were made based on DSM-IV criteria. Psychiatric disorders were grouped into 5 categories: mood, anxiety, addiction, obsessive-compulsive disorders, and psychosis. Patients could be stratified to more than one category. Rates for unchanged diagnoses, diagnoses in remission, and new-onset diagnoses after surgery for each category were calculated. RESULTS: Fifty-seven patients with primary and secondary dystonia were included. Mean ± SD age at surgery and dystonia duration at time of surgery was 50.6 ± 13.8 and 19.0 ± 13.2 years, respectively. Preoperatively, 37 Axis I diagnoses were made in 25 patients, 43.8% of those presenting with at least 1 Axis I diagnosis (mostly mood and anxiety disorders). Mean ± SD duration of psychiatric follow-up was 24.4 ± 19.6 months. Overall, after surgery no significant changes (p = 0.16) were found in Axis I diagnoses (23 patients, 40.3%): 27 (73%) unchanged, 10 (27%) in complete remission, and 4 (12.9%) new-onset diagnoses. CONCLUSIONS: Our results support the overall psychiatric stability of patients with primary and secondary dystonia treated with GPi DBS. However, considering the high psychiatric morbidity in the dystonia population, psychiatric assessments before and after surgery are strongly recommended. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that GPi DBS does not change Axis I psychiatric diagnoses in patients with primary and secondary dystonia.

Bilateral pallidal stimulation for sargoglycan epsilon negative myoclonus.

We report on the clinical efficacy of bilateral globus pallidus internus deep brain stimulation in two patients with myoclonus dystonia/essential myoclonus who lack mutations in the epsilon sarcoglycan gene. The primary outcome measures were the Burke-Fahn-Marsden Dystonia Scale motor severity and the Unified Myoclonus Rating Scale scores, and the secondary outcome measure was the 36-item Short Form Health Survey score at the last postoperative follow up. Neuronal firing rates were also calculated from microelectrode recordings. At the last postoperative follow-up (16 weeks for Patient 1 and 18 weeks for Patient 2), there was 57.1% (Patient 1) improvement in the Burke-Fahn-Marsden Dystonia Scale motor severity score and 31.3% (Patient 1) and 69% (Patient 2) in the Unified Myoclonus Rating Scale score while individual SF-36 scores showed improvement in most subdomains. Bilateral globus pallidus internus deep brain stimulation can be effective in ameliorating epsilon sarcoglycan negative myoclonus with or without concurrent dystonia. Whether an epsilon sarcoglycan negative status represents a less favorable prognostic factor for pallidal deep brain stimulation remains to be elucidated.

Spinal cord stimulation for gait impairment in spinocerebellar ataxia 7.

The aim of this study is to report on the clinical efficacy of epidural thoracic spinal cord stimulation on gait and balance in a 39-year-old man with genetically confirmed spinocerebellar ataxia 7. A RESUME Medtronic electrode was placed at the epidural T11 level. Spatiotemporal gait assessment using an electronic walkway and static posturography were obtained and analyzed in a blinded manner with and without stimulation. The Tinetti Mobility Test was also performed in the two conditions. At 11 months after surgery, there was a 3-point improvement in the Tinetti Mobility Test in the on stimulation condition, although there was no statistically significant difference in spatiotemporal gait parameters. Static posturography did not demonstrate a significant improvement in stability measures between the two conditions in a stochastic way. Thoracic epidural spinal cord stimulation had a mild but clinically meaningful beneficial effect in improving gait and balance in a patient with SCA-7. The underlying pathophysiologic mechanisms remain to be elucidated. Further experience with spinal cord stimulation in refractory gait disorders is warranted.

Low-frequency subthalamic nucleus deep brain stimulation for axial symptoms in advanced Parkinson's disease.

Axial symptoms such as freezing of gait and falls are common manifestations of advanced Parkinson's disease (PD) and are partially responsive to medical treatment. High-frequency (≥130 Hz) deep brain stimulation (DBS) of the subthalamic nucleus (STN) is highly efficacious in ameliorating appendicular symptoms in PD. However, it is typically less effective in improving axial symptomatology, especially in the long term. We have studied the effects of low-frequency stimulation (LFS) (≤80 Hz) for improving speech, gait and balance dysfunction in the largest patient population to date. PD patients with bilateral STN-DBS and resistant axial symptoms were switched from chronic 130 Hz stimulation to LFS and followed up to 4 years. Primary outcome measures were total motor UPDRS scores, and axial and gait subscores before and after LFS. Bivariate analyses and correlation coefficients were calculated for the different conditions. Potential predictors of therapeutic response were also investigated. Forty-five advanced PD patients who had high frequency stimulation (HFS) for 39.5 ± 27.8 consecutive months were switched to LFS. LFS was kept on for a median period of 111.5 days before the assessment. There was no significant improvement in any of the primary outcomes between HFS and LFS, although a minority of patients preferred to be maintained on LFS for longer periods of time. No predictive factors of response could be identified. There was overall no improvement from LFS in axial symptoms. This could be partly due to some study limitations. Larger prospective trials are warranted to better clarify the impact of stimulation frequency on axial signs.

Bilateral pallidal stimulation for Wilson's disease.

BACKGROUND: To report on the clinical efficacy of bilateral globus pallidus internus deep brain stimulation in a 29-year-old patient with severe generalized dystonia secondary to Wilson's disease. METHODS: The primary outcome measure was the Burke-Fahn-Marsden Dystonia Scale motor severity score (blinded assessment) and the secondary outcome measures were the Abnormal Involuntary Movement Scale (blinded assessment) and the Zaritt Caregiver Burden Interview score, at 20-week postoperative follow up. RESULTS: There was a 14% improvement in the Burke-Fahn-Marsden Dystonia Scale motor severity score. Abnormal Involuntary Movement Scale score remained unchanged while the Zaritt Caregiver Burden Interview score improved by 44.4%. CONCLUSIONS: Bilateral globus pallidus deep brain stimulation can be effective in ameliorating dystonia and caregiver burden in Wilson's disease. Outcomes may depend on the stage of the disease at which the surgical procedure is completed. © 2013 Movement Disorder Society.

Bilateral pallidal stimulation in cervical dystonia: blinded evidence of benefit beyond 5 years.

The local injection of botulinum toxin is accepted as the first-line treatment of primary cervical dystonia. This approach provides adequate symptomatic relief for most patients, but up to one-third will have an unsatisfactory response. Deep brain stimulation of the globus pallidus internus has been increasingly used in dystonic syndromes that are refractory to best pharmacological approaches. Although cervical dystonia is the most common idiopathic focal dystonia, evidence for long-term responsiveness to pallidal stimulation is limited. The primary objective of this study was to prospectively collect outcome data from baseline to last clinical follow-up on patients with idiopathic cervical dystonia treated with bilateral pallidal stimulation. Blinded video assessment of examinations performed preoperatively and at last video assessment were performed. Ten patients had complete prospective clinical follow-up. Baseline total Toronto Western Spasmodic Torticollis Rating Scale score (±standard deviation) was 54.5 ± 12.4 (range, 35.0-70.3). Comparison of the blinded severity sub-score on baseline video and at last video assessment at a mean of 7.7 years postoperatively demonstrated a mean improvement of 47.6% (P = 0.002) and strong inter-observer correlation between blinded raters (Spearman r = 0.78, 95% confidence interval 0.49-0.92, P = 0.0001). All 10 patients had 5 years of open prospective follow-up, documenting a 47.4 ± 26.4% (P < 0.01) mean improvement with respect to baseline. This was maintained at a mean of 7.8 years at last follow-up after surgery (range, 4.9-10.7 years) with a 54.4 ± 27.4% mean improvement (P < 0.01). Deep brain stimulation of the globus pallidus is an effective and long-lasting second-line treatment of cervical dystonia, with benefit in some of our patients extending to >10 years. More data are needed to explain variations in individual responses and to guide individual programming parameters.

Ten-year outcome of subthalamic stimulation in Parkinson disease: a blinded evaluation.

OBJECTIVE: To assess the 10-year motor outcome of deep brain stimulation of the subthalamic nucleus (STN-DBS) in patients with Parkinson disease (PD). DESIGN: Patients with PD with bilateral STN-DBS were assessed according to the Core Assessment Program for Surgical Interventional Therapies in Parkinson's Disease protocol and videotaped at baseline and 1, 5, and 10 years after surgery. An independent rater blinded to stimulation and medication condition scored the 10-year video assessments. SETTING: Movement Disorders Centre, Toronto Western Hospital, University Health Network, University of Toronto. PATIENTS: Eighteen patients with advanced PD and 10-year follow-up of STN-DBS. INTERVENTION: Bilateral STN-DBS surgery. MAIN OUTCOME MEASURES: The primary outcome was the change in blinded Unified Parkinson's Disease Rating Scale (UPDRS) motor scores/subscores between the no medication/stimulation condition vs the no medication/no stimulation condition at 10 years. Secondary outcomes were the changes in blinded UPDRS motor scores between the medication/no stimulation and medication/stimulation conditions, UPDRS II scores, UPDRS IV dyskinesia and motor fluctuations scores, and anti-PD medication dose (levodopa equivalent daily dose) at different points. RESULTS: In the 18 patients available for follow-up at 10 years, STN-DBS still significantly improved the UPDRS total motor score (P = .007) and resting and action tremor (P < .01 and P = .02, respectively) and bradykinesia (P = .01) subscores. The UPDRS II scores in the medication and no medication conditions, UPDRS IV dyskinesia and motor fluctuations scores, and the levodopa equivalent daily dose were also significantly reduced compared with baseline. Axial signs showed the most progressive decline in stimulation and levodopa response over the years. CONCLUSION: This class III study provides evidence that stimulation-induced motor improvement was sustained overall at 10 years, although part of the initial benefit wore off mainly because of progressive loss of benefit on axial signs over time.

Gamma knife thalamotomy for disabling tremor: a blinded evaluation.

BACKGROUND: Gamma knife thalamotomy (GKT) has been used as a therapeutic option for patients with disabling tremor refractory to medications. Impressive improvement of tremor has been reported in the neurosurgical literature, but the reliability of such data has been questioned. OBJECTIVE: To prospectively evaluate clinical outcomes after GKT for disabling tremor with blinded assessments. DESIGN: Prospective study with blinded independent neurologic evaluations. SETTING: University hospital. PATIENTS: Consecutive patients who underwent unilateral GKT for essential tremor and Parkinson disease tremor at our center. These patients were unwilling or deemed unsuitable candidates for deep brain stimulation or other surgical procedures. INTERVENTIONS: Unilateral GKT and regular follow-up evaluations for up to 30 months, with blinded video evaluations by a movement disorders neurologist. MAIN OUTCOME MEASURES: Clinical outcomes, as measured by the Fahn-Tolosa-Marin Tremor Rating Scale and activities of daily living scores, and incidence of adverse events. RESULTS: From September 1, 2006, to November 30, 2008, 18 patients underwent unilateral GKT for essential tremor and Parkinson disease tremor at our center. Videos for 14 patients (11 with essential tremor, 3 with Parkinson disease tremor) with at least 6 months' postoperative follow-up were available for analysis (mean [SD] follow-up duration, 19.2 [7.3] months; range, 7-30 months). The Fahn-Tolosa-Marin Tremor Rating Scale activities of daily living scores improved significantly after GKT (P = .03; median and mean change scores, 2.5 and 2.7 points, respectively [range of scale was 0-27]), but there was no significant improvement in other Fahn-Tolosa-Marin Tremor Rating Scale items (P = .53 for resting tremor, P = .24 for postural tremor, P = .62 for action tremor, P = .40 for drawing, P > .99 for pouring water, P = .89 for head tremor). Handwriting and Unified Parkinson's Disease Rating Scale activities of daily living scores tended to improve (P = .07 and .11, respectively). Three patients developed delayed neurologic adverse events. CONCLUSIONS: Overall, we found that GKT provided only modest antitremor efficacy. Of the 2 patients with essential tremor who experienced marked improvement in tremor, 1 subsequently experienced a serious adverse event. Further prospective studies with careful neurologic evaluation of outcomes are necessary before GKT can be recommended for disabling tremor on a routine clinical basis.