Aim The aim of this study was to examine the impact of dystonia aetiology and duration, contracture, and age at deep brain stimulation (DBS) surgery on outcome in a cohort of children with medically refractory, disabling primary, secondary‐static, or secondary‐progressive dystonias, including neurodegeneration with brain iron accumulation (NBIA). Method Dystonia severity was assessed using the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS) motor score at baseline and 6 and 12 months postoperatively in a cohort of 70 consecutive children undergoing DBS between June 2005 and July 2011. Results Two children (3%) received unilateral DBS for hemidystonia and were excluded and five (7%) developed infections requiring part‐DBS removal within 6 months, leaving 63 children (90%) undergoing bilateral DBS for follow‐up (34 males, 29 females; mean age at surgery for the whole group 10y 4mo, SD 4y 2mo, range 1–14y). Seventeen children were classified with primary dystonia: mean age 12 years 11 months, SD 4 years 6 months range 4 years 6 months to 17 years 3 months; 28 as having secondary‐static dystonia: mean age 10 years 2 months, SD 4 years 9 months (range 3y 3mo–20y); five as having secondary‐progressive dystonia: mean age 8 years 11 months, SD 3 years 9 months (range 5y 5mo–13y 1mo); and 13 as having NBIA dystonia: mean age 10 years 2 months, SD 3 years 11 months (range 1–14y). Children with primary dystonias demonstrated greater improvements in BFMDRS motor score than those in the other aetiological categories (Kruskal–Wallis test, p<0.001), which correlated negatively with dystonia duration and more strongly still against the ratio of dystonia duration normalized to age at surgery (DD/AS ratio) at 1 year (Spearman's rank correlation coefficient 0.4752 and −0.599 respectively). A similar significant negative correlation was found in the secondary‐static dystonia group between outcome at 1 year and DD/AS ratio (−0.461). Poorer outcome in secondary dystonia coincided with the absence of a period of normal motor development in comparison with the primary dystonia group. A significant improvement in BFMDRS motor score was seen in the NBIA group at 6, but not 12 months (Wilcoxon signed rank test p=0.028, p=0.85 respectively). No reduction in efficacy was seen in children with a musculoskeletal deformity at the time of surgery. Conclusion Response to pallidal DBS in the treatment of dystonia declines with the proportion of life lived with dystonia in primary and secondary dystonia. Other intrinsic factors reduce the median magnitude of reduction in secondary dystonia after DBS. DBS should be offered early, preferably within 5 years of onset, to maximize benefits and reduce the childhood experience of dystonia, including musculoskeletal deformity. Other multidimensional assessments are required to understand how DBS improves the lives of children with dystonia.

Please cite this article as: Kaminska M, Perides S, Lumsden DE, Nakou V, Selway R, Ashkan K, Lin J-P, Complications of Deep Brain Stimulation (DBS) for dystonia in children -the challenges and 10 year experience in a large paediatric cohort, European Journal of Paediatric Neurology (2016Neurology ( ), doi: 10.1016Neurology ( / j.ejpn.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. • Lower than previously reported infection rates following DBS for movement disorders in children were identified and no increased susceptibility for patients younger than 7 years. • We report relatively high incidence of technical problems with electrodes and extensions and in particular recharging.• Presentation of heterogeneous phenotypes requires an experienced team to manage and prevent complications. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPTThe paper confirms that DBS in young children is safe and can be offered. Abstract:Deep brain stimulation (DBS) has been increasingly used for primary and secondary movement disorders in children and young people. Reports of hardware related complications have been sparse for this population and from small cohorts of patients.We report DBS complications from a single large DBS centre with 10 year experience.Data was collected as a prospective audit and additionally from a questionnaire on recharging of the stimulators. 129 patients with a minimum 6 months follow up were identified, mean age10.8 y (range 3.0 -18.75), mean follow up 3.3y (range 0.5 -10.3), weight 10.4-94.2kg, 126 new implants (92 Activa RC) and 69 revisions for reasons other than infection. 26 patients were 7y or younger. Surgical site infections (SSI) rates were 10.3% for new implants and revisions, lower 8.6% for new Activa RC and even lower, 4.7%, for new Activa RC in patients under 7y (1/21). SSI occurred within first 6 months and necessitated total system removal in 86% of those infected. Electrode/extension problems were recorded in 18.4% of patients, fracture in 4.6% malfunction in 7.7%, short extension3.8% and electrode migration in 2.3%. Other complications involved clinically silent intracranial bleed in 1 patient, skin erosions (2.3%), unexpected switching off in 18.7% of Soletra/Kinetra and 3.4% of Activa RC, transient seroma at IPG site in postoperative period (8%). Of the 48 returned recharging questionnaires, 38% of families required recharger replacement and 23% experienced frequent problems maintaining connection during recharging. However, 83% of responders considered recharging not at all or only a little care burden.We identified lower than previously reported DBS infection rates ...

Aim To establish the prevalence of dystonic pain in children and their response to deep brain stimulation (DBS). Method Dystonic pain was assessed in a cohort of 140 children, 71 males and 69 females, median age 11 years 11 months (range 3y–19y 1mo), undergoing DBS in our centre over a period of 10 years. The cohort was divided into aetiological dystonia groups: 1a, inherited; 1b, heredodegenerative; 2, acquired; and 3, idiopathic. Motor responses were measured with the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS). Results Dystonic pain was identified in 63 (45%) patients, 38% of whom had a diagnosis of cerebral palsy (CP). Dystonic pain improved in 90% of children and in all aetiological subgroups 1 year after DBS, while the BFMDRS motor score improved in 70%. Statistically significant improvement (p<0.01) was noted for the whole cohort on the Numerical Pain Rating Scale (n=27), Paediatric Pain Profile (n=17), and Caregivers Priorities and Child Health Index of Life with Disabilities questionnaire (n=48). There was reduction of pain severity, frequency, and analgesia requirement. Findings were similar for the whole cohort and aetiological subgroups other than the inherited heredodegenerative group where the improvement did not reach statistical significance. Interpretation Dystonic pain is frequent in children with dystonia, including those with CP, who undergo DBS; this can be an important, realizable goal of surgery irrespective of aetiology. We encourage the use of multimodal approach in pain research to reduce the risk of bias.

OBJECT Intrathecal baclofen (ITB) is an effective management option for childhood hypertonia. Given the potential complications of implanted ITB pumps, trials of ITB are usually performed as part of the workup for ITB pumps. Two methods are used for ITB trials, lumbar puncture (LP) and catheter insertion into the intrathecal space. Little has been written to date on the number of positive trials and complications in trials. This study aimed to report the outcomes and complications in ITB trials for childhood hypertonia (dystonia, spastic, or mixed). METHODS A retrospective case notes review was conducted of all patients who underwent ITB trials at the Evelina London Children’s Hospital between 2005 and 2012 (inclusive). Positive trials were defined as a reduction in Modified Ashworth Scale by a minimum of 1 point in at least 2 muscle groups and improvement reported by the caregivers in the areas of goals agreed upon between professionals and the families. RESULTS Our patient group comprised children with dystonia (n = 7), mixed spasticity/dystonia (n = 29), spasticity (n = 4), and pain (n = 1). A total of 47 trials were attempted in 41 children. Forty trials were successfully completed, with 39 being positive. Thirty-three were catheter trials, and 14 were LPs. The overall complication rate in the 47 attempted trials was 53%: 61% in catheter trials, and 36% in LP trials. This difference was not statistically significant. The most common complications were vomiting (n = 9) and CSF leak (n = 4). The most serious complication was meningitis (n = 1) in a catheter trial. No patients experienced a permanent injury. CONCLUSIONS There is a high risk of minor self-limiting complications with ITB trials, which needs to be factored into the decision process of progression to trials. The rate of positive trials in this study was 98%, of which 21% did not progress to pump implantation. While the authors would still advocate for ITB trials prior to ITB pump insertion to aid parental decision-making, this figure suggests that with good patient selection, ITB pumps could be placed without a preceding trial.