facilitate much-needed longitudinal evaluation and data collection. Employing a suite of suitable functional measures provides a means for describing the status and change in individuals with BHC over time, which is essential given the nature of this condition. Whilst not intended for such a population, borrowing tools from cerebral palsy research which classify fine and gross motor function may be useful.
The Dyskinesia Impairment Scale should be relevant to apply here given that chorea and dystonia often coexist in BHC.6 Finally, the coexistence of thyroid, lung, and behavioural/learning disorders highlights the need for a comprehensive evaluation of the young child who presents with chorea and normal neuroimaging: casting the net widely may deliver a larger catch than first anticipated.
REFERENCES 1. Haerer AF, Currier RD, Jackson JF. Hereditary non-
system disorder due to a de novo mutation in the thyroid
term follow-up in a large series with new mutations in
progressive chorea of early onset. Neurology 1966; 16:
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Niermeijer MF, Heutink P. Benign hereditary chorea of
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impairment scale: a new instrument to measure dystonia
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Pallidotomy in the 21st century DANIEL E LUMSDEN Guy’s and St Thomas’ NHS Foundation Trust – Paediatric Neurosciences, London, UK. doi: 10.1111/dmcn.12414 This commentary is on the original article by Marras et al. on pages 649–656 of this issue.
There is a long history of neurosurgical interventions involving the globus pallidus interna (GPi) in the management of movement disorders. Open pallidotomy procedures were first reported in the 1930s. The development of safer stereotactic techniques popularized pallidotomy in the following two decades. The introduction of levodopa with its beneficial effect on the motor symptoms of Parkinson disease in the 1960s resulted in a dramatic decline in the number of patients undergoing functional neurosurgical treatments for movement disorders.1 The renaissance in functional neurosurgery came with increasing recognition of the limitations of medical therapies for Parkinson disease, and, in particular, the on-off dyskinesia seen with levodopa.2 The report by Laitinen et al. in 19923 of a series of 46 patients undergoing pallidotomy in the management of Parkinson disease marked the start of a surge of papers on the beneficial effects of pallidotomy, including in the management of dystonia. By the start of the 21st century interest in pallidotomy seemed to have waned. Functional neurosurgeons increasingly moved towards deep brain stimulation (DBS) of the subthalamic nucleus, GPi, and other targets in the management of movement disorders.2 As a non-destructive lesioning technique, DBS offers the perceived benefit of
reversibility over pallidotomy but is not without complications, most notably the infection of implanted neurostimulator systems. Whilst DBS of the GPi has undoubtedly improved the lives of many patients with Parkinson disease and dystonia, has pallidotomy been prematurely abandoned? Efisio et al. report the excellent response to bilateral pallidotomy in a case series of four children with status dystonicus.4 The decision to opt for pallidotomy rather than DBS for these cases was in part due to concerns about the poor clinical condition of the children increasing the risk of infection and other complications of DBS. Noteworthy in this report is the position of the surgical target for lesioning, in the mid-position of the pallidum. Evidence from numerous electrophysiological, animal tracing, and histological studies supports the existence of partially segregated functional zones within the GPi, moving posteriorly-to-anteriorly from sensorimotor to associative to limbic territories. Pallidotomy lesioning and DBS electrode placement have typically targeted the posterior sensorimotor region, where best outcomes have been reported.3 Efisio et al. report that the position of the pallidotomy lesions in their four cases spared the most posterior portion of the GPi, leaving the possibility of placement of a DBS electrode in this position in the future. Reports of a beneficial response to DBS include cases in status dystonicus.5 Which children with dystonia might benefit most from pallidotomy and which from DBS? Robustly designed prospective trials comparing the two interventions in the treatment of dystonia are absent and unlikely to be performed in the future.2 This is particularly the case for the secondary dystonias (e.g. cerebral palsy), more commonly seen in childhood. A higher level of evidence exists to Commentaries
support the use of DBS, with prospective sham-controlled studies performed in the setting of primary dystonia. A systematic review led by a joint working group of the European Federation of Neurological Societies and the Movement Disorder Society concluded in 2006 that the use of bilateral pallidotomy in the treatment of dystonia should be discouraged because of the absence of greater then class IV studies and concerns about the risk of dysarthria.6 Greater evidence to support the efficacy of DBS should not be considered as evidence of greater efficacy of DBS when compared to pallidotomy. Recent pragmatic expert opinion
has suggested that pallidotomy should still be considered over DBS when the risk of complications of DBS insertion might be particularly high, or when patients/carers decline the insertion of an implanted device.7 Pallidotomy will continue to play a role in resource-poor settings, given the associated costs of DBS implantation and ongoing programming and management. With the existing uncertainty over the place of pallidotomy in the management of dystonia, reports of outcomes following this procedure will continue to be of interest and help inform the ongoing debate.
REFERENCES 1. Guridi J, Lozano AM. A brief history of pallidotomy. Neurosurgery 1997; 41: 1169–80; discussion 1180–3. 2. Gross RE. What happened to posteroventral pallidotomy for Parkinson’s disease and dystonia? Neurotherapeutics 2008; 5: 281–93. 3. Laitinen LV, Bergenheim AT, Hariz MI. Ventroposterolateral pallidotomy can abolish all parkinsonian symptoms. Stereotact Funct Neurosurg 1992; 58: 14–21.
4. Efisio MC, Rizzi M, Cantonetti L, et al. Pallidotomy
(idiopathic) dystonia and dystonia plus syndromes:
for medically refractory status dystonicus in childhood.
report of an EFNS/MDS-ES Task Force. Eur J Neurol
Dev Med Child Neurol. 2014; 56: 649–56. 5. Fasano A, Ricciardi L, Bentivoglio AR, et al. Status dystonicus: predictors of outcome and progression patterns of
2006; 13: 433–44. 7. Moro E, Gross RE, Krauss JK. What’s new in surgical treatment for dystonia? Mov Disord 2013; 28: 1013–20.
underlying disease. Mov Disord 2012; 27: 783–8. 6. Albanese A, Barnes MP, Bhatia KP, et al. A systematic review on the diagnosis and treatment of primary
Clinical and research considerations in using the Melbourne Assessment 2 MARGARET WALLEN Cerebral Palsy Alliance – Research Institute, Allambie Heights, NSW, Australia. doi: 10.1111/dmcn.12428 This commentary is on the original article by Randall et al. on pages 665–672 of this issue.
The Melbourne Assessment of Unilateral Upper Limb Function (Melbourne Assessment) measures quality of movement for children with congenital or acquired neurological conditions. It predominantly contains items at the level of body function and structure according to the International Classification of Functioning, Disability and Health1 and measures capacity or best ability, rather than actual performance. Randall et al.2 developed the original Melbourne Assessment following rigorous test development processes based on classical test development principles, as was the norm at the time of publication. Further development of this measure extended the age group to include children aged 2 years 6 months to 15 years and provided valuable information about psychometric properties. The principal value of the Melbourne Assessment has been as an outcome measure and it has attracted the interest of researchers who have added to our knowledge on reliability and validity.3 The work presented in the current 608 Developmental Medicine & Child Neurology 2014, 56: 605–611
publication2 used Rasch modelling to evaluate and revise the Melbourne Assessment. Rasch analysis of total scores indicated that the Melbourne Assessment was not unidimensional. Further Rasch analysis of the four subscales, which were compiled as part of the original test development, resulted in deletion of misfitting or redundant items and rescaling of disordered rating scales. Differential item function (DIF) was absent for age and sex, as expected, thus providing evidence for construct validity. DIF did exist between raters, adding to evidence suggesting interrater reliability may be a relative weakness.3 Randall et al. have responded by providing access to online training and reliability resources for the revised Melbourne Assessment 2. Revision of the Melbourne Assessment is akin to a doubleedged sword. On the downside, the Melbourne Assessment 2 now needs to be evaluated with data collected using the revisions to items and rating scales in order to validate the new version. We also await knowledge regarding sensitivity to change and the amount of change following intervention which would be considered a minimally clinically important. Furthermore, we will need to consider carefully how, and if, we pool data collected with the Melbourne Assessment and Melbourne Assessment 2 in meta-analyses of the effects of interventions. The positive edge is that we have a clear understanding of important features of construct