Future directions for the assessment of gait dystonia in cerebral palsy

a significant variable and studies suggest that supratentorial tumours yield greater cognitive deficits compared to infratentorial tumours. An interesting followup study on this data set would be to identify those who are at greater risk for negative outcomes. Surgical complications and recurrence are also key variables when considering late effects. Posterior fossa tumor resection often places children at risk for cerebellar mutism syndrome, a constellation of symptoms that encompass acute mutism, irritability and agitation, ataxia, and hypotonia, lasting a few days to several months, complicating the recovery process.5 Further, whether the tumour has recurred, requiring additional surgery and/or other treatment is a variable that was not explicitly addressed in this study, this analysis would shed additional light into late effects. Overall, Pickering et al. have contributed to our greater knowledge of outcomes of childhood brain tumours, in particular the comparison of malignant versus benign tumours. There is a need in our research to include individuals from diverse backgrounds to better understand the complexities that underly the risk factors and expression of physical, cognitive, social, and psychological late effects of childhood brain tumours. Special attention should be paid to racial and ethnic differences, as well as socioeconomic status and access to timely and quality medical care. Thus, it would behoove researchers to consider pooling their collective data to determine how much influence the environment and other mediating variables have on outcomes.

a significant variable and studies suggest that supratentorial tumours yield greater cognitive deficits compared to infratentorial tumours. An interesting follow-up study on this data set would be to identify those who are at greater risk for negative outcomes.
Surgical complications and recurrence are also key variables when considering late effects. Posterior fossa tumor resection often places children at risk for cerebellar mutism syndrome, a constellation of symptoms that encompass acute mutism, irritability and agitation, ataxia, and hypotonia, lasting a few days to several months, complicating the recovery process. 5 Further, whether the tumour has recurred, requiring additional surgery and/or other treatment is a variable that was not explicitly addressed in this study, this analysis would shed additional light into late effects.
Overall, Pickering et al. have contributed to our greater knowledge of outcomes of childhood brain tumours, in particular the comparison of malignant versus benign tumours. There is a need in our research to include individuals from diverse backgrounds to better understand the complexities that underly the risk factors and expression of physical, cognitive, social, and psychological late effects of childhood brain tumours. Special attention should be paid to racial and ethnic differences, as well as socioeconomic status and access to timely and quality medical care. Thus, it would behoove researchers to consider pooling their collective data to determine how much influence the environment and other mediating variables have on outcomes.

DATA AVA I L A BI L I T Y S TAT E M E N T Not required.
ORC I D Grace A. Mucci https://orcid.org/0000-0002-9993-959X

R E F E R E NC E S
Dystonia can severely hamper gait capacity and gait performance, as seen in several neurological conditions, including cerebral palsy (CP). Detection of dystonia in CP is important to select the appropriate treatment; however, identifying it and distinguishing it from spasticity can be challenging. Aravamuthan et al. 1 provide a step forward on this topic by applying an innovative mixed-methods approach involving conventional content analysis and pose estimation techniques on gait data of 166 individuals with CP and spasticity (aged between 10 and 20 years, classified in Gross Motor Function Classification System levels I-III). Participants walked 15 feet in a straight line towards a video camera and the footage was subsequently rated by three movement disorders experts for the presence and severity of dystonia. Subsequently, their severity ratings were correlated with promising gait variable analogues obtained using the opensource software DeepLabCut. We will elaborate on three of their findings.
First, the presence of variable unilateral, hip, leg, or foot adduction was most commonly reported by the three experts to support a diagnosis of dystonia. It is unclear whether this refers to variability within a gait cycle (i.e. foot adduction during the stance phase but not during the swing phase) or between subsequent gait cycles, which could also be the result of ataxia. Because dystonia is typically task-specific (i.e. present when walking but not when sitting or standing), 2 mentions of variability would likely have been higher had these tasks also been videotaped and rated.
Second, when asked to elaborate on their severity rating, the three experts most commonly cited dystonia amplitude and the effect of dystonia on gait. What complicates matters is that frequently dystonia is not the only sign in CP; spasticity, paresis, ataxia, and contractures may also occur and have an impact on gait and movement amplitudes. For example, hip adductor spasticity may result in gait scissoring with increased hip adduction and contractures that may influence the amplitude effects of dystonia. However, the degree of spasticity and presence or absence of contractures was not reported in the study by Aravamuthan et al. 1 Third, the authors showed that expert assessment of gait dystonia correlated with variance in inter-ankle distance and the foot angle minimum. They suggested that these variables can ultimately be used to track gait dystonia assessment in the clinic or at home and may be used as outcome measures in clinical trials that evaluate the effects of dystonia treatment. However, the question is whether the video annotation tools used are sensitive enough to detect differences over time. Therefore, repeated measurements with the video analysis tool and a criterion standard (e.g. obtained using three-dimensional gait analysis) are needed. Improvement of diagnosis and severity assessment has recently been marked as one of the dystonia research priorities in CP. 3 Interestingly, in this study by Avaramuthan et al., 1 dystonia was identified in 60% of participants. This is a high rate, given that only around 10% of children with CP have predominant dyskinesia; however, it is in agreement with a recent report of dystonia being present during upper-limb tasks in up to 70% of children with spastic CP. 4 This makes the call for trials evaluating dystonia treatment in CP even more urgent.
The question remains as to whether the reported gait variables are the optimal outcome for future trials in this area. Before application, validation against verified assessment instruments and clinical meaningfulness are required. Moreover, the proposed outcomes should ideally be part of an overarching construct, which also assesses the impact of dystonia on activities and participation. To this aim, the International Classification of Functioning, Disability and Health model with its five domains may be of help. 5

DATA AVA I L A BI L I T Y S TAT E M E N T Not required
ORC I D Jorik Nonnekes https://orcid.org/0000-0003-2434-1427