ICNC Abstracts, ICNC 2018

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Can early onset ataxia phenotypically be distinguished from developmental coordination disorders?
Tinka Lawerman, Rick Brandsma, Natasha M Maurits, Octavio E Martinez-Manzanera, Roelineke J Lunsing, Oebele F Brouwer, Hubertus PH Kremer, Deborah A Sival

Last modified: 2018-09-09


Background:Reliable phenotypic ascertainment of motor dysfunction in Early Onset Ataxia (EOA) is important for genetic testing, clinical surveillance and treatment.

Aim:To investigate the diagnostic accuracy of phenotypic EOA recognition among other developmental conditions involving coordination impairment, including developmental coordination disorder (DCD) and hypotonia or hypoactive muscle activation (HHM), and to explore the effect of “EOA-assessment instructions” on the consensus of phenotypic EOA recognition.

Methods:We included 32 children (4-17 years), diagnosed with EOA (n=11),DCD (n=10) and HHM (n=11). Three pediatric neurologists performed phenotypic assessment of videotaped motor behavior and quantified coordination performances according to the SARA (Scale for Assessment and Rating of Ataxia). We determined phenotypic inter-observer agreement, phenotypic discrimination between EOA/HHM and between EOA/DCD, and determined SARA (sub)score profiles per phenotypic group. We evaluated whether “instructions” for phenotypic EOA recognition could improve the phenotypic consensus on EOA recognition during re-assessment. EOA-assessment instructions were substantiated by previous research-data, including movement sensors (IMUs).

Results:Inter-observer agreement on phenotypic EOA assessment was substantial (Gwets AC1:0.80,p<.001). EOA was phenotypically discerned from HHM and DCD in respectively 100% and 76% of patients (full consensus). Mismatches between EOA and DCD phenotypes revealed overlapping SARA scores, although sub-score profiles were different. Re-assessment with EOA-assessment instructions helped to increase phenotypic discrimination with full consensus between EOA and DCD from 76% to 86%.

Conclusion:Phenotypic discrimination between EOA and developmental disorders is reliable, but incomplete between EOA and DCD. Phenotypic re-assessment by standardized EOA instructions might improve phenotypic EOA recognition. Future IMU studies may contribute to unanimous phenotypic EOA recognition.


Early onset ataxia; developmental coordination disorder; hypotonia;phenotype;inter-observer agreement;SARA;coordination;balance

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