The neurological phenotype of developmental motor patterns during early childhood.

INTRODUCTION: During early childhood, typical human motor behavior reveals a gradual transition from automatic motor patterns to acquired motor skills, by the continuous interplay between nature and nurture. During the wiring and shaping of the underlying motor networks, insight into the neurological phenotype of developmental motor patterns is incomplete. In healthy, typically developing children (0-3 years of age), we therefore aimed to investigate the neurological phenotype of developmental motor patterns. METHODS: In 32 healthy, typically developing children (0-3 years), we video-recorded spontaneous motor behavior, general movements (GMs), and standardized motor tasks. We classified the motor patterns by: (a) the traditional neurodevelopmental approach, by Gestalt perception and (b) the classical neurological approach, by the clinical phenotypic determination of movement disorder features. We associated outcomes by Cramer's V. RESULTS: Developmental motor patterns revealed (a) choreatic-like features (≤3 months; associated with fidgety GMs (r = 0.732) and startles (r = 0.687)), (b) myoclonic-like features (≤3 months; associated with fidgety GMs (r = 0.878) and startles (r = 0.808)), (c) dystonic-like features (0-3 years; associated with asymmetrical tonic neck reflex (r = 0.641) and voluntary movements (r = 0.517)), and (d) ataxic-like features (>3 months; associated with voluntary movements (r = 0.928)). CONCLUSIONS: In healthy infants and toddlers (0-3 years), typical developmental motor patterns reveal choreatic-, myoclonic-, dystonic- and ataxic-like features. The transient character of these neurological phenotypes is placed in perspective of the physiological shaping of the underlying motor centers. Neurological phenotypic insight into developmental motor patterns can contribute to adequate discrimination between ontogenetic and initiating pathological movement features and to adequate interpretation of therapeutic interactions.

Reliability and discriminant validity of ataxia rating scales in early onset ataxia.

AIM: To determine whether ataxia rating scales are reliable disease biomarkers for early onset ataxia (EOA). METHOD: In 40 patients clinically identified with EOA (28 males, 12 females; mean age 15y 3mo [range 5-34y]), we determined interobserver and intraobserver agreement (interclass correlation coefficient [ICC]) and discriminant validity of ataxia rating scales (International Cooperative Ataxia Rating Scale [ICARS], Scale for Assessment and Rating of Ataxia [SARA], and Brief Ataxia Rating Scale [BARS]). Three paediatric neurologists independently scored ICARS, SARA and BARS performances recorded on video, and also phenotyped the primary and secondary movement disorder features. When ataxia was the primary movement disorder feature, we assigned patients to the subgroup 'EOA with core ataxia' (n=26). When ataxia concurred with other prevailing movement disorders (such as dystonia, myoclonus, and chorea), we assigned patients to the subgroup 'EOA with comorbid ataxia' (n=12). RESULTS: ICC values were similar in both EOA subgroups of 'core' and 'comorbid' ataxia (0.92-0.99; ICARS, SARA, and BARS). Independent of the phenotype, the severity of the prevailing movement disorder predicted the ataxia rating scale scores (ß=0.83-0.88; p<0.05). INTERPRETATION: In patients with EOA, the reliability of ataxia rating scales is high. However, the discriminative validity for 'ataxia' is low. For adequate interpretation of ataxia rating scale scores, application in uniform movement disorder phenotypes is essential.

Assessment of speech in early-onset ataxia: a pilot study.

AIM: The aim of the study was to determine whether paediatric ataxia speech subscores are reliably applicable for international early-onset ataxia (EOA) databases. If so, we reasoned that ataxia speech subscores should be associated with ataxia scores and involve high interobserver agreement, including those for internationally applicable Scale for Assessment and Rating of Ataxia (SARA) syllable repetition tasks (SARASRT). METHOD: Three independent paediatric neurologists and a speech therapist scored speech in 52 healthy children (mean age 10y, range 4-16y) and 40 individuals with EOA (mean age 15y, range 5-34y). We compared ataxia speech subscores for the association with age and ataxia scores as well as interobserver reliability. RESULTS: In healthy children, ataxia speech subscores were moderately associated with age (International Cooperative Ataxia Rating Scale [ICARS]: r=-0.515; SARA: r=-0.321; p<0.05) and with ataxia scores (ICARS: r=0.552; SARA: r=0.336; p<0.05), and revealed slight to moderate interobserver agreement (ICARS-intraclass correlation coefficient [ICC]: 0.380; SARA-ICC: 0.185; SARASRT-ICC: 0.509). In EOA, speech subscores have a strong association with ataxia scores (ICARS: r=0.735; SARA: r=0.730; p<0.001) and revealed substantial to nearly perfect interobserver agreement (ICARS-ICC: 0.812; SARA-ICC: 0.854; SARASRT-ICC: 0.724). INTERPRETATION: Early-onset ataxia speech subscores are associated with ataxia and also reveal high interobserver agreement, including those internationally applicable to SARASRT. We conclude that SARASRT appears to be applicable for EOA databases. However, before syllable repetition tasks are included, we would advise to wait for the results published by the international Childhood Ataxia and Cerebellar Group.

Ataxia rating scales are age-dependent in healthy children.

AIM: To investigate ataxia rating scales in children for reliability and the effect of age and sex. METHOD: Three independent neuropaediatric observers cross-sectionally scored a set of paediatric ataxia rating scales in a group of 52 healthy children (26 males, 26 females) aged 4 to 16 years (mean age 10y 5mo SD 3y 11mo). The investigated scales involved the commonly applied International Cooperative Ataxia Rating Scale (ICARS), the Scale for Assessment and Rating of Ataxia (SARA), the Brief Ataxia Rating Scale (BARS), and PEG-board tests. We investigated the interrelatedness between individual ataxia scales, the influence of age and sex, inter- and intra-observer agreement, and test-retest reliability. RESULTS: Spearman's rank correlations revealed strong correlations between ICARS, SARA BARS, and PEG-board test (all p<0.001). ICARS, SARA, BARS and PEG-board test outcomes were age-dependent until 12.5, 10, 11, and 11.5 years of age respectively. Intraclass correlation coefficients (ICCs) varied between moderate and almost perfect (interobserver agreement: 0.85, 0.72, and 0.69; intraobserver agreement: 0.92, 0.94, and 0.70; and test-retest reliability: 0.95, 0.50, and 0.71; for ICARS, SARA, and BARS respectively). Interobserver variability decreased after the sixth year of life. INTERPRETATION: In healthy children, ataxia rating scales are reliable, but should include age-dependent interpretation in children up to 12 years of age. To enable longitudinal interpretation of quantitative ataxia rating scales in children, European paediatric normative values are necessary.