Knee jerk responses in infants at high risk for cerebral palsy: an observational EMG study.

BACKGROUND: Following our clinical observation of tonic responses in response to the knee jerk in infants at very high risk for cerebral palsy (VHR infants), we systematically studied tonic responses, clonus, and reflex irradiation. We questioned (i) whether these responses occurred more often in VHR infants than in typically developing (TD) infants, and (ii) whether they were associated with abnormal general movement quality. METHODS: Twenty-four VHR and 26 TD infants were assessed around 3 mo corrected age. Surface electromyograms of leg, trunk, neck, and arm muscles were recorded while eliciting the knee jerk. All assessments were video-recorded. RESULTS: VHR infants more often than TD infants showed tonic responses in the ipsilateral quadriceps and hamstring (Mann-Whitney U; P = 0.0005 and P = 0.0009), clonus (Chi-square; P = 0.0005) and phasic responses in the contralateral quadriceps and hamstring (Mann-Whitney U; P = 0.002 and P = 0.0003, respectively). Widespread reflex irradiation occurred in VHR and TD infants. Definitely abnormal general movements and stiff movements were associated with tonic responses (Mann-Whitney U; P = 0.0005, P = 0.007, respectively) and clonus (Mann-Whitney U; P = 0.003 and P = 0.0005) in the ipsilateral quadriceps. CONCLUSION: Similar to clonus, tonic responses may be regarded as a marker of a loss of supraspinal control. Reflex irradiation primarily is a neurodevelopmental phenomenon of early ontogeny.

Slow pupillary light responses in infants at high risk of cerebral palsy were associated with periventricular leukomalacia and neurological outcome.

AIM: Having observed slow pupillary light responses (PLRs) in infants at high risk of cerebral palsy, we retrospectively evaluated whether these were associated with specific brain lesions or unfavourable outcomes. METHODS: We carried out neurological examinations on 30 infants at very high risk of cerebral palsy five times until the corrected age of 21 months, classifying each PLR assessment as normal or slow. The predominant reaction during development was determined for each infant. Neonatal brain scans were classified based on the type of brain lesion. Developmental outcome was evaluated at 21 months of corrected age with a neurological examination, the Bayley Scales of Infant Development Second Edition and the Infant Motor Profile. RESULTS: Of the 30 infants, 16 developed cerebral palsy. Predominantly slow PLRs were observed in eight infants and were associated with periventricular leukomalacia (p = 0.007), cerebral palsy (p = 0.039), bilateral cerebral palsy (p = 0.001), poorer quality of motor behaviour (p < 0.0005) and poorer cognitive outcome (p = 0.045). CONCLUSION: This explorative study suggested that predominantly slow PLR in infants at high risk of cerebral palsy were associated with periventricular leukomalacia and poorer developmental outcome. Slow PLR might be an expression of white matter damage, resulting in dysfunction of the complex cortico-subcortical circuitries.

General Movement Assessment from videos of computed 3D infant body models is equally effective compared to conventional RGB video rating.

BACKGROUND: General Movement Assessment (GMA) is a powerful tool to predict Cerebral Palsy (CP). Yet, GMA requires substantial training challenging its broad implementation in clinical routine. This inspired a world-wide quest for automated GMA. AIMS: To test whether a low-cost, marker-less system for three-dimensional motion capture from RGB depth sequences using a whole body infant model may serve as the basis for automated GMA. STUDY DESIGN: Clinical case study at an academic neurodevelopmental outpatient clinic. SUBJECTS: Twenty-nine high risk infants were assessed at their clinical follow-up at 2-4 month corrected age (CA). Their neurodevelopmental outcome was assessed regularly up to 12-31 months CA. OUTCOME MEASURES: GMA according to Hadders-Algra by a masked GMA-expert of conventional and computed 3D body model ("SMIL motion") videos of the same GMs. Agreement between both GMAs was tested using dichotomous and graded scaling with Kappa and intraclass correlations, respectively. Sensitivity and specificity to predict CP at ≥12 months CA were assessed. RESULTS: Agreement of the two GMA ratings was moderate-good for GM-complexity (κ = 0.58; ICC = 0.874 [95%CI 0.730; 0.941]) and substantial-good for fidgety movements (FMs; Kappa = 0.78, ICC = 0.926 [95%CI 0.843; 0.965]). Five children were diagnosed with CP (four bilateral, one unilateral CP). The GMs of the child with unilateral CP were twice rated as mildly abnormal with FMs. GM-complexity and somewhat less FMs, of both conventional and SMIL motion videos predicted bilateral CP comparably to published literature. CONCLUSIONS: Our computed infant 3D full body model is an attractive starting point for automated GMA in infants at risk of CP.

The tonic response to the infant knee jerk as an early sign of cerebral palsy.

BACKGROUND: Early identification of infants at risk of cerebral palsy (CP) is desirable in order to provide early intervention. We previously demonstrated differences in knee jerk responses between 3-month-old high risk and typically developing infants. AIMS: To improve early identification by investigating whether the presence of tonic responses (continuous muscle activity occurring after the typical phasic response), clonus or contralateral responses to the knee jerk during infancy is associated with CP. STUDY DESIGN: Longitudinal EMG-study. SUBJECTS: We included 34 high-risk infants (median gestational age 31.9 weeks) who participated in the LEARN2MOVE 0-2 years trial. OUTCOME MEASURES: Video-recorded knee jerk EMG-assessments were performed during infancy (1-4 times). Developmental outcome was assessed at 21 months corrected age (CA). Binomial generalized estimating equations models with repeated measurements were fitted using predictor variables. RESULTS: Infants who later were diagnosed with CP (n = 18) showed more often than infants who were not diagnosed with CP i) tonic responses - from 4 months CA onwards, ii) clonus - from 13 months CA onwards, and iii) contralateral responses - from 15 months CA onwards. LIMITATIONS: The main limitation is the relatively small sample size. CONCLUSIONS: The assessment of tonic responses to the knee jerk using EMG may be a valuable add-on tool to appraise a high risk of CP.