Atypical knee jerk responses in high-risk children: A longitudinal EMG-study. (September 2022)

• Record Type: Journal Article
• Authors: Straathof, Elisabeth J.M.; Hamer, Elisa G.; Heineman, Kirsten R.; Hadders-Algra, Mijna
• Is Part Of: European journal of paediatric neurology. Volume 40(2022)
• Page Start: 11
• Page End: 17
• Publication Date: 2022-09
• Subjects: Brain injury -- Cerebral palsy -- Electromyography -- Knee jerk response -- Neurodevelopment -- Paediatrics; Pediatric neurology -- Periodicals; Nervous System Diseases -- Periodicals; Child -- Periodicals; Infant -- Periodicals; Neurologie pédiatrique -- Périodiques; Pediatric neurology; Electronic journals; Periodicals; Electronic journals; 618.928
• DOI: 10.1016/j.ejpn.2022.07.003
• Languages: English
• ISSNs: 1090-3798

Abstract

Abstract: Introduction: We previously found that atypical responses to the knee jerk reflex, i.e., tonic responses (TRs), clonus and contralateral responses in very high-risk (VHR) infants were associated with cerebral palsy (CP) at 21 months. The current study aimed for a better understanding of pathophysiology of atypical knee jerk responses by evaluating whether infant atypical knee jerk responses are associated with CP and atypical knee jerk responses at school-age. Methods: 31 VHR-children, who had also been assessed longitudinally during infancy, and 24 typically developing children, were assessed at 7–10 years (school-age). We continuously recorded surface EMG of thigh muscles during knee jerk responses longitudinally during infancy and once at school-age. Neurological condition was assessed with age-appropriate neurological examinations. It included the diagnosis of CP at 21 months corrected age and school-age. CP's type and severity (Gross Motor Function Classification System (GMFCS)) were reported. Results: Persistent TRs in infancy were associated with CP at school-age. TR prevalence decreased from infancy to childhood. At school-age it was no longer associated with CP. Clonus prevalence in VHR-children did not change with increasing age; it was significantly higher in children without than those with CP. Reflex irradiation was common in all school-age children, and its prevalence in contralateral muscles in VHR-children decreased between infancy and childhood. Conclusions: In infancy, TRs indicated an increased risk of CP, but at school-age TRs were not associated with CP. In general, spinal hyperexcitability, expressed as reflex irradiation and TRs, decreased between infancy and school-age. Highlights: Infant tonic knee jerk responses were associated with CP at school-age. Prevalence of tonic knee jerk response in VHR-infants decreased with increasing age. Tonic knee jerk responses at school-age were not associated with CP. In our study group, clonus at school-age occurred mainly in VHR-children without CP. At school-age, reflex irradiation occurred in VHR- and typically developing children.