title: The flexion withdrawal reflex increases in premature infants at 22-26 weeks of gestation due to changes in spinal cord excitability.
abstract: OBJECTIVE
  Our aim was to study the development of the cutaneous flexion withdrawal reflex among premature infants admitted to the neonatal intensive care unit of the Children's Hospital, University of Cologne, in 2013.
  
  
  METHODS
  This longitudinal cohort study explored the development of spinal cord excitability of 19 premature infants born at 22-26 weeks of gestation. We performed five investigations per subject and studied changes in the reflex threshold with increasing postnatal age at different behavioural states. The premature infants were stimulated with von Frey filaments on the plantar surface of the foot near the first metatarsophalangeal joint during the first 3 days of life and at postnatal ages of 10-14 days, 21-28 days, 49-59 days and a corrected gestational age of 37-40 weeks.
  
  
  RESULTS
  The mean gestational age of the premature infants included in the study was 24 weeks. Premature infants with a gestational age of less than 26 weeks presented a flexion withdrawal reflex with a low threshold (0.5-2.85 milli-Newton) in the first 72 hours of life.
  
  
  CONCLUSIONS
  The flexion withdrawal reflex among premature infants born at less than 26 weeks showed a continuous threshold increase with increasing postnatal age, reflecting changes in spinal cord excitability.
authors.affiliation: Department of International Health, School CAPHRI, Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands.|Children's and Adolescents' Hospital, University Hospital of Cologne, Cologne, Germany.|Center of Prevention and Rehabilitation, University Hospital of Cologne, Cologne, Germany.
authors.forename: Kyriakos
authors.identifier: http://orcid.org/0000-0003-3982-0914
authors.initials: K
authors.lastname: Martakis
authors.affiliation: Children's and Adolescents' Hospital, University Hospital of Cologne, Cologne, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Hünseler
authors.affiliation: Children's and Adolescents' Hospital, University Hospital of Cologne, Cologne, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Herkenrath
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
authors.forename: Kruthika
authors.initials: K
authors.lastname: Thangavelu
authors.affiliation: Children's and Adolescents' Hospital, University Hospital of Cologne, Cologne, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Kribs
authors.affiliation: Children's and Adolescents' Hospital, University Hospital of Cologne, Cologne, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Roth
mesh_terms: D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male; D012018:Reflex / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*
keywords: Behavioural state; Flexion withdrawal reflex; Premature infant; Spinal excitability; Stimulation