Abstract
The STNR is a primitive reflex that is characterized by upper extremity (UE) extension and lower extremity (LE) flexion with neck extension, and by UE flexion and LE extension with neck flexion. Although often seen in children with cerebral palsy (CP), it is an uncommon finding in term neonates and infants. Its frequency has been studied in a population of 110 premature infants who were examined at and/or prior to term and who had normal motor milestones on followup at a mean age of 27 months (12-61). The STNR was graded as to intensity and completeness, in the manner of Capute et al (DMCN 26:375, 1984). Mean BW was 1141 gms (460-2190); mean GA was 28.6 wks (23-35). Forty-six had multiple exams prior to term.
At term (or NICU discharge), 42% had a definite (Grade 2) STNR and 9% had a complete (Grade 3) STNR. Only 1% had Grade 1 STNR (tone changes only). Of the 53 (48%) who were scored as no STNR, 6 (11%) had evidence of STNR in either the UE or LE (partial STNR). Of the 46 who had multiple exams, 28% had an STNR on one exam but not on an earlier or later exam. When the data on all 238 exams were analyzed by postconceptional age (PCA), the STNR was not elicited prior to 28 wks PCA and was present in 4-6% at 29-32 wks PCA. The frequency and strength of the STNR progressively increased with PCA. By term, 32% had Grade 2 and 14% had Grade 3 STNR.
The STNR is a normal finding in premature infants prior to term. It emerges at 30 wks PCA, and is present in half of premature infants at term.
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Allen, M. THE SYMMETRIC TONIC NECK REFLEX (STNR) AS A NORMAL FINDING IN PREMATURE INFANTS PRIOR TO TERM. Pediatr Res 21 (Suppl 4), 208 (1987). https://doi.org/10.1203/00006450-198704010-00254
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DOI: https://doi.org/10.1203/00006450-198704010-00254