The Evolution of Primitive Reflexes in Extremely Premature Infants
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0031-3998/86/2012-1284$02.00/0 PEDIATRIC RESEARCH Vol. 20, No. 12, 1986 Copyright © 1986 Intern ational Pediatric Research Foundat ion, Inc. Printed in U.S.A. The Evolution of Primitive Reflexes in Extremely Premature Infants M. C. ALLEN AND A. J. CAPUTE Departm ent oj Pediatrics and Eudowood Neonatal Division. The Johns Hopkin s University School of Medicine and The John F. Kennedy Institute for Handicapped Children, Baltim ore. Ma ryland ABSTRACf. A longitudinal study describes the pattern of infants, from birth through infancy. In the only published lon appearance of eight primitive reflexes in a population of gitudinal study in premature infants, the primitive reflexes were 47 viable extremely premature infants, beginning as early not graded and their frequency in the population was not re as 25 wk postconceptional age (PCA). Infants were exam ported (9). In addition, the population was limited to selected ined weekly, from 1 wk of age until discharge from the premature infants beyond 28 wk gestation. The only descriptions neonatal intensive care unit. Primitive reflexes were graded of primitive reflexes less than 28 wk gestation are in non viable as to completeness and intensity of response. Three pat aborted fetuses prior to their death (9, 23-25). Observers using terns emerged: 1) the upper and lower extremity grasp ultrasound have observed fetal movements, but have not yet reflexes were present in all premature infants, from 25 wk described discrete primiti ve reflexes in utero (26). and beyond, 2) the Moro, asymmetric tonic neck reflex With improved obstetric and neonatal care, the lower limit of and Galant (lateral trunk incurvature reflex) were present viability is now as low as 23 to 24 wk gestation. Not only has in some premature infants as early as 25 wk PCA, and in survival impro ved, but the majority of these infants has the the majority by 30 wk PCA, and 3) the lower extremity potential for a life free of major handicap (27-29). It is therefore placing, positive support, and stepping were occasionally possible, and may be useful, to observe the pattern of appearance present prior to 30 wk PCA, yet were not uniformly present of the primitive reflexes in these viable extremely premature and/or complete even at term. In each case, the primitive infants. reflex became stronger, more complete, more consistently This longitudinal study describes the appearance and evolution elicited and more prevalent with increasing postconcep of selected primiti ve reflexes in 47 viable extremely premature tional age. The pattern of primitive reflexes in the prema infants, documented by weekly examinations, from I wk of age ture infant at term (40 wk I)CA) is similar to that of full until discharge from the neonatal intensive care unit. The upper term newborns. Sequential assessment of the primitive extremity (palmar) and lower extremity (plantar) grasp reflexes, reflexes may be a useful method of evaluating extremely Moro, ATNR, Galant (lateral trunk incurvature), lower extrem premature infants prior to term. (Pediatr Res 20: 1284 ity placing, positive support, and stepping (automatic walking) 1289,1986) were selected for analysis Abbreviations METHODS ATNR, asymmetric tonic neck reflex All premature infants with birth weights less than 1300 g born PCA, postconceptional age (the sum of gestational age and at The Johns Hopkins Hospital in 1983 were examined weekly, chronologie age) beginning at I wk of age, until the time of discharge. Of 69 PVL, periventricular leukomalacia infants meeting these criteria, 56 (81%) survived the neonatal period. Birthweight ranged from 460 to 1280 g (mean 960 g). Gestational age ranged from 24 to 33 wk (mean 27.9 wk). Thirty- eight (68%) were at or below 28 wk gestation at the time of birth. The primitive reflexes were one of the earliest tools used to Gestational age was determined by mother's dates in the assess the central nervous system integrity of full-term newborns majority (>9 0%) of infants, and was generally confirmed by (1-9). They are brain-stem mediated, complex automatic move obstetric examination, sonographic data, and the neonatologist's ment patterns that are present at birth in full-term infants and, assessment. Although it was used in two infants in whom dates with central nervous system maturation, become more difficult were confusing, the Dubowitz assessment of gestational age (30) to elicit later in the 1st yr of life, when voluntary motor activity has not been useful in these extremely premature infants. The is emerging (10-14). Although Touwen (15) has argued that Dubowitz differed from the gestational age (as determined by primitive reflexes are neither primitive nor reflexes, he acknowl dates, examination, and sonographic dates) by more than I wk edges that they and their developmental course are useful com in 60%, and by more than 2 wk in 32%. ponents of the neurologic examination in infancy. Unusually Weekly examinations (± 2 days) were performed in all infants strong or persistent primit ive reflexes are present in children with by a neonatologist/developmental pediatrician . The examination cerebral palsy, and may be early markers of neurologic dysfunc was deferred if the infant was unstable (e.g. with sepsis, pneu tion (4, 16-21). mothorax, or necrotizing enterocolitis), and was resumed when Capute and associates (10-14) have graded the primitive re the infant was stable. Although 50 (89%) infants were initially flexes as to strength and completeness of response, and have intubated, 24 (43%) were not on a ventilator at the time of their described their evolution in a longitudinal study of full term first examination. Nine (16%) infants with severe chron ic lung Correspondence received May 31, 1985; accepted July 22,1986. disease and/or severe (grade IV) intraventricular hemorrhage Marilee C. Allen, M.D., CMSC 210, The John s Hopkins Hospital , 600 N. Wolfe required prolonged mechan ical ventilation, for 12 wk or more. Street, Baltimore, MD 21205. Their outcome was uniformly poor: six died and three have 1284 PRI MITI VE REFLEXES IN PR EMA T URE INFANTS 1285 cerebral palsy. This discrete group of premature infants with wk ofage (Fig. 2). Although this reflex was initiall y weak in some unifo rmly poor outcome were excluded from analysis, and will infant s, the strength of the toe flexion increased with postconcep be reported separately. tional age. All 47 premature infant s had cranial ultrasound examinations Mora. The initial component of the Moro , with extension during the first 2 wk of life. The majority (60%) had two or more and/ or abduction of the upper extremities (grade I), was gener examinations (generally at 4-7 days, then at 10-14 days, with ally present by 25 to 26 wk PCA (Fig. 3). Subsequ ent adduction subsequent follow-up if abnormal). Thirty-three (70%) had no or flexion (grade 2) appeared at 27 to 28 wk PCA. The complete evidence of periventricular/ intraventricular hemorrhage. Nine reflex (grade 3) appeared at 29 to 30 wk PCA and was present in (19%) had grade I periventricuJar hemorrhage, four (9%) had 75% at term . grade II intrave ntricular hemorrhage, and one infant had blood ATNR. Four offive infants examined at 25 to 26 wk PCA had in the ventricles with moderately dilated ventricles (grade III some evidence of the ATNR in both upper and lower extremities intraventricular hem orrh age). One infant had grade I periven (Fig. 4). By 31 to 32 wk PCA, 98% had some evidence of an tricuJar hemorrhage with bilateral multiple periventri cular cysts, ATN R, and beyond 33 wk PCA, all infants had an ATNR. The suggestive of PVL. proportion of infants with tone changes only (grade I) decreased The appearance of eight primitive reflexes are described in 47 from 40% at 25 to 26 wk PCA to 2% at 33 to 34 wk PCA. premature infant s. Of these infants, 38% were male, 62% female, Changes in posture (grades 2 and 3) predominated by 29 to 30 30% white, and 70% black. Data were incomplete in two: one wk PCA. The strong response (grade 3) becam e increasingly was a 28-wk premature infant with hemophilia and was not prevalent, occurring in almost half (44 to 48%) by 35 to 40 wk examined until 6 wk of age, one was transferred to a community PCA hospital at 3 wk of age. A total of 397 examinations was per Galant. Trunk incurvature (grades I, 2, and 3) was demon formed, an average of 8.4 per infant. Data are reported on the strated in only one of five infants examined at 25 to 26 wk PCA, basis of postconceptional age (PCA, the sum of chro nologie age but rapidly becam e more frequent and stronger with increasing and gestational age), in 2-wk intervals. postconceptional age (Fig. 5). As with the ATNR , 98% of pre The primitive reflexes were elicited in the following man ner. mature infants had a Galant by 31 to 32 wk PCA. The strongest I)Upper extremity grasp reflex-pressure over the palm elicits response, trunk incurvature with hip elevation (grade 4), ap finger flexion. Subsequent traction on the arm reinforces the grip peared at 29 to 30 wk PCA, and was present in 38 to 44% of and elicits flexion at the elbow (and shoulder). infants beyond 35 wk PCA. 2) Lower extremity grasp reflex- pressure at the base of the toes elicits plantar flexion of the toes. 3) Moro-the examiner lifts the infant's head and gentl y allows it to fall back into the examiner's hand. This elicits abdu ction 100 '3' '"3 '3 "4 and extension of the upper extremities, followed by addu ction r--:'- - - and flexion.