|Year : 2020 | Volume
| Issue : 1 | Page : 24-30
Diagnostic relevance of primitive reflexes in high-risk newborns: A systematic review
N Swapna1, Prawin Kumar2, Bincy R Kalam3, VA Anju3, K Arunraj2
1 Department of Prevention of Communication Disorders; Department of Speech Pathology, All India Institute of Speech and Hearing (AIISH), Mysore, Karnataka, India
2 Department of Prevention of Communication Disorders; Department of Audiology, All India Institute of Speech and Hearing (AIISH), Mysore, Karnataka, India
3 Department of Prevention of Communication Disorders, All India Institute of Speech and Hearing (AIISH), Mysore, Karnataka, India
|Date of Submission||21-Nov-2019|
|Date of Decision||01-Feb-2020|
|Date of Acceptance||15-Apr-2020|
|Date of Web Publication||06-Jul-2020|
Department of Audiology, All India Institute of Speech and Hearing, Mansagangotri, Mysore - 570 006, Karnataka
Source of Support: None, Conflict of Interest: None
The study was undertaken to perform a systematic review to investigate the diagnostic relevance of primitive reflexes (PR) such as Moro, Rooting, Sucking, Palmar, and Plantar/Babinski reflexes in high-risk newborns. A systematic literature search was carried out using different search engines between the years 1980 and 2018. There were 48 articles considered out of 61 articles, based on screening of the title and abstract. Finally, among 48 articles, a total of 8 articles were considered for the detailed review based on the inclusion criteria. The results of the selected articles on the different PRs have been discussed in the present study. Though most studies have evaluated the moro and the plantar reflex, every reflex considered in the study has been found to be affected in high-risk newborns and consequently, it is difficult to undermine the significance of any of these. All the studies reviewed highlighted the importance of assessing these reflexes in high-risk newborns and indicated that an abnormal reflex is an indication of a neurological abnormality. These findings indicate that the assessment of PRs should be included in the newborn screening protocol because they are not time consuming and can be performed easily with minimum or no tools. Future studies that are aimed at investigating the efficacy of these PRs in identifying children with developmental disabilities are essential.
Keywords: Babinski reflex, high-risk infants, moro reflex, palmar reflex, plantar reflex, primitive reflexes, rooting reflex, sucking reflex
|How to cite this article:|
Swapna N, Kumar P, Kalam BR, Anju V A, Arunraj K. Diagnostic relevance of primitive reflexes in high-risk newborns: A systematic review. J Indian Speech Language Hearing Assoc 2020;34:24-30
|How to cite this URL:|
Swapna N, Kumar P, Kalam BR, Anju V A, Arunraj K. Diagnostic relevance of primitive reflexes in high-risk newborns: A systematic review. J Indian Speech Language Hearing Assoc [serial online] 2020 [cited 2021 Dec 2];34:24-30. Available from: https://www.jisha.org/text.asp?2020/34/1/24/288973
| Introduction|| |
Primitive reflexes (PRs) are complex automatic movement patterns present in full-term infants which originate in the central nervous system and are brainstem mediated. These reflexes become more difficult to elicit later in the 1st year of life, when voluntary motor activity emerges. Evaluation of the PRs is one of the simplest and frequently used assessment tools among health-care professionals. The responses of PRs have been categorized as normal/abnormal or present/absent. In general, a PR in infants is regarded as abnormal when it is absent, exaggerated, or diminished during the elicitation period or when it lasts beyond the normal age limit for its disappearance.
A literature review revealed that all PRs are not uniformly present in preterm newborns. Additionally, these reflexes often have various degrees of responses, which may be significant in assessing the neurological integrity. Subtle changes of PR could be considered as significant markers of nervous system dysfunction. Further, there is a lack of clarity about the diversity of response of reflexes related to clinical conditions and the clinician's interpretation of the reflexes. Vigorous, persistent, weak, or asymmetrical responses are closely linked with neurological impairment in newborns. Severe persistence of primary reflexes predominantly is seen in cases with cerebral palsy (CP). Children with spastic diplegia and hemiplegia manifest an asymmetric pattern of reflex persistence, particularly for asymmetric tonic neck reflex (ATNR), palmar grasp, plantar grasp, Babinski, gallant, and symmetric tonic neck reflex. Milder persistence of the PRs is associated with disorders including autism spectrum disorders and learning difficulties., Of the PRs, the Rooting, Sucking, Moro, Palmar, Plantar, and Babinski reflexes are frequently documented in the literature due to their important roles and this review focuses on the above reflexes. A brief note about these reflexes is provided below.
The rooting reflex is recognized as a possible hunger cue. An intact rooting reflex in newborns assures successful breastfeeding and sucking, and it permits certain oromotor activities such as blowing, sucking through a straw, and articulation of few sounds as the child grows. Sucking reflex often follows the rooting reflex, given that infants instinctively suck anything that touches the roof of their mouth and these reflexes have obvious functional significance in all mammalian species.
Sucking is observed to be the first rhythmic behavior in the fetus, which contributes to the neurological development. Literature suggests that a fetus starts sucking at 15 weeks gestation. During gestation, sucking is under the control of a specialized neuronal circuit, i.e., suck central pattern generator (CPG), located in the brainstem reticular formation, which activates groups of motor neurons that generate specific motor patterns., Even in the absence of sensory feedback, CPGs can produce a rhythmic motor pattern. However, the connectivity of the neuronal networks that comprise the CPGs in mammalian models and the motor signals they generate are modulated by sensory inputs. Sucking plays an imperative part in the development of feeding, speech, and language, which are dependent on good muscle coordination of lips, tongue, jaw, and hands as well as proper functioning of soft and hard palates.
The Moro reflex is primitive and is seen in some preterm infants at 25 weeks of postconceptual age (PCA) and in the majority by 30 weeks of PCA. There has been some uncertainty concerning the Moro response and the startle response in the past. The startle reaction is one of the defensive reactions, the response to which is elicited by presenting a sudden unexpected stimulus. This response is primarily characterized by flexion movement, whereas Moro response essentially comprises of extension movements. Moro reflex helps in assessing the integration of the central nervous system.
Palmar grasp reflex
Palmar grasp reflex occurs in preterm infants as early as 28 weeks of gestational age. During routine ultrasound examination, grasping of the umbilical cord was repeatedly observed, which first appeared at 16 weeks of gestation. The response of this reflex is less intense during the first 2 days after birth. However, the absence of this reflex on the 1st day of birth is considered as a crucial sign of neurosensorimotor disorder. Lesions in supplementary motor area, premotor cortex, and cingulate motor cortex can lead to abnormal palmar grasp reflex.,
Plantar and Babinski reflex
The plantar response, elicited during infancy by stimulating the sole of the feet with the thumb which causes flexion of toes, is highly predictable of neurologic outcome. Diminished or negative plantar grasp reflex during early infancy can be a possible indicator of later development of spasticity. Asymmetry in the plantar grasp response strongly suggests the existence of brain dysfunction. When there is extension of toes, it is referred to as the Babinski reflex. There is considerable discrepancy in the elicitation of Babinski and plantar reflexes. The stimulation applied in Babinski reflex is scratching on the sole of the foot in the lateral side. Babinski sign, also known as extensor plantar reflex, is one of the most clinically relevant diagnostic signs of corticospinal tract dysfunction and can coexist with other signs of upper motor dysfunction. This sign disappears in infants by around 1 year, when myelination of nerve fibers is complete. [Table 1] depicts the details of the above-mentioned reflexes.
|Table 1: Primitive reflexes, their elicitation, response and age of disappearance|
Click here to view
Understanding these reflexes and their significance might be more valuable in the neurobehavioral examination of newborns and in deciding whether these need to be incorporated as a part of the newborn screening protocol. Hence, the aim of the present study was to systematically review the literature on the diagnostic relevance of PRs in high-risk newborns. We focus on the PRs such as Rooting, Sucking, Moro, Palmar grasp, and Plantar/Babinski reflexes.
| Methods|| |
The present study involved a literature search conducted between month of June 2018 and October 2018 using the databases PubMed, Medline, and PsycINFO published between 1980 and 2018. We combined search terms for the two concepts of interest. For the first concept, we included: “PRs” OR “primary reflexes” OR “Moro reflex” OR “Sucking reflex” OR “Rooting reflex” OR “Babinski reflex” OR “Palmar reflex” OR “Plantar reflex.” The second concept included: “High risk infants” OR “High risk babies” OR “High risk neonates” OR “Babies in neonatal intensive care unit (NICU)” OR “Premature infants” OR “Preterm infants” OR “Low birth weight infants” OR “Asphyxiated infants” OR “Newborns in NICU” OR “Neonatal jaundice.” The two main concepts were combined using “AND” OR “IN.” The reference lists of the articles identified were used to find other relevant studies on the topic. The inclusion and exclusion criteria are given below.
The articles which addressed
- PRs such as Moro, Rooting, Sucking, Palmar, Plantar reflexes in high-risk infants
- “High-risk infants” as babies with significant perinatal or natal history such as preterm delivery, low birth weight, delayed birth cry, birth asphyxia, neonatal jaundice, NICU admission, and aspiration of amniotic fluid
- Early diagnosis of neurodevelopmental disorders in high-risk newborns
- Impact of these PRs in speech-language and motor development
- Clinical implications of evaluating PRs.
- Articles which explained PRs in healthy term infants
- Articles in languages other than English
- Review articles
- Articles which did not clearly mention the high-risk factors.
The above inclusion and exclusion criteria were used in the present review article to meet the objective of the study and specific focus was directed toward highlighting the importance of the PRs in high-risk newborns only.
| Results and Discussion|| |
We identified 61 studies from the databases with the above-mentioned search strategy in the method section. We examined the relevance of these articles, and 48 publications were selected for a detailed review after screening the title and abstract. After applying the inclusion and exclusion criteria detailed in the methods section, a total of eight articles were included for the current study [Figure 1]. The details of the selected studies are given in [Table 2].
|Figure 1: Flow diagram of studies identified, excluded and included in the systematic review. Flow diagram adapted from: Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement|
Click here to view
The significance of PRs has been widely studied in normal infants, however, there are limited studies in the literature about PRs in infants with high-risk factors, which reveal mixed findings. This systematic review provides an overview of the significance of the selected PRs in high-risk infants.
Rooting reflex is also known as search reflex, as it helps the child for searching the source of food, nipple etc., None of the selected articles investigated the rooting reflex in high-risk newborns. However, the literature suggests the persistence of rooting reflex as an indicator of bilateral brain dysfunction, the absence of which results in swallowing speech and articulation difficulties.
The sucking reflex plays a crucial role in oral feeding in coordination with breathing and swallowing, Sucking reflex is probably one of the most important survival reflexes. Among the eight articles, only one article by Sohn et al. investigated the sucking reflex in high-risk infants. Their study consisted of two high-risk groups (physiological risk group which consisted of 22 preterm newborns, without any pathologic conditions and pathologic risk group which consisted of 41 newborns, with respiratory distress syndrome, transient tachypnea or intrauterine growth retardation in addition to prematurity). They found that 36% among 63 high-risk newborns presented with an abnormal or absent sucking reflex, which was attributed with respiratory difficulties and decreased mental status. The results of this study implied that an abnormal or absent sucking reflex may indicate a neurologic impairment in the high-risk newborns. This finding is in consonance with the study by Bingham et al. and Mizuno and Ueda., Bingham et al. reported that premature newborns who were kept in ventilator usually exhibited poor sucking ability. A study done by Mizuno and Ueda in 24 high-risk full-term infants revealed that maturity of neurological development in premature newborns can be predicted through the sucking behavior seen in them.
Studies on Moro reflex report weak or absent Moro response, which is indicative of serious neurological conditions., Five of the selected articles discussed about the Moro reflex in high-risk infants. Marquis et al. conducted a study in very low birth weight (VLBW) premature infants at 4 months corrected age, by grading the Moro reflex. Grade 1 (some abduction or extension, no adduction or flexion) was present by 25– 26 week PCA, Grade 2 (abduction and extension, followed by some adduction and/or flexion) by 27– 28 week PCA, and Grade 3 (complete reflex) appeared at 29– 30 week PCA and was present in 75% of the infants at term. The authors found that VLBW infants exhibited retention of PRs, and this interfered with early motor development. A higher incidence of motor delay was seen in preterm VLBW infants than normal term infants. The study by Allen and Capute described the pattern of appearance of eight PRs including Moro reflex, in 47 viable extremely premature infants. They found that the Moro reflex was present in some premature infants as early as 25 week PCA, and in the majority (80%) by 30 weeks PCA, which further strengthens with increasing PCA. They concluded that the pattern of PRs in the premature infant at term (40 weeks PCA) was similar to that of full-term newborns.
Burns et al. found that the assessment of Moro reflex at 1 and 4 months failed to identify infants with CP, however a subsequent assessment at 8th month helped in identifying them. Further, they recommended that the identification should be based on a combination of assessments including motor, neurological, and PRs. Similar finding was observed in Harris's study, where in they found that in high-risk populations a present Moro response at 4 months was not associated with CP.
Moro and ATNR were evaluated longitudinally for a period of 1 year as a part of neuro-developmental examination in 54 babies with the risk factors such as prematurity (gestational age <37 weeks), birth asphyxia, intraventricular hemorrhage, apnea, septicemia/meningitis, hyperbilirubinemia, seizures and birth weight <1500 g. In the follow-up assessment, they found persistence of PRs in high risk babies and concluded that babies with abnormal neurobehavior at 3 months remained delayed at 1 year. Sohn et al. examined Moro reflex in 67 high-risk infants, 38.1% and 19% of them demonstrated abnormal and absent Moro reflex respectively. Moro reflex was presented as the least frequent normal response and most frequent abnormal response compared to Babinski and Sucking reflexes. Lower muscle tone, poor resistance to passive movements, and slow arm recoil may result in weak Moro reflex in preterm newborns.
It is observed from the above studies that focused on Moro reflex, that high-risk infants exhibited abnormal or absent reflex which is an indicator of a motor delay. These studies also signify the importance of inclusion of Moro reflex in the newborn assessment and indicate that the assessment should be made periodically and should be done along with other relevant assessments.
Three of the selected studies examined the significance of palmar reflex in high-risk infants. Allen and Capute found that grasp reflex was present in all premature infants, from 25 week PCA and beyond. They reported that the pattern of PRs in the premature infant at term (40 week PCA) was similar to that of full-term newborns and thereby recommended sequential or periodic assessment of the PRs in extremely premature infants prior to term.
In a study by Burns et al., at 4 months of age, assessment of PRs (ATNR, Tonic labyrinthine reflex, Moro reflex, Palmar reflex and Plantar grasp reflex) showed limited differentiation between the study group (26 high-risk infants who were diagnosed as CP later) and control group (26 high-risk infants who were not diagnosed as CP later). Only 20% had some abnormal reflexes, however at 8 months of age, individual PRs were abnormal in up to 30% of the infants with CP. Additionally between 25% and 60% of the study group did have persisting elicitable individual PRs which were graded as suspicious. The study did not provide any significant findings.
The study by Zafeiriou et al. found that the palmar grasp reflex was preserved until age 5 months in majority of normal infants, after which it began to disappear. However, most spastic children exhibited full activity of the reflex until 11 months of age. They concluded that the presence of positive palmar grasp reflex after 7 months can be used as an early diagnostic clue to confirm whether a high-risk infants will become normal or abnormal at 2 years of age. Thus, the manifestation of palmar grasp reflex in infants >4 months of age is predictive of damage in the central nervous system, caused by anoxia, neural degenerations, trauma, among other etiological factors. Through these studies, it is clear that the persistence of this reflex can be considered as a diagnostic marker of neurological deficits.
Six of the selected articles discussed the plantar reflex in high-risk infants. The study done by Allen and Capute on plantar reflex was similar to the results reported for the palmar reflex. They claimed that the upper and lower extremity grasp reflexes were present in all premature infants, from 25 weeks PCA and beyond. Burns et al. observed abnormal individual PRs including plantar grasp reflex at 8 months of age, in upto 30% of the infants with CP. Futagi et al. profiled the plantar grasp response in normal infants, infants with CP and infants with mental retardation (MR) at the follow-up examination. Normal infants showed complete plantar grasp reflex till 6 months of age, and it disappeared at 1st year of their life. Retention of the plantar grasp reflex was seen in infants with CP and in infants with MR. The response was significant at the age of 8 months and above. This lack of response in the plantar grasp reflex during the first 6– 7 months of life, indicated a poor prognosis and served as an early diagnostic clue as to whether a high-risk infant with neurological symptoms will finally become normal or not. They concluded that neurologically abnormal children could be in part diagnosed earlier on the basis of the PRs than based on that of their posture and/or muscle tone. However, the authors caution against judging the neurological status only with a single criterion.
Zafeiriou et al., reported that the plantar grasp response exhibited nearly full activity until 7 months of age in the normal infants, while it could be elicited in only 1/5 of the patients at age 11 months. They observed retention of plantar reflex until 11 months of age in children with athetoid CP and develop MR. While in children with spastic CP, there was a gradual decrease of reflex reactivity from 3 to 11 months of age., They concluded that a negative plantar grasp reflex after 3 months of age is an early diagnostic clue as to whether a high-risk infant will become normal or abnormal at the age of 2 years. This was in concordance with the findings of studies done by Futagi et al.,
Zafeiriou et al. (1999) also studied the plantar reflex in 204 high-risk infants, of whom 58 developed CP, 22 had develop MR without motor disturbance, and 124 were normal at a follow-up examination at 3 years of age. An extensor plantar response was seen in 82.3% of infants who subsequently were found to be neurologically normal at the end of 1st month. This turned into flexor at the age of 9 and 11 months in 68.5% and 86.3%, respectively. Twenty-one (42.9%) of 49 patients with various types of spastic CP demonstrated a combined extensor response (i.e., dorsiflexion of the great toe with fanning of the remaining toes) as early as the 1st month of life. They concluded that the combined extensor plantar response is a reliable prognostic clinical tool that contributes to an earlier diagnosis of spastic CP as early as the 1st month of life. They also indicated that the persistence of the extensor plantar response beyond 7– 11 months of life in high-risk infants should be considered as a sign of abnormality.
Sohn et al. also found that one-third of 67 high-risk infants presented an abnormal Babinski reflex (33.3%). Babinski reflex was absent in 7.9% of the infants. Factors such as length of hospitalization, Apgar scores, and total scores on the Infant Coma Scale (mental status) were statistically associated with the Babinski reflex. The findings of the selected studies on plantar reflex clearly show that a negative or diminished response of this reflex during early infancy is highly suggestive of neurologic abnormalities, especially spasticity.
This review provides an outline of the findings of studies that assessed PRs in high-risk infants. Among the selected studies, considerably greater number of studies investigated Moro reflex and Plantar reflex in high-risk infants. Only one article focused on sucking reflex, while none of the studies investigated the rooting reflex. Though most studies have evaluated the Moro and the Plantar reflex, every reflex considered in the studies reviewed have been found to be affected in high-risk newborns and consequently it is difficult to undermine the significance of any of these.
All the studies reviewed highlighted the importance of assessing these reflexes in high-risk newborns and indicated that an abnormal reflex is an indication of a neurological abnormality. Some of these studies also stressed on the need for sequential assessment of reflexes along with the other assessments.,,, Futagi et al. also indicated that a presumptive diagnosis can be made in neurologically high-risk infants though the examination of the PRs and consequently, such reflexes are of specific significance, among other neurological criteria. These findings indicate that the assessment of PRs should be included in the newborn screening protocol because they are not time consuming and can be performed easily with minimum or no tools.
The studies included in the review also suggest that it is not necessary that all high-risk infants should exhibit abnormal or absent PRs. Further these reflexes may not be seen in all normal infants, but with development and maturation, they may exhibit these reflexes, which again emphasize the fact that PR assessment cannot be used in isolation to understand the neurological status of an infant and arrive at an appropriate diagnosis and should be carried out periodically. Additionally, the strength of the reflex can vary depending on the underlying neuropathology which needs further investigation. All the studies that have been reviewed have not analyzed their results based on the type of neuropathology, though Allan and Capute reported that mild (Grade I or 11) periventricular/intraventricular hemorrhages did not affect the PR profile of premature infants. Such studies undertaken to understand the effect of neuropathology on the reflex profile will improve our understanding of the motor manifestations in the children with developmental disabilities.
The studies also reported that various degrees of responses can be seen in infants during the assessment of PRs, which may be significant in assessing the neurological integrity and subtle variations in these could be considered as significant markers of nervous system dysfunction. Hence, it is not appropriate to categorize responses to PRs as dichotomous responses such as normal/abnormal or present/absent. Accordingly they had used a three point rating scale (Normal, abnormal and absence) in their study and further recommended that it would be more beneficial to assess a variety of PRs using more detailed criteria. For example, the sucking reflex may be categorized by its presence, frequency, regularity, pressure and coordination with breathing or swallowing. They also indicated that subtle changes of PR could be valuable indicators of medical conditions and future developmental outcomes and thus it would be beneficial to develop standardized assessment protocol for PRs in high-risk infants using at least four scales (absence, hypoactive, normal, and hyperactive), similar to the assessment of adult reflexes.
This review highlights the limited number of studies that have been conducted on high-risk infants. Hence in future, more studies are required that is aimed at investigating the efficacy of these PRs in identifying children with developmental disabilities. Such studies will supplement the information about the development of reflexes and strengthen our understanding about neural maturation in this clinical population.
| Conclusions|| |
Although studies on PRs in high-risk infants are limited, there is an overall agreement on the clinical utility of these reflexes. Thus, it becomes imperative to include the assessment of PRs in the newborn screening protocol. However, the studies included in the review suggest that it is not necessary that all high risk infants should exhibit absent PRs, which highlights the fact that PR assessment should be done in conjunction with other relevant assessments. Infants exhibiting a marked variation in the reflex patterns and persistence of these reflexes beyond the specified age of disappearance of each reflex should carefully be observed for the development of any neurological abnormalities. The subtle variations in all these reflexes and its persistence can affect the infant's motor, speech as well language development in the later life. Hence, speech-language pathologists should recognize their significance, learn to elicit these reflexes and analyze the responses associated with these reflexes, as it will aid in the early identification of developmental disabilities. Based on the findings of our review and a general perspective, we believe that more number of studies are required that is aimed at investigating the efficacy of these PRs in identifying children with developmental disabilities and to check which of these or a combination of these are more sensitive indicators of neurological damage and at what timeline in an infant's life, which will yield a better understanding of the significance of PRs in high-risk infants.
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[Table 1], [Table 2]