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Human Development involves the biological, psychological, cognitive and emotional changes and development that occur throughout the lifespan and during transition in every life stage. Development begins from prenatal stage. Prenatal stage and infant stage are critical periods of development in human body.
In prenatal stage, there is emergence of majority of primitive reflexes. In infant stage of development, there is simultaneousness appearance of higher level control response (righting and equilibrium reactions) and disappearance or suppression of primitive reflexes. These lower level primitive reflexes are integrated and suppressed alongwith achievement of reflexes and reactions controlled at higher level which remains lifelong and some persists only till 5 years of age.
If there is persistence or delay in integration of primitive reflexes beyond the expected developmental time period then it indicates that there is underlying developmental or neurological issues. Similarly in adults, if they face any neurological disorders or impairments due to any cause, that has majorly affected frontal lobe then this will lead to reappearance of primitive reflexes which are called as frontal release signs.
Fig: Primitive Reflex : Palmar grasp reflex
What is reflex integration?
Reflex Integration is the process to improve the neurological foundation of sensory-motor development, and making orderly connections within the nervous system by doing gentle movements of infants in developmental pattern that every newborns and infants should learn to make. Making healthy, complex and mature communications between cortex and spinal cord pathways. When there is weak or incomplete connections, we call the reflex unintegrated, active and retained.
PRIMITIVE REFLEXES :
During the process of development in prenatal stage, all the major structures of the body are forming and health concern of mother is also essential. In this stage there is initiation or emergence of development of primitive reflexes in foetus. Development of various primitive reflexes begin as early in gestational period between 10th to 30th week and are fully developed at birth in term newborns. In infant stage, by 6 to 12 months of life as CNS matures, these primitive reflexes are gradually suppressed. These reflexes disappear or are inhibited by the frontal lobes as a child moves through normal child development.
Primitive reflexes are spinal cord and brain-stem level mediated reflexes which are involuntary, automatic in nature. In preterm, premature and neurologically affected infants these reflexes are not fully developed. These neonates may appear weak and hypotonic or may be hypertonic with abnormal or persistent primitive motoric responses.
Various Primitives reflexes : time of emergency and integration
1) Primitive Reflexes which integrate or disappear with CNS maturation
- Fear paralysis reflex (FPR) : emerges in embryonic stage by 5th to 8th weeks. FPR merges into Moro reflex and has become inactive before birth.
- Extensor Thrust : Present from birth and is normal till 2 months.
- Flexor Withdrawal : present from 28th weeks of gestation period and integrate by 1 to 2 months of infancy.
- Crossed Extension reflex : present from 28th weeks of gestation period and integrate by 1 to 2 months of infancy.
- Walking / Stepping reflex : Present at birth and disappears by 2 to 4 months of infancy.
- Limb placement : Present at 35 weeks of gestation period and disappears rapidly in early months of life by 2 to 4 months.
- Moro reflex or infant Startle reflex: Emerges by 28th week of gestation period and integrates by 4 to 6 months of infancy.
- Palmar grasp reflex : Emerges by 10th to 16th weeks of gestation period and integrates by 6 months of infancy.
- Plantar grasp reflex : Emerges by 25th weeks of gestation period and integrates by 9 to 12 months of infancy.
- Babinski reflex / extensor plantar reflex : Present from birth and integrates by 10 to 12 months of infancy. This reflex is considered normal in child upto 2 years of life.
- Babkin reflex : Present from birth and fades rapidly and cannot be elicited after 4 months of infancy.
- Rooting reflex : Emerges by 28th to 30th weeks of gestation period and integrates by 4 to 6 months of infancy.
- Sucking reflex : Emerges by 32 weeks of gestation period and integrates by 4 to 6 months of infancy.
- Bite reflex : This reflex integrates by 9 to 12 months of infancy
- Spinal Galant reflex or trunk incurvation reflex : Emerges by 20 weeks in utero and integrates by 3 to 9 months of infancy.
- Spinal Perez reflex : Emerges by 20 weeks in utero and integrates by 3 to 9 months of infancy.
- Tonic Labyrinthine reflex (TLR) : TLR forward emerges in utero and integrated by 4 to 6 months of infancy. TLR backward emerges at birth and is integrated gradually fron 6 weeks to 3 years.
- Asymmetric tonic neck reflex (ATNR) : Emerges by 18 weeks of gestation period and integrates by 6 months of infancy.
- Symmetric tonic neck reflex (STNR) : Appears by 4 to 6 months of infancy and integrated by 12 months of infancy.
- Neck righting on body reflex : Emerges at 34 weeks of gestational period and integrates by 4 to 6 months of infancy.
- Positive Supporting reaction : Present from birth and integrates by 6 months of infancy.
- Negative Supporting reaction : Present from birth and integrates by 5 to 6 months of infancy.
- Landau reflex : reflex appears at approximately 3 months of infancy and disappears at 12 to 24 month of age.
2) Primitive Reflexes which remains throughout lifespan
- Gag Reflex : Seen in 19th week of gestational period and remains lifelong.
- Startle reflex : Present at birth and persists lifelong.
- Amphibian Reflex or crawl reflex : Emerge at 4 to 6 months of infancy and remain lifelong.
Fig : Types of primitive reflexes and maneuver to elicit reflex response.
- Reflex movements are the first foundation or building blocks of the nervous system. Therefore during assessment of infant or child with neurological issues, we need to evaluate their reflex base and assess at which primitive reflex level they are stuck or struggling to integrate.
- Primitive reflexes or lower level reflexes (ATNR, STNR, TLR, spinal Perez etc) allows the baby to make body movements before the cortex is fully matured. These primitive reflexes are essential in developing tone in infant's body i.e. trunk, upper limbs and lower limbs. It causes activation of muscle groups in synergy patterns (tonic movements) i.e. a movement of head causes an automatic movements in the limbs, hands or feet.
- It prepares the neonates to move against gravity and gradually leading to voluntary control over movements by the first year of life.
- Later, these reflexes (as the infant grows and achieve milestones) contributes in development of vestibular, proprioceptive, visual, tactile, auditory and perceptual systems in body. These are essential in developing head and trunk control, dissociation of trunk from limb movements and also dissociation of waist up movements from waist down movements.
- Simultaneous integration of the tonic reflexes and movements (by 6 months) occurs alongwith development of righting reactions, equilibrium reactions and protective extension responses. Equilibrium reactions, protective reactions and Labyrinthine righting reactions remains lifelong. Efficient working of these reactions, nervous system and musculoskeletal system is essential for developing static and dynamic balance alongwith achieving higher level skills in mobility tasks. Mobility within the environment requires proper functioning and coordination between static and dynamic balance systems.
- When these primitive reflexes do not integrate then they may interfere with a child's development of more advanced motor skills. If such a disruption or delay in motor skills exists then there may be impairment in the child's further overall development and difficulties in Occupational performance.
- Brain damage in neonates or infants with may occur due to asphyxia, physical damage to brain (during birth), fetal intracranial hemorrhage, neonatal intraventricular hemorrhage, infection, preeclampsia, kernicterus. This leads to mild to severe cognitive and functional impairment, developmental delay, visual and auditory deficits. Infants may struggle to achieve age appropriate motor milestones. Brain damage may interfere with maturational process of CNS and this results in pathological release and persistence of abnormal tonic reflex activity. For example, in case of spastic or quadriplegic CP, the response may be increased and reflexes are retained for longer duration in life. The reflex will be more active on the affected side of upper-limb and lower-limb in spastic CP, whereas in athetoid or hypotonic CP the infants are weak, less active with decreased reflex response.
- Successful integration of primitive reflexes depends on level of severity of brain damage. Incomplete integration of primitive reflexes can cause mild to severe symptoms. Severe brain damage symptoms are seen in spastic or quadriplegic CP infant, whereas mild to moderate symptoms contribute to anxiety, depression, ADD, ADHD, Autism, learning disability, Sensory-Integration disorder.
- Unintergrated reflexes triggers the "fight or flight" response thus creating chronic stress. In people whose primitive reflexes remain unintegrated or are not adequately suppressed at cortical level, they feel stressed because their physiology is constantly reacting as if in a threatened state without any logical reason. Stress becomes an habit often below the level of their awareness.
- Unintergrated active childhood reflexes can cause difficulties and struggle in social participation and in learning academic skills, like speaking, attention and concentration issues, eye-coordination, poor posture, fidgeting behaviour. Person function on survival level i.e. active fear paralysis response. Person demonstrate lower motivation for learning and achievement.
- When reflexes are active, body parts cannot easily move independently. A movement of head causes an automatic movement of limbs, hand or feet. While performing any task, active primitive reflexes causes unnecessary extra limb movements to happen below the surface level. These unnecessary movements causes confusion in the neuro-sensory-motor system, thus creating difficulties with growth, coordination, reading, writing etc.
- Active reflexes causes aches, muscle tension, weak muscle tone, fatigue and the need for greater amount of effort to complete tasks. Skills or movements (reading, writing, walking, cycling, dressing, playground activities etc) which are performed automatically without conscious attention, needs to be performed with continuous conscious concentration.
Examples of how primitive reflexes are essential for achieving further milestones.
- Rooting reflex later help to produce Asymmetric tonic neck reflex (ATNR).
- Influence of body on body righting: Progressing through stages of normal development enables 8 month old child to roll from prone to supine and vice versa.
- FPR is type of withdrawal reflex which later merges into Moro reflex . Active FPR often goes hand-in-hand with unintegrated Moro reflex.
- Moro reflex integration is complete when the baby develops more mature startle reflex, sometimes called as Strauss reflex. On perceiving danger, the baby will show the response of shoulder raising and then baby will seek to find the source of stimulus and either pay attention or ignore it. This ignoring response is the basis of a more mature nervous system skill to filter out unwanted stimuli and selectively pay attention.
- Integrated ATNR reflex and spinal galant reflex with later help to develop Amphibian reflex.
- An integrated palmar grasp reflex will help to develop and commence voluntary use of hand.
- STNR reflex helps to dissociate waist up movements from waist down movements i.e. upper body movements from lower body movements.
- The Spinal Perez Reflex assists in developing the Landau and Symmetrical Tonic Neck Reflex (STNR), as well as, assisting the infant in getting up on his hands and knees around six to nine months of age.
- Emergence of STNR reflex is required to inhibit TLR and allow the child to get into a position to creep or to crawl.
- Rolling over action is initiated and performed by the influence of ATNR plus Body on body righting reaction.
It is rightly said that “A stitch in time saves nine"... it is better to fix a problem when it is small than to wait and let it become a bigger problem. Therefore, Early Intervention is crucial and important to timely invest on care of premature newborns in order to save them from being functionally impaired. During the first 1,000 days, the brain grows more quickly than at any other time in a person’s life and a baby needs the right nutrients at the right time to feed her brain’s rapid development. There are three crucial stages in the first 1,000 days: pregnancy, infancy and toddlerhood.
You can also refer our previous blog on NICU feeding assessment and importance of feeding in neonate or infant development. (Click on the below link)
You can also refer to other blog on preterm infant's impairments and complications. (Click on the link below)
Thankyou for reading!!!!
Dr. Ashwini Sangar, Dr. Sheetal Tatar-Dhande, Dr. Pallavi Khadse-Kolhe
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