Course:KIN355/2020 Projects/Asymmetric Tonic Neck Reflex
Defining the Concept and Its Importance
Asymmetrical Tonic Neck Reflex (ATNR) is a primitive reflex that is produced involuntarily by turning an infant’s head. While an infant is in a supine position, turning its neck generates an involuntary response of the limbs; the limbs ipsilateral to the head extend while the limbs contralateral to the head flex (Gesell, 1938). This is caused by inhibitory neurons that are activated during neck rotation which causes inhibition of the antagonist muscles (Religioso, 1998).
ATNR is first developed in the womb, responding to rotation at around 18 weeks gestational responding to rotations and plays an important role during birthing process, as the infant positions itself to pass down the birth canal (Beuret, Blythe S., Blythe P., & Scaramella-Nowinski, 2017). ATNR is an involuntary response to a sensory stimulus and its presence in the first few months of life is an indicator of proper neurological development and function, thus, it is important to examine throughout the first few months of life (Sein, 2020). This reflex allows an infant to explore its sides, developing vision, coordination, and midline crossing that will assist in the next developmental stages and allow the emergence of new movements. At around 4-6 months of age, as the Central Nervous System (CNS) matures, ATNR typically integrates so that voluntary movements are no longer inhibited, and more purposeful movements can develop (Erdie-Lalena, Gerber & Wilks, 2010).
The presence of ATNR in the first few months is essential for motor development as it facilitates vision, hand to eye coordination, and ipsilateral movement, therefore its absence or presence indicates abnormalities (Beuret et al., 2017). Although the emergence of ATNR is significant in the development of movement, its integration is crucial for further psychomotor and neural development. If ATNR persists past 6 months it can cause issues with gross and fine motor movements, balance, coordination, eye-tracking, midline crossing, as well as learning and attention span (Arcilla & Vilella, 2020).
Role in Childhood Development and Contemporary Considerations
ATNR is first elicited at 18 weeks gestational, often corresponded with when the mother first starts feeling the baby – this reflex helps the baby adjust to the mother’s posture, begin exercising its muscles, and exploring its environment (Beuret et al., 2017). In full-term pregnancies, the reflex is already developed by birth and assists in the birthing process (Beuret et al., 2017). ATNR also plays a role in the survival of an infant because when placed in a prone position ATNR may be elicited, causing the infant to turn its head to the side and free the airway (Beuret et al., 2017). ATNR is most prominent between 1 and 4 months of age, allowing infants to develop their vision through exploration of the hand ipsilateral to their head and following the distance of the hand through flexion and extension of the arm (Beuret et al., 2017). This allows the infant to explore and differentiate both sides of the body, as well as develop eye-hand coordination (Arcilla & Vilella, 2020). As the CNS matures, ATNR and other primitive reflexes diminish so that postural reflexes can fully develop, and the child can fulfill its abilities (Sein, 2003). Riding the bicycle is an example of how important integration of ATNR is for movements; a child’s stability and postural tone allows them to sit on the bike and stay on it while producing gross movements, while their midline crossing and visual abilities allow them to take turns, notice stop signs, and achieve their desired destination. Of course, riding the bicycle is just one of many examples; the integration of ATRN is critical for many other movements.
Retention or delayed integration of the ATNR, among other primitive reflexes, is an indicator of immature motor development in a child. If primitive reflexes fail to integrate within the correct developmental stage, the postural reflexes do not fully develop, and the infant is incapable of gaining full control (Sein, 2003). Babies whose ATNR is not fully integrated may have trouble rolling, crawling, and reaching like others their age (Erdie-Lalena et al., 2010). Due to its important role in coordination and midline crossing, retainment of ATNR in children is often shown through trouble with handedness, difficulties crossing their midline – such in reading or telling the time and maintaining balance with a turned head (Arcilla & Vilella, 2020). This can impact their participation in many activities such as swimming, playing with ball, and even sitting and standing. Clearly, the persistence of ATNR and primitive reflexes in general is related to many developmental issues related to childhood movements. One topic that it is often linked to is cerebral palsy; the most common childhood disability that is characterized by abnormal neurologic control, sensation and perception, reduced bone mass, impaired hearing and vision, and many more (Krigger, 2006). Reduction of spasticity of primitive reflexes, including ATNR, is studied as a treatment for cerebral palsy to improve muscle tone and reduce athetoid (Krigger, 2006).
ATNR retention that causes difficulties crossing midline often compromises reading comprehension and writing abilities (Beuret et al., 2017). Reading can typically be improved through eye movements control but writing abilities are more difficult to improve due to involvement of both eye and hand movement and coordination (Beuret et al., 2017). Retention of ATNR can impact learning and attention regulations and is often a factor in children with abnormal neurodevelopment, such as Attention Deficit Disorder (ADHD) and dyslexia. Studies suggest that due to the delayed integration of ATNR, symptoms of ADHD may present compensation (Anthanasiaduo et al., 2020). During cognitive and behavioural tasks, primitive reflexes may occur as response to stimuli and explain ADHD symptoms, such as attentional dysregulation (Anthanasiaduo et al., 2020). This occurs during brain processing due to conflict between levels of motor and cognitive functions (Anthanasiaduo et al., 2020). Studies on dyslexia suggest that kids with difficulties reading, writing, and spelling are more likely to have persisting primitive reflexes (Beuret et al., 2017). The presence of a learning disability could impact the child’s participation in activities because they may feel excluded, social disadvantaged, or have trouble understanding and focusing.
Practical Applications
As the persistence of the asymmetrical tonic neck reflex past 6 months of life can cause issues with certain gross and fine motor skills, balance, hand-eye coordination, attention span, and learning difficulties, it is important that this primitive reflex is integrated (Arcilla & Vilella, 2020). There are certain activities and games that can promote or increase the integration of primate reflexes, such as the ATNR, while also providing other developmental benefits.
Activity 1: Crawling Ball Race
An activity called ‘Crawling ball race’ can be conducted to identify certain movement difficulties that could indicate persistence of the ATNR, to promote and increase integration of this primitive reflex by performing movements that contradict it, and to strengthen gross and fine motor skills through this activity. The target age for this activity would be for children above the age of 4. This activity should ideally be conducted on an open grass or turf field and would require 10 sponge balls and 20 pylons. Depending on the number of participants, the children should pair up and form groups consisting of 10 pairs each. Each group, consisting of 20 children (10 pairs), should line up at the starting line of the race, wherein pylons are well-spaced and equidistant, marking the starting line. Another pylon is placed to indicate the finish line. Each child is instructed to participate in a crawling race, where they will have to hold a sponge ball under their necks while tilting their head to right side. The body remains straight in a crawling position, on all fours, while only the head is tilted to face the right. The other child in the pair is instructed to stand a few metres in front of the racer to guide and direct them, as the racers will not be able to see in front because their heads are tilted. The children who guide the racers are called ‘floaters’. The racers crawl to the finish line, guided by the floaters. The floaters can, then, take their turn to race while the previous racers become floaters. Similarly, this can be repeated with the head tilted to the left side. If this activity is too tough for some children, they may be instructed to carry on with the same race, without holding the ball under their necks but still tilting their head. If there are certain children showing difficulties in the movement while tilting their heads, the persistence of a primitive reflex, like ATNR, may be identified. Once identified, steps may be taken to promote and increase integration of the reflex. As this activity also promotes the use of motor skills, it can help assist in the advancement of performance of certain gross and fine motor skills that is usually impacted by the persistence of ATNR past 6 months of life. Participating in this drill involves producing movements that oppose the movements produced during an assymetric tonic neck reflex as both the arms need to remain extended while the head is tilted to one side. Producing contradictory movements to the ATNR may promote and advance its integration.
Activity 2: Snake Throws
An activity called ‘Snake throws’ can also be conducted to identify certain movement difficulties and deficits that could indicate the persistence of ATNR, to subsequently promote and increase the integration of ATNR, and to help with the development of improved gross and fine motor skills and hand to eye coordination. The target age for this drill would be for children above the age of 5. Depending on the number of children participating in the activity, children should form groups with 4 to 5 people in each group. This activity should ideally be conducted in an open turf, grass, or mud field. Each group should get 3 or 4 tennis balls and 2 pylons each. For the ‘snake throws’ activity, each group should stand in a horizontal line, holding hands in a way that their arms are parallel to the floor. The horizontal line should be formed perpendicular to each group’s respective starting line, that would be indicated by a pylon. The finish line, which would be around 5 to 6 metres in front of the starting line, would be indicated by another pylon. To start off the drill progression, the child closest to the starting line runs to the finish line, while the next child in line, still standing perpendicularly to the starting line and holding hands parallel to the floor, throws a tennis ball toward the child standing at the finish line. The thrower makes the throw sideways as their body is perpendicular to the starting line and their non-throwing hand is held, by the next child in line, parallel to the floor. The catcher at the finish line needs to try to catch the ball and then run to the back of the line, while the thrower runs to the finish line, after making the throw, for their turn as the catcher, and then back to the end of the line. One by one, each child in line gets their turn as both the thrower and catcher. The children, then, face the opposite side to throw with their other hands, and the drill can continue cyclically. To adjust toughness for particular children, distance of the finish line to the starting line may be adjusted. Both throwing and catching can assist with improvement of hand to eye coordination and the development and refinement of certain gross and fine motor skills, which are usually negatively impacted by the persistence of the ATNR reflex past 6 months of life. This activity could help with identifying difficulties maintaining posture and throwing that indicate retention of ATNR, which can lead to subsequent focus on promoting integration. Moreover, this activity could also increase and advance integration of ATNR as it focuses on movements that contradict it. This is because both sets of limbs need to remain extended while the head is turned, contradictory to the movements produced from an asymmetric tonic neck reflex.
Summary
Asymmetric Tonic Neck Reflex is an involuntary primitive reflex seen by rotating a child’s head where ipsilateral limbs to the head extend and contralateral limbs flex when laying down. It’s developed by 18 weeks gestational and facilitates birth, hand-eye coordination, vision, posture, midline crossing, ipsilateral movement, and motor development. This primitive reflex integrates as the CNS develops during 4-6 months. Signs of abnormality are present with delayed integration. Activities to help an infant’s motor skills, hand-eye coordination, and balance with ATNR include race crawling with a ball and snake throws. ATNR integration is essential for the development of the voluntary movement.
References
Anthanasiaduo, A., Buitellar, J.K., Brovedani, P., Chorna, O., Fulcer, F., Guzzetta, A., & Scattoni, M.L. (2020). Early motor signs of attention-deficit hyperactivity disorder: a systematic review. Eur Child Adolescent Psychiatry 29, 903-916. doi: 10.1007/s0078701901298-5
Arcilla, C.K., & Vilella, R.C. (2020). Tonic Neck Reflex. StatPearls. Treasure Island, FL: StatPearls Publishing. Retrieved from: https://www.ncbi.nlm.nih.gov/books/NBK559210/
Beuret, L.J., Blythe, S.G., Blythe, P., & Scaramella-Nowinski, V. (2017). Attention, Balance, and Coordination: The A.B.C of Learning Success. (2nd Ed). Hoboken, NJ: John Wiley & Sons. doi:10.1002/9781119164746
Erdie-Lalena, C., Gerber, R.J., Wilks, T. (2010). Developmental Milestones: Motor Development. Pediatrics in Review, 31 (7), 267-277. doi:10.1542/pir.31-7-267
Gesell, A. (1938). The tonic neck reflex in the human infant: Morphogenetic and clinical significance. The Journal of Pediatrics, 13 (4), 455-464. doi: 10.1016/S00223476(38)80169-4
Krigger K.W. (2006). Cerebral palsy: an overview. Am Fam Physician.73(1), 91-100. PMID: 16417071
Religioso,E.P., I.,II. (1998). The effects of the asymmetrical tonic neck reflex on isokinetic upper extremity torque production and upper extremity electromyograph readings. Retrieved from https://ezproxy.library.ubc.ca/login?url=https://www-proquest com.ezproxy.library.ubc.ca/docview/304490862?accountid=14656
Sein, A.K. (2003). Persistent Primitive Reflexes: A Prognostic Study on School-aged Children with Intellectual Disability, Guillemard Gardens School, Movement for the Intellectually Disabled of Singapore