The Primitive reflexes of the newborn Are the reflexes that infants do involuntarily. In the medical literature, in addition to the primitive reflex, a wide variety of terms have also been used: primary neonatal reflexes, developmental reflexes, reflexes and infantile reactions or automatisms (Garcia-Alix and Quero, 2012).
Some movements are Spontaneous, Which are presented as part of the habitual behavioral repertoire of the baby. On the other hand, reflexes also occur as answer To certain stimuli (University of Rochester Medical Center, 2016).
Reflexes are one of the essential components in physical and neurological examinations, since their Abnormal presentation or absence Can be indicative of a possible Compromise in the nervous system (University of Rochester Medical Center, 2016).
On the other hand, we must take into account that Some reflexes Have a component of transience , Some types will only be presented in Specific periods of child development (University of Rochester Medical Center, 2016).
What are the primitive reflexes?
With the term Primitive reflex We refer to a set of highly stereotyped motor responses spontaneously triggered or to specific stimuli that are part of the normal motor behavior of babies (Garcia-Alix and Quero, 2012).
Most of these motor responses appear during the second half of the gestation period and will be present at the postnatal stage (García-Alix and Quero, 2012).
The whole range of involuntary movements will enable the baby to: develop the motor system, descend the birth canal or suck to feed, among other functions (BRMT, 2016).
However, some of them will disappear following a pre-established order during the first year of life (Garcia-Alix and Quero, 2012).
Reflexes are part of the motor development of the newborn and therefore, its evaluation is part of the neonatal neurological examination. This allows us to assess the general development of the nervous system (García-Alix and Quero, 2012).
When there is some type of deficit at the neurological level, it is possible that some of the primitive reflexes remain active during late stages of development, and will make it difficult to acquire motor skills such as sensory perception and cognitive development (BRMT, 2016).
When do the reflections appear?
Already during the Prenatal stage We can observe evidence of primitive reflex activity (Carlson, 2000; Roselli and Matute, 2010).
Specifically, around the Sixth week of gestation On the skin surrounding the mouth, a contralateral neck flexion may occur (Roselli and Matute, 2010).
Between Sixth and eighth week of gestation , Reflex responses can be observed by stimulating the skin of the upper thorax, the palms of the hands or the face (Roselli and Matute, 2010).
In the case of Twelve weeks of gestation , Approximately the entire body surface is sensitive, except for the back or the crown. As a result, reflex responses become more specific (Roselli and Matute, 2010).
Types of reflexes in the newborn or newborn
Primitive reflexes can be divided into two large groups: primitive reflexes and primitive tactile reflexes (Garcia-Alix and Quero, 2012):
- Early postural reflexes : They occur as a consequence of the stimulation of receptors of the vestibular apparatus by the movement of the head. At the neurobiological level, they are mediated at the level of the brainstem.
- Touch primitive reflexes : Occur as a consequence of tactile stimulation, plantar response, Galant reflex, reflex reflex, etc.). At the neurobiological level, they are mediated at the spinal cord .
Postural reflexes (García-Alix and Quero, 2012)
The postural reflexes with more relevance are: Moro reflex, asymmetric tonic neck reflex and labyrinthic tonic reflex. Everything except the reflection of Moro, are characterized by developing with variable and incomplete answers.
This type of postural reflex is only observed during postnatal life, because a suppression occurs during the gestation period so that the fetus does not respond to each movement performed by the mother.
- Moro Reflection
The moor reflex or startle reflex occurs when the baby is startled by an intense sound or a movement. In response, the baby moves his head back, extends the arms and legs (University of Rochester Medical Center, 2016).
The Moro reflex can be triggered by several stimuli: a sudden sound or a sudden movement of the surface where the baby is placed, among some others (Garcia-Alix and Quero, 2012)
When any of the previous stimuli appear, a complete opening of the hands occurs in the baby, followed by a flexion of the fingers (forming a"C"between the thumb and forefinger) (Garcia-Alix and Quero, 2012)
The Moorish reflex has several phases (Garcia-Alix and Quero, 2012):
- First phase : Extension of the forearms.
- Second stage : Adduction of the arms and flexion of the forearms.
- Final phase : Crying or grimace of anxiety.
- Asymmetric tonic cervical reflex
The asymmetrical tonic cervical reflex occurs when the baby is relaxed and lying down and moves the head to one side. The arm on the side where the head is positioned extends far from the body with the open hand and the arm on the opposite side flexes (National Institutes of Health, 2013).
If the baby turns the head to the contralateral side, the pattern of movements is reversed (National Institutes of Health, 2013).
- Labyrinthic tonic reflex
When the baby is in the supine position (the baby is lying on the dorsum on the back with the extremities extended), the extension of the head produces a shrinking of the shoulders and extension of the legs (García-Alix and Quero, 2012).
In a prone position (the baby is lying face down with the head on the side), flexion of the head produces a flexion of the legs (Garcia-Alix and Quero, 2012).
Tactile reflexes (García-Alix and Quero, 2012)
Tactile or cutaneous reflexes occur as a result of stimulation of the skin in a specific area. This stimulation triggers a motor response that takes place in the same place where the stimulation was applied.
The most important tactile reflexes are: sucking reflex, search reflex or hociqueo, Galant reflex or trunk involution, Vollmer reflex and Pérez reflex, cross extension reflex, magnet reflex or magnetic reflex, step reflex, Auto shift reflex, positive support reflex (palm pressure, finger extender, Babinski reflex , Plantar response).
- Suction reflex
When tactile stimulation is performed on the baby's upper palate or tongue, it begins to suck (University of Rochester Medical Center, 2016).
The sucking reflex has a major role in survival, as it is essential for newborn feeding (García-Alix and Quero, 2012).
- Search reflex hociqueo
When the corner of the mouth or cheek is stimulated on the surface of the face on one side and then on the other, the child responds by moving the lips and tongue towards the location of the tactile stimulus (Garcia-Alix and Quero, 2012).
- Reflection of Galant
Galant's reflex or trunk bending occurs when the skin that is found along the baby's spine is stimulated while the baby is upside down (National Institutes of Health, 2013).
Specifically, this reflex can be produced by rubbing the skin on both sides of the spine with the index finger, from the shoulder to the buttocks. Tactile (García-Alix and Quero, 2012).
Automatically, after stimulation, the baby performs an incurvation of the spine to the side where the stimulation is occurring (García-Alix and Quero, 2012).
- Reflex of Vollmer and reflex of Pérez
In Vollmer's reflex, when firm pressure is applied along the spine, flexion of the arms and legs with a dorsal extension of the spine and neck occurs (Garcia-Alix and Quero, 2012).
In Perez's reflex, when a firm pressure is applied along the cervico-thoracic spine, there is a flexion of the arms and legs with a dorsal extension of the lower spine (Garcia-Alix and Quero, 2012).
- Cross extension reflex
In the cross-extension reflex, when a tactile stimulation is applied to the sole of the foot while maintaining the extremity in which it is to be applied, it results in a response composed of three phases (Garcia-Alix and Quero, 2012):
- First phase : Spontaneous flexion of the leg that is free.
- Second stage : Extension or opening of the toes in which the stimulation has been performed.
- Third phase : Extension and adduction of the free foot towards the stimulated one.
- Magnet Reflection or Magnetic Reflection
When the baby is lying on his back and light pressure is applied with his thumb on the floor of both feet, the baby extends his legs to maintain contact (Garcia-Alix and Quero, 2012).
- Step reflex
The step or placement reflex occurs when the baby is standing upright under the armpits (García-Alix and Quero, 2012).
When stimulation is applied under the dorsum of the foot, the baby responds by raising the foot and placing it on the surface, through a knee and hip flexion with an extension of the foot Garcia-Alix and Quero, 2012).
- Automatic gear shift
The automatic gait reflex occurs when the baby is placed in a vertical position, placing his feet on a surface (Garcia-Alix and Quero, 2012).
The baby, responding to this position, responds by straightening the lower extremities and trunk, and performing a succession of steps, synchronizing hip flexion with that of the knees (Garcia-Alix and Quero, 2012).
- Reflex of palmar grasp, extensor of fingers, reflex of babinski, plantar response
The surface of the skin of the palm of the hand and the sole of the foot, with one of the cutaneous areas of the body more sensitive to stimulation, so there are several primitive reflexes associated with these:
- Palmar reflex : When we put a finger on the palm of a newborn's hand, it reacts by closing it around the finger. If attempted to withdraw, the infant tightens its fingers, exerting force against the tactile stimulus (National Institutes of Health, 2013).
- Extending finger reflex or digital response : An opening of the fingers occurs when the surface of the little finger or the back of the hand is repeatedly stimulated (Garcia-Alix and Quero, 2012).
- Babinski Reflection : When the surface of the sole of the foot is stroked, the fingers open in fan (National Institutes of Health, 2013).
- Plantar response : When an intense tactile stimulus is applied to the lateral area of the foot, from the heel to the thumb, an extensor response occurs on the thumb (Garcia-Alix and Quero, 2012).
What is the temporal evolution of primitive reflexes?
- Moro Reflection : It presents well established around the 37th week of gestation and disappears approximately between the 5-6 months of age.
- Asymmetric tonic cervical reflex : It presents well established around 1-2 months of age and disappears approximately between the 6 and 9 months of age.
- Suction reflex : It presents well established between week 34 and 36 of gestation and disappears at 4 months of age.
- Search Reflection : It presents well established between week 34 and 36 of gestation and disappears at 4 months of age.
- Palmar reflex : It presents well established on week 32 of gestation and disappears between the 6 and 9 months of age.
- Reflection of Galant : It is present and well established on week 32 of gestation and disappears between the first and second year of life.
- Labyrinthic tonic reflex : It is present approximately between the 2 and 4 months of age and disappears between the 11 and 24 months of the postnatal stage.
- Location Reflection : It is present and well established on the 40th week of gestation and disappears between the first and second month of life.
- Reflection of gait : It is present and well established on the 40th week of gestation and disappears between the first and second month of life.
- Extension reflex : It is present and well established on week 40 of gestation and disappears between the first and third month of life.
Why are reflexes evaluated in newborns?
As we have pointed out in other sections, there are several reasons for performing an analysis of primitive reflexes in newborns (García-Alix and Quero, 2012):
- They help us assess the overall development of the baby's nervous system.
- They allow us to evaluate the specific integrity of the central nervous system (CNS).
- In some cases, they may have location value and therefore, help us to identify the possible location of an injury or structure damage.
References
- BCA. (2013). Infant Reflexes . Retrieved from"Baby Care Advice": http://www.babycareadvice.com/
- García-Alix, A., & Quero, J. (2012). Primitive or developmental reflexes. In A. García-Alix, & J. Quero, Primitive or developmental reflexes.
- Nall, R. (2014). What Are Neonatal Reflexes . Retrieved from Healthlilne: http://www.healthline.com/
- NIH. (2013). Infant Reflex . Retrieved from MedlinePlus: https://www.nlm.nih.gov/
- Rosselli, M., & Matute, E. (2010). Cognitive and cerebral development. In N. d. childish, Rosselli, M.; Matute, E.; Ardila, A.;
- UR. (2016). Newborn Reflexes . Retrieved from the Univesity of Rochester Medical Center: https://www.urmc.rochester.edu/