Reflexes of a newborn: norm and pathology24.05.2022
Reflexes are certain (stereotypical, expected) reactions of the body to the effects of stimuli. These reactions are controlled by the nervous system. In addition to the nervous system, skin receptors and muscles also participate in their formation.
All reflexes can be divided into two large groups – congenital and acquired . Congenital reflexes are inherent in the body from birth, while acquired ones require a certain amount of learning.
Knowing exactly what the reactions of a healthy newborn to a particular stimulus should be, a neurologist can easily suspect a pathology and send a small patient in time for additional examination and, if necessary, for treatment.
What are the reflexes in newborns
A baby that has just been born still does not know how, he has only unconditioned reflexes. But already during the first months of life, complex voluntary reflex reactions will begin to form on the basis of these unconditioned reflexes. By the age of one year, the baby’s nervous activity has evolved so much that he will be able to perform the most difficult tasks for his age.
There are several classifications of physiological reflexes in newborns. We will focus on one of them.
1st group of reflexes – oral automatisms (associated with the search for food)
- Proboscis reflex : A quick tap of the fingers on a newborn’s lips causes the lips to pull forward. This reflex persists in an infant up to 2-3 months, and then fades away.
- Search reflex : when stroking a child in the area of the corner of the mouth, the lip drops, the head deviates towards the stimulus, and the tongue rises. When pressing on the middle of the upper lip, the mouth will open and the head will be extended. When pressing on the middle of the lower lip, the head will bend, and the lower jaw will drop. The search reflex persists in a healthy baby up to 3-4 months, and then fades away.
Asymmetry of the reflex – unilateral paresis of the facial nerve. There is no reflex – bilateral paresis of the facial nerve, damage to the central nervous system (central nervous system).
This reflex is best checked in a hungry child. It is especially pronounced half an hour before feeding.
The reflex must be symmetrical on both sides (that is, the same). The manifestation of a reflex on only one side usually indicates a unilateral lesion of the facial nerve. Complete absence of a reflex – bilateral paresis of the facial nerve or damage to the central nervous system. A child with such disorders should be urgently examined in depth by pediatric neurologists.
- Sucking reflex : when an object is introduced into the child’s mouth, characteristic rhythmic sucking movements appear. The reflex normally lasts up to 3-4 years. An unrealized need for sucking in a timely manner can manifest itself as nail biting and finger sucking in a child in the future. Prevention of such disorders is full-fledged long-term breastfeeding.
The sucking reflex is absent in case of unilateral or bilateral lesions of the facial nerves, CNS lesions, severe somatic pathologies, and in very preterm infants.
2nd group of reflexes – palmar automatisms
- Upper grasping reflex : when pressed against the palms of the newborn, he tightly grasps his fingers.
- Robinson reflex (aimed at determining the tone of the flexors) : when the baby grabbed his fingers, he can be lifted up. The reflex lasts up to 3-4 months, and then transforms into an arbitrary skill of grasping and holding objects.
With paresis of the hands, the reflex is weakened or absent; with damage to the central nervous system, it can be enhanced. Preservation of the reflex in children older than 5 months indicates damage to the central nervous system.
- Babkin reflex : when pressed on the palm of a newborn with his thumbs, he turns his head and opens his mouth. The reflex disappears by 3 months.
The absence of a reflex on the one hand may indicate peripheral paresis of the arm or facial nerve. The symmetrical absence or lethargy of the reflex may indicate damage to the central nervous system.
- Moro reflex (planning reflex). It can be seen under a variety of influences. For example, a slap on the changing table or a sudden lowering of the baby will cause the baby to spread his arms in different directions and open his fists, and then return to his original position. The reflex is well expressed up to 5 months, then fades away.
With peripheral hand paresis, the reflex may be asymmetrical. Weakening or strengthening is observed with damage to the central nervous system. Each specific case must be considered separately in conjunction with the assessment of other reflexes.
3rd group of reflexes – foot reflexes
- Lower grasping reflex (Verkhom’s reflex) : with light pressure on the sole of the newborn at the base between the second and third fingers, the fingers are bent. The reflex gradually fades away by 3-4 months.
- Babinski reflex : when the skin on the sole of the foot is irritated, dorsiflexion and fan-shaped divergence of the toes occur. It persists until the age of two, and then fades away.
The appearance of the Babinski reflex in adulthood indicates severe damage to the central nervous system.
4th group of reflexes – vertical reflexes
- Support and extension reflex . A newborn child, of course, is not ready to stand on his own, but if you hold him at a support, he straightens his body and stands on half-bent legs on a full foot. In the future, stepping movements will be formed on the basis of this reflex. The reflex fades by 2 months.
- Automatic walking : if the newborn in an upright position at the support is slightly tilted forward, he will make stepping movements. The reflex fades by 2 months.
In debilitated and premature newborns, as well as in newborns with birth traumatic brain injuries, the support and walking reflexes may be weakened and / or completely absent. In children with CNS damage, reflexes persist much longer than the prescribed period.
5th group of reflexes – in the position on the stomach
- Protective reflex : A newborn lying on his stomach automatically turns his head to the side to avoid suffocation.
In children with CNS damage, the reflex may be absent. The position of the head must be constantly monitored so that the child does not suffocate.
- Crawling reflex ( Bauer reflex ): if a newborn lying on his stomach is given support for his heels, he will make characteristic crawling movements. It has nothing to do with real crawling yet. The reflex fades after 4 months.
In weakened children, crawling may not be expressed. In spinal cord injuries, the reflex may be asymmetrical. With damage to the central nervous system, it persists much longer than the prescribed period.
- Galant reflex : when the skin on the back along the spine is irritated, the newborn bends the back in the opposite direction from the stimulus, while the leg straightens. The reflex fades by the 4th month of life.
The reflex is absent or weakly expressed in lesions of the spinal cord. With damage to the central nervous system, it persists much longer than the prescribed period.
- Peres reflex: when you hold your finger up from the bottom up along the spinous processes of the vertebrae, the baby screams, raises his head, unbends the torso, while bending the upper and lower limbs. The reflex fades by 4 months.
Testing this reflex is painful for an infant, so it should only be examined if there is a real need.
As can be understood from all of the above, checking reflexes is extremely important in a comprehensive assessment of the neurological status of a newborn. Of course, only a neurologist who specializes in working with children of the first year of life and young children can conduct such a study. Timely detection of violations allows you to take timely measures to eliminate them. That’s why it’s so important not to ignore routine neurological exams, even if it seems to the parent that everything is fine with the child.
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