Often when consulting the pediatrician, parents ask about the baby muscle tone, what it is and whether it is dangerous. In fact, the muscle tone is always there in a human’s body, maintaining a given position of the body and helping him to carry out the movement. However, the muscle tone in both baby and adult must be physiological, that is correct.
How does the muscle tone appears and why?
A child performs his first movements, still in the womb, with the help of muscle-joint contraction; the child can feel his position in space due to them. After the birth the muscle tone and movements enable the child to develop both physically and mentally. The baby learns to make his first movements – to hold his head up, reach out for to toys; to roll from side to side, from the stomach to the back; to sit later on, to crawl, to stand and walk. To ensure the timely implementation of these skills, adequate muscle tone is needed. That is, the minimum skeletal muscle tension that keeps the body in a state of complete rest. The fact is that even if the child is completely relaxed, his muscles still need to be in a certain state of stress – in tone, due to which a necessary pose is achieved, health is being maintained and movements are being performed. But not all muscles are equally tense, some groups of them are relaxed and some ones are in tense, depending on the task and load.
Muscle tone in children depends on their age – the smaller the kid, the higher the muscle tone.
Muscle tone features are due to the fact that the baby spends his first 9 months of life in the tight uterus, where his limbs and whole body are arranged as compact as possible, and the baby is not almost able to actively move his body by the birth time. All his muscles are tense. Therefore, most of the muscle groups of the newborn at birth are physiologically hypertonic. Moreover, the muscle tone is distributed among the muscle groups – it is higher in the flexors than in the extensors, therefore, baby’s hands and legs are pressed to the body, but the head is usually slightly bent backward. In addition, the tone is increased in the adductor muscles of the hips. So, when spreading the baby’s legs apart, you can feel the resistance of the muscles.
Muscle hypertonus remains symmetrical by about 3-4 months of age when it begins to gradually decline – first the tone decreases in muscle flexor group by about 5-6 months of age. And then the tone of all muscle groups is evenly reduced. By 1.5-2 years of age muscle tone of the child should be approximately the same as that of an adult.
Particularities of baby muscle tone
The first features of muscle tone can be noted visually when analyzing the baby’s position in a state of rest when he sleeps, for example, and the degree of work of individual muscle groups while moving. The baby’s position while sleeping within the first months of life after his birth is strongly influenced by the way the baby was born, like the way of delivery (natural or with the help of Caesarian section) and the way he was laying in the uterus right before the birth. If he was born headfirst, his head can be bent backward because of the neck muscles tone. If he was breech – his legs will be unfolded. Most babies’ physiological muscle tone affects the embryo’s pose that is well defined when the baby rests or sleeps.
Baby’s hands are bent and pressed to his chest, his hands are clenched into fists, and the thumb is covered by the rest of the fingers, legs are bent and pressed to the tummy, hips are slightly apart, and feet are raised up. Due to the hypertonicity, the range of movements the baby performs are limited – he can quite actively move the legs, bend or straighten them, push off the adult’s hand with them or cross them. But the range of hand movements is fewer – basically they move at the chest level, bending the elbows and wrists, rarely unclenching the fists. Due to the neck muscles hypertonicity the head is slightly bent back.
Muscle tone is largely dependent on the physical state of the child, his constitution and characteristics of the nervous system. When the baby is crying, screaming or is anxious the tone naturally increases. In addition, in the excitable babies, it will also differ from that of their calmer peers due to a greater range of movements performed.
And what if it is not the norm?
Ideally, the neurologist must examine the baby in the maternity hospital to reveal the starting deviation in time. However, the physiological hypertonicity sometimes makes it difficult to diagnose many neurological diseases at early stages. Physiological hypertonicity should maintain up to 4-6 months of age, if the tone does not disappear after this age period, it is a reason to consult an expert – a pediatrician or a neurologist.
But how to determine the tone? To do this, the doctor examines the child and studies his reflexes, because the muscle tone affects not only the nervous system work, but also the overall development of the child – physical and mental one. However, parents can determine some serious disorders on their own.
Unfortunately, there are not so many healthy moms and children nowadays. Tone disorders are affected by the conditions of pregnancy, placental insufficiency, stress and medications, labor process, induction of labor, cesarean section, and postpartum period. The nervous system is being actively formed after the birth as well, so you should closely monitor the baby noting his basic skills development time.
If the muscle tone disorders are not recognized in time, the child begins to fall behind in the physical development and therefore naturally in the mental one as his motor skills are closely linked to the development of the cortex.
Muscle tone disorders
There are several types of disorders:
– hypertonus (extreme muscular tension);
– hypotonia (insufficient muscular tension);
– dystonia (irregular tension in different muscle groups).
Hypertonus is the result of various brain and nervous system damages – the hemorrhage, birth trauma, birth hypoxia, meningitis. Furthermore, excessively excitable children are hypertonic.
Usually the baby’s muscles are tightened, the body is excessively tense, the child does not relax while sleeping, the limbs are bent, the hands are pressed to his chest, the legs are pulled up to his stomach, the fists are tightly clenched. From birth, the head is held due to the hypertonic neck muscles. Parents notice heightened anxiety in the child, poor sleep, frequent crying, and colic. Chin of such babies starts trembling because of any minor irritant, they often spit up excessively. When studying reflexes, the repeated spreading legs or arms enhances the muscle tone and physiological and pathological hypertonicity are immediately differentiated. When causing support reflex, the baby stands on tiptoes and bends fingers. When you pull the child’s hands, he does not completely extend them rising with the entire body. Hypertonicity can cause the development of torticollis as well, especially in response to the birth trauma of the cervical spine.
Hypertonicity reduces the child development speed. In these children such skills as crawling, sitting, walking are being developed later than it is required according to an age.
Hypotonicity or decreased muscle tone is an opposite phenomenon; fewer children have it, more often premature ones, and those children with abnormalities of the brain, endocrine diseases, infections. Diffuse muscle hypotonia can be a sign of intrauterine infection, severe birth injury, intracranial hematoma, etc. In severe cases, when muscles are weak there are swallowing, sucking and even breathing disorders in a baby. If certain muscle groups or limbs are hypotonic, nerve damage can be a reason.
A hypotonic baby is usually quiet, calm and he doesn’t trouble parents. Most of the time he either sleeps or is sluggish. He rarely cries, does not move, eats poorly and has troubles with weight gain. The baby does not hold his head up for a very long time, his feet and hands are extended and the hands lie along the body when he is in a supine position and the muscles of the tummy are not in tone and look like a pancake. Angle of spread thighs reaches 180 degrees. When placed on his stomach, the baby does not bend the arms and buries his face into the surface and he looks limp.
Asymmetrical tone, dystonia, is a state when the tone of some muscle groups is higher, and the tone of other ones is low. In this case, the child lies in unnatural positions, skin folds are uneven. A child can fall on the side where the tone is more pronounced, and the head and the pelvis will be turned in the direction of the muscle tension, the torso looks like an arc.
What are the effects of muscular dystonia?
If muscle tone disorders are detected at an early stage and it was completely treated, there will be no consequences of it. But if the hypertonus is not treated the posture will be incorrect, especially scoliosis will be being developed, as well as walk disorders, torticollis, or clubfoot. Psychomotor development can have disorders and be delayed. The most severe consequence is cerebral palsy – a severe neurological disorder that appears in the first few months of life.
In the next article I will provide you with a diagnostic algorithm of muscle tone in the baby and will tell you about the methods of its disorders treatment.