Craniosynostosis

Craniosynostosis is the premature closure of one or more sutures of the skull, leading to the formation of a characteristic deformation.

Craniosynostosis is a non-specific brain injury that occurs as a result of insufficient expansion of the cranial cavity during the period of most active brain growth.

Despite the fact that premature synostosis leads to characteristic deformations of the skull and facial skeleton and it is easy to suspect the disease even in a newborn, in our country this developmental defect is diagnosed quite rarely. And most importantly, in the vast majority of cases the diagnosis is made after 1 year, which significantly affects both the child's development and the final result of treatment. Modern achievements in reconstructive surgery and the change in the attitude of doctors to skull deformations as inoperable conditions that has occurred in recent years allow us to hope for more frequent and, most importantly, early detection of deformations of the craniofacial region associated with premature synostosis of sutures.

ICD-10 code

In the International Classification of Diseases, craniosynostoses are classified into several categories.

Class XVII.

• (Q00-Q99). Congenital anomalies (malformations), deformations and chromosomal disorders.
• (Q65-79) Congenital malformations and deformities of the musculoskeletal system.
• Q67. Congenital musculoskeletal deformities of head, face, spine and chest.
• Q75. Other congenital malformations of bones of skull and face.
• Q80-89. Other congenital malformations and deformities of the musculoskeletal system.
• Q87.0 Syndromes of congenital malformations primarily affecting the facial appearance.

Epidemiology

According to international statistics, premature closure of one of the cranial sutures occurs on average in 1 in 1000 newborns (from 0.02 to 4%). Syndromic craniosynostosis occurs with a frequency of 1:100,000-300,000.

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What causes craniosynostosis?

Little is currently known about the nature of premature synostosis of the sutures. Many explanations have been proposed as to why craniosynostosis occurs. The most popular of these are theories about intrauterine, hormonal, hereditary disorders, a mechanical theory (compression of the fetal head in the uterus), etc. A defect in the fibroblast growth factor receptor gene (FGFR) 1,2,3 is currently recognized as one of the main pathogenetic factors.

The main sutures of the cranial vault are sagittal, coronal, lambdoid and metopic. When a bone suture is damaged, compensatory bone growth occurs perpendicular to its axis (Virchow's law). This results in a characteristic deformation - its own for each of the closed sutures.

Thus, sagittal craniostenosis leads to scaphocephaly, synostosis of the entire coronal suture - to brachycephaly, synostosis of half of the coronal suture causes plagiocephaly, and synostosis of the metopic suture - trigonocephaly. Synostosis of the entire lambdoid suture or half of it leads to deformation of the occipital region. Its degree directly depends not only on the degree of synostosis and the number of sutures included in the deformation, but also on the condition of the brain itself. Thus, in the presence of concomitant hydrocephalus, its severity increases. In the presence of microcephaly, caused by impaired brain growth, they are barely noticeable.

How does craniosynostosis manifest itself?

The most well-known indicator of premature synostosis of the cranial sutures is the early closure of the anterior fontanelle. In some cases of syndromic synostoses, when several sutures are involved in the pathological process, and especially with concomitant dilation of the cerebral ventricles, the anterior fontanelle may not close until the age of 2-3 years.

The presence of finger impressions on plain skull radiographs is typical for patients with premature synostosis of cranial sutures. Increased finger impressions occur when other compensatory mechanisms fail to cope with intracranial hypertension. Sometimes finger impressions are already visible in newborns. In such cases, a combination of lesions of several cranial sutures is detected.

Another pathognomonic sign of increased intracranial pressure is venous congestion in the fundus and edema of the optic nerve papilla. In cases of isolated monosynostoses, such findings are not so common. In polysynostoses, long-term intracranial hypertension often leads to the formation of partial atrophy of the optic nerves.

How is craniosynostosis classified?

The most convenient etiological classification of craniosynostoses was proposed by M. Cohen (1986).

The following craniosynostoses are known:

• Non-syndromic craniosynostosis (isolated).
• Syndromic craniosynostosis:
  • Monogenic craniosynostosis:
  • with an autosomal dominant type of inheritance:
  • with an autosomal recessive type of inheritance:
  • X-linked craniosynostosis;
  • with an unspecified type of inheritance:
  • chromosomal craniosynostosis;
  • incomplete syndromic (from two to four signs):
  • syndromes caused by environmental factors.

Based on anatomical features, craniosynostosis can be divided as follows.

• Monosynostoses:
  • isolated sagittal craniosynostosis;
  • isolated metopic craniosynostosis;
  • isolated coronal unilateral craniosynostosis;
  • isolated coronal bilateral craniosynostosis;
  • isolated lambdoid unilateral craniosynostosis;
  • isolated lambdoid bilateral craniosynostosis.
• Polysynostosis.
• Pansynostosis.

In the vast majority of cases, there is a premature closure of one of the cranial sutures - monosynostosis. Sometimes two or more sutures may be involved in the process - polysynostosis. In the most severe cases, synostosis of all cranial sutures occurs - this condition is called pansynostosis.

Very often, premature synostosis is not accompanied by other developmental defects. In such cases, we speak of isolated craniosynostosis. There is another group, which is characterized by the presence of a set of developmental defects accompanying synostosis of a certain suture or which have synostosis of a separate group of cranial sutures, leading to a characteristic deformation of the face and skull. In such cases, as a rule, the type of inheritance can be established, and sometimes genetic disorders are also detected - then we speak of syndromic craniosynostosis.

Sagittal craniosynostosis

Among the total number of isolated synostoses, scaphocephaly is the most common disease, occurring with a frequency of 50-60%.

Symptoms

Sagittal craniosynostosis is characterized by an increase in the anterior-posterior size of the skull and a decrease in its width. The child's head is sharply elongated in the longitudinal direction with overhanging frontal and occipital areas and depressed temporal areas. These changes in the skull lead to the formation of a narrow oval face. This type of deformation is called scaphocephaly, or boat-shaped skull.

Diagnosis, examination and physical examination

The characteristic shape of the skull is visible from birth. When examining the head from above, the retraction of the parietal areas is noticeable, which gives a feeling of a circular constriction of the cranial vault at the level of or slightly behind the auricles. The presence of a bone ridge, palpable in the projection of the sagittal suture, is considered quite characteristic. The shape of the head changes slightly with age. By the end of the growth of the cranium (5-6 years), the deformation of the face in the form of an oval elongated along the vertical axis, narrowed in the temporal areas, becomes more obvious.

In infancy, children may have a slight delay in psychomotor development. But, as a rule, in the absence of concomitant pathology, the child develops normally until 3-4 years. Starting from this age, visual impairments caused by damage to the optic nerve and neurological symptoms such as headaches, fatigue, irritability, etc. may appear. Often, these complaints are regarded for a long time as personality traits, a reaction to weather changes, vitamin deficiency, attention deficit, etc.

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Laboratory and instrumental studies

When performing computed tomography (CT), the detection of an increased anteroposterior diameter on sections and an almost identical length of the bitemporal and biparietal diameters are considered specific for sagittal synostosis. When performing three-dimensional remodeling of the image, the absence of a lumen in the projection of the sagittal suture is visible.

Treatment

Surgical treatment is best performed on children aged 4-6 months. During this period, a fairly stable result can be achieved with minimal intervention. At this age, the L-plastic technique is usually used. The purpose of the operation is to create bone defects in the parietal bone area to facilitate the growth of the brain in width.

Children over one year of age often have to undergo remodeling of the entire cranial vault, which increases the operation time threefold and is accompanied by a high risk of postoperative complications. Usually, one operation is enough for the brain to grow unhindered and the facial proportions to become normal.

Metopic craniosynostosis (trigonocephaly)

The rarest representative of the group of isolated craniosynostoses is metopic craniosynostosis, which accounts for 5-10% of the total number.

Symptoms

Despite its low incidence, this disease is perhaps most often recognized due to its characteristic clinical picture.

With early closure of the metopic suture, a triangular deformation of the forehead is formed with the formation of a bone keel extending from the glabella to the large fontanelle. When viewed from above, a clear triangular deformation with the apex in the glabella area is visible. In this case, the upper and lateral edges of the orbits are displaced backwards, which gives the feeling of the orbital plane turning outward with a decrease in the interorbital distance - hypotellorism. This forehead pathology is so unusual that children with trigonocephaly are often consulted by geneticists and observed as carriers of hereditary syndromes accompanied by a decrease in intelligence. Indeed, trigonocephaly is considered an integral part of such syndromes as Opitz, Oro-facio-digital and some others.

With age, there is a slight correction of the forehead deformation due to smoothing of the crest apex and development of the frontal sinuses, but the pronounced curvature of the frontal bone, hypotellurism and outward rotation of the supraorbital margins remain. It is impossible to predict the extent of brain damage.

In this group of patients, good compensation and pronounced visual impairments and noticeable intellectual delay are observed with almost equal frequency.

Treatment

Such craniosynostosis can be treated as early as 6 months of age. The traditional scheme of the operation consists of remodeling the upper orbital complex with the elimination of the posterior rotation of the orbits and correction of the curvature of the frontal bone. In most cases, one operation performed on time can not only improve the functions of the central nervous system, but also achieve a good cosmetic result.

Unilateral coronal craniosynostosis

In this pathology, the coronary suture is located perpendicular to the median axis and consists of two equal halves. When one of its halves closes prematurely, a typical asymmetric deformation is formed, called plagiocephaly. The appearance of a child with plagiocephaly is characterized by flattening of the upper orbital rim of the orbit and the frontal bone on the affected side with a compensatory overhang of the opposite half of the forehead (Fig. 6-14, see color insert). With age, flattening of the zygomatic region and curvature of the nose to the healthy side begin to appear more clearly. At school age, a bite deformation is added, associated with an increase in the height of the upper jaw and, as a result, a displacement of the lower jaw on the side of the prematurely closed suture.

Visual disturbances are most often represented by strabismus. Plagiocephaly is most often regarded as a feature of the postnatal head configuration. But unlike the latter, it does not disappear in the first weeks of life.

Treatment

This craniosynostosis is the only monosynostosis in which the cosmetic significance of the operation is equal to, and sometimes even higher than, the functional one. Surgical treatment, as with other craniosynostoses, can be performed from the first months of life. An operation performed at 6 months of age, if it does not completely eliminate the presented deformation, will significantly soften its manifestation. Correction of residual cosmetic deformations of the face can be undertaken at an older age. The surgical technique consists of craniotomy of the frontal bone and supraorbital margin on one or both sides, followed by symmetrical remodeling of the upper edge of the orbits and elimination of the deformation of the frontal bone. Sometimes, to obtain a more lasting cosmetic effect, it is necessary to remodel the parietal region on the affected side.

Bilateral coronal craniosynostosis

Isolated bilateral coronal craniosynostosis occurs with the same frequency as its unilateral lesions - approximately 15-20% of the total number of synostoses.

Bilateral coronal craniosynostosis results in a broad, flattened head in the anteroposterior direction with a flat, high forehead and flattened upper orbital margins. This form is called brachycephaly. In severe cases, the head takes on a tower shape, tapering upward. This deformation is called acrocephaly.

The neurological picture, as for most cases of isolated synostoses, is non-specific, but the severity of neurological and ophthalmological phenomena is usually stronger and manifests itself at an earlier stage. This is most likely due to the large length of the suture.

Treatment

Surgical treatment is aimed at increasing the anterior-posterior size. For this purpose, a bifrontal craniotomy and osteotomy of the supraorbital complex are performed. Then the supraorbital complex is fixed with anterior advancement by 1-2 cm. The frontal bone is rigidly fixed to the supraorbital complex and left without fixation in the area of the resulting defect in the projection and the overgrown coronary suture, thereby allowing for further growth of the brain. This technique is widely used in the world and is called the "floating forehead".

The prognosis for surgical treatment of isolated coronary craniosynostosis is quite favorable; usually, one operation eliminates the deformities and ensures subsequent growth of the brain.

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Lambdoid craniosynostosis

The lambdoid suture, like the coronal suture, is divided into two halves at the point of contact with the sagittal suture, therefore, both unilateral and bilateral damage is possible.

The incidence of premature suture closure is approximately 10% and in the vast majority of cases is unilateral.

In case of unilateral synostosis, flattening of the occipital part occurs with the formation of occipital plagiocephaly. This synostosis seems to be the most difficult to diagnose due to the fact that unilateral closure of the occiput is almost always regarded by doctors as "positional", caused by the forced position of the child's head on the side. Such a forced position is often observed in children with unilateral increase in muscle tone or in the case of torticollis. Distinctive signs of synostosis: synostotic deformation is determined from birth, with age it does not change significantly regardless of the measures taken to change the position of the child's head in the crib.

Positional plagiocephaly occurs after birth, worsens in the first years of life and tends to regress significantly after the start of physical therapy.

Since the deformation is practically invisible under the hair, there are no obvious neurological manifestations, then lambdoid synostosis is the most undiagnosed in this group of diseases. Despite this, the risk of neurological disorders dictates the need for early recognition and treatment of the disease.

Treatment

Surgical treatment is usually performed at 6-9 months of age, when the child begins to spend more time awake, as the likelihood of recurrence of the deformity from pressure on the remodeled area decreases. The essence of the operation is to craniotomy the parieto-occipital flap on the side of the injury and remodel it to create an acceptable curvature.

Almost always, treatment is one-time and one-stage, since small residual deformations are reliably hidden by hair and do not require repeated interventions.

Syndromic crakiosynistoses

Syndromic craniosynostosis is the rarest and at the same time the most complex group of congenital diseases of the craniofacial region both from the point of view of surgical correction of the presented deformations and from the point of view of the prognosis of neurological and mental development.

Clinical picture and diagnostics

In the vast majority of cases, along with craniosynostosis in children, a growth disorder of the facial bones is detected, leading to breathing and eating disorders, visual impairment and severe cosmetic deformity.

Usually, the leading clinical sign is brachycephaly against the background of premature synostosis of the coronary suture. The deformation is aggravated by underdevelopment of the upper jaw, which leads to a characteristic sunken deformation of the face with exophthalmos and orbital hypertelloriemia. As a result of such a combined lesion, the newborn's breathing and feeding process are sharply impaired, which determines the severity of the condition in the first days and months of life and requires intensive monitoring. Often, in cases of syndromic craniosynostoses, not only the coronary, but also other sutures overgrow, which causes craniosynostosis. Thus, respiratory disorders and feeding difficulties are aggravated by neurological disorders, which dictates the need for early surgical treatment. It is important to remember that most patients with syndromic craniosynostoses have a sharp increase in the anterior fontanelle and even widening of the sagittal suture along its entire length. This often confuses clinicians who cannot imagine the possibility of a dilated fontanelle coexisting with premature suture closure.

As a rule, in the absence of qualified care, children with syndromic synostoses die in the first year of life due to severe and frequent respiratory diseases complicated by pneumonia. In the absence of competent timely surgical treatment, most of these patients have pronounced mental and neurological abnormalities.

Treatment

Treatment of children with syndromic synostoses should begin in the maternity hospital. It is necessary to ensure optimal breathing and feeding of such patients. Due to hypoplasia of the maxilla in children, choanal atresia is often falsely assumed, for which choanotomy is performed. Sometimes such treatment is effective, since postoperative wearing of nasal inserts improves nasal breathing. An oral airway can also be used, facilitating breathing during sleep. In some cases, the child may require a tracheostomy.

Feeding of the child should be organized as soon as possible. Naturally, in the first days of life, tube feeding may sometimes be justified, but the child should be transferred to feeding from a nipple, spoon or sippy cup as soon as possible. The expansion of the ventricular system of the brain is sometimes incorrectly interpreted as hydrocephalus and large doses of diuretics are prescribed. However, with careful monitoring of the increase in head circumference, it is important to note that there are practically no deviations from the normal growth rate. Severe exorbitism in children with syndromic synostoses should be the object of close attention of ophthalmologists. Children should undergo specific therapy aimed at preventing corneal drying. In severe cases of exorbitism, blepharorrhea may be required for several weeks to prevent severe damage to the cornea and dislocation of the eyeball. Surgical treatment of children with syndromic craniosynostoses traditionally consists of three stages.

• In the first year of life, cranioplasty is performed using the "floating forehead" technique. Brachycephaly is eliminated and the volume of the skull is increased, creating conditions for normal brain growth. In cases where the large fontanelle is closed or small, treatment can begin at 6 months.
• At the next stage, the middle zone of the face is advanced to improve nasal breathing, eliminate hypertellorism and exorbitism. At this stage, significant cosmetic correction is performed and occlusion is normalized. This stage is performed on children aged 5-6 years.
• At the last stage, final cosmetic interventions are performed aimed at normalizing the bite, correcting deformations of the nose, orbits and periorbital area.

Currently, a compression-distraction method has been developed for moving the bones of the skull and face. With the help of distraction devices, it is possible to combine the first and second stages into one, which both significantly simplifies the treatment itself and ensures early improvement of respiratory functions. Craniosynostosis should be treated with distraction devices at the age of 9 months.

Despite all attempts to accelerate the restoration of normal skull proportions and normalize breathing in cases of syndromic disorders, the prognosis for the treatment of such children is worse than in the treatment of isolated synostoses. This is due to the fact that about 90% of children have combined malformations of the brain and other organs. Despite qualified and timely treatment, about 30% of patients have a delay in neuropsychic development.

But if we consider a group of untreated children, the percentage of their intellectual fitness reaches 80%, despite the fact that exactly half of the children can be rehabilitated. Thus, craniosynostosis, despite the severity of external and functional manifestations, is successfully treated with the help of modern achievements of reconstructive surgery, and allows us to hope for significant progress in the aesthetic, functional and social rehabilitation of such patients in the near future.

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How to recognize craniosynostosis?

Of the instrumental diagnostic methods, the best is recognized to be computer tomography with three-dimensional remodeling of the image of the bones of the cranial vault and face. The study allows identifying intracranial signs of hypertension, confirming the presence of synostosis in the case of isolated damage and installing all the interested sutures in the case of polysynostosis.

The simplest way to diagnose premature synostosis of the cranial sutures is an examination. Craniosynostosis can already be suspected in a newborn based on the shape of the head alone. An abnormal skull shape, especially in combination with a facial skeletal deformity, should prompt any doctor to think about this disease.

In children with synostosis of several sutures, a clear tendency is noted for the degree of neurological deficit to increase proportionally to the number of affected sutures. In cases of damage to two or more sutures, we can already talk about craniostenosis. If in children with isolated synostosis of one of the cranial sutures, the transition from the subcompensation stage to the decompensation stage occurs in about 10% of cases, then with polysynostosis, such a transition occurs in more than half of the children. Usually, neurological signs appear at the age of 2-3 years, but by this time the brain is already damaged.

Differential diagnostics

Skull deformities may not be due to premature synostosis of the sutures. Or, conversely, craniosynostosis may be a consequence of some brain injury that causes growth arrest. In such cases, surgical treatment may be considered only for cosmetic reasons, since functional improvement cannot be achieved from such intervention.

The most common example of non-synostotic skull deformation is positional plagiocephaly. In this condition, the change in the shape of the head occurs in the neonatal period against the background of limited spontaneous motor activity of the child with forced turning of the head to one side or another. The cause is often torticollis and dystonic disorders that have arisen as a result of perinatal encephalopathy. Positional skull deformation differs from true craniosynostosis in that it manifests itself in the first weeks of life, while synostoses exist from the moment of birth. Then, with proper care of the child and physiotherapy and exercise therapy, massage and normalization of the position of the child's head in the crib with the help of various devices, the deformation can significantly decrease or even disappear completely. When conducting an X-ray examination of the skull, all cranial sutures are always clearly visible.

Bulging or sinking of individual areas of the head may be a consequence of intranatal trauma (fracture of the skull bones, cephalohematoma, etc.). In such cases, the anamnesis always indicates one or another deviation in the normal course of labor or early postnatal period. The same deformations may be a consequence of underlying cysts of the brain, vascular malformations, etc.

Previously, brachycephaly was often observed in children with craniotabiasis due to vitamin D deficiency. Currently, widespread prevention of rickets has reduced the number of such pathologies to a minimum.

In some cases, craniosynostosis is mistaken for microcephaly. Like synostoses, microcephaly is characterized by early closure of the fontanelles and cranial sutures. Moreover, in some cases, true synostosis of individual cranial sutures may occur at a time not typical for their physiological closure. It is important to remember that with microcephaly, the delay in brain growth leads to a decrease in osteogenic activity, so synostosis of the sutures occurs gradually. In the case of craniosynostosis, the decrease in osteogenic activity is primary, so a characteristic X-ray picture can always be detected from birth. Delay in psychomotor development in children with microcephaly occurs earlier and is always much more severe than with craniosynostosis.

And finally, the most important difference between microcephaly and craniosynostosis is the signs of brain damage without signs of increased intracranial pressure, detected by neuroimaging methods such as magnetic resonance and computed tomography. Correct differential diagnostics is very important in terms of prognosis, since in the case of early detection of synostosis, mental retardation can be successfully prevented, and in the case of microcephaly, surgical treatment is practically ineffective.

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How to treat craniosynostosis?

As for the treatment of craniosynostoses, surgical techniques have been thoroughly developed and are practically not accompanied by complications in a specialized clinic. And most importantly, the younger the patient, the lower the risk of complications and the better the functional and cosmetic results.

The most active period of brain growth is considered to be the age of up to 2 years. By this age, the brain reaches 90% of the volume of an adult. Thus, from a functional point of view, craniosynostosis can be prevented by early surgical treatment. According to the literature, the optimal age for treating craniosynostosis can be considered the period from 6 to 9 months. The following facts are recognized as advantages of treatment at this age:

• ease of manipulation of the strong and soft bones of the skull:
• facilitating the final remodeling of the skull shape by the rapidly growing brain:
• the younger the child, the more completely and quickly residual bone defects heal.

If the treatment is performed after 3 years, it is doubtful that it will lead to a significant improvement in the functions of the brain and the organ of vision. To a greater extent, the operation will be aimed at eliminating the presented deformation, i.e. it will be of a cosmetic nature.

The main feature of modern surgical treatment is not only increasing the volume of the skull, but also correcting its shape.

Currently, the most successful treatment is carried out where a maxillofacial surgeon and a neurosurgeon work together. Surgical treatment consists of remodeling the bones of the cranial vault. To do this, the bones of the deformed areas are removed and rearranged into the correct anatomical position, while the cranial cavity is enlarged.