Early fusion of the metopic suture connecting the two frontal bones is part of a series of phenomena known as craniosynostosis. This phenomenon can lead to significant defects in the appearance of the skull, up to the formation of a “triangular head”.
The operation, performed by Herzliya Medical Center's craniosynostosis specialists, ensures that your child receives the best and most professional treatment and that the child's future physical and mental development is not affected.
What it is
The frontal bone of the skull consists of two parts. They are connected by a metopic suture. Normally, it remains completely open in infants up to 1 year of age. Subsequently, the seam begins to heal, this process continues until the age of 8 years.
However, sometimes the connection of the frontal bones heals during the prenatal period or in the first year of life. In this case, the baby has a noticeable metopic suture on the forehead. This formation looks like a convex ridge that runs from the brow ridge to the large fontanel. In this case, the child has an irregular skull shape. Doctors call this anomaly metopic suture synostosis or trigonocephaly.
Why is craniostenosis dangerous?
The anomaly is accompanied by a hypertensive effect, which is manifested by neurological symptoms, venous stagnation of the fundus, partial or complete atrophy of light-sensitive optic fibers.
Craniostenosis is characterized by a large number of negative consequences, systemic pathologies, and severe complications. They depend on the pathogenetic picture of the anatomical anomaly.
The most common complications of craniostenosis include:
- spinal hernial protrusions;
- deformation protrusions of the frontal lobe of the skull;
- decreased visual acuity with the prospect of complete blindness;
- retardation in intellectual development;
- cosmetic defects;
- strabismus;
- underdevelopment of the eye sockets;
- regular cephalgic paroxysms of varying intensity and duration;
- spontaneous muscle cramps;
- development of epileptic pathology;
- joint dysfunctions leading to persistent musculoskeletal disorders;
- hydrocephalic syndrome;
- sleep apnea;
- respiratory disorders.
The nature and severity of the consequences is determined by the form of craniostenosis. Approximately every 5th child with premature fusion of the sagittal suture experiences intracranial hypertension, supplemented by severe disorders of higher nervous activity.
Typical for craniostenosis are ophthalmological pathologies and congestion in the cervical spine. According to international studies, in 50-60% of cases of metopic suture formation, a decrease in the child’s cognitive abilities is observed.
A common complication of craniostenosis is exophthalmos, which is a mono- or binocular displacement of the eyeballs in the anterior-facial direction beyond the anatomical bed.
The danger of a congenital disorder is regular convulsive attacks, severe headaches, and nausea and vomiting. Such children have a sharply deteriorated ability to remember information and learn.
Causes
Why does the suture between the frontal bones close prematurely? The following reasons can provoke its early overgrowth:
- Heredity. In approximately 2-8% of cases, this disease is transmitted from parents. The cause of metopic synostosis is damage to the gene responsible for the growth of connective tissue.
- Chromosomal abnormalities. Premature healing of the metopic suture may be just one of the manifestations of serious genetic pathologies. This deviation is observed in children with Jacobsen syndrome and Opithia trigonocephaly syndrome. In this case, not only synostosis and deformation of the skull are observed, but also anomalies of internal organs, as well as delayed mental development.
- Fetal hypoxia. Lack of oxygen during the prenatal period can cause premature healing of the suture.
- Prematurity. Babies born prematurely have an increased risk of developing trigonocephaly.
Discussion
After the discovery of X-rays and in connection with the widespread introduction of the X-ray diagnostic method into medical practice, the number of studies devoted to the issue of combining metopism with the absence of the frontal sinuses increased. The most significant works include [26, 27, 29—33]. The authors of these studies took different points of view on the issue of the connection between metopism and the formation of frontal sinuses; accordingly, based on the results of their work, they drew different conclusions. Most of them [17, 31, 33, 34], for example, argued that the presence of MS is basically associated with the congenital absence or insufficient development of the frontal sinuses.
In the early 1930s, our compatriots D.G. Rokhlin and A.E. Rubashev conducted a series of studies devoted to the study of the structural features and frequency of occurrence of MS [29]. Based on their observations, the authors noted a correlation between the presence of MS and the congenital absence of the frontal sinuses, weak pneumatization of the sphenoid sinus, the infantile form of the sella turcica and hypoplasia of the external occipital protuberance. The authors analyzed X-ray data of the skull in a direct projection for the absence of frontal sinuses in 110 patients with metopism and in 2 control groups without MS - 100 representatives of Russian nationality (1st control group) and 80 patients without identification of nationality (2nd control group) group). The results of the study showed that in patients with MS, unilateral absence of frontal sinuses was present in 16.3% of cases, and bilateral absence in 28%. In the control groups of Russians, unilateral agenesis was observed in 4.0%, bilateral - in 7.0%; in group 2 - 11.2 and 7.5%, respectively. The data obtained by the authors quite convincingly indicate the correlation of metopism with the development of the frontal sinuses, since the absence of one or both sinuses was observed in a total of almost half (44.3%) of patients with MS.
According to J. Torgersen [26], who studied radiographs of the skull of 62 patients with MS, agenesis of the frontal sinuses was detected in 24% of cases. In the control group, which included radiographs of 400 skulls without MS, sinuses were absent in only 5% of cases. Based on the study, J. Torgersen concluded that MS is a normal variant of the anatomical structure, but in its presence the frontal sinuses are small.
R. Marciniak and C. Nizankowski [27] conducted a comprehensive (anatomical and radiological) study of MS and its combination with pneumatization of the frontal sinuses. Metopism was detected in 252 patients, accounting for 12.4% of all study participants. Of the 252 patients, the absence of both frontal sinuses, according to the authors, was recorded in 8% of cases, and one in 7.1%. However, the authors emphasized that the material they studied does not allow us to conclude that metopism is associated with underdevelopment of the frontal sinuses, since their absence was no more common in metopism than in patients without such an anatomical feature.
Modern researchers have also not ignored this issue. Among the available publications on this topic, most authors share the hypothesis of a direct connection between metopism and insufficient development of the frontal sinuses.
For example, P. Baaten et al. [18], who studied the incidence of MS among Lebanese residents, found the absence of frontal sinuses in 7 out of 8 cases. A Guerram et al. [19] studied 143 macerated preparations of Caucasian skulls, divided into two groups, one of which included 63 preparations with completely preserved MS, the other - 80 skulls with its complete fusion.
Morphological examination in all cases was supplemented by radiography in the occipitomental projection. According to the study, the complete absence and underdevelopment of the frontal sinuses in metopic skulls was 57.9% versus only 11.9% in normal ones, while agenesis was observed in 7.1 and 2.5%, respectively, and hypogenesis in 50.8 and 9.4% respectively. The authors assessed the results obtained as statistically significant regarding the existence of a correlation between the size of the frontal sinuses and the preserved MS. S. Nikolova et al. [35] in a group of 93 skulls with metopism found aplasia of the frontal sinuses (unilateral and bilateral) in 19.35% of cases; in the control group (137 skulls) without MS, sinuses were absent in 12.41% of cases.
Among the studies advocating the opposite point of view, one can name the work of S. Bilgin et al. [21], who studied the incidence of MS in Turkish patients and the combination of MS with the absence of frontal sinuses. The authors analyzed the results of computed tomography (CT) of 219 patients and magnetic resonance imaging of 412 patients; as a result, MS was detected in 9.7% of cases, among them agenesis of the frontal sinuses was determined in 24.6% of cases (on the right - 46.7% , on the left - 13.3%, on both sides - 40.0%). In the control group (patients without MS), the authors diagnosed agenesis of the frontal sinuses in 22.5% of those studied. Based on the data obtained, S. Bilgin et al. [21] concluded that there is no correlation between the presence of MS and the development of the frontal sinuses ( p
>0,05).
Brazilian researchers L. Sandre et al. [22] studied 245 macerated skulls, of which 17 had MS, then 16 of them were subjected to direct radiography, which revealed the absence of frontal sinuses in only 1 case, which amounted to 6.25%. According to the study, the authors also concluded that there is no correlation between MS and agenesis of the frontal sinuses. However, according to the authors, in another 4 cases, radiographs revealed, in their terminology, “aplasia” of the frontal sinuses (probably meaning underdevelopment). Thus, in the study by L. Sandre et al. [22] the development of sinuses “smaller than average in size” was observed in 31.25% of cases, which cannot be called a low frequency.
The data obtained as a result of this study show that when the MS is preserved, the absence and underdevelopment of the frontal sinuses (bilateral and unilateral) is much more common than in skulls that do not have this anatomical feature. These data, together with the results of the research of a number of the authors listed above, suggest that there is a correlation between the two physiological processes (non-fusion of the frontal suture and the development of the frontal sinuses), the clarification of the nature of which requires further study.
Symptoms
The metopic suture in a child is a convex groove in the middle of the forehead. It starts on the bridge of the nose or between the eyebrows and ends at the crown of the head. At the same time, in children the volume of the frontal lobes of the skull decreases and the growth of the parietal bones is noted. Because of this, the baby's head has a triangular shape.
A photo of the metopic suture can be seen below.
Parents often confuse the manifestations of synostosis with an ordinary bump on the forehead. In trigonocephaly, the groove has a hard structure. A hematoma formed as a result of a bruise is a soft formation.
Close-set eyes are one of the signs of trigonocephaly. Doctors call this defect hypotelorism. The distance between the eyeballs decreases due to deformation of the skull.
A convex metopic suture in an adult patient can also be a manifestation of synostosis. If trigonocephaly was not treated in childhood, the groove on the forehead, the triangular shape of the skull and hypotelorism persist throughout life. This disease can be easily corrected in children. Correcting such a defect in an adult is much more difficult.
However, it is important to remember that a bulge in the middle of the forehead does not always indicate illness. In some people this is an anatomical feature. If a person has a suture on his forehead, but there is no deformation of the skull, then there is no reason for concern.
About the disease
Among the deformations of the skull there are congenital and acquired.
Congenital ones appear during pregnancy, and the child is born with a certain malformation. Acquired ones occur after childbirth, most often as a result of injury or certain intervention, such as surgery. Craniostenosis in children can be either congenital or acquired after birth. This defect is a premature fusion or absence of sutures in the bones of the skull, which normally should remain plastic for the natural growth and development of the child's brain. As a result, intracranial pressure increases and the shape of the skull changes. If we are talking about a developmental defect, craniostenosis in newborns may be accompanied by other defects that affect the brain and other organs of the body. In the case of an acquired disease, suture fusion occurs due to injury or surgery.
Craniostenosis occurs in one in 1000 newborns.
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Consequences
The metopic suture is not only an aesthetic problem. In advanced cases, deformation of the skull leads to pinching of the optic nerve and eye muscles. This leads to the appearance of ophthalmological pathologies:
- strabismus;
- exophthalmos (bulging of the eyeballs);
- decreased visual acuity.
In addition, early closure of the suture between the frontal bones leads to increased intracranial pressure. This is expressed in frequent headaches, dizziness, and nausea. Many babies with metopic synostosis suffer from hydrocephalus, a pathological increase in the volume of the head.
If trigonocephaly is not treated in early childhood, then in 15-20% of cases this disease leads to mental retardation. Intellectual impairments appear only at the age of 7-8 years. The child has problems with memorization, it becomes difficult for him to assimilate new material, which creates serious problems in learning. Mental retardation is more often observed in children suffering from high intracranial pressure.
Material and methods
The results of X-ray computed tomography (XCT) of 600 patients (284 men and 316 women) aged from 16 to 86 years who were examined in the computed tomography department of the Kursk Regional Clinical Hospital (KOKB) for the period 2012-2017 were analyzed. All patients underwent RCT for suspected brain pathology in connection with existing cerebral or focal symptoms; no pathological changes in the paranasal sinuses were detected.
When analyzing the degree of development of the frontal sinuses, the criteria of F. Ribeiro [25] were used as modernized by A. Guerram et al. [19], based on the extent of the frontal sinuses in the squama of the frontal bone relative to the supraorbital and middle orbital lines (Fig. 1).
Rice. 1. Classification scheme for the development of frontal sinuses according to their distribution in the squama of the frontal bone [19].
When comparing the results of this study with the average values of agenesis and hypogenesis of the frontal sinuses in the study population, the authors relied on those published in 2011-2012. RCT results of 3054 patients [24, 25]. According to these studies, the frequency of occurrence of such variants of the structure of the frontal sinuses is a total of 11.3%.
Diagnostics
A neurologist treats trigonocephaly. If the pathology in a child or adult is accompanied by damage to the organ of vision, then consultation with an ophthalmologist may be required.
You can notice the external manifestations of metopic synostosis already during the examination of the patient. As already mentioned, trigonocephaly can be either a separate disease or one of the signs of chromosomal abnormalities. Therefore, the patient needs to undergo a comprehensive diagnosis. The doctor may order the following tests:
- Spiral computed tomography of the skull in 3D. This is the most accurate method for detecting metopic synostosis. The procedure is carried out while the child is sleeping.
- Neurosonography (ultrasound of the skull). This test is usually given to children under 1 year of age. The procedure is absolutely painless and harmless. It shows anomalies in the structure of the cranial bones and the condition of the sutures.
- MRI of the head. This study is often prescribed to children of primary school age to identify the cause of cognitive impairment.
In addition, the distance between different parts of the face is measured. This helps to identify hypotelorism and deformations of the facial part of the skull.
Additionally, an ECG, MRI of the spine and ultrasound of the gastrointestinal tract are prescribed. This allows us to identify signs of chromosomal diseases that often accompany trigonocephaly.
Surgical intervention
The protruding seam on the forehead can only be completely eliminated through surgery. Surgery is performed in a hospital setting.
Surgery is necessary only in cases where trigonocephaly is confirmed by spiral CT in 3D. If premature healing of the suture is noticeable on the three-dimensional image, then this is considered an indication for surgical treatment.
Experts recommend performing this operation on a child aged 4-6 months. Surgery is performed under general anesthesia. The doctor cuts the fused suture and inserts special plates that support the skull bones in the correct position. The operation lasts about 4 hours.
After correction of metopic synostosis in children, the normal structure of the skull is restored and deformities disappear. In the photo below you can see the results of the surgical intervention. The left picture shows the child before surgery, and the right picture shows him 2 years after the defect was eliminated.
Forecast
With a timely and successful surgical operation, the chances of a full life are assessed as high. Accurate predictions depend on the form of the anomaly, the etiological factor, and the presence of concomitant pathologies.
It is often possible to completely eliminate the metopic suture, relieve neurological symptoms and intracranial hypertension. The pathological formation on the child’s forehead disappears as the reconstructed bones grow. Only syndromic craniostenosis is prognostically unfavorable.
After operation
The recovery period after surgery lasts quite a long time. In the first 2-7 days after correction of synostosis, the child is in the hospital. After surgery, hematomas and swelling in the eye area may appear. This is a natural phenomenon that passes quickly.
There are cases when synostosis recurs after correction. Therefore, doctors recommend that the child wear a special orthopedic helmet during the postoperative period. This device helps prevent skull deformation.
In the first year after surgery, children should be under medical supervision. During this time, it is necessary to regularly visit the doctor and periodically do a 3D spiral computed tomography scan of the head. This will help to track relapses of the disease in time.
Is it possible to do without surgery?
Parents of children often ask: “Is it possible to cure synostosis without surgery?” This is possible only with mild forms of trigonocephaly, if the child has only a cosmetic defect, but no functional impairment.
In such cases, an orthopedic helmet is used. It must be worn at least 20 hours a day. The duration of treatment may vary, depending on the severity of synostosis. An orthotic helmet allows you to correct existing defects in the formation of the skull. This device compresses only deformed areas and does not interfere with the natural growth of healthy bones.
Treatment
The only method of restoring the natural shape of the skull and reducing the severity of complications is surgery. The most appropriate time for surgical correction is considered to be a child’s age of 6-9 months.
Such timing is due to the intensive development of tissue structures of the cerebral zone during this period of life. Their growth is hampered by bone distortions. At this age, tissues that have not fully hardened quickly restore their natural structure without the risk of serious complications.
The volume of reconstruction and surgical technique are selected based on the type of pathology and the degree of abnormal changes. Once the child reaches the age of 2-3 years, surgical reconstruction is possible only to eliminate minor cosmetic defects.
The correction consists of remodeling the bone formations of the cranial vault. The best results are achieved by an operation performed jointly by a pediatric maxillofacial surgeon and a neurosurgeon.
For trigonocephaly, corrective orthotic therapy is subsequently prescribed, which includes wearing a specialized fixation helmet. This dynamic system is designed to eliminate residual deformations caused by intensive head growth.
An orthotic helmet gives the best results in the first 6-18 months of a baby’s life. In addition to surgical correction and the use of a dynamic fixation system, a change in the child’s nutritional pattern is indicated according to age requirements and observed disorders.
With the progression of intercurrent pathologies or an increase in neurological symptoms, complex drug therapy is prescribed.
The following types of craniotomy are used to reconstruct cranial bone deformities:
- linear, involving partial amputation of the periosteum;
- circulatory, performed for children 3-5 years old and aimed at eliminating intracranial hypertension;
- fragmentary – cutting of the cranial vault;
- bilateral flap, intended for correction of decompensated form of craniostenosis.
Resection lines are marked in advance with a medical marker. Typical areas of influence are the frontal lobe, anterior fontanel, coronary junction.