What is Craniosynostosis?
Craniosynostosis is the premature overgrowth of one or more sutures of the skull, leading to the formation of characteristic deformity. Craniosynostosis is understood as brain damage that occurs when the skull cavity is not sufficiently expanded during the period of the most active brain growth.
In the CIS countries (Ukraine, Russia, Belarus, etc.), a disease is recognized easily, but it is diagnosed in rare cases. The diagnosis is made after 12 months, because of which the prognosis worsens and a lot of complications arise.
According to international data, premature closure of one of the sutures of the skull on average is recorded in one of 1 thousand newborns, that is, the percentage of patients among infants is 0.02-4%. The frequency of syndromic craniostenosis 1: 100 000-300 000.
Division of the disease due to occurrence was proposed in 1986 by M. Cohen:
Syndromic, in turn, is divided into:
- X-linked craniosynostosis
- monogenic craniosynostosis
- syndromes caused by environmental factors
- incomplete syndromic
- chromosomal craniosynostosis
Monosynostoses, polynostosis, pansinostosis are distinguished by anatomical signs.
Monosynostoses are of the following types:
- isolated metopic craniosynostosis
- isolated sagittal craniosynostosis
- isolated coronary bilateral craniosynostosis
- isolated coronary unilateral craniosynostosis
- isolated lambdoid bilateral craniosynostosis
- isolated lambdoid unilateral craniosynostosis
Monosynostosis, which is an early closure of 1 suture of the skull, is almost always diagnosed. When two or more sutures are included in the process, polysynostosis is diagnosed. Pansinostosis occurs in extremely severe cases. An isolated craniosynostosis is diagnosed if, with premature synostosis, there are no other malformations in the child.
Causes of Craniosynostosis
The nature of this disease has been little studied to date. But there are a large number of theories of the occurrence of craniostenosis. Theories talk about such reasons:
- hereditary disorders
- compression of the fetal head in the uterus, etc.
A defect in the gene for fibroblast growth factor receptor (FGFR) 1,2,3 is officially recognized as a factor in pathogenesis.
The main seams of the cranial vault:
If the bone suture is affected, compensatory bone growth is fixed perpendicular to its axis, which is called the Virchow’s law in meditation. As a result of this process, a characteristic deformation arises – one for each of the closed joints. Sagittal craniostenosis causes scapocephaly, and synostosis of the entire coronary suture causes plagiocephaly. If there is a synostosis of the metopic suture, trigonocephaly occurs.
Synostosis of the entire lambdoid suture or its half 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 state of the brain itself. For example, if there is hydrocephalus along with this, then the severity increases.
Pathogenesis during Craniosynostosis
It is possible to speak about premature synostosis of skull sutures if a large fontanel is closed early. If with syndromic synostosis 2 or more sutures are involved in the process and if there is a concomitant expansion of the ventricles of the brain, the large fontanel may not be closed until the baby is 3 years old. With premature synostosis of the sutures of the skull, panoramic radiographs show finger impressions.
The pattern of finger impressions becomes stronger if other compensatory mechanisms cannot cope with intracranial hypertension. In newborns, finger impressions may also be visible. Another pathognomic sign of increased pressure in the middle of the skull is venous congestion in the fundus and edema of the optic nerve. If a person has isolated monosynostosis, the above-mentioned phenomenon may not be fixed. With polysynostosis, intracranial hypertension, which has existed for a long time, causes the formation of partial atrophy of the optic nerves.