Meningocele

Meningocele is a type of pathological condition that refers to anterior cerebral hernia caused by congenital deficiency of bone tissue in the area of the anterior scoop in the period of embryonic development under the influence of certain external (infection) and internal (genetic) causes, resulting in a delayed closure of the provertebral brain plates (Kolliker plates), which leads to the formation of holes in the lower wall of the anterior cranial fossa, through which the brain substance prolapses. These hernias are called anterior cerebral hernia.

[1], [2], [3], [4]

Causes of the meningocele

There is a hypothesis of the development of meningocele, which links the occurrence of primary ectopia of the meninges and the brain through the primary defects of the skull as a result of stopping the development of the skull in the embryonic period. Springs explains the origin of cerebral hernia and meningocele pathological changes of the cranial vault, resulting from meningoencephalitis, which was transferred to the fetus during pregnancy. Klein believes that the cause of meningocele is intrauterine hydrocephalus, which leads to a divergence of the bones of the skull and its perforations in the area of natural holes.

As already noted, they are formed by prolapse, first of the meninges, forming a bag filled with cerebrospinal fluid, and then, if the opening is large enough, and by going into this bag and brain tissue. Usually this prolapse occurs through a hole in the root of the nose and glabella. Brain hernias and meningocele are divided into two types:

1. lying on the middle line (nosholobnye);
2. lying but to the sides of the root of the nose (nasolattice) and in the inner corner of the orbit (naso-orbital).

There are various "theories" of the occurrence of meningocele.

[5], [6], [7], [8], [9], [10], [11], [12]

Risk factors

In addition to genetically determined meningocele, bone defects in the anterior cranial fossa (as well as in other parts of the skull) can occur as a result of intrauterine, transplacentally transmitted from the mother infection, intrauterine or birth injury, as well as other adverse factors that adversely affect the body pregnant woman.

A significant role is played by a violation of the metabolism of vitamin A and folic acid, calcium metabolism, as well as the action of ionizing radiation and some teratogenic toxic substances. Each of these pathogenic factors can lead to disruption of embryonic development during the period when the primary cerebral lamina was laid and closed in the brain tube, which subsequently leads to the development of cranial defects.

[13], [14]

Pathogenesis

The bone defect in most cases is in the mid-sagittal plane, less often in the region of the occipital foramen, and most often in the region of the fronto-nasal suture, nasopharynx, and orbit. The diameter of the bone defect in meningocele varies from 1 to 8 cm, and the length of the bone canal, which has an internal and external opening, in which the hernia leg is located, can be up to 1 cm.

Nasolate meningoencephalocele is always located in the area of the blind opening of the frontal bone, and its channel can be directed forward, down or lateral, which causes the types of localization of the hernial sac: downward and lateral form nasolatalnias, and downward and outward - nasalorrheal. The structure of the hernial sac consists of the outside of the inside of the skin, the hard, soft, and arachnoid of the meninges and the substance of the brain.

[15], [16], [17], [18], [19]

Symptoms of the meningocele

Signs of meningocele are divided into subjective and objective. The former mainly concern only complaints from the parents of a child or an adult patient about the presence of a tumor in the area of hernia prolapse. Other complaints, as a rule, do not arise. The size of this “tumor” can vary from lentil grain to a large apple, sometimes imitating the “second nose”. To the touch is the formation of a soft-elastic consistency, sometimes its leg goes deep into the root of the nose. The swelling may pulsate synchronously with the contractions of the heart, while straining (crying or crying a child), increase, and when pressure is applied to it, decrease. These signs indicate the connection of the tumor with the cranial cavity.

An additional sign of the front meningocele and hernias of the brain is the deformation of the facial skeleton.

[20]

Complications and consequences

Complications of meningocele - a terrible phenomenon, usually ending in death. These include meningoepcephalitis, which occurs during ulceration of the wall of meningocele. However, most of these complications result from the surgical removal of the hernia sac. These complications are:

1. intraoperative (shock, blood loss);
2. the next postoperative (meningitis, meningoencephalitis, brain swelling);
3. delayed postoperative (hydrocephalus, intracranial hypotension, cerebral edema, convulsions);
4. late (epilepsy, mental disorders, impaired intelligence).

Fistulas of the subarachnoid space, liquorrhea, recurrences of meningocele and cerebral hernias can be attributed to postoperative complications.

[21], [22], [23], [24]

Diagnostics of the meningocele

The diagnosis is based on the following symptoms:

1. typical position of the hernial bag;
2. congenital character;
3. the presence of dehiscences, determined by palpation and radiology.

[25], [26], [27], [28], [29], [30], [31],

Differential diagnosis

Differential diagnosis is difficult for small meningocele. Such formations should be differentiated from dermoid cysts, meningiomas, old organized hematomas, aneurysms, retrobulbar angiomas, deforming polyposis of the nose and cysts of the paranasal sinuses, syphilitic gum, brain echinococcus, various brain tumors and the skull.

[32], [33], [34]

Treatment of the meningocele

Congenital hernia meningocele is a rare disease, and not all children born with such a defect undergo surgical treatment, as some of them die soon after birth. Treatment of meningocele and cerebral hernia in operable cases is only surgical. The terms of treatment vary depending on many indicators, and the question of surgical treatment is decided in each case individually, taking into account the age of the child, the type of hernia, the size of the defect and swelling, as well as the threat of complications.

Some surgeons are of the opinion that the operation should begin in the first months of life. PA Herzen (1967) believed that the child should be operated on in the first year of life. With hernia of the brain with the rapid growth of swelling and the risk of complications (inflammation or rupture of thinned tissue) must be operated in the first days after birth. If the conditions allow the use of a wait-and-see tactic, then surgery should be carried out at the age of 2.1 / 2-3 years. Complicated plastic surgery using bone grafts is used at this age. Such surgical interventions are the responsibility of neurosurgeons.

Forecast

With surgical treatment, the prognosis for life is favorable. However, according to foreign statistics, even with flawlessly performed surgery, mortality from secondary complications can reach 10%.

The evolution of the process depends on the stage of hernia development and on the applied treatment. In incurable forms, when there is a significant part of the brain with vital centers in the hernial sac, death may occur at the age of 5-8 years, as a rule, it is caused by meningoencephalitis.

[35], [36], [37], [38], [39], [40]