Expansion of the Sylvian fissure. Arachnoid cyst

Congenital arachnoid cysts are also called leptomeningeal cysts. This term does not include secondary "arachnoid" cysts (eg, post-traumatic, post-infectious, etc.), nor glioepindemic cysts lined with glial tissue and epithelial cells.

Definition and etiology. Congenital arachnoid cysts are a developmental anomaly resulting from separation or duplication of the arachnoid membrane (thus they are actually intraarachnoid cysts).

The etiology of these lesions has long been a subject of debate. According to the most common theory, they develop due to a slight deviation in the development of the arachnoid membrane around the 15th week of gestation, when cerebrospinal fluid (CSF) begins to be produced to gradually replace the extracellular substance between the outer and inner arachnoid membranes (endomenings).

The developmental anomaly hypothesis is supported by the common location of arachnoid cysts at the level of normal arachnoid cisterns, their random occurrence in siblings, the presence of concomitant anomalies in venous architectonics (eg, absence of the vein of Sylvian), and accompanying other congenital anomalies (agenesis of the corpus callosum and Marfan's syndrome).

It is still unclear why arachnoid cysts tend to expand. Electron microscopy and ultracytochemical analysis showed an increase in the activity of Na + and K + pump in the cyst wall compared to the normal arachnoid membrane, supporting the theory of active CSF production by the membrane lining the cyst, which has morphological similarities with the subdural neuroepithelium and the neuroepithelial lining of the arachnoid granulation. On the other hand, movie-MPT and direct endoscopic video have shown that some arachnoid cysts can enlarge when CSF is trapped by the valve mechanism.

The pressure gradient for the movement of cerebrospinal fluid into the arachnoid cyst will be provided by a transient increase in cerebrospinal fluid pressure caused by the systolic oscillation of the cerebral arteries or the transmission pulsation of the veins.

Specific problems in determining the pathogenesis relate to intraventricular cysts. Some authors present them as a kind of "internal" meningocele; according to others, they are formed from the arachnoid layer and are transported along with the choroid plexus when it protrudes through the choroidal fissure.

Anatomical classification and topographic distribution of intracranial arachnoid cysts.

I. intracranial arachnoid cysts:

A) Frequency of occurrence. Congenital arachnoid cysts are reported to account for approximately 1% of non-traumatic intracranial masses. This rather old indicator was obtained by correlating clinical experience in the era before CT/MRI (0.7-2% of mass lesions) and autopsy data (0.1-0.5% of incidental findings at autopsy); in recent years, an increase in the incidence of these formations has been described. Intracranial arachnoid cysts are almost always solitary and sporadic.

They are 2-3 times more common in men than women and 3-4 times more common on the left side of the brain than on the right. The appearance of bilateral more or less symmetrical cysts is described in healthy children, as well as in children with neurological disorders, although rarely. In the latter case, especially in patients with bitemporal cysts, the differential diagnosis should be made with lesions resulting from perinatal hypoxia.

According to information provided from a large mixed series (including both children and adults), it turned out that the largest proportion of childhood cases occur in the first two years of life.

b) Anatomical distribution. Typical localization of arachnoid cysts within the middle cranial fossa, where 30-50% of lesions were found. Another 10% is in the medullary convex, 9-15% is found in the suprasellar region, 5-10% in the cisterna quadrimenalis, 10% in the cerebellopontine angle, and 10% in the midline of the posterior cranial fossa. The anatomical classification and topographic distribution of different types of arachnoid cysts are shown in the table below.

II. Supratentorial arachnodal cysts:

A) Sylvian fissure cysts. Cysts of the lateral sulcus account for about half of all cases in adults and a third of cases in children. Galassi et al. divided cysts of the Sylvian fissure into three types depending on their size and ratio (CT with metrizamide) with normal CSF spaces:

- Type I: small cysts, biconvex or semicircular, freely communicating with adjacent cisterns.

- Type II: cysts of medium size, rectangular in shape, associated with the anterior and middle parts of the temporal fossa with a moderate mass effect; they communicate or not communicate with adjacent tanks.

- Type III: cysts are large, round or oval, occupying the middle cranial fossa almost completely, causing permanent and severe compression of adjacent nerve structures, with the resultant displacement of the ventricles and midline; connections with the subarachnoid space are absent or non-functional.

Lateral sulcus cysts can present clinically at any age, but become symptomatic more frequently in childhood and adolescence than in adulthood, and in most studies, infants and toddlers account for about 1/4 of cases.

The diagnosis is often made by chance. The symptoms that occur are often non-specific, with headache being the most common complaint. Among the focal symptoms in advanced cases, slight proptosis and contralateral paresis of the central type are possible. Seizures and signs of increased intracranial pressure represent the clinical onset in approximately 20-35% of patients. When signs of increased intracranial pressure appear acutely, they are usually the result of a sharp increase in cyst volume due to subdural or intracystic hemorrhage.

Psychiatric disorders are found in only 10% of cases, but developmental delay and behavioral disturbances are common in children with large cysts and are almost constant and severe in patients with bilateral cysts.

Local bulges of the skull and/or asymmetric macrocrania are characteristic features observed in half of the patients. CT in such cases reveals outward protrusion, thinning of the temporal scales and anterior displacement of the small and large wing of the sphenoid bone. Cysts appear as distinct masses between the dura mater and deformed brain with cerebrospinal fluid density and no contrast enhancement. The ventricles of the brain are usually of normal size or slightly dilated. MRI shows T1-hypointense and T2-hyperintense formations.

Vascular examination is useful to determine the relationship of arteries and veins to the cyst wall. In order to determine the presence or absence of a connection between the cyst and the subarachnoid space, flow cine sequence has recently been used, which can replace the performance of CT with metrizamide. This may be especially important in asymptomatic patients and in patients with non-specific clinical symptoms. In this regard, additional information that may indicate the need for surgery can be obtained by monitoring ICP. Perfusion MRI and SPECT are also used, the latter helping to assess cerebral perfusion around the cyst wall.

There are three options for surgical treatment, used alone or in combination:
- Marsupialization by craniotomy
- Endoscopic cyst removal
- Cyst shunting

Open removal of the cyst is considered the optimal surgical intervention. Success rates vary from 75 to 100%, and surgical mortality is almost zero. There are two issues to note regarding open surgery:
- Total removal of the arachnoid cyst is no longer considered appropriate, large holes in the cyst wall are sufficient to ensure the passage of cerebrospinal fluid through the cyst cavity and reduce the risk of damage to neighboring brain structures. Moreover, partial opening of the cyst can also prevent CSF leakage into the subdural space and the development of postoperative subdural hygromas.
- All vessels that cross the cyst cavity or lie on the cyst wall are normal and therefore should be preserved.

In recent years, endoscopic cyst removal has been proposed as an alternative to open surgery. Endoscopy is also used as an adjunct to open surgery to reduce the size of the surgical access. Positive results of endoscopic technique range from 45 to 100%.

Bypassing a cyst is clearly safer, but is accompanied by a high rate of additional surgical procedures (about 30%) and lifelong dependence on the bypass.

Examples of arachnoid cysts of the Sylvian fissure according to Galassi.

b) Sellar cysts. Sellar cysts are the second most common supratentorial localization among intracranial arachnoid cysts. Affected men are slightly more than women: a ratio of about 1.5/1. Cysts can be divided into two groups:
- Suprasellar cysts located above the diaphragm of the Turkish saddle.
- Intrasellar cysts located in the cavity of the Turkish saddle.

The latter are much less common and exclusively in children.

The term sella turcica cyst does not include empty sella syndrome, intrasellar and/or suprasellar arachnoid diverticula. Metrizamide CT or cine-MPT is helpful in the differential diagnosis, showing no contrast enhancement and no flow of cerebrospinal fluid within a true cyst.

Intrasellar arachnoid cysts are asymptomatic in about half of cases. Headache is the most common complaint in symptomatic patients, and endocrinological disturbances are often observed with this location of the cyst. Suprasellar cysts, on the contrary, are most often manifested by headache, visual disturbances and neuroendocrine symptoms are typical. Hydrocephalus, as a rule, appears when, due to the expansion of the cyst, the flow of cerebrospinal fluid from the holes of Monro and / or basal cisterns is obstructed. With large cysts, a posterior dislocation of the brain stem can develop with secondary compression of the Sylvian aqueduct, which can lead to expansion of the ventricles.

This process is relatively slow, for this reason, signs of intracranial hypertension (edema of the optic nerve head, atrophy of the optic nerve occur, although often, but relatively late.

Hypopituitarism is common, to a greater extent with a violation of the metabolism of growth hormone and ACTH. Menses may also be delayed. A rare but typical manifestation in cysts over the Turkish saddle is the “doll head” symptom, characterized by slow, rhythmic movements of the head in an anteroposterior direction.

In the pre- and neonatal period and in early childhood, echoencephalography is a useful diagnostic tool to follow the evolution of these lesions during the first months of life. If possible, an MRI should be performed to assess the multilevel connections between the cyst and the surrounding nerve structures and ventricles, which is necessary for planning surgical treatment. MRI (or contrast CT as an alternative) is also important for the differential diagnosis between arachnoid cysts located above the Turkish saddle and other possible cystic lesions of the sellar region (for example, Rathke's pouch cyst, cystic craniopharyngioma, epidermoid cyst, etc.).

The rapid development of endoscopic technologies has significantly changed the treatment of cysts of the sellar region. The endoscopic transnasal approach is ideal for intrasellar cysts, replacing the traditional microsurgical approach to these lesions. Cysts located above the Turkish saddle are treated only by opening the roof of the cyst (endoscopic transventricular vengriculocystostomy) compared with opening both the roof of the cyst and the bottom of the cyst (ventriculo-cisternostomy), the latter method is actually considered safer and, compared with ventriculo-cystostomy, is associated with a lower recurrence rate (5-10% versus 25-40%).

Shunt operations are practically not carried out. Although relatively safe, they are associated with a surprisingly high reoperation rate. Microsurgical excision, opening, or marsupialization are reserved for cases where endoscopic techniques are not possible or for patients with cysts extending beyond the ventricle (eg, suprasellar arachnoid cyst involving the medial temporal lobe).

It is important to remember that, regardless of surgical treatment, existing endocrinological disorders are resolved in rare cases, which requires adequate drug therapy. Visual signs and symptoms of intracranial hypertension resolve after surgery.

V) Cerebral convex cysts. They are relatively rare (4-15% of all intracranial arachnoid cysts), women suffer more often than men. We distinguish two main varieties of these cysts:
- Hemispherical cysts, huge accumulations of fluid extending over the entire or almost the entire surface of one hemisphere of the brain.
- Focal cysts are usually small formations associated with the cerebral surface of the hemispheres.

Hemispheric cysts are considered dilated lateral sulcus cysts, characterized by a compressed rather than enlarged lateral sulcus and no temporal lobe aplasia. They are most often found in children with macrocrania, a bulging anterior fontanel, and cranial asymmetry. CT and MRI in most cases allow a differential diagnosis with chronic fluid accumulation in the subdural space (subdural hygroma and hematoma).

Localized skull protrusion usually suggests the presence of a solitary cyst. Children generally have no neurological symptoms, while adults often present with focal neurological deficits and/or seizures. The differential diagnosis is with low-grade neuroglial tumors, usually by MRI.

The treatment of choice is microsurgical marsupialization. There is no need to remove the medial wall of the cyst, which is closely associated with the cerebral cortex. Shunt implantation is recommended only in cases of recurrence, although this method has also been suggested as the main procedure in children with hemispheric cysts due to the immaturity of the ability to absorb and because of the high risk of failed open surgery. In such cases, it is recommended to install a shunt with a programmable valve to effectively control the pressure inside the cyst and favor the development of natural CSF outflow pathways.

G) Interhemispheric cysts. Interhemispheric cysts are quite rare, accounting for 5-8% of intracranial arachnoid cysts in all age groups. There are two main types:
- Interhemispheric cysts associated with partial or complete agenesis of the corpus callosum
- Parasagittal cysts, not accompanied by defects in the formation of the corpus callosum

In a large percentage of cases, macrocrania is observed, and two-thirds of patients develop symptoms of intracranial hypertension. The localization of the bulging skull is the second most common manifestation. Hydrocephalus is mild or absent in patients with parasagittal cysts, but is relatively common in patients with interhemispheric cysts.

On MRI, interhemispheric cysts of the arachnoid are differentiated by a typically wedge-shaped appearance on coronal sections, sharply dividing the crescent on one side. Primary corpus callosum agenesis and type IC holoprosencephaly may have a similar appearance on MRI; however, an interhemispheric cyst of the occipital horns of the lateral ventricles can be easily differentiated as the occipital horns are displaced by the cyst and the basal ganglia are normally separated.

The method of choice is craniotomy with cyst removal. This allows you to normalize intracranial pressure. Due to the significant high complication rate, bypass procedures should only be considered as a second choice in difficult cases.

e) Cysts of the area of ​​the quadrigeminal plate. Cysts of the area of ​​the quadrigeminal plate make up 5-10% of all intracranial cysts of the arachnoid membrane. Most of them are diagnosed in children with a higher frequency in girls than boys.

Clinical manifestations depend on the direction of cyst growth. Most of these cysts develop upward into the posterior part of the interhemispheric fissure or downward into the fossa of the superior cerebellar vermis, in some cases with the possibility of supratentorial infratentorial expansion. Because of their proximity to the CSF pathways, they are usually diagnosed in childhood due to secondary obstructive hydrocephalus. Anomalies in pupillary response or eye movement due to compression of the quadrigeminal plate or stretching of the trochlear nerve may be determined; however, impairment of upward gaze is relatively rare. When growth is directed to the lateral side and into the cisterns, hydrocephalus is usually absent, but focal symptoms are determined.

Sagittal and coronal MRI views clearly show the association of the cyst with supratentorial and infratentorial structures and the ventricles.

As with cysts of the sella turcica, modern neuroendoscopic methods have significantly changed the tactics of treating such lesions, which were previously considered technically difficult. In the case of small formations (< 1 см), вызывающих вторичную тривентрикулярную гидроцефалию, вентрикулостомию третьего желудочка следует рассматривать как необходимое хирургическое лечение. При крупных образованиях должна быть выполнена вентрикулоцистостомия, по возможности в сочетании с вентрикулостомией третьего желудочка у пациентов с гидроцефалией. Хотя на момент написания в литературе описаны небольшие серии наблюдений, исследователи однозначно пришли к выводу, что эндоскопическое удаление кист области четверохолмной пластины является безопасным и успешным практически во всех случаях.

III. Subtentorial arachnoid cysts. The arachnoid cysts of the posterior cranial fossa are quite rare and account for about 15% of all intracranial cysts. They must be distinguished from other cystic malformations of the posterior cranial fossa, namely Dandy-Walker malformation and cystic evagination of the choroid plexus. The main differential features of these various pathological conditions are summarized in the table below.

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immaturity

Hello! Please tell me, my baby is diagnosed with immaturity of the brain for a month, here are the results of the ultrasound. strengthening, echogenicity of the brain parenchyma is not changed, the echostructure of the brain parenchyma is homogeneous, the echostructure of the thalamus is not changed, the Sylvian furrow is U-shaped with D and S, the depth of the anterior horns is right 2.6 mm, left 2.4 mm, the depth of the body is right 2.5 mm, left 2.4 mm, index of the anterior horns 26.5, width of the 3rd ventricle 2.2 mm, cavity of the transparent septum 5.3 mm, periventricular area: the structure is not changed, vascular plexuses: dimensions right-5.2 left- 5.2, the contour is clear, even, the structure is homogeneous! The neurologist said that the child has all the reflexes in the norm, he prescribed picamilon 0.02 1/4 2 times a day ...

immaturity

Hello! Please tell me, my baby is diagnosed with immaturity of the brain for a month, here are the results of the ultrasound. strengthening, echogenicity of the brain parenchyma is not changed, the echostructure of the brain parenchyma is homogeneous, the echostructure of the thalamus is not changed, the Sylvian furrow is U-shaped with D and S, the depth of the anterior horns is right 2.6 mm, left 2.4 mm, the depth of the body is right 2.5 mm, left 2.4 mm, index of the anterior horns 26.5, width of the 3rd ventricle 2.2 mm, cavity of the transparent septum 5.3 mm, periventricular area: the structure is not changed, vascular plexuses: dimensions right-5.2 left- 5.2, the contour is clear, even, the structure is homogeneous! The neurologist said that the child's reflexes are normal, he prescribed picamilon 0.02 1/4 2 times a day ...

What is an arachnoid cyst? How dangerous is it to human life? In the thickness of the membranes that cover the brain, a benign sphere is formed and filled with cerebrospinal fluid. This is an arachnoid cyst of the brain.

So it is called because of the dislocation of the sphere, since the accumulation of cerebrospinal fluid in it occurs between two sheets of a thickened arachnoid membrane. The brain has only three. The arachnoid is located between the other two - hard superficial and soft deep.

The Sylvian sulcus, the cerebellopontine angle or the area above the Turkish saddle and other areas become a frequent site of cyst dislocation. The development of the liquor sphere is more often observed in children, male adolescents.

In children, the arachnoid cyst of the brain is predominantly congenital and is formed in the embryonic stage during the formation of the central nervous system. It accounts for 1% of volumetric neoplasms inside the skull against the background of impaired cerebrospinal fluid circulation.

Spheres of small sizes may not appear during life. With the growth of the cyst after the formation begins, the flow of fluid through the brain is blocked and hydrocephalus develops. With a compression effect (pressure) on the cerebral cortex, clinical symptoms appear, hernias may form or sudden death occurs.

The code for the arachnoid cyst (AC) according to ICD-10 is G93.0.

According to the anatomical and topographic features, cysts of the cerebral hemispheres include:

• AC of the lateral (Sylvian) fissure;
• parasagittal (parallel plane) AC;
• convexital cerebral surface.

Mid-basal formations include cysts:

• arachnoid intrasellar and suprasellar;
• cisterns: enclosing and quadruple;
• retrocerebellar arachnoid;
• arachnoid cerebellopontine angle.

Cysts are formed differently, so they are divided into types. AKs are:

1. True or isolated.
2. Diverticular or communicating. Disturbed liquorodynamics at the end of embryo development leads to the formation of cysts.
3. Valved or communicating partially. This development is associated with productive changes in the arachnoid membrane.

They also use the generally accepted classification (according to E. Galassi - 1989) to separate the most common AK of the lateral fissure (LS);

• type 1 cysts of small size are bilateral with a location at the pole of the temporal lobe, do not appear. CT cisternography with contrast agent shows that the cysts communicate with the subarachnoid space;
• type 2 cysts are located in the proximal and middle parts of the LB, have an oval shape due to an incompletely closed contour. They partially communicate with the subarachnoid space as seen on helical contrast-enhanced computed tomography;
• type 3 cysts are large, and therefore are located throughout the Sylvian fissure. This significantly shifts the midline, raises the small wing, the scales of the temple bone, near the main bone. They minimally communicate with the CSF system, as shown by CT cisternography with contrast.

Arachnoid cyst of the brain is of two varieties:

• primary (congenital) due to the abnormal development of the meninges under the influence of drugs, radiation exposure, toxic agents and physical factors;
• secondary (acquired) due to various diseases: meningitis, agenesis of the corpus callosum. Or due to complications after trauma: bruises, concussions, mechanical damage to the hard surface shell, including surgery.

By composition, the cyst is divided into: simple, since it is formed from cerebrospinal fluid, and a complex sphere, consisting of cerebrospinal fluid and various types of tissues.

AK is formed on the head in the area:

• left or right temporal lobe;
• crown and forehead;
• cerebellum;
• spinal canal;
• posterior cranial fossa.

A perineural cyst is also found in the spine and in the lumbar region.

Symptoms

Asymptomatic small AKs are discovered incidentally during examination for another reason. The symptomatology becomes pronounced with growth and depending on the location of the cyst, from squeezing the tissues and the medulla. The manifestation of focal symptoms occurs against the background of the formation of a hygroma or with a rupture of the AK.

Adults with the progression of formations lose their orientation, sleep. They complain of uncomfortable conditions in which muscle tone is disturbed, limbs involuntarily twitch and go numb, and lameness occurs. Tinnitus, migraine, nausea with vomiting, often dizzy up to loss of consciousness. Also in patients:

• impaired hearing and vision;
• hallucinations and convulsions occur;
• the psyche is upset;
• "bursting" inside the head and a pulse is felt;
• pains under a skull amplify at movement of a head.

A secondary (acquired) cyst complements the clinical picture with manifestations of the underlying disease or injury.

This is the basis for a complete examination of the baby in the medical center.

Diagnostics

When establishing a diagnosis, clinical, neuroimaging and neurophysiological data are compared. The child should be examined by a neurologist, ophthalmologist, pediatrician, geneticist. Confirm the diagnosis with the following clinical manifestations:

• local changes: bone deformity of the cranial vault, especially in infants under one year old;
• symptoms indicating intracranial hypertension, in which the fontanel is tense, bone sutures diverge in children under one year old;
• lethargy, drowsiness, vomiting, headache, pyramidal symptoms;
• neuro-ophthalmic symptoms arising from mechanical compression of the interpeduncular and chiasmal cistern, compression of the optic nerves by the cyst of the lateral fissure;
• dysfunction of the oculomotor nerves, chiasmal syndrome, decreased vision, atrophy and congestion in the fundus;
• neuroimaging signs: one or more AKs with CSF that cause pathological symptoms are found.

In newborn babies and infants, a screening method (NSG - neurosonography) of the brain is used. Helical computed tomography (SCT) is also recommended. An MRI is mandatory, but if the data is doubtful, it is rechecked with a contrast agent and used for diagnosis by the CISS test and of heavily T2-weighted (heavily weighted T-2 images).

MRI examines the craniovertebral region to exclude concomitant anomalies: Arnold-Chiari, hydromyelia. The anesthesiologist examines patients, preparing for surgery and assessing the degree of risk of the operation. If the operational and anesthetic risk is large, then methods of preoperative management of patients are being prepared. Examinations by related specialists are carried out to determine concomitant diseases and their degree of development. At the same time, existing violations are corrected and patients are additionally examined:

• blood tests detect (or rule out) viruses, infections, autoimmune diseases. Coagulability and bad cholesterol are also determined;
• Doppler method is used to detect violations of the patency of the arteries, which leads to a lack of blood supply to the brain.

The work of the heart is checked and blood pressure is measured during the day.

Treatment

According to the dynamics of development, cysts are frozen and progressive. Treatment of frozen cysts is not carried out if they do not cause pain and do not manifest other uncomfortable symptoms. In these cases, the underlying diseases are identified and treated, which stimulate the development of AK.

To eliminate the inflammatory process, normalize blood flow to the brain, restore damaged cells, cope with medium-sized cysts, one should be treated, for example, with means for:

• resorption of adhesions: "Longidazom", "Karipatin";
• activation of metabolic processes in tissues: "Actovegin", "Gliatilin";
• increase immunity: "Viferon", "Timogen";
• getting rid of viruses: "Pyrogenal", "Amiksin".

Important. Treatment of an arachnoid cyst should be carried out only as prescribed by a doctor. It is impossible to exceed, reduce the dosage of drugs and cancel the treatment on your own, so as not to aggravate the inflammatory process and not provoke the growth of a cyst.

Surgical operations

The absolute indications for neurosurgical treatment of AK with CSF or hydrocephalus include:

• hypertension syndrome (increased intracranial pressure);
• growing neurological deficit.

Relative indications are:

• large asymptomatic AK, as it deforms adjacent lobes of the brain;
• AK LS with progressive growth and causing a violation of the circulation of cerebrospinal fluid due to deformation of its paths.

Important. It is contraindicated to carry out surgical treatment in a decompensated state of vital functions (unstable hemodynamics, respiration), coma III, extreme exhaustion (cachexia), with an active inflammatory process.

When applying surgical treatment, craniocerebral disproportion is eliminated. For this, liquor shunting, microsurgical, endoscopic operations are used. Intraoperative ultrasound, neuronavigation are prescribed to achieve the safety of manipulations.

To determine the tactics of the operation, the shape and size of the AK, the estimated accessible area, the trajectory of movement, and possible complications are taken into account, since the vascular-neural structures can be damaged during the operation, a hyperdrainage state may occur, an outpouring of blood and cerebrospinal fluid, infection can enter when the cyst ruptures. Conduct a histological examination of the contents of the cyst and its walls.

When prescribing CSF shunting operations, for example, cystoperitoneal shunting, the surgeon achieves the goal of draining the cyst in the cavity outside the brain with minimal damage. However, it is necessary to implant an artificial drainage system, which is considered a disadvantage of this treatment method. If the CSF circulation is impaired, which has a hypo- or aresorptive character, it is combined or provoked by giant AKs. Then CSF shunting operations are the main methods of treatment.

Microsurgical surgery is used to eliminate type 2 AK. In this case, a large craniotomy is not performed. It is performed only on the temporal bone close to the base, that is, in the area of ​​\u200b\u200bthe scales. In the presence of a convexital location - at its most protruding part. Ultrasound navigation is used to determine the area of ​​the craniotomy.

Endoscopic treatment is carried out in patients with symptoms of AK, especially LP types 2-3. Endoscopic surgery is possible only if the clinic has a complete set of rigid endoscopes with different viewing angles, illumination, digital video camera, saline irrigation system, bi- and monopolar coagulation.

Complications

CSF may leak after the operation, which is called liquorrhea. Necrosis of the edge of the skin flap and divergence of the wound after the operation are possible, therefore, a revision of the incision is prescribed. If resorption is disturbed, peritoneal shunting of the cyst is performed. Cysts and hydrocephalus of the brain are also corrected to ensure favorable treatment outcomes for patients, especially young children.

Surgical correction of hydrocephalus is carried out before removal of cysts in severe hydrocephalic-hypertensive syndrome: Evans index> 0.3, periventricular edema of the optic nerve, impaired consciousness and children under one year old.

After the operation, patients are under dispensary observation. In the presence of type 1 AK, children are monitored to watch for neurological and neuro-ophthalmic symptoms. At least once a year for 3 years, SCT / MRI (spiral and magnetic resonance computed tomography) is monitored. Patients are examined by neurosurgeons, neuropsychologists, neurologists, pediatricians, ophthalmologists, neurophysiologists.

Localization of the pathological focus with MRI of the brain begins to determine the location of the focus in relation to the cerebellum. Therefore, formations above the inlay are referred to as supratentorial, and everything below is referred to as infratentorial.

MRI of the brain. Median sagittal section. Cerebellar indentation (arrow).

Above the indentation are the hemispheres of the brain. Each hemisphere of the brain consists of four lobes - frontal, parietal, occipital and temporal. If the pathology is located in the hemisphere, then it is necessary to decide to which proportion it belongs. To do this, you first need to find the furrows that serve as the boundaries of the shares.
The central sulcus (sulc.centralis) is better seen in the sagittal plane. It is located in the middle between the precentral and postcentral furrows parallel to it. There are many options for the structure and course of the furrow. Usually it has a significant length and goes in the anterior-inferior direction from the interhemispheric fissure to the Sylvian fissure, which it does not always reach. The lower end of the furrow either continues in its main direction or bends back. The central sulcus may be interrupted along the way. In the transverse plane, on the upper sections, the furrow has the greatest extent, reaching almost to the interhemispheric fissure. The lower the cut, the shorter the central furrow on it. At the level of the lateral ventricles, it is barely visible. The central sulcus separates the frontal and parietal lobes.

MRI of the brain. Lateral sagittal section. Central sulcus (arrow).

MRI of the brain. Axial cut. Central sulcus (arrows).

MRI of the brain. Axial section at the level of the roof of the lateral ventricles. Central sulcus (arrows).

MRI of the brain. Borders of the frontal and parietal lobes in the axial plane.

Another important furrow is the Sylviian fissure (fissura cerebri lateralis). On sagittal sections, it goes from bottom to top in an anterior-posterior direction (Fig. 32). In the axial plane, the Sylvian fissure itself also deviates backward, while its branches are directed perpendicularly towards the interhemispheric fissure. The Sylviian fissure separates the frontal and parietal lobes from the temporal.

MRI of the brain. Lateral sagittal section. Sylvius fissure (arrows).

MRI of the brain. Axial section at the level of the third ventricle. Sylvius fissure (arrows).

MRI of the brain. Borders of the frontal, parietal, temporal and occipital lobes on the sagittal section.

To distinguish the parietal lobe, it is also necessary to find the parietal-occipital sulcus (sulc. parietooccipitalis). This groove in the sagittal plane can be traced on the median and medial sections. It goes down from the surface of the brain, has a significant length and is often segmented. In the transverse plane, the parietal-occipital sulcus departs almost perpendicular to the interhemispheric fissure (Fig. 36) and gives rise to many small branches. Thus, the borders of the parietal lobe serve with the frontal lobe - the central sulcus, with the occipital - the parietal-occipital sulcus, with the temporal - the Sylvius fissure and the superior temporal sulcus (angular gyrus).

MRI of the brain. Medial sagittal section. Parietal-occipital sulcus (arrow).

MRI of the brain. Axial cut. Parietal-occipital sulcus (arrow).

MRI of the brain. Borders of the parietal lobe on the medial sagittal section.

The next important dividing groove is collateral (sulc.collateralis). On sagittal sections, it is visible as the lower-lateral border of the parahippocampal gyrus, in the region of the temporal lobe pole (Fig. 38). It is easier to trace in the axial plane on sections at the level of the midbrain (Fig. 39). When the axial plane of the sections is tilted backward, it is visible simultaneously with the temporo-occipital sulcus. The temporo-occipital sulcus (sulc. temporooccipitalis) on the lateral sagittal sections goes sinuously backward along the border of the brain with the temporal bone and then bends upward (Fig. 40). On axial sections at the level of the Varolii bridge, it is located in the anterior-posterior direction. Thus, the boundary of the temporal lobe (Fig. 41) with the frontal and parietal lobes is the Sylvius fissure, with the occipital lobe - the temporo-occipital sulcus and the collateral sulcus.

MRI of the brain. Sagittal section. Collateral groove (arrow).

MRI of the brain. Axial cut. Collateral groove (arrows).

MRI of the brain. Axial section at the level of the pons Varolii. Temporoccipital sulcus (arrows).

MRI of the brain. Axial section at the level of the cerebral peduncles. The boundaries of the temporal lobe.

To determine the boundaries of the occipital lobe, we already have all the landmarks. The border with the parietal lobe is the medially located parietal-occipital sulcus, with the temporal lobe the border is the laterally located temporo-occipital sulcus.

MRI of the brain. Coronal cut. Borderline sulci (SPO - parietal-occipital sulcus, STO - temporal-occipital sulcus, SCol - collateral sulcus).

MRI of the brain. Borders of the occipital lobe on the medial sagittal section.

Usually localization by lobes is enough to describe hemispheric pathologies. In some cases, when binding to convolutions or functional zones is required, we recommend using the appropriate atlases (Kholin A.V., 2005).
With centrally (axially) located volumetric formations, the ventricles of the brain and the subcortical (basal) nuclei located around them may be involved. Visual hillock (thalamus), hypothalamus (hypothalamus), hypothalamus (subthalamus) and epithalamus (epithalamus) belong to the diencephalon (diencephalon), an integral part of the brain stem.

MRI of the brain. Axial cut. Lateral ventricles and subcortical nuclei (NC - caudate nucleus, NL - lenticular nucleus, Th - optic tubercle). Parts of the brain stem (lower part of the midbrain, pons and medulla oblongata) and the cerebellum are located infratentorially.

The mesencephalon only partly occupies the supratentorial space, a significant part of it passes through the opening in the tentorium into the posterior cranium. hole. The paired legs of the brain and the roof (tectum) at the back are always clearly visible. The roof of the midbrain lies posterior to the aqueduct and consists of a plate of the quadrigemina.

MRI of the brain. Median sagittal section. Brain stem (V3 - third ventricle, V4 - fourth ventricle, Q - quadrigemina plate, Mes - midbrain, P - pons, C - cerebellum, M - medulla oblongata).

The boundary between the midbrain and the pons is the superior sulcus, and with the medulla oblongata, the inferior sulcus of the pons. The bridge has a characteristic protruding forward part. The posterior surface of the pons is a continuation of the medulla oblongata. At the upper border of the bridge between its abdomen and the middle cerebellar peduncle, the trigeminal nerves (n. trigeminus, V pair) begin. They are clearly visible on transverse MR sections, as they run horizontally forward and are about 5 mm thick. The trigeminal nerve is divided into 3 branches - optic (1), maxillary (2) and mandibular (3). All of them go forward into the Meckel's cavity to the trigeminal ganglion. From here, the 3rd branch goes down through the foramen ovale, and the 1st and 2nd branches go through the cavernous sinus, along its lateral wall. Then, branch 1 enters the orbit through the upper hole, and branch 2 leaves the cranial cavity through a round hole.
III, IV and VI pairs of cranial nerves, which provide movement of the eyeball, are usually not visualized on MRI scans.

MRI of the brain. Axial cut. Trigeminal nerves (arrow).

The facial nerve (n. facialis, VII pair) and the vestibulocochlearis nerve (n. vestibulocochlearis, VIII pair) come out of their trunk together, the facial nerve is slightly medial, and go in one bundle, crossing the cerebellar cistern, and go into the internal auditory opening temporal bone. In the internal auditory canal, the vestibular branch runs in the posterior-superior and inferior quadrants, the cochlear branch in the inferior, and the facial nerve in the anterior-superior. The VII nerve enters the labyrinth (labyrinth segment), goes inside the temporal bone to the geniculate body, turns back and passes under the lateral semicircular canal (tympanic segment) and exits the temporal bone through the stylomastoid foramen (foramen stylomastoideum). Further, the nerve goes to the salivary gland, where it is divided into terminal branches. On MR tomograms in sections, 3-5 mm thick, nerves VII and VIII are not separated and are designated as the auditory nerve. Thinner sections can separately visualize the course of each of the nerves.

MRI of the brain. Axial cut. Auditory nerve.

From the lower border of the bridge begins the medulla oblongata. At the level of the foramen magnum, it passes into the spinal cord. Pairs of cranial nerves from IX to XII depart from it, of which the initial part of the hypoglossal nerve (n. hypoglossus, XII pair) is sometimes visible on transverse MRI and, in the form of a single complex, IX, X, XI pairs.
The fourth ventricle runs from the top of the aqueduct to the foramen of Magendie at the bottom. It is located between the brainstem in front and the velum and cerebellar peduncles in the back.
Posterior to the pons and medulla is the cerebellum. It is connected to the brainstem by the superior, middle and inferior cerebellar peduncles. The cerebellum consists of a medianly located worm and paired hemispheres.

MRI of the brain. Axial cut. Cerebellum (CV - cerebellar vermis, CH - cerebellar hemisphere).

MRI in St. Petersburg, carried out by us, always clearly indicates the localization of the focus in the conclusion, which is necessary to compare with the clinic and decide on the possibility and scope of the operation.

If you are looking for information on the topic "brain cyst" or the answer to the question "what is a cyst in the brain?", then this article is for you. A cyst in the brain, or rather, an arachnoid cerebrospinal fluid cyst, is a congenital formation that occurs during development as a result of splitting of the arachnoid (arachnoid) membrane of the brain. The cyst is filled with cerebrospinal fluid, a physiological fluid that bathes the brain and spinal cord. True congenital arachnoid cysts should be distinguished from cysts that appear after damage to the brain substance due to traumatic brain injury, infection, or surgery.

Arachnoid cyst ICD10 code G93.0 (cerebral cyst), Q04.6 (congenital cerebral cysts).

Classification of arachnoid cerebrospinal fluid cyst.

By location:

1. Arachnoid cyst of the Sylvian fissure 49% (the gap formed by the frontal and temporal lobes of the brain), sometimes called the arachnoid cyst of the temporal lobe.
2. Arachnoid cyst of the cerebellopontine angle 11%.
3. Arachnoid cyst of the craniovertebral junction 10% (junction between skull and spine).
4. Arachnoid cyst of the cerebellar vermis (retrocerebellar) 9%.
5. Arachnoid cyst sellar and parasellar 9%.
6. Arachnoid cyst of the interhemispheric fissure 5%.
7. Arachnoid cyst of the convexital surface of the cerebral hemispheres 4%.
8. Arachnoid cyst of the clivus area 3%.

Some retrocerebellar arachnoid cysts may mimic a Dandy-Walker anomaly, but there is no agenesis (a term meaning complete absence) of the cerebellar vermis and the cyst does not drain into the fourth ventricle of the brain.

Classification of arachnoid cysts of the Sylvian fissure.

Type 1 arachnoid cyst of the Sylvian fissure click on the picture to enlarge Type 2 arachnoid cyst of the Sylvian fissure click on the picture to enlarge Type 3 arachnoid cyst of the Sylvian fissure

Type 1: a small arachnoid cyst in the region of the pole of the temporal lobe, does not cause a mass effect, drains into the subarachnoid space.

2nd type: includes the proximal and middle sections of the Sylvian fissure, has an almost rectangular shape, partially drains into the subarachnoid space.

Type 3: includes the entire Sylvian fissure, with such a cyst, a bone protrusion is possible (external protrusion of the scales of the temporal bone), minimal drainage into the subarachnoid space, surgical treatment often does not lead to straightening of the brain (a transition to type 2 is possible).

Separate types of congenital arachnoid cysts.

It should be separately highlighted in this article such congenital cysts as a cyst of the transparent septum, a cyst of Verge and a cyst of the intermediate sail. It makes no sense to devote a separate article to each of the cysts, since you can’t write much about them.

Click on the picture to enlarge CT scan of the brain in the axial plane. The red arrow indicates a cyst of the transparent septum. By Hellerhoff [CC BY-SA 3.0 ], from Wikimedia Commons click image to enlarge MRI of the brain in the coronal plane. The red arrow indicates a cyst of the transparent septum. Author Hellerhoff [CC BY-SA 3.0 or GFDL], from Wikimedia Commons

A cyst of the transparent septum or a cavity of the transparent septum is a slit-like space between the sheets of the transparent septum, filled with fluid. It is a stage of normal development and does not last long after birth, so it is present in almost all premature babies. It is found in about 10% of adults and is a congenital asymptomatic developmental anomaly that does not require treatment. Sometimes it can communicate with the cavity of the third ventricle, so it is sometimes called the "fifth ventricle of the brain." The transparent septum belongs to the median structures of the brain and is located between the anterior horns of the lateral ventricles.

Verge's cyst or Verge's cavity is located immediately behind the cavity of the transparent septum and often communicates with it. Occurs very rarely.

The cyst or cavity of the intermediate sail is formed between the thalamus above the third ventricle as a result of the separation of the legs of the fornix, in other words, it is located in the midline structures of the brain above the third ventricle. It is present in 60% of children under 1 year of age and in 30% between 1 and 10 years of age. As a rule, it does not cause any changes in the clinical condition, however, a large cyst can lead to obstructive hydrocephalus. In most cases, no treatment is required.

Clinical signs of an arachnoid cyst.

Clinical manifestations of arachnoid cysts usually occur in early childhood. In adults, symptoms are much less common. They depend on the location of the arachnoid cyst. Often, cysts are asymptomatic, are an incidental finding during examination, and do not require treatment.

Typical clinical manifestations of an arachnoid cyst:

1. Cerebral symptoms due to increased intracranial pressure: headache, nausea, vomiting, drowsiness.
2. epileptic seizures.
3. Protrusion of the bones of the skull (it happens rarely, I have not personally encountered it yet).
4. Focal symptoms: monoparesis (weakness in the arm or leg), hemiparesis (weakness in the arm and leg on one side), sensitivity disorders according to mono- and hemitype, speech disorders in the form of sensory (lack of understanding of addressed speech), motor (inability to speak) or mixed (sensory-motor) aphasia, loss of visual fields, paresis of the cranial nerves.
5. Sudden deterioration, which may be accompanied by depression of consciousness up to coma:

• In connection with hemorrhage into the cyst;
• In connection with the rupture of the cyst.

Diagnosis of an arachnoid cyst.

Usually, neuroimaging is sufficient to diagnose an arachnoid cyst. These are computed tomography (CT) and magnetic resonance imaging (MRI).

Additional diagnostic methods are contrast studies of the CSF pathways, such as cisternography and ventriculography. They are required occasionally, for example, in the study of median suprasellar cysts and in lesions of the posterior cranial fossa for the purpose of differential diagnosis with Dandy-Walker anomaly.

Examination of the fundus by an ophthalmologist for hypertension syndrome (intracranial hypertension).

Electroencephalography (EEG) in case there was an epileptic seizure, to determine whether it was really caused by a cyst.

Treatment of an arachnoid cyst.

As I said above, most congenital arachnoid CSF cysts are asymptomatic and do not require any treatment. Sometimes a neurosurgeon may recommend dynamic monitoring of the size of the cyst, for which it will be necessary to periodically perform computed tomography or magnetic resonance imaging.

In rare cases, when an arachnoid cyst is accompanied by the above symptoms and has a mass effect, surgical treatment is resorted to.

In some cases, with a sharp deterioration, due to rupture of the arachnoid cyst or hemorrhage into it, surgical treatment is urgently resorted to.

There is no standard size for an arachnoid cyst. Indications for surgery are determined taking into account the location and symptoms of the arachnoid cyst, and not just its size. This can only be determined by a neurosurgeon during an internal examination.

Absolute indications for surgery:

1. intracranial hypertension syndrome due to arachnoid cyst or concomitant hydrocephalus;
2. development and progression of neurological deficits.

Relative indications for surgery:

1. large "asymptomatic arachnoid cysts" causing deformation of neighboring lobes of the brain;
2. progressive increase in cyst size;
3. cyst-induced deformation of the CSF pathways, leading to impaired CSF circulation.

Contraindications for surgery:

1. decompensated state of vital functions (unstable hemodynamics, breathing), terminal coma (coma III);
2. the presence of an active inflammatory process.

There are three possible options for the surgical treatment of arachnoid cysts. Your treating neurosurgeon chooses tactics, taking into account the size of the cyst, its location and your wishes. Not all arachnoid cysts are suitable for all three methods.

Evacuation of an arachnoid cyst through a burr hole in the skull using a navigation station. The advantage is the simplicity and speed of execution with minimal trauma to the patient. But there is a drawback - a high frequency of cyst recurrence.

An open operation, that is, a craniotomy (cutting out a bone flap on the skull, which fits into place at the end of the operation) with excision of the cyst walls and fenistration (drainage) of it into the basal cisterns (cerebrospinal fluid spaces at the base of the skull). This method has the advantage of being able to directly examine the cystic cavity, avoids a permanent shunt, and is more effective in treating multi-cavity arachnoid cysts.

Bypass surgery with the installation of a shunt from the cyst cavity into the abdominal cavity or superior vena cava near the right atrium through the common facial vein or internal jugular vein. Many foreign and domestic neurosurgeons consider shunting of an arachnoid cerebrospinal fluid cyst to be the best method of treatment, but it is not suitable in all cases. The advantage is low mortality and low recurrence rate of the cyst. The disadvantage is that the patient becomes dependent on the shunt, which is placed for life. If the shunt is blocked, it will need to be replaced.

Complications of the operation.

Early postoperative complications - liquorrhea, marginal necrosis of the skin flap with divergence of the surgical wound, meningitis and other infectious complications, hemorrhage into the cyst cavity.

Outcomes of treatment of an arachnoid cyst.

Even after a successful operation, part of the cyst may remain, the brain may not fully expand, and the midline structures of the brain may remain displaced. It is also possible to develop hydrocephalus. As for focal neurological symptoms in the form of paresis and other things, the longer it exists, the less likely it is to recover.

Literature:

1. Neurosurgery / Mark S. Greenberg; per. from English. - M.: MEDpress-inform, 2010. - 1008 p.: ill.
2. Practical Neurosurgery: A Guide for Physicians / Ed. B.V. Gaidar. - St. Petersburg: Hippocrates, 2002. - 648 p.
3. Neurosurgery / Ed. HE. Dreval. - T. 1. - M., 2012. - 592 p. (Manual for doctors). - T. 2. - 2013. - 864 p.
4. Ivakina N.I., Rostotskaya V.I., Ozerova V.I. et al. Classification of intracranial arachnoid cysts in children // Topical issues of military medicine. Alma-Ata, 1994. Part 1.
5. Mukhametzhanov X., Ivakina NI Congenital intracranial arachnoid cysts in children. Almaty: Gylym, 1995.
6. K.A. Samochernykh, V.A. Khachatryan, A.V. Kim, I.V. Ivanov Features of surgical tactics for large arachnoid cysts. \\ Scientific and practical journal "Creative Surgery and Oncology" Academy of Sciences of the Republic of Belarus Media Group "Health", Ufa, 2009
7. Huang Q, Wang D, Guo Y, Zhou X, Wang X, Li X. The diagnosis and neuroendoscopic treatment of noncommunicating intracranial arachnoid cysts. Surg Neurol 2007

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