What Is a Meningocele?

Meningeal Herniation (Meningeal Herniation), also known as meningocele or meningeal hernia, refers to the bulging of brain tissue with its covered dura through the skull defect area outside the skull. Generally occurs in the occipital, top, forehead, nose, orbit, and skull base areas. The mild ones have no obvious symptoms of the nervous system. The severe cases (especially those with ventricle-encephalocele) may appear with the location and Neurological dysfunction manifestations such as decreased intelligence, epilepsy, and paralysis associated with the degree of impairment.

Basic Information

nickname

Brain swelling, meningeal hernia

English name

Meningeal Herniation

Visiting department

neurosurgery

Common locations

Skull occipital, top, forehead, nose, orbit, skull base

Common causes

Congenital abnormalities, affected by trauma, infection, metabolic disorders, etc. of pregnant women in the first few weeks of pregnancy

Common symptoms

Round or oval cystic mass; mental retardation, convulsions, and paralysis; facial deformity, cleft lip and palate, multi-finger deformity, congenital heart disease, perforation of the brain, spina bifida, etc.

Causes of meningocele

Meningoencephalocele is a congenital developmental abnormality, which is generally believed to be related to embryonic neural tube dysplasia and cessation of mesoderm development, and may be affected by trauma, infection, and metabolic disorders in pregnant women in the first few weeks of pregnancy.

Clinical manifestations of meningocele

1. sex, age

The ratio of male to female is 2: 1, which is usually found from birth and grows up with age.

Local symptoms

Generally, it is a round or oval cystic mass, and those located at the root of the nose are mostly flat masses of different sizes. The thickness of the covered soft tissue varies widely, and the base can be a fine pedicle or a wide base. The edge of the bone defect can be touched. The cystic mass is soft and elastic. The touch pressure can be fluctuated and the intracranial pressure can be increased. When crying, you can see that the mass increases and the tension increases. The light transmission test is positive, and sometimes the swollen brain tissue can be seen.

3. Nervous system symptoms

The milder ones have no obvious symptoms of the nervous system, while the severe ones have mental retardation, convulsions and paralysis of varying degrees, hypertenoid reflexes, and unstable pathological reflexes. Occurrence of olfactory sensation in one or both sides of the nasal root; , , , , cerebral nerve involvement in patients with bulges and protrusions in the orbit; cortical visual impairment and cerebellar involvement in occipital patients Damage performance.

4. Compression of adjacent organs

Those who are located at the root of the nose often cause facial deformities, flattened roots of the nose, increased eye distance, smaller orbital cavity, shifted eyes, lacrimal gland caused by compression of the lacrimal gland; those who penetrate the nasal cavity can affect breathing; those who bulge into the orbit can Eyeball protrusion and displacement, orbital enlargement; other parts can cause changes in the shape of the skull, but also local hair abnormalities.

5.Common associated malformations

Cleft lip, palate, multi-finger deformity, congenital heart disease, perforation of the brain, spina bifida, deformed foot, hydrocephalus, latent hair sinus and ears, ribs, spine, external genitalia and other deformities.

Meningocele

Head CT

Can show the location of bone defects, the size of the hernia, and the size, extent, and intracranial traffic of the soft tissue mass in the hernia. Meningoencephalocele shows soft tissue density in the cystic mass protruding from the bone defect, and the ventricle is deformed by being stretched; skull defect sites are mostly round or spindle-shaped, with smooth edges and compressive changes with expansion, and the edges are outward Tilt up, bone sclerosis can be seen around.

2. Head CT enhanced scan

Can show meningoencephalic herniated brain tissue is strengthened to the same degree as normal brain tissue.

3. Head MRI (magnetic resonance imaging)

The bulge is brain tissue, showing T ₂ and other T ₂ signals; those with deformed and displaced ventricles and hernias can be diagnosed as ventricular-cerebral bulges.

4. Plain skull

Only the size and extent of craniotomy can be understood.

Meningocele diagnosis

1. Diagnosis can be made based on medical history, clinical manifestations, and location, nature, appearance, and positive light transmission test of the mass. Generally manifested as limited soft tissue masses at the occipital, forehead, or root of the nose at birth, obvious when crying, tension, pulsation, and positive light transmission tests.

2. Judgment of the nature of the bulging tissue and whether it is combined with other complicated brain developmental abnormalities still need CT and MRI.

Differential diagnosis of meningocele

Meningocele needs to be distinguished from the following diseases:

1. Meningocele

The bulged cyst contains no brain tissue and only cerebrospinal fluid. CT examination was a cystic mass with cerebrospinal fluid density, and enhancement showed no change in mass density; on MRI, the cyst showed low T ₁ and high T ₂ signals consistent with cerebrospinal fluid, without enhancement.

2. Frontal and ethmoid sinus cysts

More common in adults, CT shows that the cyst is confined to the sinuses, the sinus wall is intact, and there is no communication with the skull.

3 Dermatoid, epidermoid cyst or teratoma

No pulsation, no change in volume, no defects or cracks in the skull.

4 Nasal polyps

Infants and young children are rare, can be reduced with vasoconstrictors, CT shows round soft tissue shadows in the nasal cavity or sinus cavity, MRI shows T ₁ high T ₂ signals, and no communication with the skull.

Meningocele treatment

Treatment method

Surgical resection is the main treatment method. Except for those with huge meningoencephalocele or meningoventricular complication with severe neurological damage, mental retardation and obvious hydrocephalus, they should be treated surgically.

2. Purpose of surgery

Close the skull defect, remove the bulging sac, and also contain the bulging brain tissue to prevent further neurological dysfunction.

3. Timing of surgery

Surgery as soon as possible, surgery can be performed within weeks to days after birth: meningoencephalocele can be operated 24 hours after birth; patients with cystic wall infection and cerebrospinal fluid leakage should actively control the infection, and perform surgery after the wound is cleaned or close to healing ; Emergency diagnosis and surgery for patients with thin or ruptured wall; Meninges, brains, and ventricles can be re-operated 2 to 3 months after birth; nasal meninges and cerebral bulges are larger than the bone defect diameter of eggs or other parts> For 2cm, surgery should be performed 6 months after birth.

4. Surgery method

(1) Occipital, apical, and temporal bulges and individual smaller nasal root bone defects: Extracranial methods are available. For the skull base nasal roots, nasopharyngeal or nasal orbital bulge, intracranial methods are used to bulge Repair can use the epidural or intradural approach.

(2) Meningocele repair at the occipital and top parts: straight incisions or spindle incisions can be taken, and the resection range is moderate to avoid excessive suture tension. The incisions reach the capsule wall, separate the capsule neck and the hole, cut the capsule wall, and accept the brain. Tissue, purse suture, and skull defects are not necessary to repair.

(3) Forehead cystic craniotomy: Intracoronary incisions are generally used, and those with a skull defect diameter> 2cm can be repaired with silicone rubber or titanium mesh.

(4) Meningocele repair at the root of the nose, orbit, and nasopharynx: two-stage surgery: double-frontal coronal craniotomy is performed in the first stage, the dura mater and the capsule neck are opened, and the brain tissue inside the capsule is separated and held. Part of the brain tissue needs to be removed and the dura mater reinforced and repaired; the second operation is mainly plastic surgery, which removes the excess cystic wall atrophy of the nasal root and reshapes it; patients with hydrocephalus can use ventriculoperitoneal shunt surgery.

5. Surgical complications

Wound infections, hydrocephalus, skin necrosis during surgery, and cerebrospinal fluid leakage in the wound.

Prognosis of meningocele

The prognosis of meningoencephalocele depends mainly on the extent of the disease: surgery for patients with meningocele alone can reduce mortality, reduce the incidence of hydrocephalus, reduce and relieve symptoms of neurological damage; meningoventricular bulges are usually associated with nerves Dysfunction, mental retardation and deformity in other parts, the prognosis is poor. Surgery cannot resolve other deformities and improve intelligence.