I. Overview
Myelomeningoeele (MMC) is a congenital malformation of the central nervous system in which the spinal cord, together with its surface-covered spinal bursa, bulges outward from a congenital lamina defect (congenital manifest spina bifida). The neck of the capsule is usually wide, and the capsule is lined with dura mater, or part of the spinal nerve roots may protrude into the capsule and attach to the wall, and the capsule may be filled with cerebrospinal fluid.
Epidemiology
The prevalence in China is about 0.1%-1.0%. In recent years, vitamin and folic acid supplementation for pregnant women has significantly reduced the incidence of neural tube malformation, but still accounts for 1/4 of the incidence of neonatal defects, of which spina bifida is common, and a few can be combined with spinal cord spinal membrane bulge.
Third, the onset of the site
The spinal cord can be located in any part of the spinal axis, but the sacrococcygeal region is more common, followed by the neck, other parts are less common.
Fourth, the etiology
It is mainly caused by impaired development of the mesoderm during the embryonic neural tube closure, which is manifested by incomplete closure of the spinal canal combined with the corresponding parts of the spinal cord and dural sac-like protrusion.
V. Clinical manifestations
Localized masses can be found at birth as cystic masses in the midline of the back in the cervical, thoracic, or lumbosacral regions, varying in size, round or oval; most have a wide base and normal skin on the surface, but can also be scar-like and thin, with cerebrospinal fluid flowing out if they rupture. The mass may increase in size when the infant cries, and when the mass is compressed, the fontanelle bulges, and the transillumination test is positive, and the shadow within the mass is sometimes visible when the spinal cord and nerve roots are included.
Neurological damage symptoms spinal cord spinal cord bulge and spinal cord terminal developmental malformations, degeneration, spinal cord cavity formation has varying degrees of bilateral lower limb paraplegia and urinary and fecal incontinence, to the lumbosacral lesions of neurological damage is heavy; spinal cord spinal cord bulge itself can form spinal cord embolism, with age, height increase can also aggravate the condition; spinal cord exposed neurological manifestations are more serious.
Meningitis bulge of the dural bursa rupture easily lead to meningitis, with skin sinus tract of occult spina bifida can also cause recurrent episodes of meningitis.
Other symptoms protruding from the chest, abdomen, and pelvis can produce masses and visceral compression symptoms; those with hydrocephalus or other malformations can have corresponding symptoms.
VI. Diagnosis
A cystic, distended mass in the middle of the back appears after birth, with a positive transillumination test, enlarging with age and a corresponding neurological deficit.
Spinal radiographs show incomplete closure of the vertebral plates and soft tissue shadow masses at the site of the lesion, with enlarged intervertebral foramina seen in those that bulge into the thoracoabdominal cavity and a significantly enlarged sacral canal in those that protrude into the pelvis.
CT cross-sectional views show abnormalities of the spinal canal and bulging dura mater, manifesting as a circular or oval shape (dura mater) with a clear posterior border of the spinal canal, the same density as the cerebrospinal fluid, and a thin peripheral layer above the cerebrospinal fluid, which may also protrude into the pelvic cavity or into the mediastinum anteriorly or laterally.
MRI sagittal and cross-sectional T1WI can show the extent and contents of the spinal bulge, and T2WI shows cerebrospinal fluid high signal and spinal cord low signal.
VII. Treatment
Most advocate early surgery to repair the spinal membrane bulge, combined with hydrocephalus need to first ventriculo-abdominal shunt and then do spinal membrane bulge resection and repair; the cyst wall has broken or its thin need for emergency or early surgery; other children are generally 1 to 3 months after birth surgery is appropriate.