Spina bifida, meningocele, and myelomeningocele

Congenital abnormalities of the spinal cord and vertebral column are not uncommon. You may see:

Spina bifida alone, in which the arches of a child's vertebrae remain open, usually in his lumbar region. He often has a Mongolian spot over the defect (this is less easily seen in a dark skin, but it is there if you look for it), and/or some extra hair and fatty tissue. Uncomplicated spina bifida is usually symptomless, but watch him carefully. If his legs become weak, refer him: he may have a bifid spinal cord separated by a bony spur (diastematomyelia, rare).

A meningocele is a CSF-filled extension of his spinal canal, without any spinal cord or spinal nerves in it; commonly in his lumbar region, and usually associated with spina bifida. His cord is normal and he has no neurological abnormality. It is a relatively simple procedure to obliterate the sac, close his spinal membranes at the level of his laminae, and then to close his skin. This is a closed lesion, so there is no hurry.

A myelomeningocele is more common than a simple meningocele, and takes two forms: (1) He may have a closed swelling containing spinal cord and/or spinal nerves. (2) More often, his spinal canal is open and leaks CSF, with his flattened cord forming a plaque on its surface. Both varieties may occur in the cervical (rare), thoracolumbar, lumbar, or lumbosacral regions, and other abnormalities are frequent, particularly hydrocephalus. Most children have irreversible paralysis of their legs, and loss of sphincter control, so that surgery merely prolongs their misery, and that of their parents. You may however be justified in operating on sacral myelomeningoceles, as described below.

Fig. 28-10 MENINGOCELES. A, a skin-covered sacrolumbar meningocele. If you cannot refer a child like this, you may be justified in operating on him. B, a cervical meningocele. Don't operate on this child.

MENINGOCELE DIAGNOSIS. If the swelling on the child's back is covered by skin, his legs are not weak, his anus is not lax, and he micturates normally, he probably has a simple meningocele. Otherwise, you cannot tell a meningocele from a myelomeningocele from its site, or its covering. Transilluminate it; you may occasionally see nerves outlined inside it.

If he has any neurological signs, he certainly has a myelomeningocele. These signs are: (1) No movement in his legs. (2) An absent or meagre response to tickling or pin-prick. (3) A lax anal sphincter which does not contract on digital examination. (4) Observe the way he passes urine; he may pass it as a jet at specific times (normal), or it may leak out from time to time (abnormal).

Look for other anomalies, particularly talipes (27.15). Measure the circumference of his head, now and later; he may develop hydrocephalus.

MANAGEMENT [s7]OF MENINGOCELES If his meningocele is covered with normal skin (usual), surgery is not urgent. Operate when convenient, normally at about 6 months.

If his meningocele is not covered by skin (unusual), surgery is urgent, because it is easily damaged, and may become infected. If he is fortunate and well cared for, it may epithelialize.

If the mass is in his cervical or thoracic regions, it is more likely to be a simple meningocele, so try to refer him. Don't try to operate on lesions in these sites yourself.

If: (1) the central canal of his spinal canal is open to the surface, or (2) he has a myelomeningocele with neurological signs (commonly in the thoracolumbar or lumbar regions), there is nothing to be done, except compassionate palliation.

If he has a sacral myelomeningocele, with normal power in his legs (normal sphincter control is unusual), urgent operation may be justified[md]see below.

CLOSING A MENINGOCELE If you cannot refer him, proceed as follows. Take the strictest aseptic precautions and be careful not to damage his cord.

INDICATIONS. A fairly small sacral or lumbar meningocele, with no neurological signs, no hydrocephalus, and no other congenital abnormalities.

CONTRAINDICATIONS. (1) Complete or virtually complete denervation below the level of the lesion. (2) Progressive hydrocephalus. (3) A very large lesion, in which you will have difficulty closing the skin and subcutaneous tissues without tension. (4) Lesions in sites other than the lumbar or sacral region.

ANAESTHESIA. (1) General anaesthesia, with precautions, particularly tracheal intubation, for the prone position (A 16.12). (2) Ketamine (A 8.5). If you use ketamine without intubating him, lie him semiprone (which will make surgery more difficult), when his breathing should be satisfactory.

PREPARATION. Lay him prone with the head of the table depressed at least 30[de], to minimize the loss of CSF when you incise the sac. Prepare and drape a wide operative field.

Clean the sac meticulously and aspirate it slowly with a 0.8 mm needle until it collapses.

If the swelling is covered by skin, make a longitudinal elliptical incision, through normal skin at the base of the swelling. Cut through the subcutaneous tissue to the deep fascia, and define the neck of the sac by blunt dissection. The defect in the fascia will usually be quite small, and easy to expose. Free all surfaces of the sac, and open it over its dome.

If there are no nerve filaments, amputate the sac at its base, and close it with continuous 4/0 or 5/0 catgut.

If you find nerve filaments, he is not a case of simple meningocele, and his prognosis is poor. Preserve the nerve filaments with the greatest care, try to free them from the sac, close it, and try to cover every filament.

Complete the repair by overlapping his deep fascia and closing his skin.

If you have difficulty closing his skin: (1) Raise flaps by undermining extensively, and making lateral relaxing incisions if necessary. Or, (2) use double pedicle advancement flaps (57-19), with split skin grafts to cover the raw areas. Seal the wound meticulously, and nurse him in the prone position.

SACRAL MYELOMENINGOCELE This is the child with a sacral myelomeningocele and normal power in his legs, as described above.

Dissect the sac from his cauda equina, being careful not to damage it. Close his dura with continuous 4/0 catgut. Raise flaps of skin and subcutaneous tissue by undercutting with scissors, making lateral relaxing incisions if necessary. Close his skin with 4/0 monofilament, apply a dressing, and nurse him as above.

Fig. 28-11 CONGENITAL VASCULAR ANOMALIES. A, a cavernous haemangioma. B, a port-wine stain. C, a capillary cavernous haemangioma of the hand. D, a capillary haemangioma of the face. E, and F, cystic hygromas. A, D, and E, after Charles Bowesman, ''Surgery and Clinical Pathology in the Tropics'. E and S Livingstone, permission requested.