Developmental anomalies

  The commonest problem to affect the spinal column is failure of the neural tube to close fully, producing one of many patterns of neurospinal dysraphism or spina bifida.

Spina bifida aperta. The neural tube is open with no skin coverage, through a defect in the posterior vertebral arch. CSF leakage usually occurs with an associated risk of infection (see Fig. 33.25).

Spina bifida cystica. In this situation there is skin covering the defect which may contain just CSF, so forming a meningocele, or may have neural tissue within the sac, a myelomeningocele.

Spina bifida occulta. The posterior vertebral arch has a defect within it, but there is no herniation of the neural tube. This defect may be found within 10 per cent of the population. On the skin over the defect various skin changes may be seen, for example a hairy patch (see Fig. 33.26), an area of pigmentation, a fatty lump or dermal sinus. There may also be associated intradural lesions, ‘Including lipomas, dermoids, epidermoid tumours and tethering of the cord with thickening of the filum terminale.

Management

Any discussion regarding the treatment of children with this condition should include inheritance. Whilst the majority (90 per cent) of cases occurs sporadically, with an incidence rang­ing from one to eight per 1000 of the population, children of parents with spina bifida have a 5 per cent risk of having the condition as well.

Prenatal screening to detect alpha-fetoprotein in blood or amniotic fluid, obtained by amniocentesis, together with the use of ultrasound allows the detection of such defects in over 80 per cent with an open neural tube.

Problems of development tend to occur in the lumbo-sacral area and are especially associated with changes in bladder and bowel function. These changes may not become apparent for the first few years of life and can be associated with a totally normal neurological examination.

The higher the lesion the more severe the defect and the worse the neurological condition. In severe cases it can be associated with a complete failure of development of the legs with a complete paraplegia and loss of bladder and bowel function.

If the lesion is open then there are attendant risks of meningitis as well.

Other associated disorders include Arnold—Chiari malformations and, in up to 80 per cent, hydrocephalus.

Investigations

The investigations include:

  complete neurological examination;

head circumference measurements;

  plain X-rays of the spine (see Fig. 33.27);

MRI scan of brain and whole spine.

Treatment

For the majority of cases of open dysraphism, closure should be carried out as soon as possible with treatment of the hydrocephalus. Often this is the first of many procedures best provided by a team of surgeons, paediatricians, therapists and nurses.

As regards the patients with closed lesions at birth, they may require surgery at a later stage should progressive neurological signs develop. It should be noted, however, that any procedure may be associated with neurological deterioration.