Clinical Features.—The presence of a swelling in the middle line of the back, which has existed since birth, and which contains fluid and increases in size and tenseness when the child cries, renders the diagnosis of spina bifida easy. The defect in the bone may be seen in skiagrams. The swelling is usually sessile, but may be pedunculated; it is usually possible to palpate the edges of the gap in the bones. It may be reduced in size by making gentle pressure over it, and in young children this may cause a bulging of the fontanelles. This test, however, must be employed with caution, as it is liable to induce convulsions. A meningocele, as it contains no nerve elements, may be translucent. In a meningo-myelocele the shadows of the cord and nerves stretched out in the sac may be recognised. The presence of the cord is sometimes indicated by a median furrow, and after withdrawal of some of the fluid the cord can sometimes be palpated. It is, however, often difficult to distinguish between a meningocele and meningo-myelocele.
Fig. 221.—Meningo-myelocele in Thoracic Region.
Sometimes there are no nervous disturbances, and this is especially the case when the defect is in the lower lumbar and sacral regions below the termination of the cord. In most cases, however, there are paralytic symptoms referable to the lower extremities, the bladder, and the rectum, and there may also be trophic disturbances in the parts below. Paralytic symptoms may be absent during infancy, and develop during childhood or adolescence.
Prognosis.—Comparatively few children born with spina bifida survive longer than four or five years. The great majority die within a few weeks of birth, death being due to the escape of cerebro-spinal fluid, or to spinal meningitis following on infection. The condition in some cases remains stationary for years, but spontaneous disappearance is rare.
Treatment.—The more severe forms of spina bifida only call for palliative treatment, which consists in protecting the protrusion against infection and applying a sterilised dressing and a supporting bandage. A meningocele may be tapped with a fine needle passed through healthy skin, and the empty sac compressed by a pad of wool and an elastic bandage.
Operative treatment is seldom to be recommended in a young child unless it is otherwise viable and the swelling is increasing rapidly and threatening to burst, and there is reason to believe that the paralysis is due to pressure. The immediate results of operation are usually satisfactory, but in a large proportion of cases the child subsequently develops hydrocephalus, from which it ultimately succumbs. The hope of improvement in the motor symptoms after operation depends on the site of the spina bifida; above the twelfth thoracic vertebra there is no prospect of improvement; below this level, inasmuch as it is the tip of the conus or the cauda equina that is involved, there may be regeneration of nerve fibres and return of power in the lower extremities, and control of the sphincters may be regained. Murphy has practised resection of cicatricial or atrophied portions of the cauda, with end-to-end suture.
The term spina bifida occulta is applied to a condition in which there is no protrusion of the contents of the vertebral canal, although the vertebral arches are deficient. The skin over the gap is often puckered and adherent, and is frequently covered with a growth of coarse hair.
A mass of fat may project towards the surface, and when situated in the lumbo-sacral region may suggest a caudal appendage or tail ([Fig. 222]).