is skin,
as well as the vertebral arches and membranes, is absent, and the cord
lies exposed on the surface. This form is comparatively common, but as
the infants are either dead born or die within a few days of birth, it
seldom comes under the notice of the surgeon.

_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.

[Illustration: 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
he