e spinal cord. The commonest cause
is haemorrhage occurring during child-birth from the veins which ascend
from the middle part of the convexity of the hemisphere to open into
the superior sagittal (superior longitudinal) sinus. The blood is
poured out beneath the dura on one or on both sides of the falx
cerebri, and as it accumulates near the vertex, the damage to the
motor centres for the legs is usually more extensive than that to the
centres for the arms. The paralysis may affect one side of the
body--_hemiplegia_, or both sides--_diplegia_; less commonly one
extremity alone is involved--_monoplegia_. In diplegia, in which both
arms and both legs are affected in the first instance, the arms may
recover while the lower extremities remain in a spastic state, a
condition known as _Little's disease_. The mental functions may be
normal but more frequently they are imperfectly developed, the
impairment in some cases amounting to idiocy. The affected limbs
exhibit muscular rigidity or spasm, which is aggravated on movement
but disappears under an anaesthetic; the reflexes are exaggerated, and
sometimes there are perverted involuntary movements (_athetosis_). The
growth of the limb is impaired, and contracture deformities may
supervene (Fig. 131). The amount of power in the limb is often
astonishing, in marked contrast to what is observed to follow upon
anterior poliomyelitis. The degree of natural improvement is by no
means great, and normal function is almost never regained.

The _treatment_ is concerned in the first place with improving the
condition of the muscles by methodical exercises and massage. When
reflex irritability of the muscles with consequent spasm is a
prominent feature, the reflex arc may be interrupted by _resection of
the posterior nerve roots_ corresponding to the part affected. This
operation, first suggested by Spiller but chiefly popularised by
Foerster, has yielded the best results in cases of Little's disease,
in which there still remains a considerable amount of voluntary
movement, and yet there is inability to walk on account of involuntary
spasm. In the case of the lower extremities, three or more of the
lumbar and one or more of the sacral nerve roots are resected within
the vertebral canal. Sensation is diminished but not abolished in the
area of skin involved. Massage and exercises and, it may be, splints
or apparatus are essential factors in promoting the recovery of
function. It has not y