#Cerebral Palsies of Childhood--Spastic Paralysis.#--These may be due to arrest of development of the brain, to injuries of the head at birth, to meningeal hæmorrhage, or to other lesions of the brain, with secondary degenerative changes in the spinal cord. The commonest cause is hæmorrhage 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 anæsthetic; 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 yet been decided whether the results of the resection of nerve roots justify the risk.