Synonym.—Dropsy of the Brain.
Definition.—An accumulation of fluid within the ventricles or subarachnoid spaces of the brain.
Etiology.—Hydrocephalus may be either congenital or acquired. Although heredity has been assigned as influencing the congenital form, several children in a family being- affected, the true cause is unknown. The acquired form may result from some impairment of the circulation in the straight sinus, from brain tumor, or from meningitis.
In the congenital form, the enlargement may be so marked as to render labor extremely difficult, and sometimes necessitate craniotomy.
Pathology.—In the congenital form, the head is noticed to be unusually large at birth, or very soon develops after coming into the world. The fontanels are bulging and the sutures separated. On opening the skull, the bones are found to be thin, the dura usually unchanged, though it may be thickened, while the brain-substance is slightly softened. The ventricles, especially the lateral, may be enormously distended, while the third and fourth show less disturbance.
The ependyma may be thickened and slightly roughened, or it may remain unchanged. Where the child survives a few years, the sutures are closed by Wormian bones. Sometimes the head reaches an enormous size.
In the acquired form, the head does not show such marked enlargement, and the ventricles are but moderately distended. The brain shows some softening.
Symptoms.—In congenital hydrocephalus the most striking feature is the large head, with sutures separated and fontanels open and bulging. As the head enlarges, the face appears unusually small, and the eyes, owing to the pressure, are peculiarly prominent. The child is unable to walk, and is soon unable even to sit up and support the great weight of the head. The child lies upon its back with the limbs flexed. Convulsions are quite common. The intellect is generally impaired, or slow in development. In rare cases the intellect is well preserved. The child is generally listless and dull. Nutrition is more or less disturbed, and the puny body bears a striking contrast to the enormously developed head. Fortunately these children do not often survive childhood, though a rare case reaches maturity.
In the acquired form, there may be headache, dimness of the sight, progressive optic neuritis, and irregular gait.
Diagnosis.—There is generally no difficulty in diagnosing a case of congenital hydrocephalus. The picture is so characteristic that it is difficult to make a mistake. In the acquired form the symptoms may be obscured and the diagnosis rendered more difficult.
Prognosis.—A child rarely lives much beyond the fifth year, though he may survive till adult years are reached.
Treatment.—Medication offers but little encouragement in hydrocephalus, and operative measures have not brought brilliant results and are always attended by considerable danger.