hydrocephalus Derived from the Greek for ‘water’ and ‘head’, hydrocephalus was recognized by Greek and Roman philosophers, including Hippocrates and Galen. Arabic medical scholars, like Albucasis, preserved and built upon the knowledge of the ancients, combining it with Arabic surgical expertise. One of the earliest illustrations of the condition, and a method of treating it, which involved opening the head and evacuating fluid, appeared in the fifteenth-century surgical manuscript by Sharaf ad Din. Nearly 200 years later, the Italian surgeon Marco Aurelio Severino depicted and described a case of infantile hydrocephalus in
De Recondita Abscessuum Natura Libri VII (Seven Books on the Obscure Nature of Abscesses).
Hydrocephalus is sometimes called ‘water on the brain’, but the excess of fluid is in fact ‘in’ rather than ‘on’. There is normally
cerebrospinal fluid filling the
cerebral ventricles — the cavities deep inside the brain — and hydrocephalus describes an increase in its volume, and therefore of the size of the ventricles. Cerebrospinal fluid (CSF) is continually produced by transfer of a watery solution from the blood into the ventricles, flowing slowly through these cavities, and into the
subarachnoid space, to bathe the outside of the brain and spinal cord; thence it is continually reabsorbed into the bloodstream. Hydrocephalus occurs if the rate of absorption does not keep pace with production.
Most often the problem is a mechanical obstruction. This may occur before birth, due to a malformation in the brain, resulting in an enlarged head which can pose problems during delivery. In other cases, although caused by a congenital defect — often associated with
spina bifida — hydrocephalus may develop only later during infancy. Up to the age of two, when the bones of the skull begin to fuse, hydrocephalus results in overall enlargement in the size of the baby's head.
Later in life, at any age, a tumour may block a narrow part of the ventricular system, so that the system above this block expands; or there can be blockage in the surface spaces due to adhesions following meningitis or haemorrhage.
Obstructive forms of hydrocephalus occurring after fusion of the skull bones result in increasing intracranial pressure, with headache, vomiting, and danger to sight, with eventual death if unrelieved. The block can be located by
imaging techniques (CT scan or MRI), which clearly show the shape and size of the ventricles. If it is not possible to remove the obstruction, the block may be bypassed by inserting a tube, with a one-way valve, leading from the ventricles either to the venous side of the heart or into the peritoneal cavity.
Hydrocephalus may result also from wasting away of the brain substance due to progressive disease such as Alzheimer's, or to sudden and massive insults such as those which lead to the vegetative state. There is no rise in pressure because the excess of ‘water’ simply takes up the space in and around the wasted brain.
Karol K. Weaver, and Bryan Jennett
Bibliography
Lyons, A. E. (1995). Hydrocephalus first illustrated. Neurosurgery, 37, 511–3.
Montagnani, C. A. (1986). Pediatric surgery in Islamic medicine from the Middle Ages to the Renaissance. Progress in Pediatric Surgery, 20, 39–51.
