Hydrocephalus is the accumulation of excess cerebrospinal fluid (CSF) inside the brain’s ventricles, which are chambers in the brain that hold fluid. The word has its origin in Greek- “hydro” or water and “cephalus,” or head. Although the phrase literally translates as “water on the brain,” the condition really refers to the accumulation of cerebrospinal fluid, a clear organic liquid that covers the brain and spinal cord. Clinically, hydrocephalus is the accumulation of CSF that causes an increase in intracranial pressure. CSF, which is produced in the ventricles of the brain leaves the ventricular system in the centre of the brain through two small openings at the base of the brain, bathes the outside of the brain and the spinal cord and performs a variety of vital tasks.
CSF build-up can increase the intracranial pressure inside the skull and damage brain’s tissue. CSF can build up due to an increase in production, a decrease in rate of absorption, or a disease that prevents the fluid from flowing normally through the ventricular system.
Although hydrocephalus can happen to anyone, it is most frequent in infants and those who are 60 years old or older. The National Institute of Neurological Disorders and Stroke (NINDS) estimates that one to two of every 1,000 children born in the United States have hydrocephalus. Most of these situations are frequently identified before pregnancy, during delivery, or in the early stages of life.
The exact cause of hydrocephalus is not exactly known. However, it is often divided into two major groups- Congenital and Acquired Hydrocephalus.
Congenital Hydrocephalus– Hydrocephalus that develop in babies either in utero or shortly after birth. This may be caused by
Acquired Hydrocephalus– Hydrocephalus that can occur at any age and is usually caused by
There are mainly two types of hydrocephalus
Signs and symptoms of hydrocephalus in infants include
Symptoms are usually that of the pathology that causes acquired hydrocephalus:
Symptoms in older adults may include:
There are multiple factors that may contribute to hydrocephalus.
In newborns and neonates
In all age groups
The diagnosis of hydrocephalus often requires a high degree of clinical suspicion as the signs and symptoms may be nebulous and may mimic several other pathologies. While it is relatively easier in infants when they present with a large head or a head circumference that is rapidly crossing the centiles on the growth chart, in some it may be more difficult to diagnose in the older child without such obvious symptoms. Those presenting with acute hydrocephalus usually have symptoms of raised intracranial pressure, the diagnosis is made after neuroimaging. In the elderly, symptoms are rarely acute and often nebulous where the scan again only tells us part of the story, with the clinical features of the patient deciding treatment. The following investigations are useful in the diagnosis of hydrocephalus.
Lumbar punctures- the exact opposite is true for the elderly population, where the ventricles are large due to age related cerebral atrophy. The pressure of CSF is not particularly high but the triad of gait disturbance, incontinence and decreased mentation show some improvement following lumbar punctures, a more permanent CSF diversion procedure like a shunt may be contemplated. This is referred to as normal pressure hydrocephalus. A variation of the slit ventricle syndrome presents in young and adolescent females (usually) who present with visual failure, headache and vomiting. The intracranial pressure can be very high but the ventricles remain small- referred to as Idiopathic Intracranial Hypertension. A lumbar puncture is often the investigation of choice in these patients.
There are two main ways that hydrocephalus is treated- one is by the placement of an external drainage device (a shunt) that has one end either in the ventricles of the brain or in the lumbar CSF (CSF after being produced in the ventricles of the brain circulate within the ventricular system before exiting the ventricles through two foramina at the base of the brain and circulating on the outside of the brain and the spinal cord) and the other end being placed either in the peritoneum (in the abdomen) or the pleura (in the chest) or may remain attached to a reservoir that sits just below the skin and can be accessed as and when required for diagnostic and therapeutic purposes. The VP Shunt (ventriculo-peritoneal shunt) is the most commonly used modality for the treatment of hydrocephalus. It involves the insertion of a tube into the ventricular cavity of the brain through a burr hole which is then connected to a valve (which can be either pressure controlled or flow controlled) which travels just under the skin and in turn connects to another tube that ends either in the chest or abdomen (usually, though there are other places like the heart or gallbladder in which the end of the tube can be placed). There are now variable pressure valves that can be monitored and controlled from the outside to increase or decrease pressure and thereby the flow of CSF. As with any tube, shunts are notorious for getting blocked, infected, misplaced or at times even extruded! Complications are more prevalent in the neonates and in children and happen less frequently in the adult.
The second and more sophisticated way of treating hydrocephalus is to make another ‘hole’ in the base of the brain (third ventriculostomy) and ‘internally’ decompress the build-up of CSF within the ventricles. This is done with the help of an endoscope and a hole is made at the floor of the third ventricle to allow CSF to escape into the subarachnoid space. This procedure does prevent all the complications of shunts, but works only when there is an obstruction to the flow of CSF, especially in tumors. There is a slight risk of fatal hemorrhage due to inadvertent injury to the basilar artery that lies just behind the area where the hole is made, but adequate imaging studies before surgery and the use of neuro-navigation during the procedure has reduced the risk of this to a minimum. It however does not work in hydrocephalus as a result of infection and in neonatal hydrocephalus.
Untreated hydrocephalus can be fatal. In children it can cause massive enlargement of the head with delayed developmental milestones that may later lead to a permanent disability, depending on the duration and the severity of the disease. Early treatment is therefore mandatory. One of the most disabling presentations of hydrocephalus is loss of eyesight- a rise in pressure inside the skull causes swelling of the optic nerves heads that gradually results in blindness. This may also present acutely in IIH, where there is no visible increase in the size of the ventricles but an increase in the intracranial pressure.
Where there is no visible increase in the size of the ventricles but an increase in the intracranial pressure.