Cerebrospinal fluid (CSF) disorders encompass a wide variety of conditions. Everyone has CSF; it is mainly produced in the choroid plexus and flows around the sub-arachnoid space surrounding the brain and spinal cord. It then passes through a series of chambers in the brain called ventricles and connecting channels called foramina. We produce about a pint (500ml) of CSF per day but the brain can contain only about 120-150ml. For this reason excess CSF is drained into the bloodstream through a series of valves called the arachnoid villi. The CSF is recycled about three times a day.
CSF helps to protect the brain by cushioning it within the skull, and also serves as a shock absorber for the central nervous system. CSF also circulates nutrients and chemicals from the blood and removes waste products from the brain. CSF leaks, hydrocephalus, Chiari malformation and Syringomyelia fall under the umbrella of CSF disorders.
Hydrocephalus
This happens when the cerebrospinal fluid (CSF) builds up, putting pressure on the brain and leading to damage. This can cause a wide range of symptoms, including headache, blurred vision, sickness and difficulty walking.
There are three main types of hydrocephalus:
- Congenital hydrocephalus – This is present at birth and can cause permanent brain damage and long-term mental and physical disabilities. It can be caused by conditions such as spina bifida, or an infection the mother develops during pregnancy, such as mumps or rubella (German measles).
- Acquired hydrocephalus – This develops after birth, usually as a result of a serious head injury or following a lesion obstructing the CSF pathways such as a brain tumour.
- Normal pressure hydrocephalus (NPH) – a rare illness which usually only develops in people aged over 50. Although it can develop after an injury or a stroke, most of the time the cause is unknown.
Diagnosing hydrocephalus is usually by an MRI or CT scan. Further tests may need to be carried out before the consultant can make a diagnosis.
Hydrocephalus is usually treated with surgery (one of two surgical treatments):
1- Shunt
The most common treatment for hydrocephalus is the insertion of a shunt, which acts as a drainage system to bypass the patient’s existing CSF absorption mechanisms. It consists of a long, flexible thin tube with a valve that keeps fluid from the brain flowing in the right direction and at the correct rate.
One end of the tubing is usually placed in one of the brain’s ventricles (this is a CSF containing chamber in the brain). The tubing is then tunneled under the skin to another part of the body where the excess cerebrospinal fluid can be more easily absorbed — this is usually the abdomen, but also be the heart atrium or chest.
People who have hydrocephalus usually need a shunt system for the rest of their lives, and regular monitoring is required.
2- Endoscopic third ventriculostomy
Endoscopic third ventriculostomy is a surgical keyhole procedure that can be used for some patients. This procedure aims to internally bypass the existing CSF pathway and no implantable device is needed. In the procedure, a small video camera is used for direct visualisation inside the brain. A hole in the bottom of one of the ventricles or between the ventricles to enable cerebrospinal fluid to flow out of the brain, circulate and absorb.
What is Chiari Malformation?
Chiari Malformation (CM) also known as Hindbrain Hernia is a rare condition involving the base of the brain and spinal cord. In this condition the cerebellar tonsils of the brain descend through an opening in the base of the skull (named the Foramen Magnum) into what should be a space alongside the spinal cord. This can cause compression of the brain stem and disruption of the flow of cerebrospinal fluid (CSF) at the top of the spinal canal. This can cause a number of symptoms: pain and tingling in the limbs, dizziness, nausea, balance problems, visual disturbances, problems swallowing, pressure headaches, which worsen when straining, laughing or coughing.
Chiari Malformation is diagnosed by an MRI scan.
Treatment
A decompression surgery may be offered to try to relieve symptoms and stop the condition progressing.
Before any surgery is undertaken, detailed discussions need to take place between the patient and the neurosurgeon, as to the potential benefits of surgery as well as the inconveniences, discomforts and risks that go with an operation on the brain or spinal cord.
What is Syringomyelia?
Syringomyelia is a disorder affecting the nervous system where fluid-filled cavities develop inside the spinal cord. The spinal cord is normally a solid structure, which passes down the back inside the spinal canal. It connects the brain to the rest of the body, passing signals to and fro, enabling an individual to move his or her limbs at will, to feel objects and to control various bodily functions.
Within the spinal canal, the spinal cord is bathed with CSF. The fluid from which Syringomyelia cavities are formed is identical to CSF.
Normally CSF flowing in the spinal canal communicates freely with CSF circulating inside the head but when CSF is trapped inside the spinal canal some of it begins to accumulate within the substance of the spinal cord.
What Causes Syringomyelia?
Next to Chiari Malfromation, the most common cause of Syringomyelia is spinal injury. A minority of victims of severe spinal cord trauma, who are already severely disabled as a result of their original injury, go on to develop additional problems as a result of Syringomyelia. Scar tissue within the spinal canal, developing as a consequence of the initial injury, obstructs CSF movement causing, once again, fluid to accumulate within the substance of the spinal cord.
There are other causes of Syringomyelia beyond the scope of these pages.
How is Syringomyelia diagnosed?
Patients who have Syringomyelia present with a variety of symptoms ranging from neck and arm pain through to fairly severe disability, with muscle weakness and paralysis. Fortunately nowadays, most cases of Syringomyelia are detected at an early stage before major disability develops.
Any of the symptoms of Syringomyelia can have other causes. Indeed, it is much more likely that somebody presenting with, say, neck and arm pain, will have a more common disorder and not Syringomyelia.
It is only when more common diseases are excluded that Syringomyelia may be considered as a diagnosis. In most cases the diagnosis of Syringomyelia is made by a specialist, usually a Neurologist.
Once the diagnosis of Syringomyelia is suspected, it is readily confirmed by an MRI scan.
How is Syringomyelia treated?
In many cases of Syringomyelia all that a patient needs is an explanation and reassurance, together with periodic review by a specialist.
The symptoms arising from Syringomyelia can be treated with drugs, other measures, or simply tolerated.
In some instances, however, if the cavity in the spinal cord is enlarging and threatens to cause significant disability, there may be a place for surgical intervention. In these circumstances the services of a neurosurgeon may be required. Before any surgery is undertaken, detailed discussions need to take place between the patient and the neurosurgeon, as to the potential benefits of surgery as well as the inconveniences, discomforts and risks that go with an operation on the brain or spinal cord.
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