The Ann Conroy Trust concerns itself, principally, with the condition known as syringomyelia, as well as with some related disorders. Syringomyelia affects mainly the spine, more specifically the spinal cord. It can affect individuals across a wide age range, from early childhood through to late adult life. It can develop without any obvious cause but, more often than not there is a recognisable, underlying cause. The most common of these is a hindbrain hernia, known more commonly as a Chiari malformation, sometimes also referred to as an Arnold-Chiari malformation. We aim to provide information and support to people living with Chiari malformations, as well as some other conditions which may lead to syringomyelia formation. We will also discuss a number of other related medical conditions.


The word syringomyelia refers to a condition in which fluid-filled cavities are present in the spinal adult cord. Things are a little different in young children, in whom such cavities are normally present although, if they are abnormally pronounced, such cavities may also be seen as abnormal and amount to syringomyelia.

To explain matters a little more, we need to consider a little more the anatomy of central nervous system, that is the brain and the spinal cord taken together.

The brain is mostly, but not entirely a solid structure. There are chambers in the centre of the brain, known as ventricles. These cavities are not empty but contain a watery fluid, known as cerebrospinal fluid – or CSF, for short. The fluid forms within the ventricles themselves and then flows out, at the base of the brain. From there some of it passes into the spinal canal but eventually all the fluid is re-absorbed, back into the blood stream, mostly via a major blood channel passing along the top of the skull, in the midline – the superior sagittal sinus.

It is therefore normal for somebody to have this fluid (CSF), both inside and over the surface of the brain. The CSF also passes down into the spinal canal, on the outside of the spinal cord. Normally, however, there is not any fluid inside the spinal cord itself, at least not when body growth is complete by the age of about 18. When we do discover CSF inside the spinal cord we use the term syringomyelia to describe this.

Syrinx is a commonly used, shortened, abbreviation for the medical condition Syringomyelia.

Syringomyelia cavities come in “all shapes and sizes”, from small cyst-like structures, limited to one part of the spinal cord, through to large, tensely distended cavities that may involve the entire length of the spinal cord.

Syringomyelia cavities form when the normal channels within the spinal canal, along which CSF normally flows, become obstructed. Because of this, the energy of rhythmic, pulsatile pressure waves within the column of CSF, generated by the heartbeat, cannot disperse normally. As a result, CSF is forced into the spinal cord, creating the syrinx cavity.

The commonest cause of obstruction to CSF flow in the spinal canal is herniation of the lowermost part of the brain, known as the cerebellar tonsils, down from the cranial cavity above into the top of the spinal canal. This anatomical abnormality is best referred to as a hindbrain hernia but is more widely known as a Chiari malformation. The second most common cause of obstruction to normal CSF flow in the spinal canal is scar tissue. This may form as a result of a previous spinal injury or, sometimes, an episode of infection such as meningitis. Other causes are also seen, on occasions.

Through the use of an MRI machine. With widespread availability and ready application of magnetic resonance imaging (MRI), we now increasingly encounter syringomyelia cavities without there being an obvious point of obstruction to normal spinal CSF flow. The term idiopathic syringomyelia is used to describe such cases.

The spinal cord is a relatively small structure, about the size of a person’s little finger. This is all the more amazing, given what it does, i.e. conducting all of the voluntary and many of the involuntary signals passing between the brain and the rest of the body. Any condition that disrupts the normal anatomy of the spinal cord, be it an injury, a tumour, a slipped disc or, as in the case of syringomyelia, a fluid filed cavity, can affect the flow of these signals. Certain reflex body functions, such as sweating, which do not depend upon connections with the brain, can also be affected. As a result, somebody affected by a myelopathy (the word used to refer to any disorder of the spinal cord) can experience varying degrees of loss of control over their body. It is for the doctor and hospital specialist to determine what is the origin of such symptoms. Syringomyelia is just one possible cause, albeit still relatively uncommon as compared with other diseases.

Despite the ease with which syringomyelia (or syrinx) cavities can now be identified on MRI, it remains a relatively uncommon condition. As a result, family doctors will seldom suggest syringomyelia as a primary diagnosis, when confronted with the variety of symptoms that the condition may produce. It is therefore common for there to be a delay of months, or even years, between when a person first experiences symptoms and the underlying cause being established.

These days, anybody with severe or persisting neurological symptoms, including those caused by syringomyelia, is likely to be referred to a neurologist, who is the specialist most likely to establish the diagnosis. Beyond this, in the UK at least, a neurosurgeon may well be consulted, to assess whether or not there might be a role for operating upon the condition. or other hospital specialist. These matters are considered in more detail under the Professional Help section of this website.

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Chiari Malformations

Chiari malformations, or hindbrain hernias, consist of an internal, anatomical abnormality where the lower-most part of the brain becomes squeezed through the large opening at the base of the skull (known as the foramen magnum), into the top of the spinal canal.
There are two main forms of Chiari malformation, type 1 and type 2. Type 1 presents mainly but not exclusively in adult life. Type 2 is seen mostly in children and is associated with the conditions of spina bifida and hydrocephalus.

In both forms of Chiari there is, essentially, a mis-match between the volume of the lower-most part of the cranial cavity (known as the posterior fossa) and the volume of that part of the brain which lies within this cavity. This part of the brain is referred to as the cerebellum – meaning the “little brain”.

More specifically, it is a part of the cerebellum known as the tonsils that protrude through the foramen magnum, into the spinal canal. The cerebellar tonsils have nothing to do with the tissue at the back of the mouth, which becomes inflamed when someone has a sore throat. It is simply the case that early anatomists, when they were dissecting the human body to see how we are all put together, happened to give the same name to two very different structures, in different parts of the body. Tonsilla is a Latin word referring to a post used for tying up a ship and perhaps the stump-like appearance of the cerebellar tonsils was likened to a ship’s mooring post.

It is important to stress that Chiari malformations are essentially benign – always provided that other conditions, which may mimic Chiari, have been excluded.

Most Chiari type 1 hindbrain hernias are probably genetically determined – simply the way that an individual is made. There may be other factors operating but these are not yet fully defined. Abnormal descent of the cerebellar tonsils can also come about if the pressure in the head is higher than it should be or, sometimes, if the pressure in the spinal canal is too low.

Chiari type 2 malformations develop because the associated spina bifida allows CSF to leak out of the head and the spine during development. This means that the posterior fossa of the skull does not develop properly and a large part of the cerebellum, not just the tonsils, may be prolapsed into the top of the spinal canal.

Chiari malformations may cause symptoms both by the herniated cerebellar tonsils pressing upon surrounding structures and because the normal flow of CSF, between the cranial cavity and the spinal canal (across the craniovertebral junction) is impaired.

Pressure on the brain stem can produce a variety of symptoms, which is not surprising given the multitude of body functions that are controlled by this part of the brain. All of the voluntary signals passing between the brain and the body also pass through the brain stem. Symptoms that are sometimes reported by people with Chiari malformations therefore include disturbances of balance, hearing and vision, as well as, sometimes, difficulties with swallowing. There are, however, many other causes of each of these symptoms and the Ann Conroy Trust would discourage people from self-diagnosing themselves based on the information we provide here. It is vital that anybody experiencing any such symptoms should seek advice from a qualified and accredited medical professional.

Disturbance of the movement of cerebrospinal fluid between the head and the spinal canal produces headaches of a type that specialists recognise. Typically such headaches are brought on during or immediately after activities such as coughing, sneezing, straining, bending over, or even laughing. They can be quite intense but are usually very short-lived. Once again, somebody experiencing such symptoms should consult with a medical professional and not self-diagnose him or herself as having Chiari malformation. There may well be an alternative cause, requiring different management.

Chiari malformations can be associated with headaches of a different nature and sometimes neck discomfort as well. Once again, there are many causes of such symptoms, other than Chiari malformation.

The conditions listed below are commonly, and some not so commonly, associated to Chiari Malformations and Syringomyelia. Click on any of the conditions to find out more about the related condition, where we have the information available to you.

  • Hydrocephalus
  • CSF Shunts
  • Spina Bifida
  • Tethered Cord
  • Basilar Invagination
  • Ehlers-Danlos
  • Spinal Cord injury
  • Intracranial Pressure