What Is Hydromyelia?


Hydromyelia is a condition that leads to the widening of the central canal of the spinal cord, resulting in the formation of a cavity called a syrinx. This cavity allows cerebrospinal fluid to accumulate, exerting pressure on the spinal cord, which can damage nerve cells and their connections.1

Hydromyelia is often mentioned in conjunction with syringomyelia, although they are two different conditions. While they both cause a cyst-like growth in your brain and have similar symptoms, there are a few differences. Hydromyelia affects infants and children whereas syringomyelia affects adults. As well as this, cysts form inside the central canal in people with hydromyelia, whereas in people affected with syringomyelia, the cysts form next to the central canal.1,2

Some children with hydromyelia experience mild symptoms or no symptoms at all, requiring no treatment. However, moderate to severe symptoms that impact daily life often require treatment in the form of surgery.

This article will tell you everything you need to know about hydromyelia, including the symptoms, diagnosis and treatment options.

Causes of hydromyelia

Hydromyelia manifests in the fourth ventricle of your brain, which is the lower part of the brain that is close to the brainstem. This hollow space is filled with cerebrospinal fluid which protects the brain from trauma.1

The fourth ventricle connects to the central canal which runs the length of your spinal cord. The central canal carries cerebrospinal fluid, which it receives from the ventricular system and helps deliver nutrients to the spinal cord. It also protects the spinal cord from damage by acting as a buffer. The central canal is lined with specialised cells known as ependymal cells. These cells are only found in your ventricles and spinal canal.1

Hydromyelia occurs when there is an abnormal widening of the central canal, which creates a cavity called a syrinx where cerebrospinal fluid builds up and puts pressure on the spinal cord. As fluid builds up, the syrinx expands, putting further pressure on the spinal cord and leading to nerve irritation and damage.1

There is no known cause of hydromyelia. However, injuries and underlying conditions during the development of the brain and spinal cord in the womb can affect the flow of cerebrospinal fluid.1

Hydromyelia is usually associated with birth defects, such as Chiari malformation type 2 and Dandy-Walker syndrome. These birth defects affect the brain structure, which can contribute to the development of hydromyelia. Chiari malformations cause the cerebellum, and sometimes the brainstem, to push into the spinal cord and block the flow of cerebrospinal fluid. Dandy-Walker syndrome is a condition where the cerebellum does not develop normally. This causes other parts of the cerebellum to become filled with spinal fluid, forming cysts. This build-up of fluid causes the head to grow bigger than it should.

Signs and symptoms of hydromyelia

In some cases, syrinxes may produce mild symptoms or none at all. Symptoms of neuropathic pain can develop over time and may include:

  • Weakness in the hands and arms
  • Numbness
  • A burning sensation
  • A tingling sensation or pins and needles
  • Headache
  • Muscle stiffness
  • Scoliosis
  • Jolts of shooting pain
  • Loss of hot and cold sensitivity
  • Sensory loss in the neck and arms


Hydromyelia is diagnosed using a neurological exam and imaging tests.

A neurological exam is used to assess the severity of your symptoms. Your doctor will first ask you about your symptoms and medical history. They will also ask you to perform certain movements and actions to test your muscle strength.

Your doctor will then use an MRI scan to confirm the diagnosis. An MRI uses powerful magnets and radio waves to produce a detailed image of the inside of the body. MRI scans are useful in detecting syrinx formation and other spinal cord abnormalities. Your doctor may also use an electromyography to rule out syringomyelia.

Management and treatment for hydromyelia

Treatment for hydromyelia depends on your symptoms and their severity. If you have mild symptoms or no symptoms at all, you may not need any treatment. Specific symptoms, such as muscle stiffness and weakness, often improve with physical therapy, whereas moderate to severe symptoms that do not improve usually require surgery. Moderate or severe neurological symptoms that require surgery include loss of balance, memory loss, and inability to speak.

Surgical treatment helps to correct the flow of cerebrospinal fluid. Surgery can permanently or temporarily treat symptoms, but it may also cause severe complications. If you require surgery, your doctor will determine the best approach based on your symptoms, the potential causes, your age, and your overall health. 

Types of surgery include:

  • Shunting - insertion of a shunt in your brain to create a small passage in the fourth ventricle and allow the drainage of cerebrospinal fluid into the abdominal cavity
  • Posterior fossa decompression - a small section of bone in the back of the skull is removed to give the brain more room and relieve pressure 
  • Third ventriculostomy - a surgeon makes a hole in the bottom of the third ventricle of the brain to divert the flow of cerebrospinal fluid.

Symptoms of hydromyelia can improve on their own, but this may take years. Surgical treatment is effective but symptoms sometimes come back (recurrence). Your doctor may suggest undergoing regular MRI scans to help detect early signs of recurrence.


How can I prevent hydromyelia?

As the exact cause of hydromyelia is unclear, there are no known ways of preventing it.

How common is hydromyelia?

Hydromyelia is a rare condition that mainly affects children and is extremely rare in adults.3

Who is at risk of hydromyelia?

Hyromyelia affects infants and children. It is more likely to occur in children with certain brain conditions, including:

  • Dandy-Walker syndrome
  • Chiari malformation (type II)
  • Hydrocephalus

In rare cases, it can also occur in children with:

When should I see a doctor?

You should see a doctor if you or your child have:

  • Severe pain that comes and goes without warning
  • Muscle stiffness and weakness (in the hands, arms and legs)
  • Sensory loss in the neck and hands
  • Difficulty moving


In summary, hydromyelia is a condition which causes abnormal widening of the central canal of the spinal cord. This creates a cavity where cerebrospinal fluid can build up which puts pressure on the spinal cord and can damage nerve cells and their connections. Common symptoms of hydromyelia include weakness of the hands and arms, numbness, jolts of shooting pain, and muscle stiffness. Diagnosis involves a neurological exam to assess the severity of symptoms and an MRI scan to identify a syrinx in the spinal cord. If symptoms are mild, treatment is not always needed. Yet, people with severe symptoms usually require surgery. Surgery is used to correct the flow of cerebrospinal fluid. Although surgery is effective, recurrence is possible. Ongoing MRI scans and neurological exams can help detect early signs of recurrence.


  1. Saker E, Henry BM, Tomaszewski KA, Loukas M, Iwanaga J, Oskouian RJ, et al. The human central canal of the spinal cord: a comprehensive review of its anatomy, embryology, molecular development, variants, and pathology. Cureus [Internet]. [cited 2023 Jul 7];8(12):e927. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5234862/ 
  2. Shenoy VS, Sampath R. Syringomyelia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Jul 7]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK537110/ 
  3. Hydromyelia | National Institute of Neurological Disorders and Stroke n.d. https://www.ninds.nih.gov/health-information/disorders/hydromyelia
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Suad Mussa

Bachelor of Science – BSc, Biology. Queen Mary University of London

Suad Mussa is a biology graduate with a strong passion for medical writing and educating the public about health and wellbeing.

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