Syringomyelia explained: a fluid-filled cyst in the spinal cord

What syringomyelia is

The spinal cord is the thick bundle of nerves that runs down your back inside the spine, carrying messages between the brain and the body. In syringomyelia, a fluid-filled cavity — the syrinx — develops within the substance of the cord itself. Normally, clear fluid flows smoothly around the brain and spinal cord; in syringomyelia, this flow is disturbed and fluid collects inside the cord. Over months or years the cavity can enlarge, gradually stretching and damaging nearby nerve fibres. Because the cord carries signals for movement, sensation and some automatic functions, a growing syrinx can interfere with several of these, though the exact effects depend on where in the cord the cavity forms and how large it becomes.

Why it happens

Syringomyelia is usually linked to something that disturbs the normal flow of fluid around the spinal cord. The most common association is a condition called a Chiari malformation, where the lower part of the brain sits slightly lower than usual, near the top of the spine, and alters fluid flow. Other causes include previous spinal injury, inflammation or infection around the cord, or a tumour. Sometimes no clear cause is found. Understanding the underlying cause matters because treatment often aims to address it — for example, relieving the blockage to fluid flow. Your specialist will investigate to work out why the syrinx has formed, as this guides the most appropriate approach to management.

Symptoms to be aware of

Symptoms usually come on gradually and can be subtle at first. A classic pattern is losing the ability to feel temperature and pain in certain areas — for example, not noticing a burn or cut on the hands — while other kinds of sensation, such as touch, are preserved. People may also develop pain, often in the neck, shoulders, arms or back, along with weakness, stiffness or wasting of muscles, particularly in the hands and arms. Some notice clumsiness, or changes in how their limbs feel. Because these symptoms can be mild and slow to progress, they are sometimes put down to other causes for a while. Any unexplained, persistent numbness, weakness or loss of temperature sensation is worth discussing with a doctor.

How it is diagnosed

Syringomyelia is diagnosed mainly with an MRI scan, which produces detailed pictures of the spinal cord and clearly shows a syrinx, its size and its position. The scan may also reveal an underlying cause, such as a Chiari malformation. A doctor will first take a careful history of your symptoms and examine you, testing sensation, strength and reflexes, which may point towards a problem in the spinal cord. If syringomyelia is found, further scans of the brain and spine may be arranged to understand the full picture. Being referred to a specialist neurology or neurosurgery team is usual, as they can interpret the scans and advise on whether treatment is needed and, if so, what kind.

Treatment and monitoring

Not everyone with syringomyelia needs immediate treatment. If the syrinx is small and causing few or no symptoms, a specialist may recommend monitoring with regular scans to watch for change. When symptoms are troublesome or getting worse, treatment usually focuses on the underlying cause — for example, surgery to relieve pressure and restore normal fluid flow, or to drain or reduce the cavity. The aim is to stop further damage and, where possible, ease symptoms, though nerve damage that has already occurred may not fully reverse. Managing symptoms such as pain is also important. Because syringomyelia can change slowly over time, ongoing follow-up with your specialist team helps ensure any progression is picked up and acted on.