What is hydromyelia?

Hydromyelia is an abnormal widening within the central canal, which is normally a very small pathway that runs through the middle of the spinal cord. This creates a cavity, called a syrinx, where cerebrospinal fluid (CSF) can accumulate and put pressure on the spinal cord. Over time, this can damage nerves in the spinal cord.

It tends to mainly occur in infants and children, but there is a similar condition called syringomyelia that tends to occur mainly in adults. Syringomyelia involves the formation of a cyst in the spinal cord that damages this structure of the body as it grows with fluid accumulation. This also can cause damage to the nerves in the spinal cord.

Mild hydromyelia doesn’t always cause symptoms. However, as it progresses, it can cause:

  • loss of feeling in the hands and arms
  • pain in neck and arms
  • muscle weakness in the hand, arms, and shoulders
  • leg pain or stiffness

Without treatment, the weakness and stiffness usually become worse and can eventually make movement difficult.

Doctors aren’t sure about the exact cause of hydromyelia. However, it’s thought to most likely be related to a blockage or disruption in the flow of CSF. This isn’t good for your central nervous system, as proper CSF flow and associated pressure are needed to protect the brain and spinal cord. Injuries, underlying conditions, and certain problems during brain and spinal cord development in the womb can all cause problems with the flow of CSF.

There’s also a strong link between hydromyelia and Chiari malformations. These are a type of birth defect that affects brain structure. They often cause the cerebellum — the area in the back of the brain that controls movement — and sometimes also the brainstem to move downward and crowd into the space reserved for the spinal cord. This blocks the flow of CSF.

Other conditions that are linked to hydromyelia include:

  • spinal cord tumors
  • arachnoiditis, which is inflammation of the arachnoid membrane surrounding the brain and spinal cord
  • meningitis, which is inflammation of the membranes (meninges) surrounding the brain and spinal cord
  • tethered spinal cord, which refers to tissue attachments involving the lowest region of the spinal cord, that prevent it from moving in the spinal canal like it should

Your child’s doctor will start by asking questions related to your child’s medical history and symptoms. They may also ask your child to perform certain movements and actions so they can check for signs of weakness or stiffness in their limbs.

To confirm the diagnosis, they’ll most likely order an MRI scan. This uses powerful magnets and radiofrequency pulses to create very detailed pictures, and there is no radiation exposure with MRI scans. This imaging test will allow the doctor to identify tumors or other abnormalities in the brain and spinal cord regions.

Some cases of asymptomatic hydromyelia may be closely monitored without treatment. It’s possible, but rare, for some cases of hydromyelia to resolve without treatment. However, if there are significant symptoms that don’t improve or even worsen, your child may need surgery to correct the flow of CSF.

Types of surgery include:

  • Shunting. A drainage system with a valve is used to drain CSF from the brain ventricles to the abdominal cavity.
  • Posterior fossa decompression. A small portion of bone at the back part of the lower skull and cervical spine (laminectomy) is removed to relieve pressure.
  • Third ventriculostomy. A hole is created in the bottom of the third ventricle of your brain to divert CSF flow.

If your child does need surgery, their doctor will determine the best approach based on the severity of the child’s condition and what may be causing it. They’ll also consider several factors, including your child’s age and overall health, to make sure they choose the safest option.

Physical therapy can also help to manage hydromyelia symptoms by increasing strength and flexibility in the arms or legs.

Hydromyelia can cause a range of neurological symptoms, such as stiffness, loss of sensation, pain, and weakness. However, not all cases produce symptoms. If you have a child with moderate to severe symptoms of hydromyelia, their doctor will likely recommend surgery to improve the flow of CSF in order to reduce symptoms.