Hydromyelia

What it is

Hydromyelia is dilation (widening) of the central canal of the spinal cord with cerebrospinal fluid. It is closely related to syringomyelia, and the two terms are often used together or interchangeably in the context of Chiari malformation.

Understanding Hydromyelia

The spinal cord has a tiny central canal that normally carries a small amount of CSF. In hydromyelia, this canal becomes dilated with fluid. The distinction between hydromyelia (dilation of the central canal, lined by its normal cells) and syringomyelia (a cavity within the cord substance, which may extend beyond the central canal) can be subtle, and in practice the two often coexist or are difficult to separate — hence the combined term "syringohydromyelia." Both are associated with Chiari malformation and the disrupted CSF dynamics at the craniocervical junction. For practical purposes, the management considerations are similar. Understanding hydromyelia clarifies a closely related term and why it is often grouped with syringomyelia.

Why it matters

Understanding hydromyelia helps families see a term closely related to syringomyelia, recognize why the two are often grouped together, and know that both relate to Chiari's disrupted CSF dynamics.