What are the key differences between syringomyelia and hydromyelia, and what are the potential causes of a syrinx in the spinal cord?

Syringomyelia refers to a fluid-filled cavity within the spinal cord outside the central canal, lined by glial cells, while hydromyelia is the dilation of the central canal lined by ependymal cells. Key diagnostic features include MRI findings of a longitudinally oriented cavity. Clinical pearls: Syringomyelia is often associated with Chiari malformation, trauma, or spinal cord tumors. Common pitfalls include confusing syringomyelia with dilated central canal or other cystic lesions. Always consider the possibility of a tumor when encountering an unexplained syrinx.