Primary syringomyelia or hydromyelia

**Definition:** A condition caused by failure of the spinal canal to correctly develop during the antenatal period. This condition is characterised by a cavity within the spinal cord in which cerebrospinal fluid can accumulate. Confirmation is through observation of a fluid filled cavity within the spinal cord by imaging.

**Exclusions:** - Idiopathic syringomyelia - Syringomyelia - Syringomyelia due to certain specified cause