The spinal cord has a large syrinx. This is syringomyelia, a cavitary expansion of the spinal cord. They are most common in the cervical region, and may extend to the medulla and pons, termed syringobulbia. Most cases are associated with Chiari malformations, but may also occur with trauma, transverse myelitis, infection, or tumors. The syrinx expands to disrupt sensory and motor tracts, leading to a central cord syndrome with sensory loss and areflexic weakness of upper extremities and lower neck. A drain may be placed to decompress the expanding cavity.