Syringomyelia (SM): is a condition in which fluid-filled cavities develop within the spinal cord near the brain.  It is also known as "neck scratcher's disease", because one of its common signs is scratching in the air near the neck. The back half of the Cavalier King Charles Spaniel’s skull typically may be too small to accommodate all of the brain’s cerebellum, and so it squeezes through the foramen magnum – the hole at the back of the skull – partially blocking the flow of cerebrospinal fluid (CSF) down the spinal cord. The variable pressure created by the abnormal flow of CSF is believed to create the SM cavities – called syrinx – in the spinal cord.