In syringomyelia, fluid cysts expand and damage the spinal cord and can lead to disabling pain, paralysis and other neurological effects. Treatment is often unsuccessful because the exact mechanisms of how fluid circulates in the spine and builds up in the spinal cord is unknown. This study will use animal experiments to determine precisely how fluid flows in and around the cord. A fluorescent fluid tracer will be injected directly into, or around the space of the spinal cord of the anaesthetised rat. Specialised cameras will capture the distribution of the tracer and thus give an indication of how fluid flows into and drains out of the spinal cord. This will be repeated in rats that have had their heart rates, blood pressure and breathing patterns manipulated by anaesthetic drugs and ventilators. We will be able to investigate whether these physiological factors affect the flow of fluids into and out of the spinal cord. Our study may give insight into how these fluid cysts form and lead to new therapies. There is also potential for our data to contribute to our understanding of spinal cord injury, other fluid disturbances of the central nervous system such as hydrocephalus and even sleep disorders.