Effect of respiration and pathways of fluid flow in spinal cord cysts
Traumatic spinal cord injury is a devastating condition affecting approximately 600 people each year in Australia and 13,000 in the USA. Of these, up to one third will develop syringomyelia. This condition is characterised by the formation of a fluid-filled cyst, which may lead to pain, paralysis, muscle weakness and wasting, loss of reflexes, and loss of sensitivity to pain and temperature. Additional neurological deficits due to syringomyelia are particularly devastating in spinal cord injury patients, who can be transformed from disabled but independent people into patients requiring assistance with basic daily tasks. If syringomyelia affects the brain stem or respiratory function (breathing) it is life-threatening.
Treatment for post-traumatic syringomyelia usually involves surgery to reduce the pressure the cyst places on the spinal cord, by draining the fluid from the cavity, and removing any obstructions to the normal cerebrospinal fluid flow. Most clinical studies report long-term surgical failure rates of approximately 50%. Syringomyelia occurring as a result of spinal cord injury has proven particularly difficult to treat, because the injured spinal cord is at substantial risk of further mechanical damage with any surgery. Determining the factors responsible for cyst formation and resolution is essential to define surgical goals and for improving treatment. We have shown that cardiac pulsations are important drivers of cerebrospinal fluid flow. Breathing, coughing, and straining also affect cerebrospinal fluid flow surrounding the brain and spinal cord. The possibility that pressure changes that occur in the chest during the respiratory cycle might contribute to spinal cord cyst formation has not been studied. The proposed research will determine the effect of respiration on fluid flow into the spinal cord of control animals and in an animal model of post-traumatic syringomyelia. In addition, we will determine if there are distinct pathways for fluid movement into the cyst using electron microscopy to study the ultrastructure at sub-nanometer resolution. A greater understanding of the specific anatomical pathways may provide precise targets for future treatment strategies.