How I Came up with the Idea of Using Cerebrospinal Fluid Drainage for Neuroprotection During Descending Thoracic Aortic Surgery

Spinal cord ischaemia, manifesting clinically as paraparesis or paraplegia, has long been recognized as one of the most devastating complications of descending thoracic and thoraco-abdominal aortic surgery. Historically, it affects up to 20% of patients who undergo these operations without protective measures.1 Animal experiments in the 1960s and 1970s provided the first compelling evidence that manipulating cerebrospinal fluid (CSF) pressure could influence spinal cord blood flow. Investigators demonstrated that aortic cross-clamping resulted in a rapid rise in intrathecal pressure, which significantly reduced spinal cord perfusion even when systemic blood pressure was maintained. Lowering CSF pressure experimentally was shown to improve spinal cord blood flow and delay the onset of ischaemic injury. Blaisdell and Cooley2 showed that in dogs, occluding the aorta raised CSF pressure and increased the risk of paraplegia; in contrast, treatment with intravenous urea lowered CSF pressure and decreased the risk of paraplegia. Miyamoto et al3 in 1960 reported on both a dog experiment and 2 clinical cases showing that CSF drainage prevented spinal cord damage after temporary occlusion of the thoracic aorta. These findings were probably the first evidence of the clinical utility of this approach.