Chronic Lumbar Intrathecal Catheterization for the Collection of Cerebrospinal Fluid in the Canine

Alzheimer's Disease (AD) is a progressive neurodegenerative disorder characterized by an excessive production of extracellular amyloid plaques and intracellular neurofibrillary tangles in the brain. Studies have shown that concentrations of tau and amyloid protein (beta-amyloid (A beta)) are altered in the cerebrospinal fluid (CSF) of patients with AD. In an effort to support the investigation of specialized CSF biomarkers, a reliable and reproducible chronic system was developed to collect lumbar CSF from conscious dogs. Several nonsurgical and surgical procedures have been published for accessing lumbar CSF. We elected to use a lumbar catheter with a vascular access port to collect lumbar CSF. Although the surgical model is not novel, we evaluated various modifications to the procedure and maintenance to increase patency of chronic indwelling lumbar CSF catheters. Different types of catheters were evaluated, and for our purposes a 3.5 Fr open-ended polyurethane catheter was selected. With our final modified surgical procedure and catheter maintenance program, 67% remained patent for longer than 30 days for the first surgery and 86% remained patent for longer than 30 days if a repair or replacement surgery was performed. Based on the results of the proof of concept studies, our model proved to be useful for single and multiple dose pharmacokinetic studies in a search for effective Alzheimer's disease treatment.