Flow dynamics in lumboperitoneal shunts and their implications in vivo: Laboratory investigation (original) (raw)

2009, Journal of Neurosurgery

T he Silastic LP shunt was introduced by Spetzler et al. in 1975 24,25 for the treatment of communicating hydrocephalus. Since then it has been used in the treatment of a host of other conditions including CSF rhinorrhea, normal pressure hydrocephalus, lumbar pseudomeningoceles, and in particular pseudotumour cerebri, where the ventricles are often small and shunt catheter placement is difficult. 3,4,23 Lumboperitoneal shunt placement is a completely extracranial procedure, thus avoiding all of the brain parenchymal damage that may occur during VP shunt insertion. 2,28 Lumboperitoneal shunts are associated with a very low mortality rate compared to VP shunts. 28 In addition, some authors have reported that the overall complication rate with LP shunts was considerably lower than when VP shunts were used. The LP shunt has long been associated with myriad complications. In some series LP shunts required an average of 3 revisions per shunt inserted. 12 Because of the high complication rate of LP shunts, some authors have recommended that they be used only as a last resort in the vast majority of cases. 12 However, medical treatment for pseudotumor cerebri often fails, and adequate weight loss is rarely achieved. One of the major concerns after LP shunt insertion is the development of hindbrain herniation, which can occur in up to 70% of patients in the long term. Associated with this is the development of low pressure symptoms including headaches, dizziness, unsteadiness, and hearing loss, indicating that overdrainage may be a problem in the design of LP shunts. Because LP shunts play an important role in the treatment of patients with pseudotumour cerebri, 28 attempts should be made to improve this device further, before seeking an alternative. We designed a simple experiment to study the flow characteristics of LP shunts in an experimental setting and attempted to determine the optimal catheter length.