Drain cannula

Abstract

An apparatus for draining cerebrospinal fluid from the ventricle of a brain includes an inner rigid tube and an outer flexible, elastic tube. The proximal end of the flexible tube has perforations to admit fluid into the elastic tube lumen in which the fluid is conducted to the distal end where the fluid exits into the remainder of a drain system, such as a ventriculoperitoneal shunt. The rigid tube contains an elbow bend intermediate the ends. In one form of the apparatus, the rigid tube has a first tubing nipple near one end and a second nipple intermediate the first nipple and the elbow bend. The first nipple extends outside and beyond the distal end of the flexible tube. The second nipple can be used to fasten the flexible tube to the rigid tube. The fastening method can employ a circumferential ligature as with suture thread or with a novel non-elastically deformable sleeve type of compression fitting. When implanted, the intercranial portion of the drain cannula descends directly into the ventricle from a burr hole in the skull and the extracranial portion remains flush adjacent the skull under the scalp. The rigid tube maintains the lumen in a patent condition at the burr hole despite the substantial angle between the distal and proximal portions of the flexible tube. The location of the two nipples permits fastening of the rigid tube to the flexible tube and joinder of the drain cannula to the drain system to be accomplished completely outside the burr hole.