<title>Laser restoration of flow in occluded ventricular shunts for pediatric neurosurgery</title>

Abstract

Keywords: laser surgery, photoablation, neurosurgery, hydrocephalus, ventricular shunt We have investigated the use of short pulses of infrared (? = 2.09 rim) light from a Ho:YAG laser to photofragment occlusions and restore flow in ventricular shunts, which provide the sole means of maintaining proper intracranial pressure in hydrocephalus patients. These experiments employed model tissues, a polymeric model compound, and patient explants in order to determine appropriate pulse energies and delivery rates for removal of occlusions material. Laser energy doses and rates of occlusion removal were established for these materials.Laser energy doses that do not damage the shunt device or surrounding tissue were identified. Optical fibers (25 ga. or smaller) can be introduced through the dome of current shunt devices and threaded to the occlusion site. Clinical application will require the continued development of an introducer tool for the transcutaneous insertion of the optical fiber into the shunt device and irrigation techniques for removing the occlusion detritus generated by photofragmentation treatment. Using this approach, a minimally invasive and benign procedure for in situ restoration of flow in occluded neurological implant devices becomes possible.

Thulium fiber laser recanalization of occluded ventricular catheters in an ex vivo tissue model

“…These include the pulsed holmium:YAG laser for fiber optic based clearance of occluded shunts, 10,11 as well as continuous-wave neodymium:YAG, thulium:YAG, and diode lasers for endoscopic third ventriculostomy, using either bare optical fibers or carbon ball tip optical fibers for precise tissue ablation. These include the pulsed holmium:YAG laser for fiber optic based clearance of occluded shunts, 10,11 as well as continuous-wave neodymium:YAG, thulium:YAG, and diode lasers for endoscopic third ventriculostomy, using either bare optical fibers or carbon ball tip optical fibers for precise tissue ablation.…”

“…These include the pulsed holmium:YAG laser for fiber optic based clearance of occluded shunts, 10,11 as well as continuous-wave neodymium:YAG, thulium:YAG, and diode lasers for endoscopic third ventriculostomy, using either bare optical fibers or carbon ball tip optical fibers for precise tissue ablation. 10,11 Laser clearance of obstructed catheters appeared to be due primarily to a photomechanical mechanism represented by the rapid expansion and contraction of the laser-induced vapor bubble at the distal fiber tip when immersed in the saline-filled catheter tube, rather than a photothermal tissue ablation mechanism. This property frees up valuable cross-sectional space within the typical 1.2-mm ID lumen of the ventricular catheter for simultaneous use of a miniature endoscope for image guidance and saline irrigation tube for visibility and safety during the procedure.…”

“…Several studies have reported both experimental and clinical use of energy-based devices including electrocautery, 6 ultrasound, 7-9 and laser 10,11 for prevention or clearance of obstructed catheters. A minimally invasive method would be ideal, preventing surgical complications, improving patient quality of life, and reducing operating room and recovery costs associated with surgery.…”

“…While previous reports have used scallops to simulate choroid plexus, 10,11 in this study, egg white was chosen as a more consistent model for providing tissue adherence to the catheter wall and occlusion of the catheter lumen. Egg white was injected into 50-mm-length sections of tubing and then baked at 85 AE 2°C for 30 min, so the tissue would stick to the walls, providing an optimal tissue phantom model [ Fig.…”