A new system for a combined laser and ultrasound application in neurosurgery

A new combined Laser and Ultrasound Surgical Therapy (LUST) device suitable for endoscopical coagulation and tissue fragmentation has been developed a t the LMTB1. The new feature is the simultaneous transmission of laser radi ation and ultrasound via flexible silica glass fibers. The ultrasound tissu e interaction is based on the well-known CUSA-technology which enables the surgeon to cut various types of tissue with different degrees of effectiven ess. Application fields are in oncology, neurosurgery and angioplasty. The laser radiation can be used, for example, for tissue coagulation purposes. With a fiber based LUST-system working at a frequency of 30 kHz, a displace ment of 100 mu m could be attained at the distal end. (The usual standard C USA displacement is 10-350 mu m.) During in vitro experiments the following tissue fragmentation rates could be achieved: brain tissue 50 mg sec(-1), liver 4.5 mg sec(-1) and kidney 4 mg sec(-1) (displacement of the tip 60 mu m; O 1.3 mm; suction setting: 5 W). Laser radiation up to 25 W was suffici ent to coagulate soft tissue. This technology offers new possibilities in m inimal invasive surgery. The flexible opto-acoustic waveguide (diameter 400 -1700 pml can be bent making areas accessible that were previously inaccess ible. Without changing the instrumentation the surgeon can use the laser ra diation for tissue coagulation or cutting and the ultrasound for tissue fra gmentation and tissue reduction.