ELECTROHYDRAULIC INTRACORPOREAL LITHOTRIPSY OF SALIVARY DUCT STONES -IN-VITRO AND ANIMAL INVESTIGATIONS

Background: The performance potential of extracorporeal lithotripsy as a method for the treatment of salivary duct stones has been demonstra ted in the scope of routine clinical applications. The question thus a rises whether electrohydraulic intracorporeal lithotripsy as applied i n urology and gastroenterology might equally serve as a useful method for curing sialolithiasis. Materials and methods: (a) In vitro experim ents: 58 salivary duct stones and II extirpated human submandibular gl ands were treated by three different electrohydraulic modalities. (b) Animal experiments: The dilated Stensen's duct and several other types of tissue (muscle, parotid gland, facial nerve) of six rabbits were e xposed to electrohydraulic shockwave immission. Results: 53 out of 58 salivary duct stones (91%) were fragmented, 39 (67%) of which had a re sidual stone diameter of less than 1.5 mm and 14 (24%) of more than 1. 5 mm. No effects were observed in five cases only. Fragmentation remai ned independent of the mineralogical stone composition and the type of implemented lithotriptor. The smaller the diameter of the probe and t he larger the stone, the higher the number of shockwaves that was requ ired for fragmentation. Complete fragmentation could not be achieved w ith the smaller probes. In human submandibular glands detectable tissu e lesions could be macroscopically and histologically evidenced after application of electrohydraulic shockwaves in vitro. Immission of elec trohydraulic shockwaves into the dilated Stensen's ducts of rabbits le d to duct perforation after one to five single pulses. Furthermore, le sions of nerves and blood vessels were observed in the environment of the duct. These effects occurred with all the employed electrohydrauli c devices, and with the entire range of applied probe diameters and in tensity levels. In our opinion, the induced damage is probably the com bined result of the direct effect of the plasma and of the resultant s tress wave. Conclusions: Indications of the described method for the t reatment of stones in narrow human salivary ducts should be clearly re stricted due to the high risk of serious damage to tissue.