ELECTROHYDRAULIC INTRACOPOREAL LITHOTRIPS Y FOR THE TREATMENT OF SALIVARY DUCT STONES - IN-VITRO AND ANIMAL-EXPERIMENTS

Background: Extracorporeal lithotripsy is now used routinely for the t reatment of salivary duct stones. The question arose whether electrohy draulic intracorporeal lithotripsy, which is applied in urology and ga stroenterology, might also be useful in the treatment of this disease. Before its possible clinical application the influence of electrohydr aulic intracorporeal shock waves on salivary stones in vitro and any i nfluence on the tissue in the head and neck region (in vivo) had to be investigated. Materials and methods: In vitro experiments. Fifty-eigh t salivary stones and 11 extirpated human submandibular glands were tr eated by three different electrohydraulic devices. Animal experiments. Electrohydraulic shock waves were applied to the dilated Stensen's du ct and other tissues (muscle, parotid gland, facial nerve) of six rabb its. Results: Of 58 salivary stones, 53 (91%) were fragmented, 39 (67% ) with a remaining size of less than 1.5 mm and 14 (24%) more than 1.5 mm. In 5 cases (9%) no effects were seen at all. Fragmentation occurr ed independent of the mineralogical components of the stone and indepe ndent of the different lithotriptors used. The smaller the probe diame ter and the larger the stone, the more shock waves were needed to achi eve fragmentation. With the smaller probes the stones could not be fra gmented completely. In human submandibular glands, extensive tissue le sions could be evidenced macroscopically and histologically after appl ication of electrohydraulic shock waves in vitro. Application of elect rohydraulic shock waves to the dilated parotid gland duct of rabbits l ed to perforations of the duct after 1-5 single pulses. Lesions of ner ves and blood vessels could also be observed within the duct environme nt. This occurred with all of the different electrohydraulic devices, probe diameters and intensities used. In our opinion the damage produc ed is probably the result of both the direct effect of the plasma as w ell as the resultant stress wave. Conclusion: In view of the severe da mage caused to different tissues, use of the described method for the treatment of stones in the narrow human salivary ducts should be great ly restricted.