Water-jet dissection in parotid surgery: An experimental study in dogs

Objective: The objective of the present study was to investigate the applic ation of the water-jet dissection method in parotid surgery by way of anima l experiments, paying particular attention to the clinical and histological reactions of the facial nerve. Study Design: An animal experimental study. Methods. Total bilateral parotidectomies with retention of the facial nerv e were performed on 19 beagle dogs by means of the Hydro-Jet device (Andrea s Pein Medizintechnik Company, Schwerin, Germany) using different jet diame ters and operating pressures. All operations were performed with continuous intraoperative facial monitoring (Neurosign 100, Inomed Company, Teningen, Germany). The dogs were monitored postoperatively over an average period o f 20.3 days (range, 14-35 d). Local findings and facial nerve status were d ocumented daily. In a second phase, the dissected nerves were resected and the animals were killed. Samples of water-jet-dissected parotid tissue, as well as all dissected nerve branches, underwent histological examination an d were compared with clinical and electrophysiological findings. Results. I t was possible to perform operations easily on all parotid glands by means of the Hydro-Jet using the small, 120-mum jet at operating pressures of 40 to 60 bar and to dissect the facial nerve quickly and safely with retention of its functional capability (n = 34). The dissection of nerves using larg er-diameter jets (150 and 200 mum [n = 64]) resulted in a total of two reve rsible and seven irreversible partial pareses. Conclusions. The study has s hown that it is possible to perform tissue-selective operations on the paro tid gland by means of the Hydro-Jet using the 120-mum jet at operating pres sures of 40 to 60 bar, ensuring safe, atraumatic dissection of the facial n erve with retention of its functional capability. The advantages of the new Hydro-Jet method offer a valuable alternative compared with the normal dis section methods adopted in parotid surgery. Thus the results of the present investigation currently are being checked within the framework of a clinic al study at our clinic.