Comparison of the incidence of facial nerve dysfunction in patients submitted to surgery for parotid gland tumors with or without facial nerve monitoring with continuous electromyographic register during the surgery

INTERVENTION: Participants with benign tumours of the parotid gland undergoing superficial parotidectomy are randomly assigned to the intervention (facial nerve monitoring) or control group on the day of surgery, using a randomized list created by random allocation software. The intervention group undergo surgery with facial nerve monitoring using continuous intraoperative electromyography, which registers any stimulus that could indicate an irritation of the facial nerve. The control group undergo standard surgery with continuous visual monitoring of the facial nerve, but no additional information from the electromyographic register. Post operative facial nerve movement will be recorded using a HD camera and graded by experienced physicians at 30, 90 and 180 days after the surgery. CONDITION: Facial nerve dysfunction following superficial parotidectomy ; Surgery ; Facial nerve dysfunction PRIMARY OUTCOME: Incidence of facial nerve dysfunction measured by experienced physicians up to 30 days (immediate) and 180 days (late) following superficial parotidectomy SECONDARY OUTCOME: Degree of facial nerve dysfunction evaluated by experienced physicians at 30, 90 and 180 days following surgery INCLUSION CRITERIA: 1. Adult 2. Aged 18 to 85 years 3. Benign parotid tumor(s) 4. Normal neuromuscular facial function prior to surgery