Facial paralysis after superficial parotidectomy: analysis of possible predictors of this complication.

Introduction: Salivary gland tumors represent 3-10% of all head and neck neoplasms. These tumors occur predominantly in major salivary glands. The parotid gland is affected most often, ranging from 36.6% to 83%. The pleomorphic adenoma comprises 45-60% of all salivary gland tumors. Several surgical approaches have been described to treat this tumor. Lesion of the facial nerve is one of the most serious complications that can occur after parotid gland surgery.

Objectives: To determine possible predictive factors related to the occurrence of peripheral facial paralysis (PFP) after superficial parotidectomy in the surgical treatment of the pleomorphic adenomas of the parotid gland.

Methods: This was a primary, observational, case-control study performed through the revision of patients' charts and histopathological reports. Data was obtained from 1995 to 2014. The analyzed events were: tumor's length and depth; duration of the disease referred by the patient (more than 1, 5 or 10 years); primary or secondary surgical approach.

Results: The analysis showed that tumor lengths equal or superior to 3.0cm were a risk factor of PFP with an odds ratio of 3.98 (p=0.0310). Tumor depths equal or superior to 2.0cm were also a risk factor with an odds ratio of 9.5556 (p=0.0049). When the tested event was secondary surgery to recurrent tumors we have found an odds ratio of 6.7778 (p=0.0029).

Conclusion: Tumors with 3.0cm or more in length and/or 2.0cm or more in depth have a significant higher risk of facial nerve injury. Secondary surgery to recurrent tumors also has a much higher risk of evolving with facial palsy after superficial parotidectomy.