Do Benign Mass Lesions in the Superficial Lobe of Parotid Gland Influence Landmark-Based Search for Facial Nerve Trunk at Surgery?Subhadip Sardar1, Mainak Dutta1, Sirshak Dutta2, Saumik Das3, Ramanuj Sinha1
1Department Of Otorhinolaryngology And Head-neck Surgery, Medical College And Hospital, Kolkata, West Bengal, India
2Department Of Otorhinolaryngology And Head-neck Surgery, Raigunj Government Medical College And Hospital, West Bengal, India
3Department Of Otorhinolaryngology And Head-neck Surgery, North Bengal Medical College And Hospital, West Bengal, India
Objective: To assess the influence of benign mass lesions in the superficial lobe of parotid on the known anatomic landmarks for identifying the facial nerve trunk.Keywords: Tragal pointer, posterior belly of digastric muscle, tympanomastoid suture, pleomorphic salivary adenoma, Warthinís tumor, superficial parotidectomy, partial superficial parotidectomy.
Method: Patients with unilateral biopsy-proven benign mass lesions in the superficial parotid were selected for this observational study. During superficial/partial superficial parotidectomy, distance of the facial nerve trunk from each landmark was assessed using spring calliper and correlated with the lesionís volume (measured from the pre-operative imaging). At least two identifiers among tragal pointer (TP), posterior belly of digastric muscle (PBDM) and tympanomastoid suture (TMS) were considered.
Results: The study involved 32 patients. The lesions mostly involved the parotid tail (50%) and pretragal region (34.3%), and constituted of pleomorphic adenoma (~66%) and Warthinís tumor (~9%), the rest being various cysts and hamartomas. TP was universally uncovered, while PBDM and TMS were exposed in 26 and 25 patients, respectively. Average distances between the facial nerve trunk and TP, PBDM and TMS were 12.79 mm (SD=2.33), 9.78 mm (SD=1.21) and 7.58 mm (SD=1.33), respectively. Correlation coefficients between the lesionís volume and the distance of facial nerve from a given landmark were -0.11, 0.04 and -0.16 for TP, PBDM and TMS, respectively.
Conclusions: TP was the most easily available landmark on surgical dissection, while PBDM was the most consistent and the least variable when volumetric data of the benign mass lesions in the superficial lobe of parotid were considered as a factor influencing the distance from the facial nerve trunk.
Subhadip Sardar, Mainak Dutta, Sirshak Dutta, Saumik Das, Ramanuj Sinha. Do Benign Mass Lesions in the Superficial Lobe of Parotid Gland Influence Landmark-Based Search for Facial Nerve Trunk at Surgery?. Medeniyet Med J. 2021; 36(1): 36-43
Corresponding Author: Saumik Das, India