ANATOMICAL VARIATIONS OF THE FACIAL NERVE AND THEIR PHYSIOLOGICAL AND FUNCTIONAL IMPACT ON OUTCOMES IN PAROTID SURGERY: A CROSS-SECTIONAL STUDY

Abstract

Background:
The facial nerve (cranial nerve VII) plays a critical role in facial expression and function. Its preservation during parotid gland surgery is paramount, yet its anatomical variations pose a significant challenge for surgeons. The complexity and unpredictability of these variations, especially in the branching pattern and relation to the parotid tissue, can contribute to postoperative complications, including transient or permanent facial nerve dysfunction. Understanding the anatomical and physiological implications of these variations is essential for optimizing surgical outcomes and minimizing nerve injury.

Objective:
To evaluate the prevalence of anatomical variations in the facial nerve encountered during parotidectomy and to analyze their physiological and functional impact on postoperative outcomes, particularly facial nerve integrity and recovery.

Methodology:
A cross-sectional study was conducted at Sughra Shafi Medical Complex over a period of two years from January 2023 to December 2024. A total of 87 patients undergoing parotidectomy for benign or malignant lesions were enrolled. Intraoperative identification and documentation of facial nerve branching patterns and anatomical deviations were performed. Variations were classified using Katz and Catalano’s system. Postoperative facial nerve function was assessed using the House-Brackmann grading system at 1 week, 1 month, and 3 months post-surgery. Demographic data, type of lesion, extent of surgery, and intraoperative findings were statistically analyzed to determine associations with postoperative nerve function outcomes.

Results:
Anatomical variations of the facial nerve were observed in 48.3% (n=42) of cases. The most frequent variation involved the temporofacial and cervicofacial division pattern. Patients with significant anatomical variations showed a higher incidence of transient postoperative facial weakness (35.7% vs. 13.2%, p=0.011). However, permanent nerve dysfunction at 3 months was low and not statistically significant between groups (4.8% vs. 1.9%, p=0.298). Extended operative time and difficulty in intraoperative nerve identification were also significantly associated with anatomical variations. No significant correlation was found between lesion pathology and nerve variation prevalence.

Conclusion:
Anatomical variations of the facial nerve are common and have a notable impact on the immediate postoperative functional outcomes of parotid surgery. Preoperative imaging and intraoperative neuromonitoring may enhance nerve preservation, particularly in cases with high anatomical variability. A thorough understanding of facial nerve anatomy and its variations is crucial for improving surgical planning and minimizing postoperative complications.