A "Window" to Protect the Facial Nerve: A Descriptive Cadaveric Study.

INTRODUCTION

Success in skeletal surgery depends on adequate access and exposure of the underlying skeletal structures. The retromandibular approach exposes the ramus condyle region through the posterior border of the mandible by utilizing the space between marginal mandibular and buccal branches of the facial nerve. Length of this safety window and accessibility varies in each individual owing to the differing ramifications of peripheral branches of facial nerve. These variations cannot be adequately assessed through clinical studies. Cadaveric studies permit us to extensively explore the surgical area to demystify the branching pattern and its relationship to the adjacent structures.

METHOD

Thirty well-preserved cadaveric facial halves were dissected using a retromandibular incision. Visibility and accessibility were objectively graded through a scale. The safety window and furcation distance were measured using caliper and scale. The appearance of the retromandibular vein was also noted.

RESULTS

Eighteen facial halves showed maximum accessibility wherein the surgeon is expected to visualize the condylar neck, subcondylar region and posterior half of ramus. In 8 facial halves, accessibility was limited to subcondylar and midportion of posterior ramus, and in 8 facial halves, accessibility was limited to the midportion of ramus of the mandible. Safety window ranged from 1.9 to 3.5 cms. Distance between the posterior border of mandible and bifurcation of the facial nerve ranged from 0.5 to 1.5 cms. Facial nerve was encountered in 24 facial halves during the retromandibular approach. Retromandibular vein was encountered in 23 facial halves during the retromandibular approach.

DISCUSSION

The retromandibular approach is a versatile approach to the condyle subcondylar area as it provides much-required visibility and accessibility. The facial nerve branching pattern and intercommunicating branches determine the safety window which is adequate in most cases. The retromandibular vein is a reliable landmark predicting the vicinity of the facial nerve.