Learning Objectives: To describe an operation to access the retrotympanum using the operating microscope and removing bone over the facial recess and sinus tympani safely by mobilizing and utilizing the chorda tympani as an indicator of the position of the facial nerve.
Introduction: The retrotympanum (facial recess and sinus tympani) is involved in a high percentage (48%) of cases of cholesteatoma. This subsite of the mesotympanum presents particular challenges in terms of access for removal of disease. Approaches suggested have included posterior tympanotomy (Janssen) and endoscopic transcanal (Tarabichi).
Method: The operation is described in detail using photography, diagrams and video material. The surgical principles are to use:
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• visualization of the facial nerve at the 2nd genu.
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• skeletonization and mobilization of chorda in its course through the bone down towards its branching off facial nerve above the stylomastoid foramen.
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• the principle that chorda is always superficial and anterior to facial nerve.
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• that if bone is removal only superficial and anterior to chorda, the facial nerve cannot be injured.
We report the use of this technique in a series of 247 cholesteatomas involving the facial recess and sinus tympani. A literature search shows that Farrior (1968) described some aspects of this approach.
Results: This surgical approach provides adequate access to this difficult anatomic area for cholesteatoma visualization and removal – far better than posterior tympanotomy. It provides binocular vision and the possibility of using both hands, unlike the endoscopic approach. In our series, adequate access was provided in 99% of cases – in only 2 cases was there any doubt about complete removal of the invasive sac. In no case was there injury to the facial nerve.
Conclusion: Retrotympanotomy from anterior, mobilizing and using chorda tympani for guidance, is a safe and reliable way of removing cholesteatoma from the facial recess and sinus tympani.
