Objectives: The study objectives are to present the neurosurgical perspective for the endoscopic
transmeatal approach to the middle ear and internal acoustic canal, and to examine
this approach for potential neurosurgical applications.
Background: Lateral skull base surgery is complex, with new approaches continually being developed
to meet surgical challenges. Smaller lesions diagnosed early may be amenable to treatment
with minimally invasive endoscopic techniques.
Materials and Methods: We documented two step-by-step endoscopic transmeatal approach procedures into the
middle ear and the internal acoustic canal using Storz 0° and 30° endoscopes at the
University of Wisconsin-Madison Microneurosurgery Laboratory. This included photographic
and video documentation with technical notes on the surgical techniques and the identification
of key anatomical landmarks. A retroauricular C-shaped incision was made, followed by resection of the tympanic membrane and drilling
of the external acoustic canal to increase exposure and improve the working angle.
Results: We successfully performed two endoscopic transmeatal approaches, identifying the
tympanic membrane and subsequently the round window, all three ossicles, and the promontory,
lateral and superior semicircular canals. Also identified were the eustachian tube,
chorda tympani, tensor tympani muscles, and the topography of the internal carotid
artery and jugular bulb. This approach also facilitated the opening of the internal
acoustic canal with a high-speed drill, identification of the VII and VIII cranial
nerves, and the anterior inferior cerebellar artery loop. Introducing the endoscope
into the internal acoustic canal enabled us to visualize the lateral surface of the
pons, the tentorium, the trigeminal nerve, and the superior petrous vein.
Conclusion: The endoscopic transmeatal approach offers a minimally invasive option for accessing
the middle ear and internal acoustic canal that may be used in selected cases.
