A detailed and comprehensive discussion of transcanal endoscopic management of cholesteatoma is presented. After a presentation of the anatomy of the area, the rationale, advantages and limitations, technique, and long-term results of each technique are presented. A case presentation follows each technique. Techniques presented are: endoscopic transcanal management of limited cholesteatoma, endoscopic open cavity management of cholesteatoma, and expanded transcanal access to middle ear and petrous apex.
Key points
- •
The endoscope offers a new perspective of cholesteatoma and related surgical procedures by increasing the surgeon’s understanding of that disorder and its progression through the temporal bone.
- •
Rediscovering the ear canal as the access port for cholesteatoma surgery is the main story and the main advantage of endoscopic ear surgery. This approach allows a more natural and direct access to and pursuit of cholesteatoma within the middle ear cleft.
- •
Endoscopic Technique allows better access to the tympanic cavity, the birthplace of cholesteatoma, and allows the surgeon to identify the cause for any selective atelectasis or poor ventilation.
- •
The Endoscope allows better access for the tympanic cavity for removal of cholesteatoma especially within the retrotympanum, the anterior attic, anterior mesotympanum, and eustachian tube.
- •
The endoscope is of limited use within the mastoid cavity proper and disease within the mastoid is best eradicated using traditional microscopic approaches.
Introduction
Although it has been 2 decades since the first use of operative endoscopy for the exploration of old mastoid cavities, the endoscope is used infrequently in the day-to-day surgical management of ear disease around the globe for several reasons. The role of the endoscope as defined by many prominent otologists is so marginal that most surgeons have not felt compelled to master newer techniques and instrumentation for its use. In effect, the use of the endoscope did not significantly benefit either the patient or the surgeon. In addition, most physicians have focused on the use of smaller diameter endoscopes for ear surgery, which is frustrating and eliminates the main (and possibly the only) advantage of endoscopy (the wide field of view provided by the endoscope is greater than that of the microscope). Our first experience of using the endoscope in ear surgery was in 1993 during years of practice in the United States. In recent years, it has replaced the microscope as the instrument of choice for use in middle ear surgery. The endoscope offers a new perspective of cholesteatoma and related surgical procedures by increasing the surgeon’s understanding of that disorder and its progression through the temporal bone. Clinicians who use the endoscope during ear surgery realize how the microscope and its limitations have colored the clinical perception of cholesteatoma and have dictated its management ( Videos 1–3 ).
Introduction
Although it has been 2 decades since the first use of operative endoscopy for the exploration of old mastoid cavities, the endoscope is used infrequently in the day-to-day surgical management of ear disease around the globe for several reasons. The role of the endoscope as defined by many prominent otologists is so marginal that most surgeons have not felt compelled to master newer techniques and instrumentation for its use. In effect, the use of the endoscope did not significantly benefit either the patient or the surgeon. In addition, most physicians have focused on the use of smaller diameter endoscopes for ear surgery, which is frustrating and eliminates the main (and possibly the only) advantage of endoscopy (the wide field of view provided by the endoscope is greater than that of the microscope). Our first experience of using the endoscope in ear surgery was in 1993 during years of practice in the United States. In recent years, it has replaced the microscope as the instrument of choice for use in middle ear surgery. The endoscope offers a new perspective of cholesteatoma and related surgical procedures by increasing the surgeon’s understanding of that disorder and its progression through the temporal bone. Clinicians who use the endoscope during ear surgery realize how the microscope and its limitations have colored the clinical perception of cholesteatoma and have dictated its management ( Videos 1–3 ).
History
The introduction of the binocular operating microscope, which was a landmark event in the development of modern otology, clearly changed the scope and character of ear surgery. Despite continuous technical improvements, however, basic optical principles and their limitations have remained the same over the last the decades. The use of the endoscope in various surgical procedures was extrapolated to otologic surgery, and the diagnostic and photographic use of that instrument in the examination of the tympanic membrane and the ear canal has been widely publicized. Transtympanic middle ear endoscopy was initially reported by Nomura and Takahashi and colleagues. Poe and Bottrill used transtympanic endoscopy for the confirmation of perilymphatic fistula and the identification of other middle ear pathologic conditions. Kakehata and colleagues used microendoscopy and transtympanic endoscopy for evaluation of conductive hearing loss and inspection of retraction pockets. Thomassin and colleagues reported on operative ear endoscopy for mastoid cavities and designed an instrument set to be used for that purpose. Badr-el-Dine and El-Messelaty and colleagues reported on the value of endoscopy as an adjunct in cholesteatoma surgery and documented a reduced risk of recurrence when the endoscope was used. The reduction in residual disease was further confirmed by Yung and Ayache and colleagues. Abdel Baki and colleagues reported on using the endoscopic technique to evaluate disease within the sinus tympani. Mattox reported on endoscopy-assisted surgery of the petrous apex. Magnan and Sanna, Bader-el-Dine and colleagues, El-Garem and colleagues, and Rosenberg and colleagues reviewed the role of the endoscope in neuro-otologic procedures. McKennan described second-look endoscopic inspection of mastoid cavities achieved through a small postauricular incision. More recently, Presutti and colleagues and Marchioni and colleagues described primary transcanal endoscopic ear surgery using a similar approach to the experience reported here.
Instrumentation
In the procedures described in this article, 4-mm wide-angle 0-degree and 30-degree Hopkins II telescopes that were 18 cm in length were most often used. More recently, a smaller 3-mm endoscope with a similar field of view to the 4-mm endoscope is being used. Other smaller diameter scopes were used sparingly. Video equipment consisted of a 3-chip video camera and a monitor. All procedures were performed directly off the monitor and were recorded. Instruments used in conjunction with routine microscopic ear surgery are shown in Fig. 1 .
Discussion
The rationale advantages and limitations , and the technique and long-term results of endoscopic transcanal management of limited cholesteatoma, endoscopic open cavity management of cholesteatoma, and expanded transcanal access to the middle ear and petrous apex are discussed in the following sections.
Rationale for Endoscopic Ear Surgery
Acquired cholesteatoma is usually a manifestation of advanced retraction of the tympanic membrane, which occurs when the sac advances into the tympanic cavity proper and then into its extensions, such as the sinus tympani, the facial recess, the hypotympanum, and the attic. Only in advanced cases does a cholesteatoma progress further to reach the mastoid cavity proper. Most surgical failures associated with a postauricular approach seem to occur within the tympanic cavity and its hard-to-reach extensions rather than in the mastoid. Therefore, the most logical approach to the excision of a cholesteatoma involves transcanal access to the tympanic membrane and tympanic cavity and the subsequent step-by-step pursuit of the sac as it passes through the middle ear. Mainstream ear surgery has usually involved the mastoid and the postauricular approaches because operating with the microscope through the auditory canal is a frustrating and almost impossible process.
Advantages and Limitations
The view during microscopic surgery is defined and limited by the narrowest segment of the ear canal ( Fig. 2 ). This basic limitation has forced surgeons to create a parallel port through the mastoid to gain keyhole access to the attic, the facial recess, and the hypotympanum ( Fig. 3 ). In contrast, transcanal operative endoscopy bypasses the narrow segment of the ear canal and provides a wide view that enables surgeons to look around the corner, even when a 0-degree endoscope is used (see Fig. 2 ). Another anatomic observation that supports transcanal access to the attic, which is the most frequent site of cholesteatoma, is the orientation of the ear canal in relation to the attic. Fig. 4 shows a coronal computed tomographic (CT) section through the temporal bone, which reveals that an axis line drawn through the ear canal ends in the attic rather than the mesotympanum. The only structure that is in the way is the scutum, and its removal allows wide and open access to the attic, which is the natural cul de sac of the external auditory canal. Rediscovering the ear canal as the access port for cholesteatoma surgery is the main story and the main advantage of endoscopic ear surgery. This approach allows more natural and direct access to and pursuit of cholesteatoma within the middle ear cleft. In contrast, traditional approaches to the attic and facial recess have provided primarily keyhole access through postauricular mastoidectomy, and many surgeons use the ear canal to access the anterior part of the attic, even during postauricular tympanomastoidectomy. Other areas, such as the hypotympanum and sinus tympani, are minimally accessible even with extensive postauricular mastoidectomy. The wide view provided by the endoscope enables minimally invasive transcanal access to all those areas and facilitates the complete extirpation of disease without the need for a postauricular approach or incision.
Transcanal Endoscopic Anatomy of the Tympanic Cavity
As discussed earlier, the transcanal endoscopic approach provides a new way of looking at the anatomy of the tympanic cavity and, more specifically, the cholesteatoma-bearing areas of that cavity. The endoscope also allows a better understanding of the ligaments and folds of the middle ear and how they affect ventilation of these different spaces. This section highlights the anatomy of some areas and reviews the concept of the epitympanic diaphragm, which plays an important role in the pathophysiology of attic cholesteatoma.
Facial recess
Using the transcanal endoscopic approach, the facial recess becomes an accessible and shallow depression on the posterior wall of the tympanic cavity ( Fig. 5 ). In contrast, the postauricular posterior tympanotomy provides keyhole access to this important area. The pyramidal eminence, along with the vertical segment of the facial nerve, forms the medial wall of the recess and helps to mark the depth of the vertical segment of the facial nerve in that area. The bony annulus that forms the lateral wall of the recess can be taken down safely as long as the pyramidal eminence is continuously observed. The relationship of the bony annulus to the vertical segment of the facial nerve is variable moving inferiorly beyond the pyramidal eminence, and great care should be taken when removing bone from the inferior/posterior aspect of the ear canal and bony annulus.
Retrotympanum
When observing the anatomy of the retrotympanum, it is useful to start by identifying the footplate and the round window. The footplate is located within the posterior sinus that extends around it and posterior to it. The round window is located within the sinus subtympanicum that extends posterior and inferior to it. In between these 2 sinuses lies the sinus tympani ( Fig. 6 ). It is a useful exercise during surgery to start superiorly with the posterior sinus and the footplate, and move inferiorly, identifying the ponticulus, the sinus tympani, the subiculum, and ending up with the sinus subtympanicum where the round window is located ( Fig. 7 ). Inferior to that is the hypotympanum, which is separated from the sinus subtympanicum by the finiculus ( Fig. 8 ).
Attic
The attic forms a compartment that is distinct and separate from the mesotympanum both anatomically and in terms of aeration. Attic retraction pockets present often as an isolated finding with normal ventilation and findings within the mesotympanum. The concept of the epitympanic diaphragm had been advocated and advanced by many clinicians, histologists, and pathologists. However, this concept did not make much of an inroad on the clinical side because of the difficulty in communicating and understanding the difficult anatomy. The endoscope allows a much better understanding of the anatomy of the attic and the reason that this area is distinct and separate from the rest of the middle ear in terms of ventilation.
The attic is a reasonably busy place with the bulk of the ossicular chains and many suspensory ligaments and folds. In the lateral attic, the lateral incudomallear and the lateral mallear folds form a lateral wall that does not allow for ventilation of the attic via the mesotympanum laterally ( Fig. 9 ). The anterior part of these lateral folds forms the medial wall of the Proussak space. The anterior attic is often separated from the anterior mesotympanum and the eustachian tubes by the tensor tympani folds. There are 2 main variations of this structure. The first is an almost horizontal orientation where the folds attach to the tensor tendon posteriorly and to the tympanic wall anteriorly close to the anterior tympanic spine ( Figs. 10 and 11 ). The second is when the supratubal recess is well developed and it pushes the folds almost to a vertical position ( Fig. 12 ). The attic and the supratubal recess are 2 distinct areas anatomically and developmentally. Anatomically, the supratubal recess is often a smooth-walled cavity; in contrast, the attic wall has numerous tags and excrescences. These 2 areas are separated by the transverse crest, a semicircular bony ridge that starts at the medial wall of the attic, runs across the roof, and then the lateral wall of the attic ( Fig. 13 ). Its medial limb starts from the area of the cochleariform process and forms the cog, a commonly recognized surgical term, and a bony protrusion on the medial anterior attic wall (see Fig. 13 ).
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
