Revision Canal Wall Down Mastoidectomy with Mastoid Obliteration

Revision canal wall down (CWD) mastoidectomy with mastoid obliteration  is most often performed to manage persistent otorrhea and debris accumulation in the mastoid bowl following CWD mastoidectomy. In this case, obliteration is performed for persistent otorrhea from the mastoid bowl and revision CWD mastoidectomy is completed to address a new retraction pocket following a prior CWD mastoidectomy for chronic otitis media with cholesteatoma in a 23-year old male. 

There have been numerous reported techniques used for mastoid obliteration, and in this case, a posterior periosteal flap is made, and the mastoid cavity is filled with autogenous bone paté. Following obliteration of the mastoid, a perichondrial graft is used to cover the area. In this case, a titanium total ossicular reconstruction prosthesis is used to rebuild the ossicular chain, and a second perichondrial graft is used to reconstruct the tympanic membrane. The canal is packed with Gelfoam to secure the fascial grafts in place. Postoperatively, patients are typically advised to remove their head dressing 24 hours following the surgery and to apply a topical antibiotic ointment daily to a cotton ball in the ear.

Mastoidectomy; bone paté; CWD; mastoid obliteration; COM; cholesteatoma.

Revision canal wall down (CWD) mastoidectomy with mastoid obliteration is most often performed to manage persistent otorrhea following CWD mastoidectomy for chronic otitis media (COM) with or without cholesteatoma.^1,2

The goal of the initial mastoid surgery is to create a dry, safe ear and preserve as much hearing as possible.³ The primary indications for mastoidectomy include cholesteatoma or neoplastic extension into the mastoid and relative indications are a history of profuse otorrhea, tympanoplasty failure, and tympanic membrane perforations requiring a greater degree of exposure.⁴ The options for mastoidectomy include a simple/cortical mastoidectomy, intact canal wall/complete mastoidectomy, CWD/modified radical mastoidectomy, and radical mastoidectomy. Primary mastoid obliteration in course of CWD mastoidectomy enhance long-term outcomes, reducing the need for secondary revision procedures, and improving overall ear stability and dryness. Numerous studies have demonstrated that the use of bone paté as a safe and effective method for obliterating the mastoid cavity either at the time of original CWD mastoidectomy or if revision procedure is required.^26–28

A simple mastoidectomy involves the removal of the mastoid cortex and underlying air cells and is generally performed to drain an acute mastoiditis with subperiosteal abscess.⁵ A canal wall up mastoidectomy involves the removal of additional mastoid air cells lateral to the facial nerve as well as the bony portion of the otic capsule with preservation of both the posterior and superior walls of the external auditory canal.³ A CWD mastoidectomy also involves air cell removal but in this case the walls of the external auditory canal are removed to afford increased exposure of the mesotympanum and epitympanum with the ability to resect middle ear disease and reconstruct the necessary components of ossicular chain in one surgery.⁶ A radical mastoidectomy involves the complete exteriorization of the middle ear and mastoid air cells to form a single cavity and this is reserved for patients with irreversible middle ear disease or unresectable cholesteatoma or neoplasms.⁷

In this surgical case, a revision CWD mastoidectomy with mastoid obliteration and middle ear reconstruction is performed in a 23-year-old male with persistent otorrhea from the mastoid bowl and a new retraction pocket following a prior CWD mastoidectomy for COM with cholesteatoma. The use of picture-in-picture offers our viewers an endoscopic view of the relevant surgical anatomy and key steps of the procedure.

A 23-year-old male with a history of chronic otitis media and cholesteatoma of the right ear with prior CWD mastoidectomy presents with a chief complaint of recurring discharge from the mastoid bowl over the past several months. This discharge is difficult to control despite frequent cleaning and the use of topical antibiotic powders. Otoscopic a new retraction pocket had formed posterior to the remnant of the tympanic membrane and anterior and deep to the head of the malleus.  

Mastoid obliteration is indicated for patients with persistent otorrhea following a CWD mastoidectomy that does not respond to frequent cleaning of the mastoid bowl or topical antibiotic therapy.^1,9 The role of surgery is to reduce the size of the cavity and while it is ideally performed at the time of the initial CWD mastoidectomy, it may be performed as a secondary revision procedure.  

As discussed previously, the primary indication for mastoid obliteration is for chronic middle ear disease following CWD mastoidectomy. However, there are additional indications for the surgery including translabyrinthine acoustic neuroma resection, cerebrospinal fluid leak, temporal bone resection for neoplasm, and extensive temporal bone trauma.^1,2

An indication for mastoid obliteration along with the entire middle ear and eustachian tube is for prevention and management of CSF leak following translabyrinthine acoustic neuroma resection.¹⁰ In addition, it may also be used to manage CSF leak from meningoencephalocele, severe temporal bone trauma, or even spontaneous CSF otorrhea.^11–13 Malignancies that require lateral, subtotal, or total resection of the temporal bone will also require tympanomastoid obliteration irrespective of whether or not there is a concomitant CSF leak.¹⁴

Unique situations requiring mastoid obliteration prior to cochlear implantation include patients with a history of chronic otitis media (COM) or labyrinthitis ossificans, where an extensive drill-out with removal of the posterior canal wall is necessary. These patients will also require mastoid obliteration following mastoidectomy to prevent infection of the electrode array in cases of COM and to ensure adequate surgical access in cases of labyrinthitis ossificans.^1,8,15

The procedure is generally performed under general anesthesia and local injection of 1% lidocaine with 1:100,000 epinephrine for hemostasis is completed via a 27-gauge needle in the posterior-superior ear canal to allow for vasoconstriction of the “vascular strip”.^16,17

A 1-mm knife is used to make one incision at 12 o’clock and another at 7 o’clock to define the locations of the vascular strip. A 15 blade is then used to make a postauricular incision to develop a fascial plane from which to harvest the temporalis fascia. A large amount of fascia is harvested and placed on a Silastic block prior to trimming the excess muscle fibers and shaping the graft for lining the bone paté and completing the tympanoplasty.

A periosteal flap is then elevated to expose the retromastoid bone that will be used to harvest the bone paté for the obliteration. The bony area superior to the squamous aspect of the temporal bone is also used for harvesting.

A large cutting burr is used to produce large, uniform bone paté particles that are collected in the Sheehy bone paté collector. A wire-mesh sleeve in the device collects the particulates while allowing any irrigants to pass through easily. The burr is used along the cortex of the mastoid as well as the squamous temporal bone. Care is taken to avoid entering the air cells to minimize the risk of collecting either epithelial cells or bacteria. Collection stops just prior to exposure of the air cells, and the collected paté is soaked in ofloxacin topical antibiotic ear drops and covered with a damp sponge prior to setting it aside.

The lining of the mastoid is elevated using a Freer and a 15 blade to obtain exposure of the middle ear anatomy. This process begins posteriorly with the periosteal flap and continues to the facial ridge. Following adequate exposure, the relevant anatomy is visualized including the remnants of the tympanic membrane, malleus, and incus.

Elevation of the tympanic membrane is attempted with insufflation of nitrous oxide; however, the membrane appears to be adherent down to the footplate. An inferior incision is made with a 1-mm knife to elevate a tympanomeatal flap and obtain access to the middle ear. A 3-mm suction and round knife are used to carefully elevate the tympanic membrane superiorly. In this case, the jugular bulb is observed in a high-riding position with superficial bony dehiscence and is delicately avoided. In the process of elevating the tympanic membrane from its collapsed position on the cochlear promontory, the chorda tympani is visualized and sacrificed due to its proximity to the retracted drum. Bellucci scissors and a round knife are used to remove the excess skin debris in and around the mastoid. The tensor tympani tendon is sacrificed as well. A dehiscent facial nerve is identified at the first genu prior to heading towards the geniculate ganglion and the facial nerve stimulator is used to assess the nerve function. The remainder of the annulus is elevated.

The mastoid is saucerized with a diamond drill, and a bulb irrigator and suction are used to cool the surface throughout this process. The surface is contoured to create a rounded shallow mastoid bowl, which will be easier to pack with the bone paté. Any remaining skin is removed via drilling and the surfaces are polished with careful attention to the anterior epitympanic space. The sigmoid is skeletonized with caution taken around the tegmen. Any bleeding is controlled. Cartilage for the tympanic membrane restoration graft is harvested.

Additional perichondrium is harvested to reconstruct the tympanic membrane as well as to prevent extrusion of the titanium total reconstruction prosthesis that will be used. The prosthesis is sized. Gelfoam and Amerigel are placed underneath the tympanic membrane remnant.

Proper coverage of the dehiscent facial nerve is essential to prevent postoperative facial nerve palsy and ensure optimal surgical outcomes. Various materials and techniques are used to cover and protect the nerve, including autologous materials (fascia, cartilage, or bone paté), bioactive glass, and alloplastic materials such as silicone slices or hydroxyapatite cement. These materials are chosen for their durability and ease of use. Before mastoid obliteration with bone paté, we cover the dehiscent facial nerve using gel film to minimize the risk of facial nerve damage and reduce scarring. Although the bone paté will also cover the dehiscent facial nerve, double protection is important. The mastoid is completely obliterated with bone paté. Careful attention is necessary to keep the bone paté dry by blotting with the cotton tip applicators and suctioning when necessary.

The fascia graft is then shaped and prepared for placement. A Rosen needle is used to slide the graft underneath the remnant tympanic membrane, and the inferior tympanomeatal flap is then secured over the graft to complete a medial underlay tympanoplasty. A titanium Alto total ossicular reconstruction prosthesis (Grace Medical) is adjusted to the appropriate length (4.5 mm) by ratcheting the platform up and down on the prosthesis stem. A trimmer is used to remove the stem of the prosthesis. The prosthesis is then positioned with its head placed just medial to the cartilage graft, and the longer, thinner foot inserted into the stapes footplate at the oval window. Additional Gelfoam packing is applied to secure the graft and prosthesis in place.

Additional Gelfoam is applied to cover any areas of exposed bone paté. The vascular strip, created at the beginning of the procedure, is then placed flat against the posterior canal wall. The overlying fascial layer is anchored to the surrounding fascia, covering the remainder of the bone paté and providing a strength layer for incision closure. After securing the deep fascial layer, the overlying skin of the ear is loosely reapproximated to close the postauricular incision. Finally, the canal is packed with additional Gelfoam.

Mastoid obliteration to address a mastoidectomy defect has been performed since the early 20th century with the original technique first described by Mosher in 1911.¹⁸ Over the last century, a range of approaches have been used to obliterate the mastoid cavity including muscle, periosteal, or fascial flaps as well as free grafts/ceramics (bone, cartilage, hydroxyapatite), and even the combination of the two strategies as introduced by Palva in 1978.^19–24 In this case, an autologous bone paté in combination with an inferiorly based fascia graft was performed to complete the mastoid obliteration.

As proposed by Takahashi et al in 2007, a key advantage of using bone paté is that it minimizes the likelihood of pocket formation as it can be shaped smoothly against the exteriorized surface of the mastoid cavity.²⁵ Numerous studies have demonstrated that the use of bone paté as a safe and effective method for obliterating the mastoid cavity either at the time of original CWD mastoidectomy or if revision procedure is required.^26–28

Askar et al. (2019) report on mastoid reconstruction using platelet-rich plasma (PRP) and bone paté after CWD mastoidectomy. Involving 21 patients, the study found that PRP and bone paté led to good healing outcomes, with no cases of external canal stenosis or mastoid fistulas during the 12 to 16 months follow up. The reconstructed mastoid cavities were smooth, well-aerated, and had minimal complications.³⁰

Bernardeschi et al. (2017) evaluated the use of bioactive glass S53P4 for mastoid and epitympanic obliteration in 41 patients. The study found significant improvements in hearing, well-healed anatomical structures, and enhanced quality of life, with minimal complications. Bioactive glass S53P4 proved effective for mastoid and epitympanic obliteration.³¹

Pontillo et al. (2023) evaluated the quality of life (QoL) after revision CWD mastoidectomy with mastoid obliteration in cholesteatoma patients. The study found no significant difference in postoperative QoL between those who underwent revision CWD and primary CWD with obliteration.³²

Given the heterogeneity in the surgical options as well as the lack of standardization in reported outcomes from each case series, it is difficult to determine an ideal procedure, material, or timing for mastoid obliteration. In fact, a recent systematic review of all available mastoid obliteration and reconstruction techniques reported in the literature suggests that there is a specific lack of uniformity in reporting auditory outcomes, quality of life improvement, and imaging studies for evaluation of postoperative disease.²⁹

Future prospective work is necessary to evaluate the efficacy of mastoid obliteration in comparison to repeat CWD mastoidectomy on prevention of recurrent mastoiditis agents on the rate of healing and surgical outcomes.

Meatoplasty is often performed in conjunction with CWD mastoidectomy for several important reasons:

• Improved access and ventilation, which helps in maintaining a dry and healthy mastoid cavity, reducing the risk of infection.
• Enhanced drainage by widening the ear canal.
• Reduced risk of stenosis of the ear canal.
• Ease of follow-up care to manage and monitor the surgical site.
  

However the decision to forgo meatoplasty following revision CWD mastoidectomy with mastoid obliteration was based on several considerations:

• Anatomical Preservation: By not performing meatoplasty, we aimed to preserve the natural anatomy of the external auditory canal, which can be beneficial for postoperative healing and patient comfort.
• Obliteration Technique: The mastoid obliteration technique employed in our study utilized autologous materials, which effectively reduced the size of the mastoid cavity and minimized the need for additional surgical modifications such as meatoplasty.
• Postoperative Outcomes: Our clinical outcomes indicated that the obliteration alone provided sufficient stability and dryness of the ear, with no significant cases of chronic otorrhea or cavity issues that would necessitate meatoplasty.
• Patient-Specific Factors: Each case was evaluated individually, and the decision was tailored to the specific anatomical and clinical needs of the patient. In instances where the external auditory canal was adequately sized and the obliteration was successful, meatoplasty was deemed unnecessary.
  

We believe that this approach optimizes surgical outcomes while minimizing additional surgical interventions. Further studies and long-term follow-up will continue to inform and refine our surgical strategies.

Author C. Scott Brown also works as editor of the Otolaryngology section of the Journal of Medical Insight.

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.