11 Obliteration of the Middle Ear (Subtotal Petrosectomy) in Cholesteatoma Surgery

In some patients, obliteration of the middle ear (subtotal petrosectomy) using abdominal fat with blind sac closure of the external auditory canal and closure of the eustachian tube is reasonable, or even necessary.

In case of cholesteatoma in dead ear, the only concern of that ear is to avoid recurrence. If the technique is properly executed, subtotal petrosectomy is an ultimate solution to eliminate any possibility of recurrence.

Even though there is some residue of bone conduction, heavy erosion of the labyrinth makes leaving matrix on it difficult. It eventually further invaginates into labyrinth, or causes labyrinthitis to make situation more complicated. In such cases, the labyrinth is drilled and the cavity is packed with abdominal fat.

In some advanced cases of unilateral cholesteatoma with mental retardation, maintenance of the open cavity for life is impractical. In such cases, closure of the ear might be a good solution. Meticulous audiologic examination using objective measures such as auditory brainstem response (ABR) and auditory steady-state response (ASSR) is required before surgery to verify good contralateral hearing.

A chronically inflamed open cavity with nonserviceable hearing is one of the most common candidates for obliteration of the middle ear. The patient is annoyed with multiple surgical interventions, repetitive odorous otorrhea, or frequent episode of vertigo due to thermal stimulation. This technique frees the patients from such a troublesome state, reduce frequency of office visits, and eventually improves the quality of life.

The technique can be applied even in cases with intact bony canal wall if the patient still has an inflamed ear with no recovery of hearing after multiple ear surgery.

In some advanced cases of recurrent cholesteatoma with huge pneumatization, achievement of a trouble-free canal wall down cavity using partial obliteration technique with bone paste and/or vascularized flaps is not practical. In such cases, obliteration of the middle ear can be one of the therapeutic choice, depending on contralateral hearing and the patient’s age.

Cholesteatomas with unmanageable exposure of the dura, and presence of a large labyrinthine fistula with no possibility of good hearing are other indications for subtotal petrosectomy.

A CSF leakage from a tear of the dura may occur as a surgical complication. If the leak is severe, obliteration of the cavity after repairing the dural defect with either fascia or piece of muscle is indicated. To reduce the risk of possibly lethal meningitis, air cells are intensively removed to eliminate possible pathway for CSF.

In the majority of large meningoencephalic herniation with cholesteatoma can be treated with combined extradural middle fossa and transmastoid approach. However, in some cases of very large meningoencephalic herniation reconstruction of the bone erosion is impractical, and obliteration of the middle ear after reducing the herniation and dissecting the cholesteatoma matrix is a safer choice.

The obliteration technique is also applied to cochlear implants in some special situations of cholesteatoma surgery (see Chapter 12).

In the obliterating procedure, it is very important to remove all squamous epithelium within the cavity by carrying out meticulous dissection and correct drilling techniques. However, especially in cases of cholesteatoma with thin matrix covering the dura, remnant of such epithelium may eventually form residual cholesteatoma, and radiologic follow-up of the obliterated cavity with magnetic resonance imaging (MRI) using fat suppression and diffusion sequences is mandatory.

11.1 Surgical Steps to Close the External Auditory Canal

1. 
   

   After the wide retroauricular incision that extends superior and inferior more anteriorly for better access and possibility to reflect the pinna, the external ear canal is identified (▶Fig. 11.1).

   
   
2. 
   

   The skin of the lateral part of the external ear canal is then circumferentially elevated for the width of about 1 cm. For elevation of the skin the microscope or loop glasses can be used for better visualization (▶Fig. 11.2).

   
   
3. 
   

   The external ear canal is now transected. Transection should not be performed too medially as the skin is thinner here, making dissection of the lateral part more difficult (▶Fig. 11.3).

   
   
4. 
   

   Now also the anterior part of the external ear canal is transected (▶Fig. 11.4).

   
   
5. 
   

   Anteriorly, the skin is loosened from the tragal cartilage using blunt scissors (▶Fig. 11.5).

   
   
6. 
   

   The skin of the lateral part of the external meatus is circumferentially loosened for about the width of 1 cm (▶Fig. 11.6).

   
   
7. 
   

   The skin of the external auditory canal is reflected laterally through the meatus to be sutured using resorbable surgical threads (4–0 Vicril; ▶Fig. 11.7).

   
   
8. 
   

   The closure of the second layer of the blind sac is performed using either tragal cartilage or an anteriorly pedicled subcutaneous flap (▶Fig. 11.8, ▶Fig. 11.9).

Case 11.1 (Right Ear): Blind Sac Closure of External Auditory Canal

See ▶Fig. 11.10, ▶Fig. 11.11, ▶Fig. 11.12, ▶Fig. 11.13, ▶Fig. 11.14, ▶Fig. 11.15, ▶Fig. 11.16.

Case 11.2 (Right Ear)

See ▶Fig. 11.17, ▶Fig. 11.18, ▶Fig. 11.19, ▶Fig. 11.20, ▶Fig. 11.21, ▶Fig. 11.22, ▶Fig. 11.23, ▶Fig. 11.24, ▶Fig. 11.25, ▶Fig. 11.26, ▶Fig. 11.27, ▶Fig. 11.28, ▶Fig. 11.29, ▶Fig. 11.30.

Case 11.3 (Right Ear)

See ▶Fig. 11.31, ▶Fig. 11.32, ▶Fig. 11.33, ▶Fig. 11.34, ▶Fig. 11.35, ▶Fig. 11.36, ▶Fig. 11.37, ▶Fig. 11.38, ▶Fig. 11.39, ▶Fig. 11.40, ▶Fig. 11.41, ▶Fig. 11.42.

Case 11.4 (Right Ear)

See ▶Fig. 11.43, ▶Fig. 11.44, ▶Fig. 11.45, ▶Fig. 11.46, ▶Fig. 11.47, ▶Fig. 11.48, ▶Fig. 11.49, ▶Fig. 11.50, ▶Fig. 11.51, ▶Fig. 11.52, ▶Fig. 11.53, ▶Fig. 11.54, ▶Fig. 11.55.

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