Keywords
mastoid - ear deformities - acquired - otologic surgical procedures - vascularized
bone flap - wound closure techniques
Introduction
A most common complaint of patients after mastoidectomy is depressions in the mastoid
cortical bone in the retroauricular region, which is the surgical site ([Fig. 1]). This depression occurs mainly in procedures that require wide openings on the
mastoid, such as: open or closed mastoidectomy for chronic ear and cholesteatoma;
translabyrinthine approach for tumors of the acoustic nerve; congenital cholesteatomas;
decompression of the facial nerve; approaches to endolymphatic sac; and cochlear implants,
among others.
Fig. 1 Late retroauricular depression in a patient who underwent schwannoma resection via
the presigmoid approach.
For closing the cavity resulting from cell removal, most surgeons simply overlay the
cavity with connective tissue and skin, and then suture it in two layers, while some
overlay it with a muscle periosteal flap.[1]
Invariable retractions arise after surgery, with more or less intensity in all patients
and remain even after years of surgery, even when using materials such as muscle or
fat underneath the muscle periosteal flap to obliterate the cavity and close dura
mater defects or prevent cerebrospinal fluid leaks.
The most common complaints of patients include pain and discomfort to the touch, uncomfortable
feeling while wearing glasses because of the contact of the temple tips with the depression
caused by the surgery, accumulation of skin peeling, difficulty of dirt removal, and
aesthetic problems. It is common to find dirt accumulation in bone depressions when
examining patients who underwent mastoidectomy surgery ([Fig. 2]).
Fig. 2 Dirt accumulated in the retroauricular depression in a late-postoperative patient.
In addition to these complaints and aesthetic problems, we know that the mastoid cavity
maintains the middle ear pressure, acting as a reservoir of air, and aids in the effective
conduction of sound as a sound box.[1] Reconstruction of the mastoid defect is desirable to maintain the mastoid cavity
closest to its physiological function, preventing the growth of fibrous tissue into
the surgical cavity.
Several types of flaps have been described to minimize depression, as reported by
Yanagihara et al[2] who found good results with mastoid cortical bone reconstructions using bone pate.
Muscular or periosteal flaps were also used, but favor the formation and invasion
of the cavity by fibrosis and do not prevent depression.[1]
Yuen and Chen[3] synthesized the main reconstruction options available for the correction of bone
defects in schwannoma resection surgeries via the presigmoid approach to prevent further
depression of the region. These options are divided between endogenous and allogeneic
materials. For the allogeneic materials, Jung and Park[4] describe the correction of these depressions in revision surgeries after complaints
from patients on whom they used a titanium mesh to close the resulting bone cavity.
Another option is allogeneic hydroxyapatite cements, which can be prepared and molded
intraoperatively. These favor osseointegration and do not cause foreign body reaction,
but entail a high cost and hamper revision surgeries.[3] The following are endogenous options: local muscle flaps, which also exhibit volumetric
shrinkage over time,[5] and vascularized and non-vascularized bone grafts.[3]
Couldwell and Fukushima[6] and Rica et al[7] described local non-vascularized bone graft techniques. In their cases, the whole
periosteum was peeled off, exposing the cortical bone to be removed. The cortical
bone was removed with the aid of craniotomy blades, kept in saline solution outside
the body during surgery, and repositioned and fixed with titanium plates and screws
at the end of the surgery. Yuen et al[8] described a cranioplasty technique in schwannoma surgeries via the presigmoid approach
by using an inferior pedicle osteomuscular flap, with the periosteum and sternocleidomastoid
muscle preserved, and the flap attached to bone cortical mastoid. The flap was folded
inferiorly to the tip of mastoid process and repositioned at the end of the surgery
without fixation by plates and screws, just suturing the periosteal flap to the periosteum
around it.
The aim of this study was to describe the surgical technique of using a pedicle osteoperiosteal
flap in the anterior region of the mastoid approach to prevent retroauricular depression
and evaluate the intraoperative and immediate postoperative outcomes.
Methods
This technique was performed to date in 14 patients, of whom 5 underwent primary surgery
for schwannoma vestibular resection via the pre-sigmoid approach and 9 underwent cochlear
implant surgery ([Table 1]). All the patients underwent computed tomography (CT) of the temporal bones for
surgical planning and preoperative evaluation of the position of the sigmoid sinus.
We excluded patients with sigmoid sinuses that were lateralized and prominent due
to the risk of injury during flap creation.
Table 1
Patients already subjected to the osteoplastic flap technique
|
Patient
|
Surgery Type
|
Age (years)
|
Sex
|
|
1
|
Schwannoma excision
|
31
|
Female
|
|
2
|
Schwannoma excision
|
35
|
Male
|
|
3
|
Schwannoma excision
|
54
|
Female
|
|
4
|
Cochlear Implant
|
29
|
Male
|
|
5
|
Cochlear Implant
|
4
|
Male
|
|
6
|
Cochlear Implant
|
46
|
Male
|
|
7
|
Cochlear Implant
|
52
|
Male
|
|
8
|
Schwannoma excision
|
66
|
Male
|
|
9
|
Schwannoma excision
|
62
|
Male
|
|
10
|
Cochlear Implant
|
38
|
Male
|
|
11
|
Cochlear Implant
|
26
|
Female
|
|
12
|
Cochlear Implant
|
56
|
Female
|
|
13
|
Cochlear Implant
|
5
|
Male
|
|
14
|
Cochlear Implant
|
72
|
Female
|
After retroauricular incision, the periosteum of the retroauricular region was exposed.
We performed a U-shaped incision, delimiting the periosteum area appropriate to the
size of the mastoidectomy to be achieved ([Fig. 3]). With a small elevator, the periosteum was deviated from the entire incision to
expose the mastoid cortical bone to achieve drilling ([Fig. 4]).
Fig. 3 U-shaped incision of the periosteum.
Fig. 4 Exposure of the cortical bone with the aid of a curette, removing the periosteum.
We opened the cortical bone with a 2.5-mm drill around the perimeter of the “U,” at
a depth of ∼3mm ([Fig. 5]). Then, with the drill acting at an angle of ∼20 degrees to the cortical bone, a
bone flap ∼3 mm thick was created around, deepening to ∼1 cm parallel to the cortical
bone ([Fig. 6]). We gently introduced a chisel through the surface cells of the mastoid and hammered
to an anterior direction until it got close to the ear canal ([Fig. 7]).
Fig. 5 Boring of the mastoid cortical bone in the “U” region.
Fig. 6 Deepening and anteriorization of the drilling.
Fig. 7 Separation of the mastoid osteoperiosteal flap with the aid of a chisel and hammer.
When the entire length of the osteoperiosteal flap detached from the cortical bone,
it was lifted, leaving the periosteum adhered to it and forming a “cap” of bone, with
the periosteum pedicled on the anterior portion ([Fig. 8]). The flap was fixed anteriorly to not hinder the surgical procedure ([Fig. 9]), and the mastoid drilling was performed normally.
Fig. 8 Lifting of the osteoperiosteal flap.
Fig. 9 Flap anterior fixation with suture to protect it and not hinder surgery.
After the procedure, the flap was folded over the cavity and the periosteum edges
were sutured to the corresponding periosteum ([Fig. 10]). The subcutaneous and skin sutures were performed normally, in two layers.
Fig. 10 Flap repositioning and suturing of the periosteum with the adjacent periosteum by
using absorbable suture at the end of surgery.
Results
The first 14 cases had no intraoperative complications, and their appearances in the
intraoperative and immediate postoperative periods were adequate, staying firm and
stable upon digital pressure. CT performed in the immediate postoperative period (the
day after the procedure) revealed the bone flap in position and the aerated aspect
of the mastoid ([Fig. 11]). The average time added to the surgical duration for obtaining this flap was ∼10
minutes.
Fig. 11 Bone axial computed tomographic image obtained immediately after surgery in a patient
who underwent cochlear implant surgery with a flap.
Discussion
Post-mastoidectomy retroauricular depressions are extremely common and cause inconvenience
to many patients. It is desirable to keep the aeration of the mastoid as close to
normal so that the cavity is not filled with fibrosis, which alters its natural function
of volume balance and the gas pressure of the middle ear, as well as their compositions.[9]
The use of synthetic materials such as titanium meshes to cover the cavity has been
successful. However, these materials can cause foreign body reaction, entail high
costs, and require availability of different sizes during surgery. Moreover, their
management in revision surgery can pose a great difficulty and their reuse is not
always possible. Moreover, these materials are not recommended for use in surgeries
for infections such as chronic otitis media, as they may evolve with biofilm and need
future removal for complete control of the infection.
The use of free grafts, bone pate, or even bone plates from bone stock has the disadvantage
of not being pedicled and, therefore, non-vascularized. This makes their nutrition
difficult and facilitates resorption with time, becoming necrotic and easily infected.
The flap described by Yuen et al[8] is also vascularized. However, unlike our proposed flap, it is inferiorly pedicled
in the sternocleidomastoid muscle region. Because of this feature, this technique
cannot be used with minor flaps, which always require a flap that goes near the dura
mater of the middle fossa to the tip of the mastoid, as this is unnecessary for most
non-tumor ear surgeries. Another drawback of this technique is the handling of the
sternocleidomastoid muscle, which can increase postoperative pain.
The flap we proposed has the advantage of being obtainable from the patient. It can
be made to the size appropriate for the intended procedure. Being pedicled, it allows
for irrigation and thus minimizes the risk of infection and necrosis.
The risk of complications is minimal. The major one is the possible exposure of the
sigmoid sinus when it is elevated and lateralized. Thorough evaluation of preoperative
CT scans can prevent this exposure and aid in flap planning and selection of patients
for whom it can be performed safely. Another advantage is that if found during surgery
that it cannot be used, the flap can be converted to a periosteal flap, as it has
always been used.
Conclusion
The osteoplastic flap pedicle is a safe, fast, and simple procedure, presenting good
results in the immediate postoperative period. Several cases are being followed up
so that results from at least 1 year of follow-up can be reported in future publications.
