Keywords
skull base - reconstruction - facial artery musculomucosal flap - chordoma
Introduction
The facial artery musculomucosal (FAMM) flap was first described by Pribaz et al in
1992.[1] It consists of the mucosa and the submucosa of the cheek and a portion of the buccinator
muscle. It can be pedicled inferiorly on the facial artery and superiorly on the angular
artery, depending on the site of the defect that needs reconstruction. The superiorly
based FAMM flap was successfully used in the reconstruction of the palate, upper vestibule,
nasal cavity, and orbit.[2] Recent research focused on developing modifications to expand the indications of
this flap.[3]
[4] Among these, Xie et al[5] have developed a modification of the FAMM flap in cadavers that increased its length
by adding an extension using the fascia of the masseter for skull base reconstruction.
They demonstrated the feasibility of using this well-vascularized flap for a tension-free
coverage of key areas of the skull base.
The details of the surgical technique are well described and illustrated in their
study.[5] In summary, this modification required a submandibular incision for dissection and
ligation of the cervical facial artery. Then, the buccal and marginal branches of
the facial nerve are carefully dissected from the parotidomasseteric fascia to prevent
a lower facial paralysis. Care should be taken to leave the masseteric fascia in continuity
with the facial artery for proper vascular perfusion of the extension flap. The fascia
and the facial artery are then transferred intraorally through a blunt dissection
anterior to the masseter muscle. The remaining steps in the harvest of the FAMM flap
are achieved according to the standard technique.[1]
The use of the FAMM flap in posterior skull base or nasopharynx reconstruction has
never been reported in a living patient. We report the first case of skull base reconstruction
using a superiorly pedicled FAMM flap modified with an extension to the masseteric
fascia and muscle in a living patient. The defect involved the exposure of the nasopharyngeal
and petrous portions of the internal carotid after an extensive surgical resection
of a chordoma.
Case Report
Our patient is a 71-year-old man who presented at our clinic with odynophagia, dysphagia,
atrophy of the left hemi tongue, and diplopia. His past medical history included dyslipidemia,
hypertension, diabetes, and myocardial infarct. Imaging investigations showed the
presence of a voluminous lesion (4.8 × 6.5 × 8.7 cm) in the left parapharyngeal space
with superior invasion of the clivus, lateral process of C1, and the left occipital
condyle ([Figs. 1] and [2]). A biopsy confirmed the diagnosis of a chordoma ([Fig. 3]).
Fig. 1 Preoperative MRI axial and coronal views in T2W-TSE showing voluminous tumor mainly
located in the left parapharyngeal space with superior invasion of the clivus, lateral
process of C1, and the left occipital condyle.
Fig. 2 Preoperative MRI sagittal T1W-TSE C+ showing the craniocaudal extension of tumor.
Fig. 3 Histologic sections demonstrating cords and lobules of large cells, with small, bland
nuclei and abundant cytoplasm, eosinophilic or vacuolated, in a loose, myxoid stroma.
These cells are positive for the epithelial markers (CK AE1/3, CK8–18, EMA), vimentin
and brachyury; all other markers were negative (S100, RCC, CK5/6, CEA, MOC31).
He first underwent a fusion of the occipital bone to C5 for cervical instability.
Tumor removal required an endoscopic transnasal approach combined with an open cervical
approach for excision of the left parapharyngeal extension. Because adjuvant radiation
therapy was planned for this patient, the defect would best be reconstructed using
a robust vascularized flap.
We harvested an extended retrograde FAMM flap measuring 10 cm in length and 2.5 cm
in width ([Fig. 4]). The flap was transferred through a Caldwell-Luc fenestration to the maxillary
sinus ([Fig. 5A]). An endoscopic maxillary antrostomy was performed and allowed the flap to reach
the nasopharynx by passing through the maxillary sinus ([Fig. 5B]). Once in place, the flap completely covered the petrous portion of the exposed
internal carotid and the extension island flap covered the retrostyloid parapharyngeal
space. The flap was held in place with fibrin sealant topical and petroleum gauze
nasal packing to reduce the risk of retraction from the pulling gravity force.
Fig. 4 Perioperative view of the facial artery musculomucosal (FAMM) flap with an island
extension to the masseter muscle (FAMME flap).
Fig. 5 (A) The transfer of the superiorly pedicled facial artery musculomucosal flap through
the maxillary sinus to the skull base. (B) Postoperative MRI T1W-TSE C+ showing the transmaxillary passage of the FAMM flap
pedicle.
Discussion
The workhorse in skull base reconstruction is the vascularized nasoseptal flap as
described by Hadad et al in 2006 with the ability to lower cerebrospinal fluid leak
rate to 5%.[6] In this case, the nasoseptal flap or the inferior turbinate flap could not be used
because of the extensive invasion of the tumor in the nasal cavity and the posterior
septum. We also anticipated that this patient would need postoperative adjuvant radiation
therapy based on the size and the extent of the tumor. A pericranial flap would have
required a coronal incision leaving a very thin flap for reconstruction with limited
protection for the petrous part of the internal carotid artery (ICA). The use of a
free flap was not considered because of the significant comorbidities of this patient.
The FAMM flap was ideal as it is a robust and well-vascularized regional flap. Furthermore,
the need of a cervical incision for tumor extirpation also encouraged us to use this
flap. Recent studies have focused on developing modifications to expand the indications
of this flap by increasing its length.[3]
[4]
[5] These studies demonstrated the feasibility of using this well-vascularized flap
for a tension-free coverage of key areas of the skull base. The details of the surgical
technique were well described and illustrated in our previous study.[5] In this specific case, a portion of the masseter muscle was harvested along with
its fascia to obtain a bulkier island extension flap ([Fig. 4]). The benefit of this modification is the location of the island extension being
at a certain distance from the distal FAMM flap, which was ideal for our two sites
defects (parapharyngeal and petrous carotid) located at a distance from each other.
At 2 weeks postoperative follow-up, endoscopic examination showed a viable FAMM flap
completely covering the defects ([Fig. 6]). The patient later received adjuvant radiation therapy by means of 60 Gy in 30
fractions. He fully recovered from the diplopia and was temporarily dependent on gastrostomy
tube for feeding. At 49 months of follow-up, the flap and its attached masseteric
island have now mucosalized and are well perfused with no signs of retraction ([Fig. 7]). The most recent magnetic resonance imaging (MRI) showed stability in residual
disease at the clivus and retropharyngeal space ([Fig. 8]).
Fig. 6 Endoscopic view of the facial artery musculomucosal (FAMM) flap 2 weeks postoperative.
The arrow indicates the fascia of the masseter muscle as the extension flap. * Maxillary
sinus.
Fig. 7 Endoscopic view of the facial artery musculomucosal (FAMM) flap 2 months postradiation
therapy and 5 months postsurgery. The arrow indicates the fascia of the masseter muscle
as the extension flap. The dotted line denotes the course of the internal artery covered
by the FAMM flap. * The petrous portion of the skull base.* Maxillary sinus.
Fig. 8 Postoperative and postradiotherapy axial MRI T1W-TSE C+ showing stability of intracranial
and cavernous tumoral residue at 4 years follow-up.
Conclusion
Although successful reconstruction was achieved in our patient, the retrograde FAMM
flap should only be used as an alternative when other clinically proven options are
not suitable. This article serves as an opener to newer indications of the FAMM flap
in head and neck reconstruction of skull base defects.
