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Bredell M, Grätz K. Sublingual gland flap for reconstruction of anterior and antero-lateral floor of mouth defects. Head Neck Oncol. 2013 Apr 01;5(4):38.

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Sublingual gland flap for reconstruction of anterior and antero-lateral floor of mouth defects

M Bredell; K Grätz

Department of Craniomaxillofacial and Oral Surgery, University Hospital of Zürich, Zürich, Switzerland

Corresponding Author:

M Bredell

E Mail:

M Bredell: marius.bredell@usz.ch

K Grätz: klaus.graetz@usz.ch

Manuscript type: Research All authors contributed to conception and design, manuscript preparation, read and approved the final manuscript. All authors abide by the Association for Medical Ethics (AME) ethical rules of disclosure. Competing interests: none declared Conflict of interests: none declared

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Abstract:

Background:

Functional closure of floor of mouth defects remain a challenge. A new method of

reconstruction of the anterior and antero-lateral floor of mouth and mandibular

defects after ablative surgery is described.

Methods:

Six consecutive patients with suitable T1 and T2 floor of mouth and mandibular

alveolar carcinomas were investigated regarding the use of the sublingual gland as a

flap for the coverage of the resection defects.

Results:

In all patients it was possible to mobilize the remaining part of the sublingual gland or

contra lateral sub lingual gland to such an extent that full coverage of the defect was

possible. Vascular perfusion could be maintained in all cases and further healing

was uneventful apart from a mucocele development in one patient.

Conclusions:

The sublingual flap should be considered as a reliable reconstructive option for most

T1 and smaller T2 lesions for the anterior and antero-lateral floor of mouth or

mandible.

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Introduction:

Floor of mouth defects; especially when combined with anterior mandibular defects

may be challenging to reconstruct. Often the defects are closed primarily, left to

granulate or covered by local or regional or even distant flaps.

Most commonly, floor of mouth malignancies such as squamous cell carcinomas lead

to wide resection of the floor of mouth mucosa and submucosal structures (1). Same

can be said for the anterior or antero-lateral mandibular region where the lingual or

buccal mucosa may be involved leading to resection of the mandibular alveolar bone

as well as part of the floor of mouth. For smaller lesions direct closure may be

possible with the aid of local or regional tissue flaps or left to heal by secondary

intention, however larger defects are most commonly covered by split thickness skin

grafts, nasolabial flaps (2-5) or free flaps, mostly radial forearm free flaps.

Lesions may be unilateral; however the resultant defects may then extend over the

midline to the contra lateral side. Anatomical structures that may be involved are

multiple and include the mucosa, submandibular and sublingual ducts and orifices(6),

peripheral lingual as well as hypoglossal nerve branches, lingual and deep lingual

arteries, the lingual and sublingual veins, sublingual gland (SLG), genioglossus

muscle as well as the anterior mandibular alveolar bone and mucosa.

Nearly all reconstructive efforts that do not involve the transfer of vascularised tissue

have the potential of scarring with resultant limited mobility of the tongue and

potential speech or chewing impairments. When the labial mucosa is mobilized the

lower lip may be retracted lingually. Ideal reconstructive efforts will utilize local and or

regional tissues with minimal donor site morbidity.

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The purpose of this paper is to describe the use of the sublingual gland, mobilized

sufficiently to be utilized as a vascularised flap with an axial blood supply for

coverage of anterior or antero-lateral floor of mouth and mandibular defects. To the

authors knowledge it is the first description of the use of the sublingual gland flap for

reconstructive purposes.

Anatomical basis:

The sublingual gland is paired and located in the anterior most position of the floor of

mouth. It is wedged between the mandible and genioglossus muscle medially and

lies on the mylohyoid muscle, covered by a thin layer of mobile mucosa. It is

separated from the genioglossus muscle by the lingual nerve as well as the

submandibular duct. Vascular supply comes from the sublingual artery, a branch of

the lingual artery that also supplies the mylohoid muscle and surrounding mucosa

with a midline arterial anastamosis between the left and rights arterial systems.

Venous drainage is through the sublingual and lingual venous system and lymphatic

drainage is to the submental lymph nodes. Parasympathetic innervation exists

through the submandibular ganglion and sympathetic innervations through the

superior cervical ganglion(7). Extension through the mylohyoid muscle may exist with

contact and in some cases apparent fusion with the submandibular gland (SMG) as

the SLG is not bordered by a capsule. Most commonly the sublingual gland is

described to have 8-20 secretory ducts (ducts of Rivinus) while the smaller ducts fuse

into a major duct (Bartholin’s duct). Three variants of ductal anatomy can be

identified with the most common variant where the SLG as well as SMG have major

ducts that merge. Second commonest appears to be multiple small diameter ducts

without a major duct. Least common is where both the SLG and SMG have major

ducts that do not appear to fuse.(6)

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Size of the SLG varies greatly with hypertrophy being described frequently, possibly

more in edentulous patients (8, 9). Age related changes do occur with progressive

increase in ductal structures, acinar atrophy and an increase in adipose tissue that is

often not related to an increase in alcohol intake(10). Herniation of the SLG through

the mylohyoid muscle often occurs and should be considered when performing

mobilization of the SLG (11, 12).

Patients and methods:

Patients with T1 or T2 floor of mouth or anterior alveolar tumors where resection

would lead to a significant defect requiring reconstruction were identified. All patients

routinely received detailed informed consent for tumor resection as well as

reconstruction with either local or regional flaps as well as a possible free flap

reconstruction, mostly a radial forearm free flap if the defect size was greater than

expected. After tumor resection with frozen sections, confirming clear and safe

margins of 5mm or more the defects were accessed for possible reconstructive

options. As the submandibular duct orifices were frequently involved in the resection,

transection of the ducts and more posterior displacement was performed when

indicated. Resections may have involved none or in larger tumors a lesser or larger

component of the component of the SLG.

Careful mobilization of one or both of the whole or remaining part of the SLG from the

overlying mucosa, submandibular duct, the lingual nerve and mylohyoid muscle as

well as from the mandible was then performed, with careful preservation of the

feeding and draining vasculature that can be seen entering the SLG from the side of

the lingual artery. No attempt was made to identify the ducts of the SLG. In most

cases significant mobilization of the SLG could be achieved, even past the anterior

border of the mandible that allowed passive positioning of the SLG flap without

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significant tongue displacement (Fig 2a). Where herniation of the SLG through the

mylohyoid muscle was present the dissection was extended to this level and

separation from the SMG was performed. Fixation was achieved with resorbable

sutures, either to surrounding soft tissues or to the mandibular bone through bur

holes. Surgery was completed by ensuring adequate haemostasis and covering the

defect with a layer of fibrin glue and iodine gauze packing sutured in place and

removed after 7-10 days, further healing took place by secondary intent. Where a

marginal mandibular resection was performed a partial denture was placed as soon

as possible to act as a soft tissue expander. Three patients had concurrent

supraomohyoidal neck dissection and one patient received a sentinel lymph node

biopsy.

Results:

Five patients with defects in the anterior or lateral floor of mouth with concurrent bony

defect and one patient without marginal mandibular resection were treated by this

method. Four patients had T2 and two patients had T1 lesions. In three patients the

resented area was within the canine to canine region and two had more posterior

defects. (Fig 1a) All patients recovered well, one patient presented with a retention

cyst six weeks after surgery that was treated by de-roofing of the retention cyst under

local anesthesia. (Fig 2 b) All patients were partially or fully dentate. Even where an

extensive surface of uncovered bone was involved this could be covered without a

problem.

Table I:

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Where the flap was used to cover a mandibular defect a substantial thickness of

tissue was achieved, but in all cases the placement of a partial denture would be

possible after the removal of the iodine gauze packing. A vestibuloplasty may be

indicated to lower the floor of mouth at time of implant placement or exposure.

Tongue mobility was not inhibited significantly and no secondary revisions were

necessary. No oro-cutaneous fistulas developed and no patients complained of

xerostomia. Slight elevation of the floor of mouth could be observed, but was of little

clinical significance.

Figure 1a

Figure 1b

Figure 2a

Figure 2b

Discussion:

Anterior floor of mouth and anterior mandibular resection defects may pose

significant challenges to the surgeon. Smaller defects can be left to heal by

secondary intention or covered by a split thickness skin graft that fairly consequently

leads to scar contraction. Increasing depth of tumor invasion leads to a deeper

resection and the likelihood of a partial or full resection of the one or both sublingual

glands increases. Microscopic infiltration of the SLG is significantly more common

when the tumor infiltration depth exceeds 5mm (13). Generally reported infiltration

rates of the SLG are as low as 27% (13) or may be as high as high as 48%(1). Intra

operative clinical judgment of the invasion of the SLG may be correct in up to 88% of

cases (13) which can possibly be increased by pre-operative MRI examination. Due

to the various infiltration rates the recommendation to routinely excise the sublingual

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gland as well as the genioglossus muscle (1) cannot be universally accepted. An

individualized approach probably is a wiser way of approaching the different

scenarios regarding infiltration of deeper structures. In most of the smaller tumors

involving the floor of mouth as well as the lingual mucosa of the mandible a

significant portion of the sublingual gland can be preserved. Uncovered mandibular

bone after a marginal resection remains a challenge and has to be covered by local

or regional flaps(14). In smaller defects mobilization of the labial mucosa is an option,

however retraction of the lower lip may be problematic. Regarding regional flaps, the

nasolabial and facial artery musculo-mucosal (FAMM) flaps are the most useful,

however may be problematic in dentate patients. A possible solution to this may be

the island variation of the FAMM flap (3, 4) where the vascular pedicle may be

tunneled through a space of an absent tooth.

Further options are the various tongue flaps (15)or the mere mobilization of the floor

of mouth tissues anteriorly (16). All these options have the risk of impaired tongue

mobility. Another regional flap that allows adequate reconstruction of larger defects of

the floor of mouth is the submental island flap (17) that may be comparative to the

radial forearm free flap. Potential problems with the submental island flap are the

potential excess of adipose tissue and limitations when performing a simultaneous

neck dissection. In our experience the radial forearm free flap stays the flap of

choice for larger defect coverage (18) due to the thin pliable skin that undergoes

minimal scarring and allows for maximal tongue mobility. All of the mentioned

options for defect closure have some component of donor site morbidity or has to be

performed as a two stage procedure.

As the sublingual gland or remnants thereof are freely available and can be utilized

with minimal morbidity, the sublingual salivary gland flap has been demonstrated as

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an option for the closure of defects in the anterior or even the lateral floor of mouth

and anterior or lateral part of the mandible. Significant defects of the mandible as well

as unilateral or contra lateral defects may be covered with adequate mobilization of

this available glandular tissue. Depending on the size of the SLG(8, 9), sizable

defects can be closed in this manner with minimal morbidity and scarring. In this

series no significant complications were noted and the one mucus retention cyst was

treated with minimal effort. As the SLG lends itself to adequate mobilization it has

been demonstrated to be a flap option in the reconstruction after extirpation of T1

and T2 lesions.

In conclusion, many options exist for the reconstruction of anterior and antero-lateral

floor of mouth and mandibular defects and all have their specific advantages and

disadvantages. The sublingual flap should be considered as a reliable reconstructive

option for all T1 and smaller T2 lesions for the anterior and antero-lateral floor of

mouth or mandible.

List of abbreviations:

SLG: Sublingual gland

SMG: Submandibular gland

FAMM: Facial artery musculo-mucosal

Competing interests:

None

Author’s contributions:

Marius Bredell initiated the surgical principle, surgery and drafted the paper

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Astrid Kruse Gujer contributed to the surgery and contributed to the paper

Klaus Grätz contributed to the drafting of the paper

References:

1. Steinhart H, Kleinsasser O. Growth and spread of squamous cell carcinoma of the floor of the mouth. European Archives of Oto-Rhino-Laryngology. [Research Support, Non-U.S. Gov't]. 1993;250(6):358-61. 2. Napolitano M, Mast BA. The nasolabial flap revisited as an adjunct to floor-of-mouth reconstruction. Annals of Plastic Surgery. 2001 Mar;46(3):265-8. 3. Rose EH. One-stage arterialized nasolabial island flap for floor of mouth reconstruction. Annals of Plastic Surgery. [Case Reports]. 1981 Jan;6(1):71-5. 4. Uglesic V, Virag M. Musculomucosal nasolabial island flaps for floor of mouth reconstruction. Br J Plast Surg. 1995 Jan;48(1):8-10. 5. Varghese BT, Sebastian P, Cherian T, Mohan PM, Ahmed I, Koshy CM, et al. Nasolabial flaps in oral reconstruction: an analysis of 224 cases. Br J Plast Surg. 2001 Sep;54(6):499-503. 6. Zhang L, Xu H, Cai Z-g, Mao C, Wang Y, Peng X, et al. Clinical and anatomic study on the ducts of the submandibular and sublingual glands. Journal of Oral & Maxillofacial Surgery. [Research Support, Non-U.S. Gov't]. 2010 Mar;68(3):606-10. 7. S S. Gray's Anatomy. The anatomical basis of clinical practice. 39th ed. London: Elsevier,Ltd.; 2005. 8. Campos LA. Hyperplasia of the sublingual glands in adult patients. Oral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics. 1996 May;81(5):584-5. 9. Domaneschi C, Mauricio AR, Modolo F, Migliari DA. Idiopathic hyperplasia of the sublingual glands in totally or partially edentulous individuals. Oral Surgery Oral Medicine Oral Pathology Oral Radiology & Endodontics. 2007 Mar;103(3):374-7. 10. Azevedo LR, Damante JH, Lara VS, Lauris JRP. Age-related changes in human sublingual glands: a post mortem study. Archives of Oral Biology. 2005 Jun;50(6):565-74. 11. Kiesler K, Gugatschka M, Friedrich G. Incidence and clinical relevance of herniation of the mylohyoid muscle with penetration of the sublingual gland. European Archives of Oto-Rhino-Laryngology. 2007 Sep;264(9):1071-4. 12. Nathan H, Luchansky E. Sublingual gland herniation through the mylohyoid muscle. Oral Surgery, Oral Medicine, Oral Pathology. 1985 Jan;59(1):21-3. 13. Clark JR, Franklin JH, Naranjo N, Odell MJ, Gullane PJ. Sublingual gland resection in squamous cell carcinoma of the floor of mouth: is it necessary? Laryngoscope. [Comparative Study]. 2006 Mar;116(3):382-6.

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14. Flynn MB, Moore C. Marginal resection of the mandible in the management of squamous cancer of the floor of the mouth. American Journal of Surgery. 1974 Oct;128(4):490-3. 15. Harris JP, Fabian RL. Central island myomucosal tongue flap. Head & Neck Surgery. [Case Reports Research Support, U.S. Gov't, P.H.S.]. 1983 Jul-Aug;5(6):495-9.

16. Pai PS, Chaturvedi P, D'Cruz AK, Chaukar DA, Pathak KA, Deshpande MS, et al. Reconstruction of early lower gingivo buccal complex lesions using floor of mouth advancement augmented with hyoglossus release. Journal of Surgical Oncology. 2004 Apr 1;86(1):41-3.

17. Paydarfar JA, Patel UA. Submental island pedicled flap vs radial forearm free flap for oral reconstruction: comparison of outcomes. Archives of Otolaryngology -- Head & Neck Surgery. [Comparative Study Multicenter Study

Research Support, Non-U.S. Gov't]. 2011 Jan;137(1):82-7. 18. Matthews RN, Hodge RA, Eyre J, Davies DM, Walsh-Waring GP. Radial forearm flap for floor of mouth reconstruction. British Journal of Surgery. 1985 Jul;72(7):561-4.

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Legends:

Table 1: Overview of patients with floor of moth defects and reconstruction with

sublingual gland flaps

Figures:

Fig 1a: Lateral mandibular and floor of mouth defect with rotation of the SLG to cover

the premolar and molar area

Fig 1b: Healing 10 days after surgery

Fig 2a: Mobilized sublingual flap for coverage of large anterior mandibular defect

Fig 2b: Mucus retention cyst evident 6 weeks after initial surgery (mirror image)

Patient TNM Concurrent

Neckdissection

Depth of

infiltration

Age Area Functional

restriction

Complications

1 T1N0M0 No not reported 54y Mouth floor right No None

2 T1N1M0 Yes 5mm 47y Anterior floor of mouth Slight tongue

movement

restriction

Small area of bone

exposure (healed

spontaneously)

3 T2N2bM0 SLN (sentinel

lymph node)

not reported 81y Anterior floor of mouth

and alveolar bone

No None

4 T1N0M0 SLN 2.5mm 59y Anterior floor of mouth

and alveolar bone

No None

5 T2N0M0 Yes 5mm 59y Anterior floor of mouth No Mucus retention

cyst

6 T1N0M0 No, patient

refused

9mm 73y Anterior floor of mouth

and alveolar bone

No None

Figure legends:

Fig 1a: Lateral mandibular and floor of mouth defect with rotation of the SLG to cover the premolar

and molar area

Fig 1b: Healing 10 days after surgery

Fig 2a: Mobilized sublingual flap for coverage of large anterior mandibular defect

Fig 2b: Mucus retention cyst evident 6 weeks after initial surgery (mirror image)

Table I: Patient data and respective functional results