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K. Payne et al.
f
Fig. 42.14 (continued)
ab
g
Fig. 42.15 (a) Mandibulotomy for access to a posterior maxillary and infratemporal fossa tumour. (b) After tumour removal, demonstrating
access the whole way to the medial aspect of the mandibular condyle
42.5 Post-operative Care
42.5.1 Early Post-operative Monitoring
Patients who have undergone a maxillectomy have often had
concomitant procedures such as a neck dissection and potentially microvascular free ap reconstruction; hence, these
patients are often observed overnight in intensive care and
often have a tracheostomy in situ and a nasogastric tube
inserted. Often, patients are given two doses of intravenous
dexamethasone and at least two post-operative doses of broad-
spectrum intravenous antibiotics (as per local guidelines). If no
reconstruction is performed and the patient has an obturator
and packing in situ, then oral antibiotics for 7–10days may be
required. The packing needs to be changed at day 10 post-operatively. If a microvascular free-ap is performed for reconstruction, then routine ap observations are performed as usual.
If the orbital contents have been preserved, then postoperative eye observations are required especially within the
rst 24h after surgery to ensure the patient does not develop
a retrobulbar haemorrhage and associated orbital compartment syndrome. Facial incisions are protected from desicca-
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449
tion with topical parafn three to four times a day. Oral
intake is commenced rapidly if an obturator is inserted and
progresses within a few days to a soft diet. If a free-ap is
used, then after a period of healing, oral intake can commence depending on the protocol of the unit.
42.5.2 Late Post-operative Considerations
Late post-operative considerations are mainly related to
improving mouth opening and scar management. Scarring
around the posterior maxilla will result in limited mouth
opening and trismus if mouth opening exercises are not commenced early in the post-operative period. These exercises
should commence within 2 weeks after surgery. Patients
should be given a Therabite™ device and instructed on how
to use it. Massaging of scars will minimize the thickness of
the scars and improve surrounding skin mobility especially
in the lower eyelid. It will also help minimize lower lid
lymphoedema that can occur with a subciliary incision.
Chronic complications such as nasal crusting, nasal discharge, velopharyngeal insufciency and epiphora may
require further long-term intervention and support. Speech
and language therapy may be needed to help manage any
swallowing dysfunction or velopharyngeal insufciency.
Symptomatic chronic epiphora may require a
dacryocystorhinostomy.
References
1. Breik O, Idle M, Martin T, Praveen P, Parmar S. Three-Dimensional
Computer-Assisted Surgical Planning and Manufacturing in
Complex Maxillary Reconstruction. Atlas Oral Maxillofac Surg
Clin North Am. 2020;28(2):151–64. https://doi.org/10.1016/j.
cxom.2020.05.008. PMID: 32741512.
2. Butterworth CJ, Lowe D, Rogers SN. The Zygomatic Implant
Perforated (ZIP) flap reconstructive technique for the management of low-level maxillary malignancy - clinical & patient
related outcomes on 35 consecutively treated patients. Head
Neck. 2022;44(2):345–58. https://doi.org/10.1002/hed.26933.
Epub 2021 Nov 26. PMID: 34825746.
3. Cordeiro PG, Santamaria E.A classication system and algorithm
for reconstruction of Maxillectomy and Midfacial defects. Plast
Reconstr Surg. 2000;105(7):2331–46.
4. Davison SP, Sherris DA, Meland NB.An algorithm for maxillectomy defect reconstruction. Laryngoscope. 1998;108(2):215–9.
5. Brown JS, Shaw RJ. Reconstruction of the maxilla and
midface: introducing a new classication. Lancet Oncol.
2010;11(10):1001–8.
6. Liu Z, Yu H, Wang D, Wang J, Sun X, Liu J.Combined transoral
and endoscopic approach for total maxillectomy: a pioneering
report. J Neurol Surg B Skull Base. 2013;74(03):160–5.
7. Weisman R. Lateral rhinotomy and medial maxillectomy.
Otolaryngol Clin N Am. 1995;28(6):1145–56.
8. Vural E, Hanna E.Extended lateral rhinotomy incision for total
maxillectomy. Otolaryngol Neck Surg. 2000;123(4):512–3.
9. Fergusson W.A system of practical surgery. Philadelphia, PA: Lea
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10. Obwegeser HL. Temporal approach to the TMJ, the orbit,
and the retromaxillary–infracranial region. Head Neck Surg.
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modied retromaxillary approach to the infratemporal fossa: three
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12. Altemir FH. Transfacial access to the retromaxillary area. J
Maxillofac Surg. 1986;14:165–70.
13. Andi KA, Holmes SB, Hutchison IL.Infraorbital orbitotomy: modication of the Weber-Ferguson approach. Br J Oral Maxillofac
Surg. 2010;48(1):44–5.
14. Sweeney AR, Walker B, Bhrany AD, Chang SH, Jian-Amadi
A. Ophthalmic changes following maxillectomy with or
without postoperative radiation therapy. J Craniofac Surg.
2019;30(5):1448–51.
15. Cordeiro PG, Chen CM.A 15-year review of midface reconstruction after total and subtotal maxillectomy: part II.Technical modications to maximize aesthetic and functional outcomes. Plast
Reconstr Surg. 2012;129(1):139–47.
16. Goyal A, Tyagi I, Jain S, Syal R, Singh AP, Kapila
R. Transconjunctival incision for total maxillectomy—an
alternative for subciliary incision. Br J Oral Maxillofac Surg.
2011;49(6):442–6.
17. Casson PR, Bonanno PC, Converse JM. The midface degloving
procedure. Plast Reconstr Surg. 1974;53(1):102–3.
18. Maniglia AJ. Indications and techniques of midfacial degloving: a 15-year experience. Arch Otolaryngol Neck Surg.
1986;112(7):750–2.
19. Kitagawa Y, Baur D, King S, Helman JI. The role of midfacial degloving approach for maxillary cysts and tumors. J Oral
Maxillofac Surg. 2003;61(12):1418–22.
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total maxillectomy: midfacial degloving with extended transconjunctival retrocaruncular approach. Br J Oral Maxillofac Surg.
2017;55(8):857–8.
21. Nair S, Sridhar KR, Shah A, Kumar B, Nayak K, Shetty
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review. J Oral Maxillofac Surg. 2011;69(7):2040–7.
Craniofacial Resection
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43
43.1 Introduction
Head and neck malignancies that involve the skull base present a management challenge due to their proximity to important structures and resultant morbidity from treatment. The
primary sites of malignant tumours with anterior skull base
involvement are usually the paranasal sinuses, nasal cavity,
orbit or skin. Skull base involvement generally occurs
through direct invasion from these adjacent anatomical sites.
Treatment options for skull base malignancies continue to
evolve and require a multidisciplinary approach, which is
dependent on tumour histology, subsite, stage, patient factors
and institutional experience. Advances in endoscopic
approaches, radiation type and chemotherapy have allowed
progress in reducing morbidity and optimising outcomes.
Endoscopic endonasal approaches have led to a paradigm
shift in the way that many anterior skull base tumours are
managed, particularly for benign lesions. Its role in the management of malignant neoplasms continues to evolve, but
there remains a need for open approaches and for surgeons to
have familiarity with such techniques.
This chapter will discuss the presentation, work-up and
surgical management of malignant anterior skull base
tumours and describe surgery for craniofacial resection.
43.2 Clinical Presentation
Many anterior skull base malignancies are relatively asymptomatic in their initial stages. As they progress, symptoms tend
to reect local mass effect and invasion of adjacent structures.
These include unilateral nasal obstruction, blood- stained rhinorrhoea, facial pain and paraesthesia. Orbital signs may
include proptosis, diplopia and epiphora. Tumours involving
the masticator space may give rise to trismus or other cranial
nerve decits. Clinical examination may show a visible mass
or bulge in the midface or hard palate region. Skin involvement may be apparent through tethering or xity.
43.3 Investigations
Cross-sectional imaging with both CT and MRI with contrast is
recommended to assess tumour extent and to help guide treatment planning and surgical decision-making. The neck (MRI or
CT) and thorax (CT) should also be included to assess for cervical lymph node and distant thoracic metastases, respectively. In
high-stage disease, a PET-CT scan may also be considered to
rule out non-thoracic distant metastases, particularly if extensive surgery is planned, and in cancers with predilection to such
patterns of metastases (e.g. neuroendocrine carcinomas).
A tumour biopsy is required to diagnose the tumour type.
When a malignant diagnosis is considered a possibility, the
biopsy should constitute a relatively small representative
sample. If the diagnostic surgeon performs a debulking/
debridement procedure, it can make subsequent surgery
more difcult to plan, as the extent of the original tumour
may not be clear. This is especially the case if the only imaging performed before biopsy is a non-contrast CT sinus scan.
Repeat endoscopic appraisal, with mapping biopsies, may be
required by the operating surgeon if the extent of the tumour is
unclear. In this case, assessment under general anaesthetic is
preferred and allows a more detailed examination of the tumour.
N. Mani (*)
Central Manchester University Hospitals, University of
Manchester, Manchester, UK
e-mail: Navin.Mani@mft.nhs.uk
J. J. Homer
Department of Otolaryngology-Head and Neck Surgery,
Manchester Academic Health Sciences Centre, Manchester, UK
© Springer Nature Switzerland AG 2024
R. Simo et al. (eds.), Atlas of Head and Neck Surgery, Springer Surgery Atlas Series,
https://doi.org/10.1007/978-3-031-36593-5_43
43.4 Histology
A large variety of histological subtypes can occur in malignant lesions of the anterior skull base. These varying subtypes demonstrate biologically diverse behaviour and
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treatment response. Histological diagnosis itself can be challenging requiring specialist pathology input. Malignant
tumours can be of epithelial, soft tissue or neuroectodermal
origin.
Histologically, the most common malignant tumours
involving the anterior skull base are listed in Table43.1.
Table 43.1 Common malignant tumours affecting the anterior skull
base
Common malignant tumours affecting the anterior skull base
Squamous cell carcinoma (SCC)
Adenocarcinomas (intestinal and non-intestinal types)
Sinonasal undifferentiated carcinoma (SNUC)
Neuroendocrine carcinomas (or cancers with endocrine
differentiation)
Salivary gland histopathology’s (adenoid cystic, mucoepidermoid,
acinic carcinomas)
Sarcomas (low and high grade)
Olfactory neuroblastoma (esthesioneuroblastoma)
Sinonasal mucosal melanoma
Fig. 43.1 Superior view of
the midline anterior skull base
43.5 Anatomy oftheAnterior Skull Base
A detailed anatomical knowledge of the skull base is required
for appraisal of cross-sectional imaging studies, surgical
planning and undertaking safe surgery.
The anterior skull base separates the anterior cranial fossa
superiorly from the naso-ethmoidal complex and orbits inferiorly. It comprises a midline portion and lateral components
either side of this. The midline portion includes the posterior
table of the frontal sinus, cribriform plate and crista galli,
ethmoidal roof, planum sphenoidale and tuberculum sellae
(Fig.43.1). The lateral component is the orbital roof made up
from the orbital plate of the frontal bone and lesser wing of
sphenoid.
The cribriform plate is composed of two olfactory grooves
separated in the midline by the crista galli. The bone and
dura are thin in this area and pierced by olfactory neurons,
with a dural envelope following the neurons towards the
olfactory mucosa. The superior and middle turbinates insert
ridge and origin
of falx cerebri
Ye llow: olfactory
groove and
crista galli
Blue: planum
sphenoidale
Red:
sellae
Cr
Orbit
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43 Craniofacial Resection
Crista
Olfactory
bulb
ibriform
plate
Olfactory
mucosa
Fig. 43.2 Coronal view of anterior skull base
onto the skull base here. The crista galli is a triangular process of the ethmoid bone where the falx cerebri inserts anteriorly and inferiorly (Fig.43.2).
43.6 Treatment Options
Optimal treatment requires a multidisciplinary team
approach and is often multimodality, involving a combination of surgery, radiotherapy and chemotherapy.
A detailed discussion on this area is outside the scope of
this chapter, with treatment options dependent on histology,
stage and institutional preferences. Given the heterogeneity
of tumour types and the uncommon nature of them, the evidence for optimal treatment is poor.
However, surgery is usually considered the mainstay of
primary treatment if the tumour is resectable, followed by
postoperative adjuvant radiotherapy with or without chemotherapy [1]. Neoadjuvant chemotherapy is increasingly given
for some tumour types such as sinonasal undifferentiated
carcinomas.
43.7 History ofCraniofacial Resection
Initial surgical techniques using trans-facial approaches for
resection of tumours at the anterior skull base failed to
address the skull base due to limited access, leading to local
453
recurrence and poor outcomes [2]. The landmark paper by
Ketcham led to the introduction of a combined craniofacial
approach for tumour resection involving the cribriform plate
and anterior skull base region [3]. This technique, known as
the anterior craniofacial resection, became the gold standard
for the treatment of anterior skull base malignancies, with
Shah and others reporting long-term durable results [4].
The original surgical technique has had a variety of modications described in the literature, with the aim of reducing
brain retraction and resultant morbidity. The subcranial
approach described initially by Raveh [5, 6] allows for a
smaller transfrontal craniotomy, whilst still affording good
access to the anterior skull base and posteriorly to the planum sphenoidale, for tumours not involving dura.
Endoscopic techniques have further added to the surgeon’s armamentarium, allowing endonasal resection of
selected tumours of limited extent, which would previously
have required an open approach [7]. Hybrid techniques combining subcranial and endoscopic approaches allow advantages of both. Additional approaches may also be required as
dictated by the tumour. The defect necessitated by tumour
resection may form part of the access, for example, orbital
exenteration or maxillectomy. In addition, tumours with high
infratemporal fossa extension may also require an additional
lateral sub-temporal approach. Ultimately, choice of
approach will be dependent on the individual tumour and
patient, institutional preferences, experience and skill set
available.
Clinical assessment and imaging are used to assess resectability, to guide the surgical approach and to plan the extent
of resection and method of reconstruction.
The international consensus statement in endoscopic
skull base surgery suggests an open surgical approach when
there is tumour involvement of the anatomical structures
shown in Table43.2 [8].
The aim of surgery should be complete tumour resection
with negative margins. Ideally, when performing an open
approach, the surgeon should aim for an en bloc resection of
the tumour to allow a three-dimensional oncological resection
and accurate pathological assessment of margins [9]. Given
Table 43.2 Involvement of anatomical structures with likely need for
open surgical approach to skull base tumours
Involved structure
Ascending process of maxilla
Nasal bones
Orbital oor/orbital soft tissue
Anterior or posterior table of frontal sinus
Hard or soft palate
Signicant posterior maxillary wall/pterygopalatine or infratemporal
fossa
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the complex technical considerations of tumour resection in
this area, an en bloc resection may not always be feasible. In
such cases, detailed tissue mapping, marginal biopsies and
close working between surgeon and pathologist are essential.
Although an R0 resection (no residual tumour) is preferable, up to 40% or more of resections are R1 (tumour close
or microscopically present at margin) on nal pathological
review [10]. This both reects the challenge of preserving
vital structures such as the orbit and also proving histological
margins in this complex anatomical area. Debulking of disease with an R2 resection (leaving macroscopic residual
tumour) is not generally recommended, although it might be
indicated for palliation or in mucosal melanoma.
An important facet therefore of initial decision-making in
these patients is to decide which tumours are resectable,
avoiding an R2 margin. Specic areas to consider are the
cribriform plate and extension beyond this into the dura or
brain, orbital invasion and the need for orbital exenteration,
the extent of maxillectomy, sphenoid sinus involvement and
proximity to the internal carotid artery, cavernous sinus
involvement, extension into the masticator space or pterygopalatine fossa and skin involvement.
Anterior skull base malignancies involve centrally the
cribriform plate, fovea ethmoidalis or planum sphenoidale,
or laterally the roof of the orbit. Invasion or adherence of
tumour to the anterior skull base requires resection of the
involved portion. If the tumour involves dura and adequate
margins can be achieved, then dural excision can be undertaken, with reconstruction using a dural patch. When there is
gross brain, invasion outcomes are poor even with brain
resection, and this is therefore considered a relative contraindication to surgery. Other relative contraindications include
extension to the cavernous sinus or clival invasion.
With the use of proton beam therapy (PBT) treatment, paradigms in relation to resection margins may change. It may be
that a tumour should be regarded as operable even if a small
residuum is likely to be left (e.g. cavernous sinus) on the basis
that the post-operative PBT can be utilised in this setting.
The decision as to whether to perform orbital exenteration
on the affected side is dependent on the ability to preserve a
functioning eye. Involvement of the medial orbital wall is
common in anterior skull base malignancies, and this is usually removed as part of the resection. The periorbita is a
relatively robust barrier to tumour invasion; therefore, if the
periorbita is not involved, orbital contents may be preserved.
If there is localised periorbita invasion, this may be resected
with preservation of the remaining orbital contents. Extension
of tumour through periorbita and into periorbital fat or
beyond is usually considered an indication for orbital exenteration. In some cases, the decision to exenterate may need
to be made intra-operatively.
Reconstruction is dependent on the resultant defect. Larger
ablative procedures, particularly those associated with skin
excision and more extensive maxillectomy, will usually
necessitate free ap repair. Exposed dura when repaired may
be covered with a vascularised pericranial ap. Removal of
the medial bony orbit does not require reconstruction, if the
orbital periosteum is preserved. If the orbital oor has been
resected, reconstruction for support of the globe is required.
Free bone grafts, pericranium or alloplastic material can be
used. A free ap can be used if this is being used for reconstruction of the remaining surgical defect.
Cervical nodal metastases will require neck dissection at
the time of surgery. For N0 necks, elective neck dissection is
not usually performed. There is no data available specically
addressing the role of elective neck dissection in malignant
tumours of the anterior skull base, although some data exists
for maxillary and paranasal sinus squamous cell carcinoma
(SCC). Studies have reported conicting evidence for neck
dissection in the N0 neck in this setting [11–13]. Extrapolating
data from maxillary sinus SCC, for T1–T2 tumours, elective
treatment of the N0 neck is not recommended. In T3–T4
tumours, neck dissection may be considered if the neck is to
be entered for free ap anastomosis; otherwise, elective irradiation of the neck at the time of post-operative radiotherapy
to the primary site is appropriate [14]. In this scenario, levels
1b, 2a and 3 would be appropriate for dissection.
43.8 Surgical Technique
The term craniofacial resection has been used to describe
surgery that combines transfacial access and frontal craniotomy for extirpation of tumours involving the anterior skull
base. A variety of surgical techniques and approaches may
be used in combination to achieve this. Table43.3 describes
typical approaches that are used in combination for the transfacial and intracranial skull base components.
The classical anterior craniofacial approach is initially
described below, and this combines lateral rhinotomy and
medial maxillectomy with a bicoronal incision for frontal
craniotomy (Fig.43.3). The subcranial approach is described
separately, and an overview of endoscopic techniques is also
given.
Table 43.3 Combination approaches for craniofacial resection
Tranfacial access Skull base access
Lateral rhinotomy and
medial maxillectomy
Mid-facial degloving and
medial maxillectomy
Via maxillectomy defect Endoscopic
Via cutaneous/orbital
rhinectomy defect
Endoscopic
Frontal craniotomy/
craniectomy
Subcranial
Additional
access
Lateral
sub-temporal
Orbitozygomatic
Infraorbital n.
Supratrochlear
l
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Medial
canthal lig.
Lacrimal sac
Fig. 43.3 Classical anterior craniofacial approach, combining lateral
rhinotomy and bicoronal incisions for access
455
43.9 Anterior Craniofacial Approach
A bicoronal incision is performed. If a pericranial ap is to
be used for skull base reconstruction, the scalp is reected
anteriorly in a plane deep to the galea aponeurosis. This
plane, supercial to the pericranium is easily developed. If a
galeal-pericranial ap is to be used, a plane supercial to the
galea aponeurosis is developed, which requires sharp dissection. Bleeding from subcutaneous scalp vessels can be controlled with the use of Raney clips. The scalp ap is raised to
the level of the glabella and upper nasal bones.
A large pericranial ap measuring 10cm in width and at
least 15cm in length is raised from posterior to the incision
to the orbital rims, and this may have to be modied depending on the extent of resection. The blood supply to this ap is
from the supraorbital and supra-trochlear vessels, and care
should be taken to preserve these. The supercial temporal
vessels may also be encountered laterally and can be potentially used for microvascular anastomosis if a free ap is
required (Fig.43.4).
Fig. 43.4 Relevant
vasculature encountered when
raising bicoronal scalp ap
arteries
Supraorbital
arteries
Skin
incision
Superficia
temporal
artery
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A bifrontal craniotomy is performed using powered bone
cutting instrumentation. Care should be taken when lifting
the bone ap at the midline so as not to tear the sagittal sinus.
The lower cuts should be low, within 1 cm of the superior
orbital rims, so anterior access is not compromised and frontal lobe retraction kept minimal. The outline of the craniotomy may be altered if frontal bone resection is required. The
frontal lobes are retracted to allow access to the anterior skull
base. Extradural dissection is performed initially. The subsequent options are to aim for complete extradural resection
for tumours that extend up to the bony skull base but not
through it (with the option of separate dural resection). Or,
for tumours which extend through the bony skull base or
involve dura, the dura is incised around the area of tumour
involvement so that the dura in this region can be left attached
to the anterior skull base (Fig.43.5).
Trans-facial access can be done at this point or before craniotomy access and is dependent on extent of resection via a
lateral rhinotomy or other approach. At minimum, osteotomy
cuts for a medial maxillectomy with total ethmoidectomy on
the ipsilateral tumour side is performed. The extent of larger
resections including orbital exenteration is based on the individual tumour.
Bone cuts of the anterior skull base can now be made
from either below, with the frontal lobes retracted, or from
above, to join the transfacial osteotomies. This can be done
using a high-speed bone cutting drill. The precise location of
these cuts depends on the tumour but will often be through
the frontal bone laterally and through the planum sphenoidale posteriorly. If the posterior extent involves removal of
the planum, the optical canals need to be unroofed, so they
are protected when the posterior bony cuts are made.
cd
Deep temporal
fascia and
temporal muscle
Supraorbital
artery and vein
Pericranium
Dural defect
Planum
sphenoidale
Roof of orbit
Cribriform plate
with attached
dura and olfactor
nerves
Supraorbital
bar
Fig. 43.5 Initial steps of transcranial component for anterior craniofacial resection. (a) Incision, (b) Flap raised, (c) Bone marking, (d)
craniotomy
Cr
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457
Anteriorly, the bony cuts may be such that the supra-orbital
bar is preserved, although it can be removed and replaced for
additional access.
The specimen can then be removed in an en bloc
fashion.
The dural defect can be repaired either with a dural
allograft or fascia lata. The authors’ preference is for fascia
lata as an underlay graft and then pericranial ap, reected
over the dural repair and anterior skull base. A galealpericranial ap can be used for larger skull base defects.
Alternatively, a free ap may be required if pericranium is not
available and/or to reconstruct any resultant midface defect.
43.10 Subcranial Approach
This variation involves a more inferior access to the anterior
skull base, generally through the frontal sinuses. This, in
turn, minimises or totally avoids any frontal lobe retraction.
As with craniotomy described above, it can be combined
with any trans-facial access method.
A bicoronal or supra-orbital incision is made. In a bicoronal approach a pericranial ap is elevated. The supraorbital
nerves and vessels are separated from the supraorbital notch.
The superior and medial orbital walls and nasal bones are
exposed, and the anterior ethmoidal arteries are clipped or
ligated.
The bone window over the frontal sinus and upper nasal
bones is marked out, pre-plated and removed. Navigation
systems can be used for accuracy in marking out the frontal
sinus. The bone ap removed consists of frontal bone overlying the frontal sinuses and upper nasal bone. Some distal
nasal bone must be preserved to support the nasal valve and
the replaced bone ap at the end of the procedure. Care must
be taken to avoid fracturing the bone ap at the frontal-nasal
suture line (Fig.43.6).
The posterior table of the frontal sinus is burred to expose
dura. Extradural dissection over the cribriform plate and crista
galli is performed. The dura is adherent at the olfactory bres
and less adherent laterally (Fig.43.7). Small dural tears can be
repaired with homograft or allograft fascia lata. Dissection can
continue posterior to the planum sphenoidale. The bony skull
base can be removed as part of the posterior dissection.
Alternatively, bone cuts can be made and the tumour resection
completely en bloc, if an open transfacial approach is used.
One of the advantages of this approach is the fact that it,
in effect, joins up the transfacial and transcranial approach. If
Fig. 43.6 Transfrontal bone window removed for subcranial approach
Fig. 43.7 Oblique
transcranial access via
subcranial approach. The dura
is adherent at the cribriform
plate
ibriform
plate
458
First incision
Superior
Lateral
Medial
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utilising a bicoronal ap, the ap itself obstructs the transfacial view gained by this technique. A supraorbital/eyebrow
incision can be used, which allows excellent access, with no
intervening ap within the eld and facilitates low nasal
bone cuts, further improving access. The incision from this is
minimally visible after a few months. For some tumours, all
surgical access/tumour resection can be achieved through
this. A pericranial ap can still be raised, albeit smaller than
via a bicoronal incision. Most dural defects can be reliably
repaired using fascia lata alone (underlay and overlay) and so
not having the option of a large pericranial ap is not generally a signicant issue.
Inferior access, when required, can be performed either
via transfacial or midface degloving approaches. However,
an endoscopic approach from below is preferable, depending
on extent of tumour. Resection of the tumour can be performed as an en bloc specimen or piecemeal, in which case
the main tumour specimen can be initially resected and the
skull base portion removed separately. Margins and additional specimens are sent separately, but accurate mapping is
crucial to gauge the adequacy of resection.
43.11 Endoscopic Approach
This can be performed alone or in combination with a combined transcranial approach superiorly. The key steps involve
an initial debulking of the tumour with the aim of identifying
the site of origin. Adequate exposure is then gained with
removal of posterior two-thirds of the nasal septum. A frontal
sinus approach with a Draf type 3 procedure allows identi-
cation of the antero-superior part of the dissection and wide
sphenoidotomy with removal of the inter-sphenoid septum
and sphenoid rostrum exposes the postero-inferior margin.
Lateral dissection is dependent on the extent of tumour
and will usually involve medial maxillectomy on the affected
side, which can be via a pre-lacrimal approach. The ethmoid
complexes are dissected with the ipsilateral lamina papyracea included if the tumour is adjacent to this. The tumour
region can then be mobilised through dissection of the basal
lamella of the turbinates. This then allows removal of the
specimen either trans-nasally or pushed though through the
nasopharynx and removed trans-orally.
Anterior skull base dissection can then take place with
exposure of the ethmoidal roof using a drill and identication of the anterior and posterior ethmoidal arteries. These
vessels may be managed with bipolar diathermy or surgical
clips and divided. The crista galli is then dissected from the
surrounding dura and removed.
If dural resection is required, the dura should be exposed
over the orbital roofs laterally, the planum sphenoidale posteriorly and the posterior table of the frontal sinus anteriorly.
The dura may then be incised and cut around the area of
resection with the remaining anterior skull base attached
along with one or both of the olfactory bulbs and removed.
Skull base reconstruction is performed using a multilayer
technique with dural underlay, overlay between the residual
bony skull base and dura and a nal layer to cover. Fibrin
glue is used between layers. If the tumour has not involved
the nasal septum, then a vascularised pedicled naso-septal
ap based on branches of the sphenopalatine artery (Hadad
ap) may be used (Fig.43.8).
Fig. 43.8 Pedicled nasoseptal ap for anterior skull
base repair
Superior
turbinate
Middle
turbinate
Inferior
Turbinate
Choana
Sphenoid
ostium
Second
incision
Third
Incision
Inferior
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