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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4458_Библиотеки_им_академика_М_И_Перельмана
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Clinical examples/
Endotype
Anatomic
28 Frontal Sinusitis
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341
SecondaryCRS
distribution
Localised
(unilateral)
Diffuse
(bilateral)
dominance
Local pathology
Mechanical
Inflammatory
Immunity
Phenotypes
Odontogenic
Fungal ball
Tumour
PCD
CF
GPA
EGPA
Selective
immunodeficiency
Fig. 28.2 Classication of secondary CRS (adapted from Grayson etal. [5])
Endotype Dominance
Anatomy
CRS is then further characterised at the mucosal
level by the dominant type of immune response
triggered by the causative antigen. Inherently,
immune responses across mucosal barriers trigger alternate molecular pathways to address
specic pathogens; Type 1 responses target
viruses, Type 2 parasites and Type 3 extracellular bacteria and fungi. These responses subsequently produce tissue inammation and repair.
A dysregulation of these immune responses are
thought to be the pathophysiological driver
behind many diseases.
In CRS, Type 2 immune responses drives
severe nasal polyposis most commonly, and
resultantly have been the target of much therapeutic research [6]. Thus, the current system
divides CRS into Type 2 and non-Type 2 as this
also reects the current range of therapeutic
options as well as the knowledge base.
The management of frontal sinusitis is challenging
due to its anatomical location which is not readily
accessible, proximity to the orbit and brain and the
ease of surgical disorientation. It is highly variable
in its size and structure, and it relies on the integrity
of its drainage pathway through the lower sinonasal
cavity to correctly function [7]. Understanding and
condently identifying xed anatomical boundaries is essential for safe frontal sinus surgery. These
being the nasofrontal beak anteriorly, the posterior
table and ethmoid roof posteriorly, the orbital wall
and roof laterally and the middle turbinate/intersinus septum medially. This is the concept of the vertical box (Fig.28.3a) [8].
Inferiorly, the frontal sinus is funnelled down
to an area referred to as the ‘ostium’, but it is
really a transition zone between upper ethmoid
and frontal sinuses. It is here where the vertical
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C. Morris and R. J. Harvey
Fig. 28.3 (a) Frontal
sinus anatomy as a
concept of a vertical
box. Anteriorly (red)
nasofrontal beak,
posterior (green)
posterior table and
ethmoid roof, laterally
(grey) orbital wall and
roof, medially (blue)
middle turbinate/
intersinus septum. (b)
Frontal sinus vertical
box and its relationship
to the horizontal
paranasal surgical box
a
b
Table 28.1 International Frontal Sinus Anatomy Classication (IFAC) system
Cell type Cell name Denition Abbreviation
Anterior
cells
Posterior
cells
Medial
cells
box of the frontal sinus joins the horizontal paranasal surgical box of the nasal cavity, ethmoid
sinus and sphenoid sinus (Fig.28.3b).
The variable anatomy and relative relation-
ships of the frontal bone partitions arising from
Agger nasi cell Most anterior ethmoid cell. Anterior to the middle turbinate origin or
above the anterior insertion of the middle turbinate into the lateral
nasal wall
Supra agger cell Anterior-lateral ethmoid cell; sits above the agger nasi. Does not
extend into the frontal sinus
Supra agger
frontal cell
Supra bulla cell Cell above bulla ethmoidalis. Does not enter the frontal sinus SBC
Supra bulla
frontal cell
Supraorbital
ethmoid cell
Frontal septal
cell
Anterior-lateral ethmoidal cell that extends into the frontal sinus SAFC
Cell above bulla ethmoidalis. Pneumatises into the frontal sinus SBFC
Ethmoid cell that pneumatises over the roof of the orbit SOEC
Medially based anterior ethmoid or the inferior frontal sinus cell,
attached to or located in the interfrontal sinus septum
ANC
SAC
FSC
the rst and second ethmoturbinals have been
well classied by the International Frontal Sinus
Anatomy Classication (IFAC) and are demonstrated in Table28.1 and Fig.28.4 [7]. However,
the variability of the anatomy within the frontal
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343
a
Fig. 28.4 Coronal (a) and sagittal (b) CT scan images
depicting the anatomy of the frontal sinus and surrounding structures. Arrow shows frontal drainage pathway.
recess is relatively unimportant surgically, and
condent identication of the xed boundaries of
the frontal recess is essential.
b
RFS right frontal sinus, LFS left frontal sinus, ISS inter
sinus septum, A agger nasi cell, B bulla ethmoidalis, MT
middle turbinate, S septum
Draf endoscopic sinus procedures are
described below, but how they are applied in
each frontal sinus phenotype is further discussed
later.
Surgical Technique
Mucosal inammation of frontal sinusitis is
usually resolved through a multi-modal
approach which may include topical therapy,
surgical intervention and systemic medication.
Surgery aims to obtain tissue specimen and culture, facilitate the delivery of topical therapy
and restore or mechanically facilitate mucus
clearance.
Surgical interventions have been well described
including endoscopic surgical Draf procedures
(Type I, IIa, IIb, IIc, III). External procedures
include trephination and, rarely, open approaches
[9].
Choice of operation on the frontal sinus is
dependent on:
• The nature of the underlying mucosal
inammation
• The goal of subsequent management
• How the proposed anatomical modication
helps to achieve this goal
Draf I
Draf I procedure involves the removal of cells
within the frontal recess, usually the uncinate,
ager nasi and anterior ethmoid bulla but does not
remove any of the frontal sinus oor (Fig.28.5).
Draf IIa, b, c
We approach all Draf II procedures in a consistent
way, by removing all sinus partitions via a
‘Carolyn’s window’ approach. This involves
removing the bone of the frontal process of the
maxilla and the nasal process of the frontal bone.
This is the ‘nasofrontal beak’ or the agger-frontomaxilla bony structure. By removal of this bone,
the anteroposterior dimension is extended and aids
the dissection. This allows for greater visualisation
of the boundaries of the frontal recess ensuring
complete clearance of the ethmoids at the junction
of the posterior table and against the medial orbit.
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C. Morris and R. J. Harvey
a
Fig. 28.5 Draf I removal of cells within the left frontal recess without removing the frontal sinus oor, coronal (a) and
sagittal views (b). Arrow depicts frontal drainage pathway
Key principles include the raising an inferiorly
based subperiosteal mucosal ap from the lateral
wall. The bone of the nasofrontal beak is removed
by high-speed drill (Medtronic IPC 30 K 4 mm
choanal burr). The lateral limit is the periosteum of
the frontal process of the maxilla (Fig.28.6). The
lacrimal sac is exposed. Although the dissection
remains lateral to the middle turbinate lamella, the
extent of bone removal of the oor of the frontal
sinus medial and anterior to the rst olfactory neuron denes an extension to a Draf IIb. The Draf IIa
is a dissection that remains entirely lateral to the
middle turbinate; extension across the nasal septum
denes a Draf IIb. The removal of the frontal intersinus septum, opening the contralateral frontal
sinus into the surgical approach, denes a Draf IIc,
often referred to as a Hemi-Lothrop (Figs. 28.7,
28.8, and 28.9).
b
of lateral wall mucosa over the frontal process
of the maxilla is described above or can be
extended onto the septum [10]. The rst olfactory neuron is always the posterior limit of the
dissection.
The septal extension of this ap can be awkward, and the septum is often thickened/polypoid. In this instance, the septal extension of the
graft is foregone, and a free mucosal graft is used.
The superior septum posteriorly no further than
the rst olfactory neuron and anterior to inferiorly incorporate the swell body and any high
deviation.
Using a 4mm high-speed drill (Medtronic
IPC 30K 4mm choanal burr) and a 0 degree
endoscope, lateral limits of the periosteum are
identied to maximise surgical eld and dene
the lateral limits. Bone is removed medially
between these limits using a drill and connected to the frontal recess by a Kerrison
Draf III or theModied Endoscopic
Lothrop
rongeur.
Frontal recess partitions and inter-sinus septum are removed. The cavity is squared off by
The Draf III procedure allows a wide bilateral
opening of the frontal sinus by removing the
entire nasofrontal beak (periosteum to periosteum), the frontal sinus oor and superior septum (Fig.28.10). A subperiosteal mucosal ap
following the orbital wall up to the orbital roof.
Mucosa is replaced with a combination of the lateral wall ap, and free mucosa grafts are used to
cover any raw bone. Silastic splints are placed in
the cavity [11].
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a
b
c
Fig. 28.6 Carolyn’s window approach to Draf IIa/b/c, (a) Monopolar of mucosal ap, (b) Mobilisation of ap, (c) Drill
to remove the nasofrontal beak
Frontal Mini-Trephine forCulture
ened slightly with blunt dissection to allow for
the drill guide to sit ush on the bone. A small
Frontal sinus mini-trephination, for obtaining a
specimen for culture, is commonly performed
with a Seldinger technique (Mini-Trephination
Set, Medtronic ENT, Jacksonville, FL) or small
incision directly. Optimal placement is 1cm
from midline, at the height of the supraorbital
foramina, superior to the superior orbital rim.
The skin can be mobilised to place the incision
within the eyebrow for optimal aesthetics. A
drill is then used with gentle irrigation to drill
through the anterior table. Using a guidewire,
the frontal cannula is placed. Aspiration of air,
blood, mucus or pus may conrm position
[12]. Using a 20mL syringe, normal saline is
introduced and then aspirated. Resultant uid
can be sent via specimen pot, or if low volume
(e.g. 0.5 mL) directly into a paediatric blood
culture bottle.
stab incision is made through the skin and wid-
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C. Morris and R. J. Harvey
a
b
c
Fig. 28.7 Draf IIa: Limits include the periosteum of the
frontal process of the maxilla laterally to the root of the
middle turbinate medially. Coronal (a) and sagittal (b) CT
a
Fig. 28.8 Draf IIb: Limits include the periosteum of the frontal process of the maxilla laterally to the nasal septum medially.
Left Draf IIb illustrated by coronal CT scan (a) and zero degree endoscopic view (b)
images and endoscopic post-operative photograph (c).
Arrow depicts frontal drainage pathway
b
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a
c
b
d
e
Fig. 28.9 Draf IIc or hemi-Lothrop: Limits include the
periosteum of the frontal process of the maxilla laterally,
medially the removal of the frontal inter-sinus septum
occurs to enter the contralateral frontal sinus. CT scans of
pre-operative coronal (a) and sagittal (b) ndings followed by post-operative coronal (c) and sagittal (d) ndings for a patient with AFS. (e) demonstrates the
post-operative appearance with zero degree endoscope
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C. Morris and R. J. Harvey
ab
c
d
e
Fig. 28.10 Pre (a) and (b), and post (c) and (d), coronal and sagittal CT scans respectively in patient with eCRS who
underwent a Draf III procedure. (e) Post-operative view with a 0° endoscope into the frontal sinus cavity
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The Management oftheFrontal
Sinus by Sinusitis Disease
Phenotype
The management of the frontal sinus differs
according to the underlying nature of the frontal
sinusitis disease phenotype. There are three principles that guide surgical decision-making when
frontal sinus surgery is performed: rstly, to
dene the nature of the underlying mucosal
inammation. Secondly, to identify the goal of
subsequent management and nally, how the proposed anatomical modication through surgery
helps to achieve this goal.
Acute Frontal Sinusitis
The vast majority of patients with acute upper
respiratory exacerbations, including those with
frontal sinus symptoms, especially when bilateral, have a viral, allergy or combination aetiology. Simple symptomatic relief is the mainstay of
management. It is important to avoid unnecessary use of antibiotics and subsequent potential
side effects in this instance [13].
In the 0.5–2% of patients with a suspected
bacterial origin, often those with unilateral symptoms, antibiotics are recommended as the mainstay of therapy. Antibiotics should be culture
driven, with the use of broad-spectrum empirical
antibiotics covering the most common pathogens
(Streptococcus pneumoniae, Haemophilus inu-
enzae and Moraxella catarrhalis) in the interim
[14]. A middle meatal swab is the best option for
gaining a culture result for treatment purposes
[15]. If the middle meatus does not reveal a culture opportunity, the use of trephination for washout and culture may be useful [1].
While obtaining culture information is important in ARS of the frontal sinus, there is little role
for acute frontal sinus surgery. Even in the setting
of intracranial and orbital abscess formation, surgery on the frontal sinus is not thought to improve
outcomes [16]. The spread of bacterial infection
is by indirect spread via thrombophlebitis, and
the abscess location is often distant to the sinus
cavity itself. Even when there is bone loss, this is
not the site of ‘connection’ but an osteomyelitic
change and a sign of the need for long-term antibiotic therapy and not for sinus surgery. This is
the nature of the development of complications
such as ‘Potts puffy tumour’. Surgery is often
required to evacuate or drain an abscess, and a
microbiological sample can be taken from the
frontal sinus at the time of managing the
complication.
Frontal Sinus Involvement inCRS
Primary-Localised CRS
When a single frontal sinus is involved in CRS, it
is referred to as a localised CRS.This may be isolated to the frontal sinus alone or, if it involves
the osteomeatal complex (OMC), includes the
anterior ethmoid and maxillary sinus, as they
share a common drainage pathway. This pattern
of localised CRS suggests an issue with the anatomy of that subunit.
The predication for management and extent of
surgery required depends on underlying on
mucosal factors, namely, their endotype dominance (Type 2 dominant and non-Type 2 dominant). Thus, primary-localised CRS is further
characterised.
Localised Type 2 Dominant Frontal CRS:
Allergic Fungal Rhinosinusitis
Allergic fungal rhinosinusitis (AFRS) is not simply an inammatory reaction to fungus; it is a
hypersensitivity condition [17, 18]. It is characterised by the presence of fungal hyphae and
eosinophilic mucin within sinuses, in which
mucus clearance is impaired and a hypersensitivity reaction has occurred in response to fungal
contact. It is imperative to be able to remove the
fungal burden from the sinus cavity, both at the
time of surgery, and provide clearance of fungalcontaining mucus in the future. The only way to
achieve this is by providing a very large
opening.
Surgical principles in localised AFS-related
frontal sinus disease should include a Draf IIa
(with wide natural dimensions), Draf IIb or IIc to
allow for complete removal of fungi, a wider
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C. Morris and R. J. Harvey
mucosal drainage pathway and the application of
topical corticosteroid therapy (Fig.28.9).
Peri-operative oral corticosteroids have been
shown to be important, with limited evidence on
the use of immunotherapy or antifungals in
refractory cases [18]. Additional antifungal therapies offer little benet [1].
Localised Non-type 2 Dominant Frontal
CRS: Isolated or Ostial Occlusion
FrontalCRS
Isolated sinusitis is typically an infective phenomenon. This is the classic ‘ostial occlusion’
sinus disease [19]. There are many reasons why
the mucosa of the frontal recess or OMC may not
respond to medical therapy. There are welldened mucosal remodelling events, such as subepithelial brosis and basement membrane
thickening, that may not respond to medical therapy and result in long-term ostial occlusion [20].
For most primary localised non-type 2 dominant CRS patients with frontal sinus involvement
after medical therapy, formal modication of the
frontal recess itself is often required.
Surgical options include balloon dilatation
and Draf IIa. Other modications can be used
depending on the anatomy, but extended openings are not generally required as reventilation
and one-off drainage/washout usually resolves
the chronic state [19]. Sinus function, in the form
of mucociliary clearance, almost always resumes
for these patients.
Primary Diuse CRS
Here, changes are related to inammation rather
than anatomical abnormalities and therefore diffuse in nature. They are further categorised by
endotype dominance and subsequently expressed
phenotype.
Primary Diuse Type 2 Dominant:
Eosinophilic Chronic Rhinosinusitis (eCRS)
The nature of this condition is characterised by
diffuse mucosal inltration by eosinophils (10>/
HPF) and a subsequent inammatory response
[1]. It is important to appreciate that eCRS is a
chronic inammatory airway disease, often with
coexistent adult-onset asthma, which will
require ongoing maintenance. Hence the general goal of management is to surgically alter
the sinuses to produce a simple anatomical box
(neo-sinus) allowing for maximal application of
topical corticosteroid therapy, and maximal
dimensions to prevent mucus plugging in a condition that is both hypersecretory and likely to
undergo exacerbations during the course of the
disease.
Surgery involves creating a simple neo-sinus
cavity, and the frontal sinus is connected by Draf
III or extended Draf II if the anatomy is wide and
disease severity is low (Fig. 28.10). We rarely
apply simple Draf IIa surgery in this condition as
the frontal sinus is the most common site of
poorly controlled mucosa and recurrent polyps
[21]. Corticosteroid irrigations are the mainstay
of post-surgical therapy [22].
The recent addition of biologicals (monoclonal antibodies targeting IgE, IL4 and IL5 inammatory pathways) to the management ladder in
recalcitrant eCRS, particularly in the presence of
comorbid asthma, is improving the ability to control the condition in its most severe forms where
topical corticosteroid irrigations and surgery
have failed [23–25].
Primary Diuse Type 2 Dominant: Central
Compartment Atopic Disease (CCAD)
The nature of central compartment atopic disease (CCAD) is an exuberant allergic rhinitis
resulting in oedema and polypoid change in the
central sinonasal cavity with mucus trapping
[26]. This typically occurs in younger patients
with a good history of inhalant allergy. Imaging
often shows central opacication of the paranasal sinuses, with superior and lateral sparing
of the sinus mucosa known as the ‘black halo’
sign [27].
Left untreated, secondary sinus dysfunction
occurs that includes mucosa within the frontal
sinus, related to the direct extension of polypoid
changes into the sinus outow pathway or from
lateralisation of the middle turbinate [28].
Patients often complain of barotrauma but still
retain smell until late in the disease course.
Management is targeted at the inhalant allergy
driving these changes, and once the specic aero-
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