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Endoscopic Lateral Nasal Wall and Anterior and Posterior Ethmoid Sinus Dissection
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FR
BE
STL
ST
vii
Fig. 3.9b Posterior ethmoidectomy: removal of the basal lamellae (BL). Complete ethmoidectomy in endoscopic view (i-viii). AEA,
anterior ethmoidal artery; AWSS, anterior wall of the sphenoidal sinus; BE, bulla ethmoidalis; ER, ethmoidal roof; FE, fovea ethmoidal;
FR, frontal recess; FS, frontal sinus; LP, lamina papyracea; MT, middle turbinate; ON, optic nerve; PEA, posterior ethmoidal artery; SS,
sphenoidal sinus; ST, superior turbinate; STL, superior turbinate lamellae.
AWSS
LP
viii
• The safe area to perforate the third basal lamella is its
vertical aspect.
• Superior and lateral areas within the posterior ethmoid
are to be approached with care to keep away from the
optic nerve.
• Floor of the orbit and posterior wall of the maxillary
sinus provide useful landmarks that allow a better
AEA
LP
BL
STL
For beginners, it is recommended to limit the use of the
microdebrider for the removal of polypoid mucosa that
allows identification of further landmarks. Then change
to conventional instruments. The complication rate has
not reported to be higher or lower with either. However,
microdebriders do not allow to stop suctioning, for exam-
ple, the orbital fat.
orientation in regard to depth and level of the posterior
ethmoid cells (and sphenoid sinus).
• Try to always position the head of patients similarly
to have the same angle of approach to the skull base.
Be aware that the skull base slants downwards as the
posterior ethmoid is approached.
3.6.5 General Tips and Pearls
• Before surgery, perform a complete endoscopy of the
nose following the nasal floor and exploring the inferior,
middle, and superior meatus and the nasopharynx.
Preference of the lens is a choice of each surgeon. For
beginners, the 0-degree endoscope provides a realistic
view when handling instruments at the same time.
• Understanding at least the location of the uncinate pro-
cess, bulla ethmoidalis, and middle turbinate as first,
second, and third basal lamellae, respectively, as they
provide landmark during the surgery that allow counting 1–2–3 when orientation is lost.
• Through-cutting instruments are used to remove eth-
moid bony partitions. Also, they help in preserving the
mucosa, avoiding denuding the bone that leads to a
prolonged crusting.
• Keep the height of the roof of the maxillary sinus in
mind when dissecting anterior to posterior through the
ethmoid cavity.
References
1. Stammberger H. Functional Endoscopic Sinus Surgery: The
Messerklinger Technique. Philadelphia, PA: BC Decker; 1991
2. Fokkens WJ, Lund VJ, Mullol J, et al. EPOS 2012: European position
paper on rhinosinusitis and nasal polyps 2012. A summary for
otorhinolaryngologists. Rhinology 2012;50(1):1–12
3. Kennedy DW, Ramakrishnan VR. Functional endoscopic sinus
surgery: concepts, surgical indications, and techniques: In: Hwang
PH, Kennedy DW, eds. Rhinology Diseases of the Nose, Sinuses, and
Skull Base. New York, NY: Thieme; 2012:305–335
4. Otori N, Yanagi K, Moriyama H. Maxillary and ethmoid sinuses in
skull base surgery. In: Stamm A, ed. Transnasal Endoscopic Skull
Base and Brain Surgery Tips and Pearls. New York, NY: Thieme;
2011:109–114
5. Casiano R. Basic endoscopic sinonsal dissection. In: Casiano R, ed.
Endoscopic Sinonasal Dissection Guide. New York, NY: Thieme;
2012:19–58
6. Wormald PJ. Surgery of the bulla ethmoidalis, middle turbinate,
and posterior ethmoids and sphenoidotomy, including threedimensional reconstruction of the posterior ethmoids.
In: Wormald PJ, ed. Endoscopic Sinus Surgery Anatomy,
Three-Dimensional Reconstruction, and Surgical Technique. 2nd
ed. New York, NY: Thieme; 2007:101–114
7. Simmen D, Jones N, Brine HR. Applied anatomy for endoscopic
sinus and skull base surgery. In: Simmen D, Jones N, eds. Manual
of Endoscopic Sinus and Skull Base Surgery. 2nd ed. New York, NY:
Thieme; 2014:80–90
8. Saleh H, Nouraei R. Basic surgical techniques in endoscopic
sinus surgery. In: Georgalas C, Fokkens W, eds. Rhinology and
Skull Base Surgery from the Lab to the Operating Room: An
Evidence-Based Approach. Stuttgart: Georg Thieme Verlag KG;
2013:331–325
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Chapter 4
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4.1 Anatomy of the Frontal Recess
and Frontoethmoid Cells 38
Frontal Sinus and
Draf Approaches
4.2 Preoperative Evaluation 38
4.3 Indications 40
4.4 Surgical Steps 40
4.5 Case Examples 44
4.6 Complications and
Tips and Tricks 44
Frontal Sinus and Draf Approaches
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4 Frontal Sinus and Draf Approaches
Eugenio Cárdenas, Ariel Kaen, Isam Alobid, Manuel Bernal-Sprekelsen
Introduction
The endonasal approach to the frontal sinus is considered one of the most difficult parts of endoscopic sinus
surgery. At the same time, benign or malignant lesions
located anteriorly along the skull base require a maximum visualization of the frontal sinus and anterior skull
base for which a Draf type III (also known as modified
endoscopic Lothrop) procedure needs be performed. This
technique is a well-established approach for refractory
chronic rhinosinusitis involving the frontal sinus disease,
mucoceles, bone-derived tumors (osteomas, fibrous dysplasia), and exposure of the anterior skull base.
A Draf type III is indicated as a prior step for the transcribriform approach (tumors along the anterior skull
base, such as esthesioneuroblastomas, carcinomas, and
adenocarcinomas of the anterior ethmoid, tumors involving the olfactory bulb, etc.).
This chapter deals with surgical anatomy of the frontal
sinus, preoperative imaging needed, and different surgical steps to complete the Draf approaches. Illustrated cases and guidelines on how to avoid complications during
surgery are included.
4.1 Anatomy of the Frontal
Recess and Frontoethmoid
Cells
The frontal sinus is localized in the anterior cranial vault
between two thick layers of cortical bone. The frontal sinus shares a common embryologic and anatomic
relationship with the ethmoid sinus; several authors refer
to this sinus as a “large ethmoidal cell.” In an adult, two
frontal sinuses are usually seen. Each frontal sinus cavity
takes on the shape of a pyramid, with a thick anterior
table and a thinner posterior table. This posterior wall
forms the most anteroinferior boundary of the anterior
cranial fossa. It has a superior vertical, and a smaller inferior horizontal, portion. The horizontal portion will form
part of the orbital roof. Both are in close contact with the
frontal lobes, separated only by the dura. An intersinus
septum divides the frontal sinuses into separately draining sinus cavities and almost always is closed to the midline in the most inferior portions.
The frontal sinus narrows down inferiorly and medially
into a funnel-shaped point, which is defined as the frontal
infundibulum. The latter ends in an almost circular area
called frontal sinus ostium or frontal sinus opening.
The frontal ostium/opening is defined as the narrowest
area of the transition zone from the frontal sinus to the
frontal recess with its anterior edge formed by the frontal
sinus beak (best seen on the parasagittal computed tomography [CT] scan).
The angulation (posteromedially) and maximum diameter of this funnel may vary greatly between patients,
or even between sides, and this funnel is surrounded
2
1
by an intricate complex area covered by ethmoid cells
and other anatomic structures. The frontal recess is the
three-dimensional (3D) space below the frontal sinus that
does include the drainage pathway. This space is usually
occupied by several ethmoidal cells which affect the direction and position of this drainage pathway. The medial
wall of the frontal recess is formed by the lateral lamella
of the cribriform plate and the vertical lamella of the middle turbinate, and the lateral wall is formed by the lamina
papyracea and lacrimal bone. The anterior ethmoidal artery may be situated in the posterior region of the roof of
the frontal recess, right at the level of the attachment of
the anterior wall of the bulla or right behind. It can be at
risk if it runs in a mesentery off the skull base (Fig. 4.1).
The frontal recess drains into the superior end of the
ethmoidal infundibulum in anatomic variants in which
the uncinate process is attached to the skull base or the
superoanterior portion of the middle turbinate. The ethmoidal infundibulum then communicates with the middle meatus via the hiatus semilunaris. However, when
the uncinate process attaches to the lamina papyracea,
the frontal recess drains directly into the middle meatus.
In this case, the ethmoidal infundibulum terminates in
a blind-ending recess known as the recessus terminalis
(Fig. 4.2).
pathway (FSDP) in many ways and have given all sorts of
names, depending on the surgical approach or perspective by which the frontal sinus is visualized. However,
most authors would agree this to be the most difficult
anatomic region to manage in endoscopic frontal sinus
surgery due to the extreme variability of cell patterns
observed in this area. Surgeons often lack confidence
when exploring this area, which can result in an inadequate removal of disease. This is why, the frontal recess is
the most likely area for the recurrence of sinus disease.
sinus drainage area, we recommend the study of cell classifications in the literature, particularly the one recently
published by Wormald et al.
3
Authors have described the frontal sinus drainage
2
To facilitate the understanding of this complex frontal
4,5
4.2 Preoperative Evaluation
4.2.1 Preoperative Study
The first, and possibly the most important, step in this
area is to make an accurate surgical planning. A complete
and individualized study is required in each patient. The
study of the anatomy in three planes and their correlation
with the disease to be treated is crucial. There are different 3D viewers such as Osirix or Carestream designed for
navigation and visualization of multimodality and multidimensional images.
Successful surgery in the frontal recess relies critically
on a detailed knowledge of the complex anatomy in this
region.6 Programs specially designed for handling images have been proven useful to increase knowledge of
this anatomy. These 3D viewers usually offer all modern
38
Basal Lamella
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S
MT
UP
MT
Frontal Sinus and Draf Approaches
Fig. 4.1 Schematic sagittal drawing
of the frontal infundibulum, ostium,
and recess. Black arrows indicate
the extension of the frontal recess
(irrespective of existing cells).
Please note that the frontal recess
encompasses all, but the frontal
AEA
Agger
nasi
EB
UP
IT
S
UP
MT
S
UP
outfl ow tract encompasses only the
drainage pathway of the frontal.
AEA, anterior ethmoidal artery; EB,
ethmoidal bulla; IT, inferior turbinate;
UP, uncinate process.
Fig. 4.2 Schematic drawing of the
three most frequent variations of
attachments of the uncinate process
(UP) in coronal sections and its
relationship with the frontal recess
and frontal outfl ow tract as proposed
by Stammberger and Hasler.3 IT,
inferior turbinate; MT, middle
turbinate; UP, uncinate process.
IT
IT
rendering modes—multiplanar reconstruction, surface
rendering, volume rendering, and maximum intensity
projection—allowing a better surgical planning.
4.2.2 Computed Tomography
CT scans offer the most accurate images to study the frontal recess and the frontoethmoidal cells.
are necessary to avoid losing relevant information. The
preoperative evaluation of the frontal recess can also
avoid severe complications related with vital structures
around the sinus.
The configuration of the following structures must be
checked in the preoperative CT before a frontal sinus procedure:
• Ostiomeatal complex anatomy.
• The width of the lateral lamella of the cribriform plate,
which articulates with the roof of the ethmoids (see
Keros classification).
• Insertion of the superior portion of the uncinate pro-
cess that could have superior attachment to different
structures (Fig. 4.2).
7
Slices of 1 mm
IT
• Pneumatization of the frontoethmoid cells (agger nasi
and o
ther cells).
• Presence of supraorbital, frontobullar, suprabullar, and
interfrontal sinus septal cells.
• Position of the anterior ethmoidal artery.
• Check the relationship between the nasal septum and
the head of the middle turbinate (septal deviation or
nasal spine).
• Thickness of the nasofrontal beak.
CT scan has proved to be useful in the postoperative evaluation of the frontoethmoidal cells and frontal recess.
The sinuses may display persistent opacification, residual
anterior ethmoidal and agger nasi cells, and a new bone
formation (osteoneogenesis) obstructing the FSDP.
4.2.3 Magnetic Resonance Imaging
The ability of magnetic resonance imaging (MRI) to better
discern the soft tissue becomes an ideal supplementary
test to CT. Sometimes the anterior fossa approach allows a
better planning with the CT scan, but the tumor resection
is easiest to design with the MRI as it depicts soft tissues.
8
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The surgeon must review the preoperative images and
evaluate the extent of the tumor along the parasagittal
plane. Lesions located at the anterior cranial base along the
anterior ethmoidal artery region require maximum visualization of the frontal sinus and skull base (Fig. 4.3a, b).
4.3 Indications
Table 4.1 summarizes the indications and respective sur-
gical extensions of the approach to the frontal sinus as
exposed by Draf.
9
4.4 Surgical Steps
The options for endoscopic surgery of the frontal sinus
range from a very limited opening of the anterior ethmoid to expose the natural ostium/opening to a bilateral
transseptal approach of the frontal sinus. Draf proposed
a classification system for endonasal frontal sinus surgery: type I, simple drainage; type IIa and IIb, extended
drainage; and type III, the endonasal median drainage
(Fig. 4.4).
9
a
Fig. 4.3 (a) Coronal and (b) parasagittal MR scans demonstrate a large olfactory groove meningioma in contact with the posterior
table of the frontal sinus.
Table 4.1 Indications of surgical approach to the frontal sinus following Draf
Draf I Acute sinusitis
Chronic sinusitis
Draf II type IIa drainage
Type IIb drainage
Draf III • Persistent chronic frontal sinusitis with failure of appropriate medical therapy and after unsuccessful
• Failure of conservative surgery
• Orbital and endocranial complications
• First time surgery
• No risk factors (aspirin intolerance, asthma, triad)
• Revision after incomplete ethmoidectomy
• Serious complications of acute sinusitis
• Medial mucopyocele
• All indications of type IIa if the drainage is too small in regard to the underlying pathology
primary endoscopic frontal sinusotomy
• Primarily in patients with prognostic risk factors and severe polyposis
• Mucoviscidosis
• Kartagener’s syndrome
• Ciliary immotility syndrome
• Benign and malignant tumors (lesions close to the anterior ethmoidal arter y region)
b
8
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Fig. 4.4 Type I drainage: simple
drainage (green area).
Type IIa drainage: Opening of frontal
sinus between lamina papyracea and
middle turbinate (orange area).
Type IIb drainage: Opening of frontal
sinus between lamina papyracea and
nasal septum (red area).
Type III drainage (not depicted
in this fi gure): The frontal sinus
fl oor is resected from the right
lamina papyracea to the left lamina
papyracea by resection of the
interfrontal sinus wall and the superior
nasal septum in front of the fi rst
olfactory fi ber.
4.4.1 Draf Type I
Type I drainage is established by anterior ethmoidectomy. This approach involves a simple drainage in which
all cells within the confines of the frontal recess are removed. The inferior part of the frontal infundibulum and
its mucosa are not touched.
First of all, we identify the ostiomeatal complex
(Fig. 4.5). The uncinate process should be seen (Fig. 4.5a)
and resected to expose the entire ethmoid bulla (Fig. 4.5b).
As the frontal outflow tract is directed toward the
infundibulum, there is no need to open the bulla to
expose the frontal ostium. This approach is understood
as the “intact bulla technique,” which maintains its anterior wall and thus protects the anterior ethmoidal artery,
located at its attachment at the skull base or right behind,
and the anterior skull base. For the sake of understanding the anatomy, the bulla ethmoidalis will be resected as
depicted in Fig. 4.5c.
4.4.2 Draf Type IIa
Type IIa drainage is an extended type I drainage and is accomplished through resection of the frontal sinus “floor”
from the lamina papyracea laterally to the middle turbinate medially by removing all cells at the frontal recess
that obstruct the outflow tract of the frontal and cells that
have pneumatized into the frontal. Thus, the “vertical
barr” and the agger nasi cell must be resected if pneumatized, as well as supra–agger nasi cells and supra–agger
nasi frontal cells (Fig. 4.6a, b). Usually no drilling is necessary in primary Draf type IIa.
4.4.3 Draf Type IIb
In this extended drainage, the frontal sinus floor is resected from the lamina papyracea to the nasal septum
(anterior to the ventral margin of the olfactory fossa)
(Fig. 4.7a, b). A drill is usually used because of the increasing thickness of the bone medially toward the nasal
septum.
by exposing the lacrimal bone and reducing it, as well as
part of the frontal process of the maxilla. This facilitates
better visualization of the frontal recess to allow further
work on the frontal sinus floor.
10
The wide approach to the ethmoid is obtained
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Frontal Sinus and Draf Approaches
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MT
UP
EB
EB
a
SAFC
c
Fig. 4.5 (a) Overview of the middle meatus of the left nasal cavity. The middle turbinate has been pushed medially. EB, ethmoidal
bulla; MT, middle turbinate; UP, uncinate process. (b) The uncinate process and the head of the middle turbinate have been resected
for a proper visualization of the dissection. Resection of the middle turbinate is not necessary for a Draf I and Draf II procedures. EB,
ethmoidal bulla. *Remnant uncinate process. Black arrow points at the remnant middle turbinate. (c) Resection of the ethmoid bulla.
Small circles show the extension of the frontal recess; the rectangle depicts the “vertical barr,” which limits laterally the medially
located frontal outfl ow tract. Lateral to it, a supra–agger nasi frontal cell (SAFC) can be seen pneumatizing into the frontal sinus
anteriorly to the bulla ethmoidalis (its remnants identifi ed with *), behind which the arrow points at the anterior ethmoidal artery.
b
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Frontal Sinus and Draf Approaches
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VB
a
Fig. 4.6 (a) The same case as in Fig. 4.5 after removal of the vertical barr (VB) (a small remnant is has been left) and the supra–agger
nasi frontal cell (O), its posterior wall still in place. The arrow points at the anterior ethmoidal artery located behind the anterior wall of
the ethmoidal bulla (*). (b) Another dissection of the left frontal recess after a Draf type IIa procedure with the lamina papyracea (LP)
as lateral limit and the most superior attachment of the middle turbinate (MT) as its medial limit. Note the curvature of the anterior
ethmoidal artery (arrows). FS, frontal sinus.
O
MT
b
FS
LP
LP
MT
a
Fig. 4.7 (a) The rectangle represents the area to drill out to complete a Draf Type IIb to reach the septum interfrontal. LP, lamina
papyracea; MT, middle turbinate. (b) An overview of the left side after a complete Draf type IIb. Please note the insertion of the
middle turbinate (MT), the olfactory cleft (OC), the anterior ethmoidal artery (arrows) embedded in the bony skull base, the lamina
papyracea (LP) as the lateral limit, the situation after drilling the nasofrontal beak (NFB), and medially the superior aspect of the nasal
septum (NS). PWFS, posterior wall of the frontal sinus.
4.4.4 Draf Type III (Median Drainage)
This surgery begins with a 0-degree scope that is used for
the majority of the procedure. Later, one can switch to a
30- or 45-degree scope at the end of the procedure when
the nasofrontal beak is taken down. Basically, a Draf type
III consists of a bilateral Draf type IIb including removal of
the interfrontal septum.
Two approaches can be chosen for this approach: the
“inside-out” or the “outside-in.” The first one is used to
identify landmarks at the skull base, such as the anterior
ethmoidal artery, and of the fully exposed frontal sinus in
a Draf type IIb procedure. It is thus safer, as the posterior
wall of the frontal sinus is always exposed.
b
The “outside-in” procedure can be indicated in cases
of obliterative scarring for the frontal, when the anatomy of the frontal recess has been considerably changed
due to osteoneogenesis and little anatomic references,
if any, can be identified. The first step consists of the
identification of the first olfactory fiber in the olfactory cleft, as this is the most posterior landmark behind
which we would face the anterior skull base and the
brain.
A trick to know where to start the dissection is to insert
one branch of a bajonette forceps into the nose directed toward the skull base. While the external branch of
the forceps points toward the frontal sinus, the internal
branch will, in parallel, point at the floor of the frontal
NS
NFB
PWFS
OC
MT
LP
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Frontal Sinus and Draf Approaches
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sinus endonasally. Usually, the branch of the forceps will
be a prolongation of the ascending process of the maxilla
toward the olfactory cleft.
It is important to make sure that there is enough
anteroposterior pneumatization of the frontal sinus
before starting the drilling. Fig. 4.8a–h depicts the
approach stepwise.
4.5 Case Examples
4.5.1 Case 1
A 28-year-old woman presented with headache. The results of the physical examination showed no neurologic
deficit. MRI showed the presence of an extra-axial enhancing lesion located in nasal cavity with anterior cranial fossa bone erosion (Fig. 4.9 a, b). After biopsy, histologic
examination confirmed the diagnosis of colonic rhabdomyosarcoma. The patient was refractory to chemotherapy and radiotherapy. Options were discussed with the
patient. A two-nostril endoscopic endonasal approach for
resection with radical ethmoidectomy and Draf type III
was selected (Fig. 4.9c). Total resection was achieved. The
patient was discharged 4 days postoperatively.
4.5.2 Case 2
A 41-year-old man presented with loss of sense of smell
and left epistaxis. MRI showed the presence of a heterogeneous and hyperenhanced lesion located in the nasal cavity with erosion of the adjacent bony structures
(Fig. 4.10a). Intracranial extension was not observed.
Unilateral endoscopic endonasal anterior cranial base
resection with Draf IIb was performed (Fig. 4.10 b, c)
to achieve total resection. Histologic examination confirmed the diagnosis of esthesioneuroblastoma. Postsurgical MRI showed no residual tumor (Fig. 4.10d).
4.6 Complications and Tips
and Tricks
Injury to the anterior ethmoidal artery when working
along the anterior skull base can be avoided by keeping
the anterior wall of the bulla intact when working on the
frontal drainage pathway. Identifying the artery first in
more extended approaches is helpful.
Missing the first olfactory fiber may lead to further exposure of the cribriform plate, risking a cerebrospinal fluid leakage. A subperiosteal dissection in the “outside-in”
approach will expose a small branch of the anterior ethmoidal artery first and then the first olfactory fiber in
a cleft.
Curved handpieces for the drill-out procedure will
avoid the risk of the typical “jump” of the burr, as may
happen when using angulated handpieces from middle
ear surgery. That “jump” may produce a lesion in the
posterior wall of the frontal sinus.
• Almost the entire approach to the frontal sinus can be
done with a 0-degree scope. Hyperextension of the
patient’s head is mandatory.
• The head of the middle turbinate is essential. Start
your dissection forward with this structure always
in mind.
• The largest possible opening should be made during
the Draf type III procedure. When you think you have
taken enough bone, continue drilling the nasofron-
tal beak anteriorly until you identify the external
periosteum of the frontal bone. Identify the “skin” at
least at one point of the nasofrontal beak as a land-
mark. It will show that the drilling has been exten-
sive enough.
Long-term packing of the frontal (around 7–10 days)
seems to promote mucosal regrowth on denuded
bone. Small mucosal flaps created with the first incisions or free mucosal grafts to cover denuded bone
have been proposed to overcome potential obliterative
osteoneogenesis.
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