SCIENTIFIC COMMUNICATION
Endoscopic resection of the olfactory
cavity
Roger Jankowski
Service O.R.L. et Chirurgie Cervico-Faciale, C.H.U. - Hôpital Central - Nancy
ABSTRACT
The development or extension of malignant neoplasms into the olfactory cavity of the nasal fossa can be approached by a technique of endoscopic endonasal surgery that we describe in the present article. A complete and carcinologic resection of the olfactory cavity appeared possible in three esthesioneuromas and twenty six adenocarcinomas. The dissection of the mucosa covering the cribriform plate, after section of the olfactory fibers, lead inconstantly to minor CSF leaks that fade most of the times before the end of the procedure. Only one patient needed
revision surgery to close a persisting CSF leak. No one developed meningitis after a follow-up of six months to six
years. Endoscopic resection of the olfactory cavity represents an innovative technique in the field of endonasal
endoscopic surgery. It can be transformed in endoscopic endonasal craniofacial resection, if necessary.
(Presented on September 2005 at Congress NOSE, Porto and
on Mai 2006 at the Congress of Mexican Society of ENT, Accapulco)
(Fr ORL-2007;93:341-346)
Key words: Olfactory cleft, Endonasal endoscopic surgery, Malignant neoplasms of the nose and sinuses,
Cribriform plate, Conchal lamina of the ethmoïdal bone, Ethmoid.
Submitted for publication: Mai 2006
Accepted for publication: November 2007
Corresponding author: Roger Jankowski
S e rvice O.R.L. et Chiru rgie Cervico-Fa c i a l e,
C . H . U. – Hôpital Central
29 ave nue du Mal de Lat t rede Ta s s i g ny
54035 Nancy Cedex
e-mail: r.jankowski@chu-nancy.fr
341 - Fr ORL - 2007 ; 93
Endoscopic resection of the olfactory cavity
INTRODUCTION
The turbinate wall of the ethmoid [1] and the adjacent
part of the nasal septum limits an air-filled narrow and
vertical cavity called the olfactory groove [2]. This
cavity connects with the nasal fossae via its base and
it is closed above by the cribiform plate of the ethmoid bone, behind by the anterior surface of the sphenoid bone, and in front by the roof of the nasal bones.
It forms an olfactory air reservoir situated above the
nasal fossa through which respiratory airflow occurs.
Endoscopic surgery of the olfactory groove has received little attention to date apart from the controversial
resection of the middle nasal concha [3] or the resection of inflammatory polyps [4]. The olfactory grove
is currently an area that is off-limits for endonasal
endoscopic surge ry, particularly its superior part
which is in contact with the cribiform plate. The aim
of the article is to describe a controlled surgical excision of the olfactory cavity after tumor development
or invasion. Detachment of the olfactory mucosa of
the cribiform plate after sectioning of olfactory fibres
makes this intervention possible.
Endoscopic excision of the olfactory cavity appears to
be an innovative technique which could be added to
the current list of endonasal interventions. Our experience with this technique currently includes three
olfactory esthesioneuromas and 26 adenocarcinomas.
DESCRIPTION OF THE TECHNIQUE
We limit the description to cases of unilateral tumors
without intracranial extension at preoperative imaging. The intervention takes place within the standard
setting of endonasal endoscopic surgery. The reduction of tumor volume by removing the non-invasive
free portion of the tumor in the nasal fossa is usually
required to identify the limits of excision of normal
tissue.
Dissection of the septal wall
A healthy region of the septal mucosa is incised at a
distance of at least 5 mm from the tumor margins
down to the level of bone or cartilage with the aid of
a Beaver® lancet. A first incision, parallel to the floor
of the nasal fossa, is performed from back to front, a
second frontal incision is made from top to bottom to
join perpendicularly with the first. The mucosa delineated between these two incisions is raised to the
subperichondrial-subperiostal level as far as the posterior edge of vomer and anterior surface of the sphenoid bone behind, and to the cribiform plate above.
The olfactory fibres are incorporated within the mucosal layer and do not delay dissection; in contrast progression could be impeded if tumoral invasion of the
plane of dissection is discovered at this stage. If the
contralateral mucosa of the olfactory cavity is macroscopically normal, it is possible to widen the septal
dissection to the point of septal resection; but rather
than persisting with the intervention, rather, it is worth
reconsidering surgery for bilateral tumors of olfactory
cavities.
Dissection of internal orbital wall [5]
The ethmoid bone is a buffer zone interposed between
the olfactory cavity and the internal orbital wall,
which offers a margin of tumor dissection when the
external or orbital ethmoid cells appear not to be invaded on preoperative imaging.
Unciformectomy permits the ex p o s u re of the maxillary ostium, from wh i ch a a large middle meat o t o my is
p e r fo rmed from front to back to the palatine bone and
f rom bottom to top between the superior edge of the
i n fe rior nasal concha and the roof (wh i ch is also the
floor of the orbit). The subperiostal dissection of the
i n t e rnal wall of the orbit can be perfo rmed from bottom to top from the level of the roof of the maxillary
sinus. Advancing the dissection of the compartment of
u n c i fo rmcells situated at the anterior- s u p e rior angle of
the ethmoid box is fa c i l i t ated by seeking the subperiostal plane ahead of the ethmoid box, on the rising
ap o p hysis of the maxillary bone. Sphenoidotomy is
p e r fo rmed systemat i c a l ly as it offe rs two points of
i n t e rest: it allows the confi rm ation, if re q u i re d, of the
l o c ation of the ethmoid roof and the internal wall of
the orbit to their posterior parts, and as a result it permits the safe completion of the excision of cells of the
anterior-superior angle of the ethmoid box and go o d
identification of the cells of Onodi and frequent relief
of the optical canal. The bony infra s t ru c t u re of the
i n t e rnal wall of the orbit can be also dissected sub-peri o s t i a l lyalong its entire surface in total safe t y.
Dissection of the ethmoid roof
This starts in normal tissue in contact with the internal
wall of the orbit; and is performed subperiosteally
from the frontal ostium to the orifice of the sphenoidotomy. The dissection of its internal half can be relaFr ORL - 2007 ; 93 : 342
Endoscopic resection of the olfactory cavity
Figure 1: Anatomy of the ceiling of the
olfactory groove in sagittal section [10]
The ceiling of the olfactory groove presents
three segments distinguished by their orienta tion: the anterior oblique segment above and
behind formed by the inferior surface of the
nasal and frontal bones; a middle horizontal
segment formed by the cribiform plate of the
ethmoid and the ethmoidal process of the
sphenoid; a posterior segment, initially verti cal and then oblique downwards and back wards, formed by anterior surface of the sphe noid to the opening of the sphenoid ostium.
tively delicate depending on the presence or absence
of tumoral invasion, but when preoperative imaging
shows the absence of intracranial extension the technique of endoscopic subperiostal dissection offers a
margin of oncologic safety at least comparable with
excision using the para-latero-nasal approach. The
aim of the dissection of the ethmoid roof is to find the
inner surface of Mouret’s conchal plate (Figure 3)
along its entire length or in part if it has been destroyed by the tumor. The junction of the ethmoidal
roof and the conchal plate is carefully dissected in the
subperiosteum.
Dissection of the cribriform plate and excision of
the olfactory groove
If it has not already been performed, the resection of
the middle concha is performed at this stage; this facilitates access to the olfactory cavity. With the help of
a Beaver® lancet the frontal incision of the septal
343 - Fr ORL - 2007 ; 93
Figure 2: Anatomy of the lateral wall of the
right nasal fossa and the turbinate wall of
the right ethmoid [1]
The turbinate wall of the ethmoid consists of
superiorly a continuous bony plate (Mouret’s
conchal plate) suspended at the junction of
the cribiform plate and the ethmoidal roof,
from which it detaches from front to back the
middle, inferior and eventually superior turbi nates, which between them demarcate the
meatuses of the name.
Figure 3: Mouret’s conchal plate continues
above the cribriform plate as the lateral plate
of the intracranial olfactory groove which
makes the junction with the roof of the lateral
mass of the ethmoid.
mucosa is prolonged diagonally under the nasal bone,
then outside on the rising apophysis of the maxilla
coming down to the level of the resection line of the
middle concha.
The detachment of the mucosa from the inferior surface of the nasal bone and the maxillary apophysis is
Endoscopic resection of the olfactory cavity
Figure 4: Anatomy of the endocranial surface of the cribriform plate [2]
Foramina of the cribriform plate allow the
p a s s age of the olfa c t o ry nerves, with the
exception of two orifices situated at its ante rior extremity: the ethmoidal groove, which is
situated opposite to the apophysis of the cris ta galli; ethmoidal foramen which is located
outside of the ethmoidal groove allows the
passage of the internal nasal nerve, a branch
of optic nerve, which accompanies the ante rior ethmoidal artery in its path and separates
from it later at the internal orifice of the ante rior ethmoidal canal to follow the ethmoidal
groove and rejoin the ethmoid foramen.
performed in the subperiosteum to rejoin the subperichondrial plane of detachment on the septum. The
subperiostial dissection of the anterior oblique segment of the ceiling of the olfactory groove (Figure 1)
does not present any difficulty; arrival at the cribiform
plate (Figure 4) is indicated by the emergence across
the ethmoid of the internal nasal nerve which arises as
a resistant cord preventing the progress of submucosal
detachment. After section of this nerve using a curved
micro-scissors the detachment of the mucosa of the
cribriform plate is again easy for one to two millimetres, the point where the first olfactory fibres are
encountered.
The extension of dura mater of the ethmoid groove
(Figure 4) does not seem often affect the inferior surface of the cribriform plate, as it has never been an
obstacle to the progression of the mucosal detachment
or the source of a CSF leak. The olfactory fibres are
much thinner than the internal nasal nerve and can be
arranged 2 randomly or in two rows which emerge on
the inferior surface of the cribriform plate, one internal row in contact with the septum and an external
row along Mouret’s conchal plate (Figure 4). The
olfactory fibres are easily cut or pulled with a sharp
Blakesley forceps, which does not in general lead to
an endoscopically visible CSF leak. However, pulling
seems to be a gre ater risk for a CSF leak due to
connections between olfa c t o ry fibres and the
meninges.
The detachment of the mucosa on the inferior surface
of the cribriform plate does not present any resistance
in areas apart from the emergence of the olfactory
fibres and progresses easily at the rate they are sectioned to the level of the septum-cribriform plate junction. The section of Mouret’s conchal plate (Figure 2)
from the cribriform plate is facilitated if it is fractured
before by internal dislocation, this dislocation reveals
the olfactory fibres and it is sufficient to cut these in
order to detach the conchal plate step by step from
front to back.
Meanwhile, it is necessary to keep in mind from the
scan images of the patient, that the ethmoidal roof is
situated above the plane of the cribriform plate, particularly in front. Fracturing by internal dislocation of
the lateral plate (figure3) leads to intracranial damage
with not only a CSF leak but also the risk of a haematoma in case of an associated lesion of the ethmoidal
artery. The dissection of the cribriform plate ends
behind by meeting the anterior sphenoidal surface. In
favourable cases, the olfatory cavity excision could be
performed in one piece.
Perioperative wound-dressing and care
In the absence of a visible CSF leak the cribriform
plate and ethmoidal roof are coated with 2 ml of biological glue to which a compress of Surgicel ® is
applied. The cavity does not receive any other packing. The patient can leave the department after 48
hours of perfused antibiotic prophylaxis (the protocol
is copied from that of neurinoma surgery).
Postoperative care is that of endonasal surgery, and
the surgical intervention is integrated into a protocol
of combined care adapted to the tumor pathology. The
management of a visible CSF leak is handled using
classical filling techniques.
DISCUSSION
The excision of malignant sinus tumors by the endoscopic endonasal ap p ro a ch remains controversial.
Fr ORL - 2007 ; 93 : 344
Endoscopic resection of the olfactory cavity
Figure 5: Endoscopic view of the left operative cavity at the end of an excision.
Figure 6: MRI appearance of an adenocarcinoma of the left olactory groove (a) and
postoperative follow up after one year (b).
a
Rsm = Resection of septal mucosa;
Fs = Frontal sinus; Cp = Cribiform plate;
Te = Roof of the ethmoid; Sph = Sphenoid;
Po = Wall of the orbit
b
CSF flow in seven patients, of whom six had spontaneous drying in intra-operative period. None of the
patients had postoperative meningitis after a followup period of between 6 months and 6 years. All were
irradiated.
CONCLUSION
The recent publication by Goffart et al [6] in 78
patients and that of Lund et al [7] in 49 patients,
however, seriously strengthen the arguments in favour
of an endoscopic approach: the follow-up periods of 3
to 5 years are at least equal to those published for
external approaches. Our experience also shows promising results, although the endoscopic approach has
mostly permitted us to identify limiting factor for this
approach, which is the dissection of the tumor developed in or extending to the olfactory groove. The aim
of this publication is not to report our oncologic
results as our series is too small and without sufficient
follow-up for the majority of our patients.
The object is to present an innovative surgical approach for the excision of malignant tumors that have
developed in or extending to the olfactory groove, but
without endocranial invasion. Our technique could be
completed, if necessary, according to intra-operative
findings regarding intracranial invasion, by endoscopic resection of the skull base [8,9]. The excision of
the olfactory cavity does not increase surgical trauma
and does not modify classical operative results of ethmoidal surgery. Several of our patients who had
advanced age or fragile general health have tolerated
the procedure without difficulties. Only one of our
patients had a CSF leak, which required a second surgery. The section of olfactory fibres has lead to visible
345 - Fr ORL - 2007 ; 93
The dissection of the cribriform plate and the excision
of the olfactory cavity by the endoscopic endonasal
approach could be performed using a codified surgical
protocol that was not accompanied by particular
neuro-meningeal risk. This technique necessitates,
however, solid experience in endonasal endoscopic
surgery and the respect of rules of medical management of malignant tumors in keeping with a multi-disciplinary approach.
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