Research Article
ORL
DOI: 10.1159/000514458
Received: November 24, 2020
Accepted: January 11, 2021
Published online:■■■
Sphenoid Sinus: Pneumatization
and Septation Patterns in a Hispanic
Population
José Luis Treviño-Gonzalez a Félix Maldonado-Chapa a
Joel Adrián Becerra-Jimenez b Germán Armando Soto-Galindo a
Josefina Alejandra Morales-del Angel a
aDepartment
of Otolaryngology-Head and Neck Surgery, Faculty of Medicine and University Hospital
“Dr. José Eleuterio González”, Monterrey, Mexico; bDepartment of Radiology, Faculty of Medicine and University
Hospital “Dr. José Eleuterio González”, Monterrey, Mexico
Abstract
Introduction: Pneumatization of the sphenoid sinus (SS) varies widely among different ethnic groups. Information regarding the prevalence and significance of SS variants
among Hispanic groups is limited. This study aims to describe and analyze pneumatization and septation patterns
of the SS in a Hispanic population. Methods: A total of 160
paranasal sinus computed tomographies were reviewed by
a head and neck-specialized radiologist and 2 otolaryngologists. Results: The postsellar and sellar types were the most
frequent patterns of pneumatization observed, with a prevalence of 52.5 and 40%, respectively. Accessory septations
were present in 59.4% of the patients. Septa were inserting
over the internal carotid artery (ICA) in 43.8% and over the
optic nerve in 17.5% of the population. No significant association (p > 0.05) was observed when comparing the different accessory septation patterns among the types of the SS.
The frequency of septa inserting on the ICA was significantly
higher in postsellar types (p < 0.001). Pneumatization of the
anterior clinoid process, pterygoid processes, and greater
karger@karger.com
www.karger.com/orl
© 2021 S. Karger AG, Basel
wing was present in 20, 17.5, and 45.9% of the sinuses, respectively. Onodi cells were encountered in 40% of the sinuses. There were no significant differences in any of the
pneumatization and septation variables when compared by
gender and age (p > 0.05). Discussion/Conclusion: Differences regarding anatomical variants and septations of the SS
were observed in our study when compared with findings
reported in other ethnic groups. Preoperative assessment of
the anatomical variants of the SS in Mexican patients is imperative to select the most optimal surgical approach and
prevent iatrogenic injuries to related neurovascular structures.
© 2021 S. Karger AG, Basel
Introduction
The sphenoid sinuses (SSs) represent one of the most
variable structures in the body. Their pneumatization
process starts between the third and the fourth year of life,
ending around the age of 16 years. Pneumatization of the
sphenoid bone frequently is asymmetrical and might extend to an anterior clinoid process (ACP), posterior clinoid process, greater wings of the sphenoid bone (GWS),
Correspondence to:
José Luis Treviño-Gonzalez, jose.trevinog @ uanl.mx
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Keywords
Computed tomography · Sinus surgery · Skull base
b
c
d
pterygoid process (PP), and dorsum sellae (DS) [1]. This
complex anatomy is further complicated by the different
complete or incomplete septation patterns that could be
present [2]. Computed tomography (CT) is the gold standard for evaluating the anatomy and pathology of the paranasal sinuses [3].
The anatomy of the SS has been acquiring growing importance during the past decades due to its relevance for
different transsphenoidal endoscopic surgical approaches not only for pituitary lesions but also for lesions arising
in the perisellar region, clivus, petroclival region, and cavernous sinuses [4]. In these cases, it is of utmost importance to assess preoperatively anatomical variants of
pneumatization by CT scan as an extensive pneumatization might result in bulging of significant neurovascular
structures, such as the internal carotid artery (ICA) or
optic nerve (ON), into the aired space. Their exposure
within the SS might result in iatrogenic damage to these
structures, resulting in significant hemorrhage or permanent blindness [5]. Moreover, traumatic disinsertion of
the main or an accessory septum from the bony canal of
these neurovascular structures could cause the same complications [1].
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DOI: 10.1159/000514458
A highly variable prevalence of the different pneumatization and septation patterns have been reported among
several ethnic groups [3, 6]. However, growing but limited data exist on the Hispanic population in which to
support on. The scope of advanced endoscopic skull base
and paranasal sinus surgery has been consistently expanding, and this fact stresses the importance of studying
the SS anatomy and the implications of the presence or
absence of anatomical variants in the surgery´s complexity and related risks. This study aims to describe the pneumatization patterns of the SS and its septations and establish a relationship between these variants with the insertion of a septum over the ICA or ON in a Hispanic adult
population.
Materials and Methods
This retrospective and descriptive study was conducted in the
University Hospital “José Eleuterio González,” a tertiary referral
center in Monterrey, México, according to the principles of the
Declaration of Helsinki and was approved by the local Research
and Ethics Committee, registered with the key OT16-00004. Paranasal sinus CTs of the last 160 patients complying with the inclu-
Treviño-Gonzalez et al.
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Fig. 1. Sphenoidal sinus types: conchal (a),
presellar (b), sellar (c), and postsellar (d).
a
*
*
Fig. 2. a Accessory septum inserting on the
ICA (asterisk). b Main septum inserting on
a
b
sion and exclusion criteria were reviewed. The study population
was Mexicans aged 18 years and older. The exclusion criteria were
evidence of acute or chronic rhinosinusitis involving the SS, skull
base fractures, sinus tumors, skull base tumors, craniofacial deformities, and history of surgery of the paranasal sinuses or skull base.
All CT scans were obtained from the radiology department and
contained axial slices of 1.25 mm and sagittal and coronal reconstructions from the vertex of the cranium to the level of the hyoid bone in
a high-definition bone window. These were obtained with a General
Electric Medical Systems Light Speed VCT, with a tube voltage of 120
Kv, 18 effective mAs, and a field of view of 14.2 × 27.8 cm. CT scans
were reviewed by 3 investigators to reach a consensus, a radiologist
with training in head and neck imaging and 2 otolaryngologists. In
case of discrepancies among investigators, another head and neck
specialized radiologist was consulted to reach a mutual consensus.
Along with sex and age, the following variables in the CT scans
were investigated:
• SS pneumatization: It is defined as conchal (posterior wall of
the sinus ends anterior to the sellae), presellar (pneumatization
ends anterior to the sellae, forming the posterior wall of the sinus), sellar (pneumatization ends between the anterior and
posterior border of the sellae), and postsellar (pneumatization
extending beyond the posterior limit of the sellae) (Fig. 1). This
variable was best evaluated in the sagittal plane.
• SS dominance: It is classified as none, right, or left, according
to the sinus with higher volume.
• SS accessory septation: It is classified as none, 1 incomplete, 1
complete, 2 complete, and 3 or more complete septa. Septa
were evaluated using the axial and coronal planes.
• Septation insertion (main or accessory septa) over the bony canal of the ICA (Fig. 2a) or ON (Fig. 2b). For the ON, this was
best evaluated in a coronal plane, whereas the ICA was evaluated in the axial and coronal planes.
• Pneumatization of the ACP: This was evaluated in the coronal
and axial planes (Fig. 3a).
• Pneumatization of the DS: It is evaluated in the sagittal and
axial planes (Fig. 3b, c).
• Pneumatization of the GWS: It is defined as pneumatization
extending laterally to a vertical plane crossing the foramen rotundum, creating a lateral recess, best evaluated in the coronal
plane.
• Pneumatization of PP: It is defined as pneumatization extending inferiorly to a horizontal line crossing the vidian canal, evaluated in the coronal plane.
• Pneumatization of ipsilateral GWS and PP (full lateral recess)
(Fig. 3d).
• Presence of Onodi cells (OC): This variable was evaluated in
the sagittal, axial, and coronal planes (Fig. 4).
Dependence between variables was investigated using the χ2
test. A value of p < 0.05 was considered statistically significant. Statistical evaluations were performed using the Statistical Package
for Social Sciences (SPSS) version 20.0.
Sphenoid Sinus: Pneumatization and
Septation Patterns
ORL
DOI: 10.1159/000514458
Results
We analyzed a total of 160 paranasal sinus CTs. There
were 89 (55.6%) male and 71 (44.4%) female cases. The
mean age was 45.67 ± 17.46 (18–88) years. The mean age
for the male group was 46.91 ± 18.47 (18–87) years,
whereas for the female group, it was 44.11 ± 16.10 (20–88)
years. There were no significant differences in age among
groups (p > 0.05).
The prevalence of type pneumatization of the SS, dominance, accessory septations, insertion of septation over
ICA and ON, pneumatization of ACP, DS, GWS, and PP
by the sinus is shown in Table 1. We found pneumatization of any the ACP in 27.5% of the population, 25% of
the DS, 26.7% of the PP, and 57.5% of GWS. Pneumatization and septation patterns of the SS were analyzed according to sex and are also shown in Table 1. There were
no significant differences between the pneumatization of
different parts of the sphenoid bone according to sex
stratification. In the same manner, there were no significant differences when the same patterns were analyzed
according to age by stratifying patients in decades of life
(p > 0.05).
The prevalence of the accessory septa configurations
according to the type of SS pneumatization is depicted
in Table 2. We observed a significant increase in the frequency of no accessory septations in presellar compared to sellar and postsellar configurations (p = 0.03).
3
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the ON (asterisk). ICA, internal carotid artery; ON, optic nerve.
*
*
a
b
Fig. 3. Pneumatization of the right ACP
(asterisk) (a), sagittal view showing pneumatization of the DS (asterisk) (b), axial
*
c
The prevalence of septation insertion (main or accessory) over the ON and ICA according to SS pneumatization is shown in Table 3. We found that the postsellar pneumatization was associated with a significant
­increase in the insertion of bony septations on the ICA
(p < 0.001).
We determined the prevalence of distinct patterns of
lateral pneumatization (PP, GWS, or both) according to
SS pneumatization to correlate anterior-posterior to lateral pneumatization (Table 4). We observed a significant
association for all the different lateral pneumatization
patterns to the anterior-posterior pneumatization (p <
0.05), finding a higher frequency of lateral pneumatization in sellar and postsellar configurations.
The prevalence of at least 1 OC in our population was
53.8%. The frequency right OC for different SS configurations was 0 (0%) for conchal, 3 (27.3%) for presellar, 29
(45.3%) for sellar, and 33 (39.3%) for postsellar (p =
0.543). Left OC were present in 0 (0%), 7 (63.6%), 24
(37.5%), 32 (38.1%), respectively (p = 0.319). Similarly,
bilateral OC were observed in 0 (0%) of the conchal, in 2
(18.2%) of presellar, in 18 (28.1%) of sellar, and in 22
(26.2%) of postsellar SS pneumatization (p = 0.839).
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DOI: 10.1159/000514458
*
d
*
*
Fig. 4. Bilateral Onodi cells (asterisks).
Discussion/Conclusion
Radiologic assessment and recognition of aberrant
patterns of pneumatization of the paranasal sinuses are of
major importance before performing endoscopic sinus
surgery. The presence of anatomical variants within paranasal sinuses might facilitate or difficult access to the
parasellar region and influence the risk of iatrogenic inTreviño-Gonzalez et al.
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view showing pneumatization of the dorsum sellae (asterisk) (c), and pneumatization of full bilateral lateral recesses (asterisks) (d). ACP, anterior clinoid process;
DS, dorsum sellae.
*
Table 1. Pneumatization and septation patterns according to sex
SS pneumatization
Conchal
Presellar
Sellar
Postsellar
SS dominancy
Right
Left
None
Accessory septations
None
Incomplete septum
One complete septum
Two complete septa
≥3 complete septa
Septa insertion on ON
Septa insertion on ICA
Pneumatization of ACP
Right
Left
Bilateral
Pneumatization of DS
Lateral pneumatization of SS
Right PP
Left PP
Bilateral PP
Right GWS
Left GWS
Bilateral GWS
Full right lateral recess
Full left lateral recess
Full bilateral lateral recess
Onodi cell
Right
Left
Bilateral
Total
(n = 160) (%)
Male
(n = 89) (%)
Female
(n = 71) (%)
p value
1 (0.6)
11 (6.9)
64 (40)
84 (52.5)
1 (1.1)
8 (9)
33 (37.1)
47 (52.8)
0 (0)
3 (4.2)
31 (43.7)
37 (52.1)
0.37
0.237
0.398
0.93
54 (33.8)
73 (45.6)
33 (20.6)
30 (33.7)
42 (47.2)
17 (19.1)
24 (33.8)
31 (43.7)
16 (22.5)
0.99
0.656
0.594
65 (40.6)
30 (18.8)
38 (23.8)
24 (15)
3 (1.9)
28 (17.5)
70 (43.8)
31 (34.8)
20 (22.5)
25 (28.1)
12 (13.5)
1 (1.1)
14 (15.7)
40 (44.9)
34 (47.9)
10 (14.1)
13 (18.3)
12 (16.9)
2 (2.8)
14 (19.7)
30 (42.3)
0.095
0.177
0.149
0.547
0.433
0.51
0.733
32 (20)
32 (20)
20 (12.5)
40 (25)
20 (22.5)
20 (22.5)
13 (14.6)
23 (25.8)
12 (16.9)
12 (16.9)
7 (9.85)
17 (23.9)
0.381
0.381
0.367
0.783
28 (17.5)
28 (17.5)
13 (8.1)
68 (42.5)
79 (49.4)
55 (34.4)
27 (16.9)
28 (17.5)
13 (8.1)
14 (17.5)
19 (21.3)
7 (7.7)
35 (39.3)
43 (48.3)
28 (31.5)
14 (15.7)
19 (21.3)
7 (7.7)
14 (19.7)
9 (12.7)
6 (8.4)
33 (46.5)
36 (50.7)
27 (38)
13 (18.3)
9 (12.7)
6 (8.4)
0.51
0.151
0.893
0.363
0.764
0.385
0.665
0.151
0.893
65 (40.6)
63 (39.4)
42 (26.3)
35 (39.3)
34 (38.2)
22 (24.7)
30 (42.3)
29 (40.8)
20 (28.2)
0.708
0.734
0.622
jury to related neurovascular structures [7]. The Assessment of Pneumatization of Paranasal Sinuses (APPS) is a
recently introduced and validated metric which evaluates
the presence of anatomical variants among all the paranasal sinuses [8]. This instrument contains 2 different
items regarding the SS: ACP pneumatization and pneumatization lateral to a line crossing through the foramen
rotundum and vidian canal. The APSS has also been demonstrated to correlate strongly with the total sinus vol-
ume, thus can be used as a reliable measure of the overall
prevalence of different anatomical configurations in large
populations [9, 10]. The prevalence of the anatomical
variants of the SS cannot be generalized as incredibly significant differences have been observed among different
ethnic groups [3]. These observations along with the lack
of data in our population motivated the development of
our study.
Sphenoid Sinus: Pneumatization and
Septation Patterns
ORL
DOI: 10.1159/000514458
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SS, sphenoidal sinus; ON, optic nerve; ICA, internal carotid artery; ACP, anterior clinoid process; DS, dorsum
sellae; PP, pterygoid process; GWS, greater wing of the sphenoid. Chi-squared test was used to assess dependency
between variables (p < 0.05 was considered statistically significant).
Table 2. Number of accessory septations according to type of SS
Accessory septation
Conchal,
n (%)
Presellar,
n (%)
Sellar,
n (%)
Postsellar,
n (%)
p value
None
One incomplete septum
One complete septum
Two complete septa
≥3 complete septa
0 (0)
1 (100)
0 (0)
0 (0)
0 (0)
9 (81.8)
2 (18.2)
0 (0)
0 (0)
0 (0)
25 (39)
12 (18.8)
14 (21.9)
13 (20.3)
0 (0)
31 (36.9)
15 (17.9)
24 (28.6)
11 (13)
3 (3.6)
0.03*
0.223
0.176
0.287
0.429
SS, sphenoidal sinus. *Statistically significant according to χ2 test (p < 0.05).
Table 3. Frequency of septa insertion over ON and ICA according to the type ofSS
Insertion
of septa
Conchal,
n (%)
Presellar,
n (%)
Sellar,
n (%)
Postsellar,
n (%)
p value
ICA
ON
0 (0)
0 (0)
0 (0)
0 (0)
17 (26.6)
11 (17.2)
53 (63.1)
17 (20.2)
<0.001*
0.394
ICA, internal carotid artery; ON, optic nerve; SS, sphenoidal sinus. *Statistically significant according to χ2
test (p < 0.05).
Table 4. Lateral pneumatization according to type of SS
Lateral pneumatization degree
Conchal,
n (%)
Presellar,
n (%)
Sellar,
n (%)
Postsellar,
n (%)
p value
Right PP
Left PP
Bilateral PP
Right GWS
Left GWS
Bilateral GWS
Full right lateral recess
Full left lateral recess
Full bilateral lateral recess
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
1 (9.1)
0 (0)
0 (0)
1 (9.1)
0 (0)
0 (0)
1 (9.1)
0 (0)
0 (0)
5 (7.8)
3 (4.7)
1 (1.6)
18 (28.1)
22 (34.4)
15 (23.4)
5 (7.8)
3 (4.7)
1 (1.6)
22 (26.2)
25 (29.8)
12 (14.3)
49 (58.3)
57 (67.9)
40 (47.6)
22 (26.2)
25 (29.8)
12 (14.3)
0.025*
<0.001*
0.029*
<0.001*
<0.001*
0.001*
0.025*
<0.001*
0.029*
SS Type Pneumatization
Hammer and Radberg first classified SS pneumatization into conchal, sellar, presellar, and postsellar [3]. This
classification emphasizes posterior pneumatization in
relation to the sellae and predicts the surgical corridor
used for transsphenoidal surgeries [11]. Sellar and postsellar types of SS facilitate endoscopic procedures as the
6
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DOI: 10.1159/000514458
SS presents thinner walls and less bone drilling is required to access the sellae. This might also represent a
risk as increased pneumatization is also associated with
bulging of neurovascular structures or dehiscence of
their bony canals. Endoscopic transsphenoidal procedures are less suitable for presellar and conchal types as
perforation through a thicker SS is required [12]. In our
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PP, pterygoid process; GWS, greater wing of the sphenoid; SS, sphenoidal sinus. * Statistically significant
according to χ2 test (p < 0.05).
Table 5. Prevalence of sphenoidal types and other anatomical variants among different populations in several CT-based studies
Study
Population
Conchal, Presellar, Sellar, Postsellar, AS,
%
%
%
%
%
ACP,
%
DS,
%
Present study
Gibelli et al. [1]
Jaworek et al. [2]
Lu et al. [4]
Gibelli et al. [7]
Hiremath et al. [11]
Tawfik et al. [12]
Anusha et al. [13]
Dal Secchi et al. [14]
Tomovic et al. [15]
Rahmati et al. [16]
Asal et al. [24]
Siricki et al. [25]
Arslan et al. [26]
Hewaidi et al. [27]
Kazkayasi et al. [28]
Ilków et al. [29]
Refaat et al. [30]
Mexican
Italian
Croatian
Chinese
Italian
Indian
Egyptian
Malaysian
Brazilian
American
Iranian
Turkish
Turkish
Turkish
Libyan
Turkish
Polish
Turkish
0.6
6.9
40.0
6.0
0.0
0.0
3.2
0.3
0.0
1.8
0.0
28.5
8.0
1.2
0.0
6.7
2.0
7.3
1.9
65.5
77.3
98.8
96.8
93.0
98.0
47.6
14.6
0.0
28.2
39.4
PP,
%
52.5
59.4
78.1
78.0
27.5
25.0.0 26.7
14.7
62.7
20.3
32.9
0.0
11.6
46.3
39.0
43.5
69.8
17.9
12.0
13.0
33.1
43.7
29.3
6.0
15.3
17.2
38.9
43.3
86.0
32.4
27.6
12.0
GWS, OC,
%
%
57.5
53.8
9.3
31.8
1.0
47.0
18.0
14.3
39.6
29.3
16.0
29.0
39.7
26.5
23.0
20.0
10.0
22.9
population, higher pneumatized SS were more frequent;
52.5 and 40% were postsellar and sellar, respectively. This
result is different from that observed in Italian, Egyptian,
and Malaysian populations in whom sellar configurations have been shown to be more frequent with a prevalence of 74, 96.8, and 93%, respectively [7, 12, 13]. In 2 of
these studies, postsellar pneumatization was not observed in any patient [12, 13]. Dal Secchi et al. [14] reviewed CT scans of 90 Brazilian patients; however, sellar
and postsellar were reported and conjoined into 1 category, with a prevalence of 98%. Our findings seem to
concur with studies performed in Indians, a Hispanic
subgroup in a US population, and Iranians, in whom
postsellar pneumatization has been observed as the most
predominant subtype [11, 15, 16]. All the mentioned investigations are CT-based studies. Several other investigations performed in cadavers with less sample size have
also been undertaken, and results are also variable among
different ethnicities [17, 18]; however, this method might
not be as accurate as the CT. The conchal type is constantly rare among studies and usually represents an incomplete pneumatization process [13]. We only observed 1 case of conchal SS in a masculine patient aged
48 years (Table 5).
SS Septation
Accessory septations have also been widely studied
among different populations, with contrasting observations. The rate of accessory septa has been observed to
range from 14.6% up to 78.1% among studies performed
in distinct populations [1,2, 12, 13]. When present, 2 septa was the most frequent variant in 2 studies. We observed
accessory septations in 59.4% of our population (Table 5).
When present, more frequently, they were complete, traversing the full SS.
Fewer studies looking for the insertion of septations over
the ICA or ON have been performed, and in the same manner, several differences have been noted among studied
populations. When considering the rate of septations over
the ICA and ON in separate populations, authors have reported prevalence ranging from 20.8 to 89% for the ICA [1,
19, 20] and 7.7% for the ON [1]. By individual sinuses, 2
studies from Turkey and 1 from Egypt reported a prevalence of insertion over the ICA of 26.7, 8, 12.9%, respectively. These same research teams reported a prevalence of
insertion over the ON of 19.6, 8, and 5.9% [21–23]. We observed higher rates of these parameters in our population,
finding a prevalence of 43.8% insertion over the ICA and
17.5% insertion over ON in the evaluated patients.
Sphenoid Sinus: Pneumatization and
Septation Patterns
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DOI: 10.1159/000514458
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In some studies, no particular data were reported and spaces were left in blank. CT, computed tomography; AS, accessory septa; ACP,
anterior clinoid process pneumatization; DS, dorsum sellae pneumatization; PP, pterygoid process pneumatization; GWS, greater wing
of the sphenoid pneumatization; OC, Onodi cell.
ACP Pneumatization
We observed the pneumatization of at least 1 ACP in
27.5% of the population. Bilateral pneumatization was
observed in 12.5% of the patients. This prevalence falls
among the range reported in the literature in other ethnic
populations of 6–47.2% (Table 5) [12, 13, 16, 21, 24–28].
Two studies have shown an association between pneumatization of ACP with protrusion of the ON into the aired
space [12, 25] and 1 of them with dehiscence of the bony
canal of the ON [12]. Pneumatization of the ACP creates
an optic-carotid recess, a small space in the superolateral
portion of the SS limited superiorly by the ON and by the
ICA inferiorly. Bulging and dehiscence of the ON into the
aired space of the SS predispose it to iatrogenic injury and
subsequent vision loss [3].
DS Pneumatization
Pneumatization of the DS is related to postsellar SS
types. Only a few studies have evaluated the pneumatization of this structure and discussed its clinical implications. Reported rates of pneumatization are between 10
and 32.9% [4, 7, 29] compared to 25% in our evaluated
population (Table 5). This comparison highlights the importance of precise descriptions of the several anatomical
variants among different ethnicities to obtain more data
about their origin, distribution, and possible associations.
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PP and GWS Pneumatization
PP pneumatization has been defined as pneumatization extending inferior to a horizontal plane crossing the
vidian canals [27] or pneumatization lateral to a tangential plane crossing the foramen rotundum and the vidian
canal [25]. The former definition was used in the present
study to present comparable results as it has been used by
most authors. The reported prevalence of patients with
pneumatized PP varies among Egyptian, Italian, Libyan,
and Turkish populations from 9.3 to 38.9% (Table 5) [7,
12, 16, 27]. We observed pneumatization of the PP in
26.7% of the population. A total of 8.1% of the reviewed
CT scans had bilateral pneumatization. This pattern of
pneumatization provides access to the central skull base
for the repair of cerebrospinal fluid leaks as well as for biopsies of skull base lesions [27].
Pneumatization of the GWS of the sphenoid is defined
as pneumatization extending laterally to a vertical plane
crossing the foramen rotundum [3]. The lateral recess has
been classically defined as pneumatization of the GWS.
Under this definition, prevalence among different ethnic
groups varies from 20 to 47% (Table 5) [12, 14, 27, 30]. In
another study, by Tomovic et al. [15], the lateral recess
was defined as pneumatization not only of the GWS but
also of the ipsilateral PP. He observed a lateral recess in
72.4% of the population and found a significantly higher
prevalence in African Americans (84.6%) than Hispanics
(58.2%). We observed pneumatization of the GWS in
57.5% of the population. A total of 34.4% of the patients
had bilateral pneumatization. A full lateral recess, with
pneumatization of the GWS and ipsilateral PP, was observed in 17.2% of the reviewed sinuses and 8.1% of the
patients had a full bilateral recess. Although this pattern
of pneumatization provides wide access to the middle
cranial fossa for transsphenoidal endoscopic surgery, it is
associated with protrusion of the maxillary nerve [31].
Moreover, this recess might communicate with the Stenberg canal and cause a spontaneous cerebrospinal fluid
leakage or meningoencephalocele [12].
Onodi Cells
We decided to analyze the prevalence of OC because
of its relevance for SS surgery. The sphenoethmoidal cells
are posterior ethmoidal air cells that extend superolateral
into the SS. They are closely related to the ON and ICA.
Possible injuries can occur during ethmoidectomy when
intending to enter de SS by passing through the OC. Bony
walls separating these neurovascular structures from the
OC are as thin as 0.03 mm [3].
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Gibelli et al. [1] observed that a higher SS volume was
significantly related to the presence of accessory septa and
the insertion of septa over the ICA. While we did not
measure volume, we sought to determine this association
by using SS type. There was no significant association between the category of accessory septa and each SS type. As
Gibelli et al. [1], we found a significant association between a higher volume and insertion of septa on the ICA
bony canal. These data, taken together, suggest that a septum inserted over the ICA might be expected in large sinuses, and insertion over ON could be present in any SS
volume size.
Accessory septa might not be the only issue, but the
skewing of the main intersphenoidal septa might also
produce asymmetric SS. We observed that 69.4% of our
reviewed patients showed SS dominancy toward the left
or right side. For these reasons, the main intersphenoidal
septum might not be a reliable guide toward approaching
the midline in the sinus. An appropriate preoperative assessment of SS septa and insertions is highly recommended to avoid removing unnecessary septa that might result
in significant morbidity.
We observed OC invading the SS in 53.8% of the population. A total of 26% patients had bilateral sphenoethmoidal cells. These rates are higher than 14, 18, and 23%
reported in Malaysian, Egyptian, and Turkish populations, respectively (Table 5) [12, 13, 24]. Tawfik et al. [12]
found a significant association between the presence of
OC and ON protrusion and dehiscence. Based on these
observations, it seems appropriate to evaluate preoperatively for OC before operating the SS in Mexicans.
Based on our results, detailed analysis of CT scans prior to SS surgery is of paramount importance to plan the
most optimal surgical approach. This study describes the
anatomical variants of pneumatization and septation in a
Mexican population and complements the literature that
exists in other ethnic groups. Our study has limitations
that should be mentioned. First, the sample is relatively
small and was performed in a single center. Second, our
study did not include any child. Finally, our data are insufficient to find relationship between anatomical variants of the SS and different SS- and skull base-related pathologies. Further studies in our country with larger samples describing the pneumatization patterns associated
with bulging and dehiscence of neurovascular structures
in the SS are needed to confirm our observations. Studies
addressing anatomical variants in the presence of disease
would also provide valuable data for the evaluation and
approach to patients with SS-related pathology.
Statement of Ethics
Ethical approval was waived by the local Ethics Committee of
University Hospital “Dr. José Eleuterio González” with the key
OT16-00004 in view of the retrospective nature of the study, and
all the procedures performed were part of the routine care.
Conflict of Interest Statement
The authors have no conflicts of interest to declare.
Funding Sources
The authors did not receive support from any organization for
the submitted work.
Author Contributions
All authors contributed to the study conception and design.
Material preparation, data collection, and analysis were performed
by Joel Adrián Becerra-Jiménez, Germán Armando Soto-Galindo,
and José Luis Treviño-González. The first draft of the manuscript
was written by Félix Maldonado-Chapa and Josefina Alejandra
Morales-del Ángel, and all authors commented on previous versions of the manuscript. All authors read and approved the final
manuscript.
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