versión On-line ISSN 0717-9502
Int. J. Morphol. v.26 n.4 Temuco dic. 2008
Int. J. Morphol., 26(4):803-808, 2008.
Anatomical Variations of the Frontal Sinus
Variaciones Anatómicas del Seno Frontal
*José Marcos Pondé; *Raimundo Nonato Andrade; *José Maldonado Via; **Patick Metzger & **Ana Clara Teles
* Department of Morphology Escola Bahiana de Medicina e Saúde Pública, Brasil.
** Student of Medicine Escola Bahiana de Medicina e Saúde Pública, Brasil.
SUMMARY: An anatomical study of the frontal sinus in 100 macerated skulls. The study introduces an innovation on the literature by means of the measurement of the sinus's volume. All the found information in the literature attained to other aspects including the diameters of the sinus and the geometric área of the same. Objective: Evaluation of the measures of the frontal sinus frequently involved in cranial base surgeries and supraorbital craniotomies in order to help the surgical approaches that cross this anatomical route Methods: The measurement included: sagital, transverse and an tero-posterior diameter acquired with a paquimeter and the volume obtained after filling the sinus with sand. Results: They are in accordance with the literature that shows the male's predominance in all measurements done.
KEY WORDS: Frontal sinus; Supraorbital craniotomy; Paranasal sinus.
RESUMEN: Se presenta un estudio anatómico del seno frontal que fue realizado en 100 cráneos. El estudio introduce una novedad en la literatura, que es la medida volumétrica del seno frontal. Toda la literatura se refiere a otros aspectos, incluyendo los diámetros de los senos y su área geométrica. El objetivo del estudio fue estimar las medidas del seno frontal que con frecuencia hacen parte en las cirugías de la base del cráneo y en las craneotomías supraorbitarias, con la finalidad de facilitar las vías de acceso quirúrgico por estas regiones. Las medidas realizadas fueron: diámetro sagital, transversal y antero-posterior con un caliper, y el volumen fue obtenido llenando el seno con arena fina. Los resultados están de acuerdo con la literatura que demuestra un mayor predominio del sexo masculino en todas las medidas efectuadas.
PALABRAS CLAVE: Seno frontal; Craneotomía supraorbitaria; Seno paranasal.
The minimally invasive surgeries have acquired a growing importance in surgical interventions in order to avoid tissue damage and reduce surgical time.
In neurosurgery, the number of publications concerning these kind of approaches has also increased (Fukushima et al, 1991; Menovsky et al, 1999; Perneczky et al, 1993; Steiger et al, 2001; Taniguchi & Perneczky, 1997). When cranial base surgery is made in the frontal región or when the supraorbital mini-craniotomy is realized, the involvement of the frontal sinus may become troublesome. The entrance by means of the craniotomy in the frontal sinus can lead to postoperative complications as CSF leakage, bone flapp infections, besides the late consequences of meningitis and brain abscess.
The frontal sinuses are two, situated in the posterior part of the supercilliary ares, between the external and internal faces of the frontal bone. They are seldom symmetrical; generally, there is a septum between both, which usually deviates from the midline. They point upwards beyond the middle part of the supercilious and backwards to the medial part of the orbital roof. The sinuses are divided into several recesses, which communicate with each other through incomplete bony septa. Occasionally, one or both sinuses may be absent. The prominence of supercilliary ares does not indicate the absence, presence or size of the frontal sinus. The extensión upwards beyond the frontal bone may be a small one, while the orbital part may be bigger. In some cases, a sinus may be overlapping in front of the other one. Each one opens into the corresponding médium meatus of the nose, through the ethmoidal infundibulum of the frontonasal duct, and crosses the anterior part of the ethmoidal labyrinth.
The blood supply originates from the ethmoidal and supraorbital arteries, and the venous drainage takes place at the anastomotic vein located in the supraorbital notch, binding the supraorbital and superior ophthalmic veins. The lymphatic drainage is directed towards the submandibular lymphonodi. The área is innervated by the supraorbital nerve, a branch of the frontal nerve of the first trigeminal división.
MATERIAL AND METHOD
One hundred macerated skulls were randomly assigned for evaluation after section on axial plañe 1 inch above the supercilliary ares (Fig. 1).
The measures of anteroposterior, sagital and transversal diameters were taken. The presence or absence of the metopic suture were assigned. With bone-wax, the frontonasal ducts were occluded bilaterally. A syringe with fine sand was utilized to fill completely the frontal sinus and then the amount of sand necessary to complete this was quantified, verifying the volume that left the syringe. With this measure we had the approximate volume of the sinus.
The distribution by sex is described in the tables below, followed by the location of the sinuses observed in the sample (Tables I and II). The frontal sinus was present in 75.3% of the cases and absent in 24.3%. The metopic suture was absent in almost 63% (Table III) of the cases and there was no correlation between this occurrence and the frontal sinus presence.
The results obtained with measures were the following ones summarized in Table VI. The mean age was 63.55 years, with a minimal of 22 and a máximum 95 and a standard deviation of 18.20.
The average volume of the sinuses measured with sand was 10.25, with a minimal valué of 1.1 and maximal of 38 and a standard deviation of 7.15. The mean antero-poste-rior diameter was 7.849 mm, with a minimum valué of 3.1 mm and a máximum 18 mm with a standard deviation of 2.91mm. The mean transversal diameter was 40.59 mm, with a minimum of 4mm and a máximum of 96 mm and of standard deviation 21.96 mm. The median sagital diameter was 33.40 mm, with a minimum of 11 mm and máximum 75 mm.
Libersa & Faber (1957) have observed that the frontal sinus usually appear in the third year of life. Krogman (1962) reports that the frontal sinus become an extensión of the nasal cavity after the second year of life and grows progressively until the age of 20 years.
Porbonikova (1974) carried out a study with 720 X-ray pictures in 1 to 13 years oíd children by evaluating the frontal sinus growth. She observed that growth begins on the thirteenth month of age, being the same in both sexes, and goes on up to the age of 20 years when the parameters start diverging in girls who display a horizontal sinus enlargement while boys show a vertical enlargement of the sinuses. Apart this, she observed a larger growth of the left sinus when compared to the right one.
The measures showed difference related to gender in all analyzed diameters in favor of males (Table VI). The independent sample analyses failed to demónstrate any statistical significance in taken measures but there was a trend of greatest difference in transversal diameter between genders (Table VII).
Andreas Vesalius is considered by many scholars as the father of the Anatomy. He described the frontal sinus in his famous book " Di Humani Corporis Fabrica" , as a cave full of air. Falopius, one of Vesalkfs pupil, has detailed the sinus referring to their absence in newborns. Blaney (2000) reports that the frontal sinuses are anatomical structures only found in the human being and in some large African apes. Such faets draw the attention to the anatomical similarities between both species.
Schuller (1943) has verified in radiological studies that the frontal sinuses are quite bigger in males than in females, and emphasized that the presence of metopic suture is associated with absence of the frontal sinuses.
Szilvassy (1981) studied the variability of the frontal sinus in children and young people aged between 3 and 7 years, in 215 children. He observed that between the age 8 to 12 years, the growth rate of male frontal sinus is a very low one. Between the age 14 to 15 years, male frontal sinuses exceed female ones, where size is concerned, so we can conclude that a complete formation of the sinuses takes place at the age of 18.
The measures of diameters have all been signiñcantly higher in males than in females according the literature (Blaney; Hanson & Owsley, 1980; Libersa & Faber; Pondé et al., 2003; Porbonikova; Szilvassy), though none of these authors had ever measured the antero-posterior neither the volume, only the área of the sinuses. Ponde found a significantly higher antero-posterior diameter when comparing both genders (p<0.001) in a study with computer tomography (Pondé et al.).
Brown et al. (1984) have found in a simple X-ray study that the sagital diameter is signiñcantly larger in males. They have found an average of 32.6 mm in males against 26.6 mm in females. In a similar work, Harris et al. (1987) have found a height of 30.1 mm in males against 26.0 mm in females. Pondé et al. have found that the sagital diameters were significantly higher in males (p<0.04).
Porbonikova reports that females have a proportionally larger frontal sinuses than males, when compared to the sagital diameter, which is much larger in males. She justifies this finding as being due to a more homogeneous growing of frontal sinuses in females if compared with sinus growth in males. Pondé found measures of 58.3 mm and 46.9 mm in males and females respectively, but without statistical significance (p< 0.10).
Harris et al. has found such measures as 58.3 mm in males and 46.9 mm in females. In the total sum of measures, it was possible to verify that the frontal sinuses of males showed a quite higher development than those of females (p<0.01) according others authors (Krogman; Menovsky et al, 1999; Phrabhakaran et al, 1999; Schuller). Pondé et al. have emphasized the antero-posterior diameter as the most important contribution for the significant increase of volume in the malevs sinuses when compared with females (Pondé et al.).
What regards the absent frontal sinus, Krogman has observed its absence in 5% adults, while Gulisano et al. (1978) observed its absence in 4.8% of the cases. We observed 24.7% of frontal sinus missing with 20.8% in males and 27.9% in females. Gulisano et al. has also observed that the left sinus tends to be larger than the right one, a fact that could be observed by Pondé et al. though they had not found any difference between the genders and within the sample itself.
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Received: 17-03-2008, Accepted: 22-09-2008.