|Year : 2013 | Volume
| Issue : 3 | Page : 151-155
Infraorbital foramen - Morphometric study and clinical application in adult Indian skulls
Rohit Varshney1, Nidhi Sharma2
1 Department of Anaesthesia, Teerthanker Mahaveer Medical College, Moradabad, Utter Pradesh, India
2 Department of Anatomy, Teerthanker Mahaveer Medical College, Moradabad, Utter Pradesh, India
|Date of Web Publication||14-Feb-2014|
Department of Anaesthesia, Teerthankar Mahaveer Medical College, Delhi Road, Moradabad, Utter Pradesh - 244 001
Source of Support: None, Conflict of Interest: None
Background: Infraorbital foramen is an important site for various surgical and anesthetic procedures. Accurate localization of the foramen holds the key to success, although racial variations exist in various population groups. Aims: To study the morphometry of infraorbital foramen and its location with respect to nearby anatomical landmarks. Materials and Methods: A total of 100 dry skulls (60 male and 40 female) were collected and observed for the study. Various parameters in the sagittal and transverse planes were noted from infraorbital foramen on both sides, together with its vertical and horizontal dimensions. In addition, the location of infraorbital foramen with respect to upper tooth and presence of any accessory foramina were noted. Results: We measured 198 sides in 100 Indian skulls. The most common position of infraorbital foramen was observed to be in line with second premolar tooth (64%). The mean distance from infraorbital foramen to infraorbital margin was 7.65 ± 1.35 mm on the right side and 7.11 ± 1.73 mm on the left side and from infraorbital foramen to lower border of alveolus of maxilla on the right and left sides (25.98 ± 1.89 and 25.27 ± 2.17 mm; P = 0.01). Conclusions: This study makes possible the identification of exact position of infraorbital foramen and its application in various surgical procedures.
Keywords: Infraorbital foramen, Infraorbital nerve block, Morphometry
|How to cite this article:|
Varshney R, Sharma N. Infraorbital foramen - Morphometric study and clinical application in adult Indian skulls. Saudi J Health Sci 2013;2:151-5
| Introduction|| |
The infraorbital foramen (IOF) is an anatomical structure present bilaterally on the maxillary bone 1 cm below the infraorbital margin  (IOM), at the uppermost part of the canine fossa. The infraorbital nerve is a terminal branch of the second division of the trigeminal nerve (maxillary), and exits through the IOF, lying in the same vertical plane as the pupil when the eye is in a forward gaze. It is a sensory nerve to the lower eyelid, cheek, lateral aspect of the nose, upper lip, and part of the temple. 
The infraorbital nerve is located near vital structures such as the orbit, nose, and buccal regions. Therefore, it is important for professionals in maxillofacial surgery and anesthesia to know its definite location for performing different diagnostic, surgical, and other invasive procedures. , The modern era of emerging pain practice requires appropriate landmarks for the neurotomy of infraorbital nerve and radiofrequency ablation in pharmacologically unresponsive trigeminal neuralgia treatment.  Moreover, successful infraorbital nerve block is the cornerstone management of pain in cleft lip surgery. ,
Extensive MEDLINE search revealed numerous data regarding the morphometric assessment of the IOF with large racial variations in their results. ,,,,,,,,, However, limited morphometric information is available for the location of IOF using Indian skulls as reference. ,
Thus, this study was conducted to identify the dimensions, orientation, and position of IOF in relation to different clinically important anatomical landmarks in adult Indian population.
| Materials and Methods|| |
A total of 100 dry skulls (60 male and 40 female) collected from medical and dental colleges of Teerthanker Mahaveer University, India, were used for the study. We excluded skulls of children and skulls with damaged piriformis opening/lower end of alveolus of maxilla. All parameters were measured in the following planes:
Sagittal plane: A plane parallel to the mid-sagittal plane and passing through the center of infraorbital foramen was adoptedfor taking various vertical dimensions [Figure 1].
Transverse plane: A plane passing through the center of infraorbital foramen and perpendicular to the above-mentioned sagittal plane was used for measuring transverse dimensions [Figure 1].
|Figure 1: Saggital and transverse plane passing through centre of infraorbital foramen|
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After aligning the skull in Frankfurt horizontal plane (using rulers and manipulating or adding sand bags as required), following parameters were measured to evaluate the location of infraorbital foramen on both sides of skull.
- Distance from center of IOF to IOM along sagittal plane
- Distance from center of IOF to Piriform aperture (PA) along transverse plane
- Distance from center of IOF to lower end of alveolus of maxilla along sagittal plane
- Vertical (VD) and horizontal diameters (HD) of IOF
- Locational relationship of IOF to upper tooth
- Presence of accessory foramina.
The measurements related to IOF were taken with double-tipped compass and then transferred to calipers (least count 0.01 mm) to measure the distances. The dimensions were taken three times by the same person and mean was taken, thus increasing the accuracy of the data.
Statistical Analysis: From the above measurements, mean and standard deviation (mean ± SD), median (range), and mode were calculated. Data analysis was done by using Statistical Package for Social Sciences (SPSS) 19 version, and P < 0.05 was considered statistically significant.
| Results|| |
Total skulls examined: 100 (198 sides)
Male skulls: 60
Female skulls: 40
Number of sides not examined due to destruction: Right- 0, Left- 2
Total number of sides examined: 198.
IOF was observed in all the skulls studied. In 95% of the skulls, a single foramen was present on both sides, whereas 5% demonstrated ipsilateral double foramina on the right side [Figure 2].
The location of IOF was observed to be in line with the second premolar tooth, with an incidence of 64%, followed by the position between first and second premolar tooth in 23% of the skulls [Figure 3],[Figure 4] and [Figure 5]; [Table 1]. However, the presence of IOF along the first molar tooth in 6% of the cases was the rarest one [Figure 6].
|Figure 3: Presence of infraorbital foramen in line with second premolar tooth|
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|Figure 4: Presence of infraorbital foramen in line with first and second premolar tooth|
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|Figure 5: Frequency of location of infraorbital foramen in relation to upper tooth|
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|Figure 6: Presence of infraorbital foramen in line with first molar tooth|
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The dimensions of IOF and its linear relationship with surrounding anatomical landmarks on the skull are summarized in [Table 2]. The mean vertical and horizontal diameters of IOF on the right side are 3.94 ± 1.04 and 3.31 ± 1.37 mm, while those on the left side are 3.89 ± 1.23 and 3.25 ± 1.51 mm, respectively [Table 2]. The shape of IOF was vertically oval, horizontally oval, and circular in 76%, 16%, and 8% of the skulls, respectively.
The mean distance from IOF to IOM was 7.65 ± 1.35 mm on the right side and 7.11 ± 1.73 mm on the left side (P = 0.01) [Table 2]. In addition, statistical significance was seen among the mean distance from IOF to LAM on the right and left sides (25.98 ± 1.89 and 25.27 ± 2.17 mm; P = 0.01) [Table 2]. The minimum distance recorded from IOF to IOM was 2.31 mm and the maximum distance was 11.73 mm. Moreover, the mean distance from IOF to PA was statistically insignificant [Table 2].
| Discussion|| |
In our study, the most common site of IOF in Indian skulls was found to be in line with the second premolar tooth (64%), followed by its position between the first and second premolar tooth (23%). Thus, these two locations constitute 87% of the prevalence, while Ilayperuma et al.  observed in Sri Lankan skulls the dominance of same locations in 85.19% cases and Kharb et al.  noted this in 78.3% of Indian skulls. The close similarity between the prevalences of Indian and Sri Lankan skulls could be attributed to the two races being close inhabitants of the Indian sub-continent. Aziz et al.  observed the location of IOF in line with the first premolar tooth in White, Black, and Hispanics skulls, verifying the racial differences among these. IOF was observed at the first molar tooth (6% of Indian skulls); although a rare finding, this advocates a possibility of either a complicating or failed infraorbital nerve block during regional anesthesia.
According to Hanihara and Ishida, accessory foramina were more commonly found in Northeast Asian skulls.  The presence of IOF in all skulls of our study was supported by previous studies. ,, The incidence of accessory foramina (two) in our study was 5%, while Kadanoff et al. found two, three, and more than three foramina in 9%, 0.5%, and 0.3% of the cases, respectively. Wide variations were observed in multiple IOF among different sub-groups with both higher ,, and lower incidences , compared to our study. The clinical significance of multiple IOF explains the cause of failure during regional anesthesia for various surgeries.  Furthermore, accessory foramina raises a mark of caution for surgeons and anesthetists in case of nerve retraction and accidental intraneural injection, which can lead to partial/complete nerve damage or paresthesia. 
In our study, the mean sagittal distance from IOF to IOM on the right and left sides was 7.73 ± 1.23 and 7.81 ± 1.45 (P = 0.01) respectively. Smaller distances were observed between IOF to IOM by other authors; however, these were statistically significant. ,,,, Wide variations (3-10 mm) between the distance from IOF to IOM had been observed in several studies, ,,,,,,,,,,,, again justifying the racial possibility behind them. According to Dubrul,  the security margin to anesthetic deposition near the orbit was 1.50 mm, and Sayeedi et al. encountered global injury probably crossing the limit mark. Thus, we agree with Kazkayasi et al. for a thorough preoperative evaluation of the IOF in patients who are candidates for maxillofacial surgeries and regional block anesthesia.
In our study, we analyzed our observations using statistical parameters [mean (standard deviation), median (range), and mode] to improve the accuracy for the location of IOF. The mean distance indicates the location of IOF, while standard deviation provides the variability in its position. The range also provides an indication for the location of IOF, but depends on sample size and the dispersion of values. Such parameters prove to be very informative in locating the position of IOF during anesthetic block and surgical interventions. The mode is the dimension, which should be considered while locating IOF during maxillofacial procedures. However, in order to increase the accuracy of results, we had not obtained any specific mode data regarding the location of IOF. This observation strongly emphasizes the presence of widespread variability in locating IOF among same ethnic groups. Moreover, it enables surgeons and anesthetists to address different surgical complications and failed regional blocks, respectively.
The mean distance from IOF to lower end of alveolus of maxilla along the sagittal plane in the right and left sides (25.98 ± 1.89 and 25.27 ± 2.12 mm; P = 0.01). The measurement of such a dimension makes our study distinctive from other available literature as during an intraoral infraorbital block, vigilance is required for an anesthetist regarding appropriate depth while approaching the foramen. Weinand et al. reported a case of endophthalmitis after intraoral infraorbital nerve block due to an inadvertent injury of the eye globe. The mean distance from IOF to PA along the right and left side (17.34 ± 1.69 and 17.58 ± 1.23 mm) was statistically insignificant in our study, supported by other contributors. ,,
The transverse and vertical diameters of the IOF displayed insignificant results while comparing both sides. Information regarding the size and symmetry of the skull foramina is helpful for radiologists when diagnosing difficult pathologies of the skull foramina by using computed tomography/magnetic resonance imaging. 
Our findings emphasize the ethnic variations in the occurrence of IOF as supported by other studies. ,, We consider that the diversity could be a result of factors such as age, sex, and race as pointed by Hanihara and Ishida  and differences in the reference points, which are taken as criteria in the measurements. In addition, our study provides valuable information on the location of IOF with respect to the surrounding anatomical landmarks in adult Indian skulls. These linear dimensions will facilitate anesthetic and surgical procedures, thereby preventing unpleasant complications.
| Conclusion|| |
This study helps determine the precise location of IOF in relation to various anatomical structures, particularly IOM and lower end of alveolus of maxilla. The landmarks described could be identified and effectively applied with success in various clinical scenarios, thereby decreasing the risk of failures and complications.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2]