The Infraorbital Foramen Is Located Midway Between the Nasospinale and Jugale: Considerations for Infraorbital Nerve Block and Maxillofacial Surgery

Intraoperative Mapping of the Sensory Root of the Trigeminal Nerve in Patients with Pontocerebellar Angle Pathology

OBJECTIVE

The aim of the present study was to determine the position of the 3 sensory branches of the trigeminal nerve in the preganglionic tract using intraoperative neurophysiological mapping.

METHODS

We included consecutive adult patients who underwent neurosurgical treatment of cerebellopontine angle lesions. The trigeminal nerve was antidromically stimulated at 3 sites along its circumference with different stimulus intensities at a distance of ≤1 cm from the brainstem. The sensory nerve action potentials (SNAPs) were recorded from each main trigeminal branch (V1 [ophthalmic branch], V2 [maxillary branch], and V3 [mandibular branch]).

RESULTS

We analyzed 13 patients. The stimulation points at which we obtained the greatest number of congruous and exclusive SNAPs (SNAPs only on the stimulated branch) was the stimulation point for V3 (20.7%). The stimulation intensity at which we obtained the highest number of congruent and exclusive SNAPs with the stimulated branch was 0.5 mA.

CONCLUSIONS

Using our recording conditions, trigeminal stimulation is a reliable technique for mapping the V3 and V1 branches using an intensity not exceeding 0.5. However, reliable identification of the fibers of V2 is more difficult. Stimulation of the trigeminal nerve can be a reliable technique to identify the V3 and V1 branches if rhizotomy of these branches is necessary.

Anatomy of Infraorbital Foramen: Influence of Sex, Side, and Cranium Size

Several researchers have analyzed the collocation of infraorbital foramen, but no study has so far considered the possible influence of cranial size.Three measurements (distances from anterior nasal spine, inferior orbital rim, angle at the intersection between the line from anterior nasal spine and the transversal plane parallel to the Frankfurt plane) were taken on 100 skulls belonging to a contemporary skeletal collection. In addition, maximum cranial length, maximum cranial breadth, cranial height, and bizygomatic breadth were measured, together with 2 indices (horizontal cephalic index and Giardina Y-index). Differences according to sex and side were assessed through 2-way analysis of variance test (P <0.05). Measurements showing statistically significant differences according to sex were further assessed through 1-way analysis of covariance test including cranial measurements and indices as covariates (P <0.05).Statistically significant differences according to sex and side were found respectively for the distance from anterior nasal spine and the angle at infraorbital foramen (P <0.05). One-way analysis of covariance test verified that the sexual dimorphism of infraorbital foramen- anterior nasal spine distance was independent from the general measurements of cranium.The present study first proved that sexually dimorphic parameters useful for the localization of infraorbital foramen do not depend upon the cranium size.

Infraorbital foramen location in the pediatric population: A guide for infraorbital nerve block

BACKGROUND

Infraorbital nerve blocks are often performed for the management of postoperative pain associated with cleft lip correction. Infraorbital nerve block procedures depend on the identification of the infraorbital foramen; however, there is little information regarding the infraorbital foramen location in the pediatric population.

AIMS

The aim of this study was to identify the location of the infraorbital foramen in the pediatric population relative to a midpoint between the nasospinale and jugale.

METHODS

The study assessed the location of 152 infraorbital foramina relative to a midpoint between the nasospinale and J on dry crania. Crania were from individuals ranging in age-at-death from 6-month fetal to 18 years. The population was subdivided into fetal/infant (≥6 months fetal age-<2 years), child (≥2-<12 years), and adolescent (≥12-≤18 years) groups for comparison.

RESULTS

The average distance of the infraorbital foramen from the nasospinale-to-jugale midpoint was 1.55 ± 0.78 mm (Mean ± SD) in the fetal/infant group, 0.80 ± 0.91 mm in the child group, and 1.31 ± 1.68 mm in the adolescent group. Furthermore, infraorbital foramina tended to be located medial to the nasospinale-to-jugale midpoint in the fetal/infant population, directly upon or superomedial to the nasospinale-to-jugale midpoint in the child population, and directly upon or superior/superolateral to the nasospinale-to-jugale midpoint in the adolescent population.

CONCLUSIONS

The infraorbital foramen was located within 2 mm, on average, from the nasospinale-to-jugale midpoint regardless of age group. Therefore, the nasospinale-to-jugale midpoint may serve as useful means of identifying the location of the infraorbital foramen in the pediatric population and aid in optimizing infraorbital nerve block procedures. The information in this report is valuable in general, but may be particularly useful in developing countries where there is a lack of ultrasound training and availability for health care providers; or places where infraorbital nerve block may be the sole anesthetic modality for cleft lip surgery, even among adolescent patients.