Orbital Depth Measurements of Human Skulls in Relation to Retrobulbar Anesthesia

Anthropometric analysis of orbital and nasal parameters for sexual dimorphism: New anatomical evidences in the field of personal identification through a retrospective observational study

Orbital and nasal parameters among modern humans show considerable variation, which affects facial shape, and these characteristics vary according to race, region, and period in evolution. The aim of the study was to ascertain whether there are sex differences in the orbital and/or nasal indexes and/or the single measurements used to calculate these in a Kosovar population. The following parameters were taken into consideration: orbital height (OH), orbital width (OW), nasal height (NH), and nasal width (NW). The ratios between orbital index/nasal index (RONI) were calculated. All measurements were obtained from a population sample comprising 408 individuals. The accuracy in sex prediction was 52.86% (CI95% = 45.05%-60.67%) for NW and 64.96% for NH (CI95% = 57.50%- 72.42%). The difference between male and female indexes was statistically significant (P < 0.05). The anthropometric study revealed that only NW and NH are configured as predictors of sexual dimorphism. It could be useful to increase the number of samples to test the discriminant function in other population groups.

Evaluation of the Cranial Aperture of the Optic Canal on Cone-Beam Computed Tomography Images and its Clinical Implications for the Transcranial Approaches

OBJECTIVE

This study aimed to investigate morphometric properties of the cranial aperture (CA) of the optic canal.

METHODS

Cone-beam computed tomography images of 400 individuals (200 males and 200 females) aged 37.32 ± 15.87 years were retrospectively examined to assess the morphometry and morphology of the CA.

RESULTS

The height and width of CA were found as 4.22 ± 0.74 mm and 7.27 ± 1.15 mm, respectively. The distances between the CA and the midsagittal line, the anterior and lateral boundaries of the anterior skull base were measured as 5.77 ± 1.32 mm, 64.97 ± 6.36 mm, and 41.00 ± 4.05, respectively. The angle of the optic canal in the sagittal plane was measured as 7.57° ± 3.95°, whereas in the horizontal plane as 38.96° ± 4.36°. The aperture shape was defined as the tear-drop (413 foramina, 51.62%), triangular (180 foramina, 22.50%), oval (158 foramina, 19.75%), round (30 foramina, 3.75%), and polygonal (19 foramina, 2.38%).

CONCLUSIONS

The authors observed that the diameters, and angulations of the CA may change relative to gender and the shape. The anatomic features of CA are important for the positioning of the patient's head, the choice of the appropriate surgical approach or equipment, and the detection of anatomical landmarks during interventions. In this context, our dataset may be beneficial for surgeons helpful as a reference for radiological evaluations.

Anatomic features of the cranial aperture of the optic canal in children: a radiologic study

OBJECTIVE

This study aimed to peruse anatomic features of the cranial aperture of the optic canal (CAOC) for obtaining an extended morphometric dataset in children.

METHODS

Computed tomography images of 200 children were included in this retrospective work to analyze the shape, location and diameters of the CAOC.

RESULTS

The CAOC area, width and height were observed as 17.53 ± 2.80 mm², 6.12 ± 0.84 mm, and 4.35 ± 0.64 mm, respectively. The angle of the optic canal in axial plane was found as 39.28 ± 5.13°, while in sagittal plane as 16.01 ± 6.76°. The distance between the CAOC and the midsagittal line was 7.17 ± 1.48 mm. The CAOC was measured as 54.04 ± 5.23 mm and 42.55 ± 3.28 mm away from the anterior and lateral boundary of the anterior skull base, respectively. The CAOC shape was described as the tear-drop (186 foramina, 46.5%), triangular (156 foramina, 39%), oval (47 foramina, 11.8%), and round (11 foramina, 2.8%).

CONCLUSION

The depth, angle and diameter measurements belonging to the CAOC were changing according to its shape or demographic data (e.g., sex and age). Therefore, preoperative radiologic evaluation containing the shape, location and size of the CAOC should be considered by multidisciplinary operating teams in terms of surgical interventions such as implant positioning.

Anatomical landmarks for maxillary nerve block in the pterygopalatine fossa: A radiological study

INTRODUCTION

The aim of this study was to describe the anatomical landmarks for maxillary nerve block in the pterygopalatine fossa. The risk of injury to the skull base and maxillary artery was assessed.

METHODS

This retrospective study was based on the analysis of 61 consecutive computed tomography angiographies obtained from patients suffering from different pathologies. Anatomical relationships between optic canal (OC), foramen rotundum (FR), inferior orbital fissure (IOF) and puncture point (PP) were assessed. A "maxillary section" was virtually carried out on the CTs, following a plane passing through PP, IOF and FR in order to mimic the anaesthesia needle route.

RESULTS

No gender difference was observed except for the PP-OC distance that was longer in men. The mean PP-IOF distance was of 31.9 (± 0.7mm). PP-OC (43.9±0.5) and PP-FR (44.2±0.7) distances increased significantly with the patients height (PP-FR=17.25+0.16×height (cm); PP-OC=20.54+0.13×height (cm)). The route to the skull base was curved, with an angle of 168±1.6° at the FR level. The angle to reach the OC was greater than 7°.

DISCUSSION

With a 35-mm needle length, the probability to reach the IOF was high (79%), while the risk to injure the skull base (2%) and the optical nerve (0%) was low. Artery injuries were only found in 13% of cases. Therefore, a 35-mm needle length allows for the best efficacy/risk ratio in maxillary nerve block.

Pediatric Orbital Depth and Growth: A Radiographic Analysis

BACKGROUND

Orbital reconstruction requires knowledge of orbital depth in order to prevent optic nerve injury. Numerous analyses of adult orbital dimensions have been undertaken previously in order to characterize this measurement, including skull specimen and computerized tomography studies. However, there is a paucity of information regarding the pediatric orbit.

METHODS

The authors used pediatric magnetic resonance imaging (MRI) studies in order to quantify the change in orbital depth in relationship to patient age, and to develop methods to estimate and calculate orbital depth for individual pediatric patients. MRIs of the head in normal pediatric patients were reviewed retrospectively. Orbital depths were measured and correlated with age and cephalometric dimensions. In a randomly selected subgroup of patients, measurements were repeated by an independent investigator to determine interobserver reliability.

RESULTS

Measurements were obtained in 72 patients ranging from 3 months to 18 years of age (mean=7.8 years). There was a significant exponential relationship between orbital depth and patient age (r=0.81, F(2,69)=143.97, P<0.001). Depth increased more rapidly in the first 6 years of life, but leveled off in the early teen years toward a horizontal asymptote of approximately 45 mm. There was also a significant relationship between orbital depth and the sum of the biparietal width plus the anterior-posterior length (r=0.72, F(2,69)=87.44, P<0.0001). There was high interobserver reliability in measurements between 2 independent investigators (r=0.79, P<0.0001).

CONCLUSION

In children, orbital depth increases predictably with rising age and increasing head size. Knowledge of this growth curve and the relationship between head size and orbital depth can complement careful surgical dissection to improve safety and efficacy in pediatric orbital reconstructions.

Combined ocular anesthesia via a single entry

Although topical anesthesia techniques for cataract surgery are evolving, injections are unavoidable in some cases. Our technique of injecting local anesthetic agents for akinesia of the orbicularis oculi and the globe via a single entry near the lateral canthus decreases the pain and patient anxiety about the number of injections and avoids the complications of retrobulbar injection.

Local anaesthesia for vitreoretinal surgery: an audit of patient and surgical experience

PURPOSE

Local anaesthesia for vitreoretinal surgery is little used as these procedures are deemed to be too long and uncomfortable for patients to tolerate. In this unit anterior intraconal local anaesthesia is used for most routine surgery. We undertook an audit to ensure that surgical standards and patient acceptability were not compromised.

METHODS

A prospective observational audit was performed. Audit data included: Grade of anaesthetist and surgeon; details of anaesthetic and operation; compliance of patient; operating conditions and pain scores. Anaesthesia was provided with a combined peribulbar and intraconal anaesthetic, using bicarbonate buffered lignocaine and bupivacaine 50:50 mixture.

RESULTS

135 (76%) had local anaesthesia alone, 13 (7%) had local anaesthesia with sedation and 29 (16%) had general anaesthesia. 96.4% of patients were compliant and 98.8% of operating conditions were good or excellent. The mean perioperative pain score was 0.1 (range of 0-1), 97% said they would choose local anaesthesia again.

CONCLUSIONS

LA for vitreoretinal surgery is a useful and flexible method of anaesthesia, which has been shown to have excellent patient tolerance.

Anesthesia for intraocular surgery

Surgeons must decide on the type of anesthesia to use when performing cataract surgery. These "viewpoints" articles provide a well-balanced discussion offering the pros and cons of both topical anesthesia and retrobulbar/peribulbar injection. Dr. Dutton gives an overview of both techniques, focusing on relevant orbital anatomy. Drs. Hassan, Edelhauser and Kim, review the various types of topical anesthesia currently in use, and Drs. Spriggs and Broocker examine retrobulbar and peribulbar injections. Both techniques are associated with advantages and risks, so each surgeon must decide which technique is best suited for his or her own practice.