Topography, syntopy and morphology of the human otic ganglion: a cadaver study

Identification of cranial nerve ganglia using sectioned images and three-dimensional models of a cadaver

Background

Cranial nerve ganglia, which are prone to viral infections and tumors, are located deep in the head, so their detailed anatomy is difficult to understand using conventional cadaver dissection. For locating the small ganglia in medical images, their sectional anatomy should be learned by medical students and doctors. The purpose of this study is to elucidate cranial ganglia anatomy using sectioned images and three-dimensional (3D) models of a cadaver.

Methods

One thousand two hundred and forty-six sectioned images of a male cadaver were examined to identify the cranial nerve ganglia. Using the real color sectioned images, real color volume model having a voxel size of 0.4 × 0.4 × 0.4 mm was produced.

Results

The sectioned images and 3D models can be downloaded for free from a webpage, anatomy.dongguk.ac.kr/ganglia. On the images and model, all the cranial nerve ganglia and their whole course were identified. In case of the facial nerve, the geniculate, pterygopalatine, and submandibular ganglia were clearly identified. In case of the glossopharyngeal nerve, the superior, inferior, and otic ganglia were found. Thanks to the high resolution and real color of the sectioned images and volume models, detailed observation of the ganglia was possible. Since the volume models can be cut both in orthogonal planes and oblique planes, advanced sectional anatomy of the ganglia can be explained concretely.

Conclusions

The sectioned images and 3D models will be helpful resources for understanding cranial nerve ganglia anatomy, for performing related surgical procedures.

The Effect of Mandibular Angulation on Preoperative Assessment of Dental Implant Insertion at Premolar Region: CBCT Study

Backgrounds

This study investigated the effect of mandibular angulation on the perioperative evaluation of the implant placement at the premolar region on panoramic reconstructed images using cone beam computed tomography (CBCT).

Methods

A total of six dried anonymous human mandibles was included. Two implants were inserted in the left and right first premolar region. CBCT scans were obtained from each mandible at the standard position, +20° extension, and -20° flexion. The distance of the implant from the anterior loop of the inferior alveolar nerve and mental foramen was measured. Mean absolute error (MAE) of the distance of the implant from both anatomical landmarks was measured. The Wilcoxon matched-pair signed-rank test was used for the comparison of the measurements. All data were analyzed with the Stata program (version 15.1).

Results

No statistically significant differences were found between the distance of the implant from the mental foramen and the anterior loop of the inferior alveolar nerve up to 20° extension and flexion at both sides of the mandible. (All p > 0.1) However, a variable range of MAE (SD) in the distance of the implant from different anatomical landmarks was found (0.9 ± 0.7 to 3.3 ± 2.1).

Conclusions

We found no statistical difference in measurements of the distance of the implant from two anatomical landmarks at different head positions up to 20° extension and flexion. However, clinically, variable range in the distance of the implant from anatomical landmarks should be considered. Our findings could alert dentists of the possibility of error up to 20° extension and flexion on the perioperative evaluation of dental implant placement.

Effect of Endoscopic Sinus Surgery on Eustachian Tube Function in Adult Sinusitis Patients: A Prospective Case-Control Study

The eustachian tube (E-tube) function is known to be related with sinusitis; however, the effect of endoscopic sinus surgery (ESS) on E-tube function is not clearly documented. This study aimed to prospectively evaluate the function of the E-tube by using both subjective and objective tests in adult chronic sinusitis patients undergoing ESS, and to compare with those of the patients without sinusitis. Thirty adult patients who underwent ESS for treatment of chronic sinusitis and another thirty patients without sinusitis who underwent other nasal surgeries (septoplasty, rhinoplasty, or closed reduction) were evaluated and compared for E-tube function before and after three months of their surgeries. The E-tube function tests included the seven-item eustachian tube dysfunction questionnaire (ETDQ-7), Valsalva test, and inflation-deflation test that were compared preoperatively and postoperatively in both groups. Compared with the group without sinusitis, the ESS group showed significant improvement of E-tube function after surgery in the ETDQ-7 (p = 0.002), right Valsalva test (p = 0.015), right deflation test (p = 0.005), and left deflation test (p = 0.006). A binary logistic regression analysis revealed that ESS significantly improved E-tube function in the right Valsalva test in a univariate (p = 0.021) and multivariate analysis (p = 0.008), and E-tube function in the left deflation test in a univariate (p = 0.021) and multivariate analysis (p = 0.039). These findings indicate that E-tube function is significantly improved after ESS in adult sinusitis patients, and that the presence of sinusitis and implementation of ESS should be considered (if sinusitis is present) in managing patients with ear diseases that are affected by E-tube function.

Anatomical landmarks for localizing the otic ganglion: A possible new treatment target for headache disorders

Background:

The otic ganglion (OG) is a cranial parasympathetic ganglion located in the infratemporal fossa under the foramen ovale (FO) and adjacent to the medial part of the mandibular nerve. Parasympathetic innervation of intracranial vessels from the OG has been shown both in animal and human models and evidence suggests that the OG plays an important role in the cranial vasomotor response. We review the evidence that positions the OG as a viable target for headache disorders. The OG is a small structure and not detectable on medical imaging. The FO is easily identifiable on CT scans and the mandibular nerve on MRI, hence, the position of the OG may be predicted if the mean distance from the FO is known.

Objective:

The objective is to describe the average distance between the FO and the OG in a sample of 18 infratemporal fossae from 21 cadavers.

Methods:

A total of 21 high definition photographs of 21 infratemporal fossae from 18 cadavers were analyzed. The distance between the inferior edge of the medial part of the FO to the OG was measured.

Results:

Four photographs of infratemporal fossae of four cadavers were excluded due to the inability to localize the inferior edge of the FO. A total of 15 infratemporal fossae from 17 cadavers were measured. The mean distance from the FO to the OG was 4.5 mm (SD 1.7), range 2.1–7.7 mm.

Conclusions:

We have described the average distance from the OG to an easily identifiable anatomical landmark that is visible in CT scans, the FO. This anatomical study may aid in the development of strategies to localize the OG in order to explore its role as a therapeutic target for headache disorders.

Pre- and postnatal development of the otic ganglion in humans

Only a few papers exist dealing with the development and aging of the autonomic nervous system - and even rarer are studies that investigated the otic ganglion. Using a special trepan, we removed and investigated 172 samples from 86 corpses, ranging from 20 weeks of gestational age (GA) to 95 years of age. The aim of the study was to measure different morphometric parameters of the ganglionic neurons in order to study age-related changes from early development until old age. Fetuses show the highest numerical density of neurons. Then, in the first years of life, a rapid growth of the cytoplasm takes place, which is the main reason for the neuronal growth and the increase of the general size of the otic ganglion at this age. Also, the number of satellite cells increases till puberty. In adults, the parameters are relatively stable over decades and decrease slowly, in contrast to the steep increase in the first years of life. Moreover, neuronal degeneration, storage of pigments, neuro-axonal dystrophy, and lymphocytic infiltrates increase with age.

An anatomical study of arcuate foramen and its clinical implications: a case report

BACKGROUND

The objective of this paper is to describe the relationship of the vertebral artery (VA) to the Atlas (C1) in the sub-occipital region in the presence of arcuate foramen; and discuss the clinical implications related to manual therapies and surgical implications related to screw placement. This study is an anatomical cadaveric case report of symmetrical bilateral lateral and dorsal arcuate foramina on the C1 dorsal arch.

CASE PRESENTATION

Out of 40 cadavers that were available for use in teaching anatomy in the university setting, three presented with anomalies of the C1 dorsal arch. The sub-occipital regions were skillfully prosected to preserve related structures, especially VAs, sub-occipital and greater occipital nerves. Visual observations, photographs, measurements, and radiographic examinations were performed between January 15, 2014 and August 25, 2014. One cadaver (Specimen A) presented with complete bilateral ossified arcuate foramina, and two presented with partial ossification of the atlanto-occipital membrane. Specimen A presented the bilateral anomaly which is almost symmetrical. The VAs were found passing through double foramina (lateral and dorsal) on each side.

CONCLUSIONS

Arcuate foramina have been shown to be commonly found anomalies with highly variable shapes and sizes, even in the same individual with a bilateral condition. This study found a rare type of the anomaly associated with the C1 dorsal arch, which protected the VA against manual pressure. However, VA, in this case, would be more susceptible to dissection. The presence of the arcuate foramen would also complicate screw placement during surgery. Clinical pre-screening for signs of vertebrobasilar insufficiency is important for chiropractic and manual therapies.