The Anatomical Relationships of the Ocular Motor Nerves with an Emphasis on Surgical Anatomy of the Orbit

Imaging characteristics of orbital peripheral nerve sheath tumors: Analysis of 34 cases

BACKGROUND

Peripheral nerve sheath tumors (PNSTs), a rare group of neoplasms in the orbit, comprise only 4% of all orbital tumors. At present, there are very few studies detailing the features of these tumors identified using imaging technology.

AIM

To compare the differences in location, morphology, magnetic resonance imaging (MRI) signal intensity/computed tomography (CT) value, and enhancement degree of tumors of different pathological PNSTs types.

METHODS

Clinical, pathological, CT, and MRI data were analyzed retrospectively in 34 patients with periorbital sheath tumors diagnosed using histopathology from January 2013 to August 2021.

RESULTS

Among 34 cases of orbital peripheral nerve sheath tumors, 21 were schwannomas, 12 were neurofibromas, and 1 was a plexiform neurofibroma. Common clinical symptoms presented by patients with these types of tumors include eyelid swelling, exophthalmos, and limited eye movement. Schwannomas mostly occur in the intramuscular space with small tumor volume and rare bone involvement. Neurofibromas develop in the extrapyramidal space with larger tumor volume and more bone involvement. Radiologically, schwannomas and neurofibromas are characterized by regular morphology and uneven density and signal. One case of plexiform neurofibroma showed tortuous and diffuse growth along the nerve, with a worm-like appearance on imaging.

CONCLUSION

Different pathological types of orbital peripheral nerve sheath tumors have unique imaging characteristics. Comprehensive consideration of the patient's clinical and imaging manifestations is of great value in the diagnosis of orbital peripheral nerve sheath tumors.

Quantitative Assessment of the Pupil: An Underrecognized Yet Important Factor Related to Orbital Blowout Fracture Repair

PURPOSE

To investigate dynamic pupil changes after orbital blowout fracture repair. To compare postoperative changes in under photopic and mesopic pupil size and center position after orbital blowout fracture repair surgery.

METHODS

The study evaluated 19 eyes. Pupils were imaged for pupil size and center position before and 3 months after orbital blowout fracture repair surgery. Pupil size changes were measured, and the correlation between preoperative and postoperative pupil centroid shift was evaluated.

RESULTS

After repair, operative eyes exhibited a growth of 9.3% ± 8.6% in pupil size, and contralateral eyes showed a growth of 8.6% ± 8.2% (P = 0.011, P = 0.007). Similar findings were noted in mesopic conditions. Under mesopic conditions, the pupil of operative eyes in medial orbital wall fracture deviated 0.030 ± 0.019 mm towards the nasal side along the X-axis (P = 0.031). The postoperative orbital floor fracture group demonstrated statistical significance at a spatial frequency of 5 (P = 0.041).

CONCLUSIONS

Orbital blowout fracture repair surgery affects pupil size and center position.

MRI of the intraorbital ocular motor nerves on three-dimensional double-echo steady state with water excitation sequence at 3.0 T

PURPOSE

To explore the capability of three-dimensional double-echo steady state with water excitation sequence (3D-DESS-WE) to determine the intraorbital ocular motor nerves (IOMN).

MATERIALS AND METHODS

A 3.0 T scanner was applied to investigate 30 healthy volunteers based on the 3D-DESS-WE sequence. Dunnett t test was conducted to evaluate the signal intensity (SI) of the left oculomotor nerve (CNIII), frontal white matter, cerebrospinal fluid (CSF), and lateral rectus (LR). The oculomotor nerve's detectability, trochlear nerve (CNIV), and abducens nerve (CNVI) were evaluated independently by two observers. The average assessment scores were determined, and interobserver variability for these nerves' detectability was determined using a weighted kappa analysis.

RESULTS

The SI of CNIII is similar to that of the frontal white matter (t = 2.26, P > 0.05), lower than the CSF, and higher than the LR (t = 3.81, - 3.45, P < 0.05). The average scores of the superior division of CNIII and the branch to medial rectus (MR), inferior rectus (IR), inferior oblique (IO), CNIV, and CNVI were 3.01, 3.07, 3.78, 2.98, 2.88, and 3.97, respectively. The interobserver variability was excellent (κ = 0.83-1.00).

CONCLUSION

The 3D-DESS-WE sequence shows an ability to detect the IOMN course in healthy volunteers effectively.

Cranial Nerves: Morphology and Clinical Relevance

This Special Issue entitled "Cranial Nerves: phylogeny, ontogeny, morphology and clinical significance" has been divided into two consecutive volumes. This second volume is devoted to morphology and clinical relevance. Articles in this volume examine these topics from a macroscopic point of view and with a surgical interest. This volume includes articles on oculomotor nerves III, IV, and VI and their course in the orbit; intracranial and extracranial views of the V and VII pairs; and branching patterns of IX, X, XI, and XII pairs with medical significance. Together, these articles provide a general overview of cranial nerves' gross anatomical organization, as well as improving on the knowledge necessary for clinical approaches. Anat Rec, 302:555-557, 2019. © 2019 Wiley Periodicals, Inc.