Orbital fat volume in the inferolateral quadrant in Japanese: a guide for orbital fat decompression without injury to the oculomotor nerve

Endoscopic Transconjunctival Deep Lateral Wall Decompression for Thyroid-associated Orbitopathy: A Minimally Invasive Alternative: Transconjunctival Endoscopic with Wall Decompression for TAO

PURPOSE

To investigate the feasibility, efficacy, and safety of endoscopic transconjunctival transorbital deep lateral wall decompression for thyroid-associated orbitopathy (TAO).

DESIGN

Prospective single-surgeon interventional case series.

METHODS

Twenty-two patients (39 orbits) diagnosed with thyroid-associated orbitopathy without dysthyroid optic neuropathy were enrolled in this study. All patients underwent endoscopic transconjunctival transorbital deep lateral wall decompression for proptosis reduction. The data, including measurement on exophthalmometry, volumetric change on computed tomography, and surgery-related complications, were analyzed.

RESULTS

We observed a proptosis reduction (mean, 3.42 ± 0.87 mm; range, 2.10-5.52 mm) and a corresponding decrease in the bony volume of the greater wing of the sphenoid bone (mean, 1.89 ± 0.81 cm³; range, 0.56-3.79 cm³) postoperatively. Preexisting diplopia improved in 5 patients (22.73%). Transient zygomaticotemporal hypoesthesia developed in all patients, and cerebrospinal fluid leakage occurred in 1 orbit (2.56%). No patient complained of temporal hollowing, oscillopsia, or new-onset or worsening diplopia during follow-up.

CONCLUSIONS

Endoscopic transconjunctival transorbital deep lateral wall decompression is an effective and minimally invasive treatment for proptosis reduction in patients with thyroid-associated orbitopathy. The surgery-related complications with this technique were fewer compared with traditional approaches.

Extraocular muscle expansion after deep lateral orbital wall decompression: influence on proptosis reduction and its predictive factors

PURPOSE

To examine the relationship between extraocular muscle expansion and proptosis reduction (Δproptosis) in patients with thyroid eye disease who underwent deep lateral orbital wall decompression and to analyze the factors that contribute to extraocular muscle expansion.

METHODS

This retrospective, observational study included 133 sides from 77 patients with thyroid eye disease. The cross-sectional areas of the greater wing of the sphenoid bone (trigone), extraocular muscles, and superior ophthalmic vein were measured on computed tomographic images. Variables influencing Δproptosis were analyzed using multivariate linear regression analyses with stepwise variable selection. Predictive factors for the rate of postoperative increase in the cross-sectional extraocular muscle areas (Δextraocular muscle) were analyzed using the same statistical method.

RESULTS

The amount of orbital fat removed (P < 0.001) and rate of Δlateral rectus muscle (P < 0.001) were positively and negatively correlated with Δproptosis, respectively (r = 0.425; adjusted r² = 0.168; P < 0.001). The cross-sectional trigone area (P < 0.001) was positively correlated with the rate of Δlateral rectus muscle, whereas the preoperative cross-sectional lateral rectus muscle area (P < 0.001) and amount of orbital fat removed (P = 0.036) were negatively correlated with the rate of Δlateral rectus muscle (r = 0.551; adjusted r² = 0.288; P < 0.001).

CONCLUSION

Lateral rectus muscle expansion was negatively correlated with proptosis reduction and proved to be predictable before surgery. The results of this study will help predict proptosis reduction after deep lateral orbital wall decompression and to preoperatively plan additional orbital bony and fat decompression.

Radiological findings of orbital blowout fractures: a review

Purpose: To summarize the radiological findings in patients with orbital blowout fractures. Methods: We reviewed the published literature on radiological findings of orbital blowout fractures that were searched on PubMed and included our own radiologic findings on patients with orbital blowout fractures that were seen at our hospital. Results: Radiologic examination reveals a variety of findings in each case. However, common radiological findings of orbital blowout fractures include comminuted/unhinged, hinged, and linear fractures. These fractures are usually located in the orbital floor medial to the infraorbital nerve and in the medial orbital wall. Orbital fat is frequently herniated in the paranasal sinus or incarcerated at the fracture site. Orbital emphysema and haematoma sometimes occur as complications. Conclusions: This review will provide surgeons with a better understanding of various radiological findings, which could be helpful in the management of patients with orbital blowout fracture.

Location of the myoneural junction of the inferior oblique muscle: An anatomic study

PURPOSE

To examine both the horizontal and vertical locations of the myoneural junction of the inferior oblique muscle (IOM) in reference to the ala nasi, IOM origin, and inferior orbital rim.

MATERIALS AND METHODS

Fifty-six orbits from 56 Japanese cadavers (15 male and 41 female cadavers; average age at time of death, 86.5±9.4 years) were used in this experimental anatomical study. The inter-alae-nasi distance and the horizontal distances from the ipsilateral ala nasi to the IOM origin (ala-nasi-origin distance) and to the myoneural junction (ala-nasi-junction distance) were measured. The horizontal distance from the IOM origin to the myoneural junction (origin-junction distance) was calculated by subtraction of the ala-nasi-origin distance from the ala-nasi-junction distance. The vertical distance from the inferior orbital rim to the myoneural junction (rim-junction distance) was also measured.

RESULTS

The ala-nasi-junction, origin-junction, and rim-junction distances were 12.2±3.2mm, 10.6±3.2mm, and 3.4±1.0mm, respectively. Males had a longer inter-alae-nasi distance than females (P<0.001), although the other distances did not show statistically significant sex-related difference (P>0.050). The ala-nasi-junction distance tended to be negatively correlated with the inter-alae-nasi distance (r=-0.222, P=0.050).

CONCLUSIONS

The ala-nasi-junction distance can be affected by the inter-alae-nasi distance, which was found to be longer in males. Therefore, the IOM origin and the inferior orbital rim can be considered as more practical and reliable reference points to predict the location of the myoneural junction during the posterior inferior orbitotomy, irrespective of sex.