Retrieval of ruptured medial rectus muscle with an endoscopic endonasal orbital approach. A case report and indication for surgical technique

Traumatic rupture of the inferior rectus muscle: case report and review of the literature

Traumatic inferior rectus muscle rupture secondary to blunt injury in the absence of associated orbital or ocular fractures or injury is rarely encountered, and there are limited published reports on subsequent surgical repair. We present the case of a 74-year-old man with complete inferior rectus transection following a fall with facial strike. A computed tomography scan of the face was unremarkable. Surgical exploration and repair of the muscle was performed by hooking the inferior oblique muscle to identify the inferior rectus muscle. Subsequent strabismus surgery was performed for residual binocular diplopia, resulting in excellent anatomic and visual outcomes and postoperative ocular alignment.

Aetiology, clinical features and surgical outcomes of isolated medial rectus palsy

IMPORTANCE

Isolated medial rectus palsy is extremely rare in clinical practice.

BACKGROUND

To report demographics, aetiology, clinical findings, imaging features and surgical outcomes in patients with isolated medial rectus palsy.

DESIGN

Retrospective study.

PARTICIPANTS

All patients treated for isolated medial rectus palsy at Zhongshan Ophthalmic Center, Sun Yat-sen University, between September 2003 and March 2019.

METHODS

Review of patient records.

MAIN OUTCOME MEASURES

Aetiology, clinical findings, imaging features and surgical outcomes.

RESULTS

A total of 32 patients (22 males, 10 females) were included. Mean age was 33.19 ± 19.78 years. The right eye was involved in 17 patients, the left eye was involved in 14 patients, and both eyes were involved in one patient. The most common causes were iatrogenic injury (43.75%), followed by trauma (37.50%) and congenital (18.75%). The most common clinical findings included outward deviation, diplopia and limited adduction. Six patients showed combined small-angle vertical strabismus, and 10 patients experienced a scale of -1 motility defect in other directions. After individualized strabismus surgery, preoperative exotropia of 60 ± 25 prism diopters (PD) was significantly reduced to 12 ± 13 PD (t = 10.938, P < .0001). Ocular motility improved in 21 patients, and five patients achieved normal ocular motility. Successful correction was obtained in 20/32 (62.50%) patients, with under-correction in 12/32 (37.50%) patients. Twenty-eight patients had only one surgery, three patients had two surgeries and one patient had three surgeries.

CONCLUSIONS AND RELEVANCE

The most common cause of isolated medial rectus palsy was local injury. Satisfactory results were obtained after individualized surgical interventions based on personalized preoperative evaluations.

Medial Rectus Anastomosis Under Endoscopic Endonasal Orbital Approach With Image-Guided Navigation: A New Way of Repairing a Ruptured Medial Rectus

BACKGROUND

With the extensive development of endoscopic sinus surgery, iatrogenic medial rectus muscle injury should be treated with caution. Traditional methods to repair a ruptured medial rectus need an anterior orbitotomy approach, with more injury and difficulty in finding the posterior end of the ruptured medial rectus.

OBJECTIVE

To explore a new method to repair a ruptured medial rectus.

METHODS

Eight cases of iatrogenic medial rectus rupture after endoscopic sinus surgery were reviewed from July 2015 to January 2019. Assisted by image-guided navigation, the ruptured medial rectus was sutured under an endoscopic endonasal orbital approach. Two methods were designed to suture the ruptured medial rectus. Optic nerve and orbital decompression were performed in 5 cases with visual impairment. The extent of exotropia and diplopia were followed up for 5 to 33 months after surgery.

RESULTS

With the help of image guidance, the posterior and anterior ends of the ruptured medial rectus of all patients were pinpointed, and operations using medial rectus anastomosis were successfully completed in 7 patients. The exotropia of these patients was corrected, and they have recovered. The vision of 2 patients recovered. There were no minor or major complications intraoperatively or postoperatively.

CONCLUSION

Assisted by image-guided navigation, medial rectus anastomosis under an endoscopic endonasal orbital approach is a feasible method. The key to preventing orbital complications is strict professional training, including identification of the Onodi air cell and correct application of powered instrumentation.

Medial rectus muscle loss: Is immediate lateral rectus disinsertion a solution? A case report with review of the literature

Purpose

To report a case of medial rectus (MR) muscle loss during the strabismus surgery with a late successful management and review of the literature.

Methods

The left MR was lost during resection in a 14-year-old girl who had undergone strabismus surgery elsewhere. The surgeon disinserted the antagonist lateral rectus (LR) muscle in the same session following unsuccessful attempts to retrieve the lost muscle. She was referred to our clinic two months later with a large angle exotropia and a complete lack of adduction. We performed a half-tendon transposition of vertical rectus muscles to the MR insertion and attached the residual fibers of the LR to the orbital periosteum.

Results

She was orthotropic after the surgery and remained stable until 6 months with a significant improvement of the adduction.

Conclusions

Simultaneous LR disinsertion is not a solution for MR loss. Half-tendon transposition of the vertical recti to the original insertion of the lost MR and periosteal fixation of the LR are good options as a second-stage operation in patients with MR loss during strabismus surgery.

Biomechanical analysis of likelihood of optic canal damage in peri-orbital fracture

PURPOSE

Detection of optic canal fractures is often difficult because of the subtleness of the fracture. If we could clarify impact on which region around the orbit is likely to accompany the fracture of the optic canal, the knowledge should be useful to make early diagnosis of optic canal fractures. The present study was conducted to elucidate this issue.

METHODS

Ten finite element models were produced simulating the skulls of ten humans (8 males and 2 females; 43.8 ± 10.2 y/o). The peri-orbital area of each of the ten models was divided into eight regions in a clockwise fashion per 45 degrees. These regions were defined as Superior-Medial (0-45 degrees), Medial-Superior (45-90 degrees), Medial-Inferior (90 to 135 degrees), Inferior-Medial (135 to 180 degrees), Inferior-Lateral (180-225 degrees), Lateral-Inferior (225 to 270 degrees), Lateral-Superior (270-315 degrees), and Superior-Lateral regions (315-360 degrees), respectively. Dynamic simulation of applying traumatic energy on each of these regions was conducted. Resultant fracture patterns were evaluated using finite element analyses. Thereafter, frequencies of fracture involvement of the optic canal were evaluated for each of the eight regions.

RESULTS

The involvement of the optic canal was most frequent for the Superior-Medial region (7/10), followed by the Medial-Superior region (5/10).

CONCLUSION

Optic canal fracture is likely to occur when the area between the supra-orbital notch and the medial canthus are strongly impacted. When evident fracture or serious damage of soft tissue is observed in this area, occurrence of optic canal fracture should be suspected.