2016 Section 5 Green Book

Bleier et al.

TABLE 5. Outcomes vs tumor location

facilitate dissection around the tumor capsule. Both warm water irrigation and bipolar cautery were utilized success- fully to provide hemostasis; however, the use of monopo- lar electrocautery was avoided by all groups. Although the precise current and proximity required to injure the optic nerve is unknown, the literature 18 supports the blanket rec- ommendation to avoid the use of monopolar cautery within the orbit or in proximity to the orbital apex. Adequate and atraumatic retraction of the medial rectus muscle represents another important consideration when accessing intraconal lesions. Injury to the muscle fibers, neurovascular supply, or medial displacement may all re- sult in postoperative muscle dysfunction and subsequent diplopia. A range of both static and dynamic medial rec- tus retraction methods were employed among all of the groups. The only external method involved placing a su- ture around the medial rectus at its insertion on the globe. Although the presence of immediate postoperative diplopia was evenly distributed among patients with or without re- traction, the only method not associated with any diplopia was the transseptal double ball technique. In this approach, the right angle of a double ball probe is passed under the in- ferior border of the muscle, allowing the muscle to be pulled superomedially as needed. Despite this, the numbers are too small to provide a meaningful recommendation regarding the optimal method for medial rectus retraction. Regard- less of the method utilized, however, a working knowledge of the course of the oculomotor nerve along the lateral as- pect of the medial rectus muscle and its ramification and penetration of the muscle belly approximately one-third of the distance from the annulus of Zinn to its insertion on the globe, will help to protect this nerve from inadvertent traction injury. 16 A complete resection was possible in the majority of cases of both extraconal and intraconal lesions. This is consistent with the fact that OCHs tend to be well en- capsulated and rarely infiltrate adjacent structures. 13 As expected, tumors located within the intraconal space were associated with a greater incidence of incomplete removal and postoperative morbidity including new onset diplopia and enophthalmos. This may be attributed to the fact that approaches to the intraconal space mandate a larger or- bitotomy as well as a greater degree of medial rectus in- strumentation than extraconal lesions. In light of these technical requirements, it follows that 37.5% of patients with intraconal lesions underwent some form of medial or- bital reconstruction as opposed to 0.00% in the extraconal group. This work represents the largest reported series of purely endoscopic endonasal resection of OCHs. The indica- tions for this approach are currently limited to lesions lo- cated medial to the optic nerve. However, it carries mul- tiple advantages over open techniques including improved visualization and illumination while providing direct access to the lesion and reducing trauma and retraction of adjacent normal structures. Consequently, our reported functional outcomes are comparable or better than those reported

Location

n

%

Intraconal (n = 16) Results

Complete resection

11

68.8

Partial resection

1

6.3

Biopsy

2

12.5

Decompression

2

12.5

Morbidity

New diplopia

4

25.0

New enophthalmos

4

25.0

Reconstruction

6

37.5

Extraconal (n = 7) Results

Complete resection

6

85.7

Partial resection

1

14.3

Biopsy

0

0.0

Decompression

0

0.0

Morbidity

New diplopia

1

14.3

New enophthalmos

1

14.3

Reconstruction

0

0.0

TABLE 6. Diplopia vs method of medial rectus retraction

Diplopia

Method of retraction

n

%

No

None

13

76.5

Double ball probe

3

17.6

Transseptal suture

1

5.9

Yes

None

3

50.0

External

1

16.7

Transseptal suture

1

16.7

Muscle detachment

1

16.7

of our cases; however, this was generally performed in the extraconal space. The removal of intraconal fat to improve visualization should therefore be performed with extreme caution because this may inadvertently traumatize the del- icate inferomedial branches of the ophthalmic artery that traverse medially from the main ophthalmic arterial trunk to supply the belly of the medial rectus muscle 16 as well as branches of the third cranial nerve. The use of a saline soaked cottonoid (neuropatty) may be used instead to gen- tly displace a broad area of fat and absorb blood in order to

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