Anatomy of the medial orbit and various approaches to access it

Osamu Akiyama, MD1,2; Akihide Kondo, MD1; Hajime Arai, MD1; Albert L. Rhoton, Jr., MD2†

1Juntendo university, Department of Neurosurgery, Japan2Department of Neurological Surgery, University of Florida

Osamu Akiyama MD, PhD.Juntendo University, Department of NeurosurgeryEmail:akiyamao@juntendo.ac.jp

Contact1. Düz, B., Secer, H. I., & Gonul, E. (2009). Endoscopic approaches to the orbit: a cadaveric study. min-Minimally Invasive Neurosurgery, 52(03),

107-113.2. Wu, W., Selva, D., Jiang, F., Jing, W., Tu, Y., Chen, B., ... & Qu, J. (2013). Endoscopic transethmoidal approach with or without medial rectus

detachment for orbital apical cavernous hemangiomas. American journal of ophthalmology, 156(3), 593-599.3. Gönül, E., Erdogan, E., Düz, B., & Timurkaynak, E. (2003). Transmaxillary approach to the orbit: an anatomic study. Neurosurgery, 53(4), 935-

942.4. Moe, K. S. (2003). The precaruncular approach to the medial orbit. Archives of facial plastic surgery, 5(6), 483-487.5. Rhoton Jr, A. L. (2003) Cranial anatomy and surgical approaches. Neurosurgery, 53(2)331-362.6. Natori, Y., & Rhoton Jr, A. L. (1994). Transcranial approach to the orbit: microsurgical anatomy. Journal of neurosurgery, 81(1), 78-86.

References

The medial orbit can be the site of several pathological lesions such as cavernomas, neurinomas, and lymphomas. However, approaching the medial orbit remains a challenging task because of the narrow surgical corridors, surrounding critical neural structures, and complicated vascular relationships.

BackgroundThe surgical approaches to the medial orbit can be classified into three categories: (1) transcranial approach, (2) trans-sinus approaches: transethmoidal and transmaxillary approaches, and (3) transorbital approaches: precaruncular and medial orbital approaches. The transcranial approach exposes the superior and medial surfaces of the orbit and the optic apex widely. The trans-sinus approach exposes the medial and inferior surfaces of the orbit and optic nerve. The transorbital approach exposes the anterior and medial surfaces of the orbit, but the surgical corridor to the optic canal and apex in this approach is relatively narrower and deeper compared to that in the previous two approaches.

Ten adult cadaveric specimens were examined using magnifications ranging from 3X to 40X after perfusion of the arteries and veins with colored silicone. The microsurgical anatomy of the medial orbit and surgical approaches to it were examined. All approaches were performed using 0° rigid endoscopes or the surgical microscope.

Methods and Materials

The knowledge of the microsurgical anatomy of the medial orbit and surrounding critical structures and the selection of an appropriate surgical approach will make surgical procedures safe and precise.

Conclusions

ObjectiveTo examine the microsurgical anatomy of the medial orbit and compare the various surgical approaches1-6 to access it.

Results

Microsurgical anatomy of the medial orbit

Transcranial approach

Trans-sinus approach

Illustrative case –Orbitofrontal approach-A Illustrative Case. A 37-year-old woman presented with right exophthalmos. The orbitofrontal approach was performed. The pathological finding was schwannoma.

A: Oblique anterior view B: Anterior view of the combined medial orbital and maxillary exposures. C: Inferior view of the anterior and middle cranial base. D: Enlarged inferior view of the orbit. E: Anterior view. F: Enlarged lateral view of the orbit. G: Medial view of the orbit.

Illustrative case –Medial approach-7-year-old girl presented with exophthalmos. MR imaging demonstrated aanteromedial tumor of the orbit. The medial approach was performed. The pathological finding was a lymphangioma.

Transmaxillary approach

A: Anterior view. B: Medial view. C: Anterior view D: Inferior view.

Transorbital approachOrbitofrontal approach Medial approach Precaruncular approach

V2

CN I

Front. Sinus

Eth. Sinus

Ant. Eth. A.

Sphen. Sinus

Sup. Troch. N.

Supraorb. N.

Lac. Gland Lev. M.

Sup. Rec. M.

Front. N. CN IILac. N.

Post. Eth. A.

Trochlea

Sup. Obl. M.

Infra. Temp. Fossa

Sup. Rec. M.(Reflected)

Lev. M. Reflected) V1

Ophth. A. Nasocil. N.

Car. A.

Bifrontal approach

Sphen.Sinus

Car. A.

Max. A.

Med. Obl. M.

Temp. M.

Inf. Rec. M.

Inf. Orb. N. & A.

Pterygopal. A.

CN I

Clivus

Max. Sinus

CN II

Inf. Rec. M.

Lat. Rec. M.

CN IV

CN III to Inf. Rec. M.

Med. Rec. M.

Sphen. Sinus

Car. A.Pit.

Gland

Ophth. A.

Chiasm

Sup. Hyp. A.

V2Infraorb. N. & A.

Max. A.

Pterygopal. A.Zygo. N.

Ophth. V.

CN II

CN III Sup. Div.

to Lev. M.

CN III Inf. Div. to Inf. Obl. M.

Sup. Rec. M.

Front. N.

V 1

V 2

CN III

Cil. Gang.

Ophth. A

CN III Sup. Div.To Sup. Rec. M.

Periorbita(reflected)

Inf. Obl. M.

Short Cil. N.

Long. Cil. N.

Nasocil. N.

CN III Motor Root

Inf. Rec. M.CN III Inf. Div. to Inf. Rec. M.

CN III Inf. Div.

Med. Rec. M.

Inf. Obl. M.

Lat. Rec. M.

CN III Inf. Div.To Inf. Obl. M.

Inf. Ophth. V.

Short. Cil. N.

Cent. Ret. A.

Nasolac. Duct

Eth. Sinus

Nasal Septum

Ant. Eth. A.

Med. Canth. Lig.

Inf. Concha

Max. Sinus

Mid. Concha

Sup. Concha

Nasal Septum Max. Sinus

Font. Sinus Eth.

Sinus

Zygoma

Nasolac. Duct

Nasal Cavity

Oral Cavity

Inf. Orb. N.

Short. Cil. N.

Inf. Orb. N. & A.

Lat. Rec. M.

Nasal Cavity

Med. Rec. M.

Inf. Rec. M.

Inf. Orb. N. & A. Max. A.

Cav. Sinus v

Müllers’s M.

V2

OpticCanal

Inf. Rec. M.

Lat. Rec. M.

Med. Rec. M.

Sup. obl. M.

Sup. Ophth. V.

Ophth. A.

Max. A.

Orbit FloorInf. Orb. N. Nasal

Cavity

Max. Sinus

Nasal Septum

Cav. Sinus

Car. A.

Optic Canal

Eth. Sinus

Max. A.

CN II

Med. Rec. M.

Inf. Rec. M.

Sup. Rec. M.

Ophth. A

CN IIPit. Gland

Sphen. Sinus

Inf. Rec. M.

CN III Sup. Div.to Lev. M.

Pterygopal. A.

Max. A.

Inf. Orb. N. & A.

V2

Cav. Sinus

Front. Sinus

Sup. Opthal. V.

Trochlea

Lev. M. Lac. Gland

Ant. Eth. A.

Sup. Troch. N.

Supraorb. N.

Sup. Obl. M.

Front. N.

Lac. N. & A.

Optic. Canal

Lat. Rec. M.

Eth. Sinus

Sphen. Sinus

Post. Eth. A.

Long Cil. N.

Ophth. A.

Ant. Eth. N. & A.

Front. N.(reflected)

Lat. Rec. M.

Nasocil. N.

Sup. Rec. M.(Reflected)

CN VI

ShortCil. N.

Med. Rec. M.

Sphen. Sinus

Front. N.

Periorbita

Eth. Sinus

Front. LobeCN II

Front. Lobe

Orbit

Temp. M.Front. Sinus

Front. Bone

Transethmoidal approach

Front. Bone

Orbit Orbit

Nasal BoneTemp. M.

Orbit

Front. Lobe

Ant. Eth. Sinus

Post. Eth. Sinus

Nasal Cavity

Nasal Septum

Ant. Eth. A.Optic Canal

Post. Eth. A.

Periorbita

Med. Canth. Lig.

Med. Canth.

Lig.

Med. Rec. M.

Ant. Eth. A.

Periorbita CN II

Ophth. A

Inf. Obl. M.

Inf. Rec. M.

Sup. Ophth. V.

Periorbita

Med. Wall

Caruncle

Caruncle

Med. Canth.

Lig.

Preoperative MRI (T1 High Resolution Isotropic Volume Excitation: THRIVE) Postoperative MRI (THRIVE)

Periorbita

Tumor

Tumor

Orb. Oculi M.

Tumor

Preoperative MRI (T1WI) Postoperative MRI (T1WI)

Tumor

Sup. Orb. N.

Sup. Rec. M.

Intraoperative photograph

Intraoperative photograph

Globe

Globe

Medial Lateral Medial Lateral