Neurosurgery notes/Anatomy/Skull base anatomy/Meningeal anatomy/Meningo-orbital band (MOB)

Meningo-orbital band (MOB)

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Meningeal anatomy

General

  • Aka:
    • Orbitotemporal periosteal fold
    • Tentorial duplicature
    • Sphenoid orbital ligament (same ?- this term was stated by Mario Teo)

Formed by

  • It is made of when the frontal and the temporal meninges come together to go into the orbit to form the periorbita fascia
  • Connects the periorbita to the temporal and frontal lobe dura,
    • But disrupts access to the anterolateral skull base

Cutting the MOB

  • Enables wide exposure of the
    • Anterior clinoid process (ACP)
    • Superior orbital fissure (SOF)
    • Anterior portion of the cavernous sinus
  • Increases the potential risk of cranial nerve injury
  • Need to cut only if you need to go more medial near the anterior clinoid.
  • Cut little and peal it off with penfield dissector if not peal-able cut somemore and peal again. When it is easily peal-able you can peal the meninges all the way to the anterior clinoid
Dolenc9 Curved scissors Lateral edge of SOF, safe limit 4 mm to prevent entry into SOF; Scissors blades directed posteriorly Techniques to Cut MOB Froelich et a121 No. 15 blade At the level of sphenoid ridge and parallel to direction of Coscarella et a126 No. 15/11 blade Incision should start medial to foramen Rotundum followed by lateral wing of sphenoid; limited sharp incision over MOB to periosteal bridge FIGURE 6. Different techniques to cut the meningo-orbital band (MOB) at the anterior clinoid process (ACP). F, foramen; SOF, superior orbital fissure; VI, ophthalmic division of the trigeminal nerve.
Different techniques to cut the meningo-orbital band (MOB) at the anterior clinoid process (ACP). F, foramen; SOF, superior orbital fissure; V1, ophthalmic division of the trigeminal nerve.
Periorbita Lacrimal n. — Frontal lobe dura sov OTPF ACP Temporal lobe dura Frontal lobe dura Temporal lobe dura FIGURE 3. Afrontotemporal approach depicts exposure of the ACP before (A) and after (B) release of the orbitotem- poral periosteal fold (OTPF) lateral to the lacrimal nerve. Courtesy of Mayfield Clinic, Cincinnati, OH.
A frontotemporal approach depicts exposure of the ACP before (A) and after (B) release of the orbitotemporal periosteal fold (OTPF) lateral to the lacrimal nerve.
Periorbita ntal d OTPFi Temporal dura Periorbita Opti canal CN Il CN VI CN Ill ICA Clinoid tip FIGURE 4. Extradural anterior clinoidectomy technique and section of the orbitotemporal periosteal fold (OTPF) using the right frontotemporal approach. A, OTPF incision should be made at the level Of the sphenoid ridge to avoid injury to the CN coursing through the SOF. B, temporal fossa dura is elevated from the contents of the SOF. C, optic canal is iden- tified and unroofed. D, ACP is freed from the optic strut and the clinoid tip is removed. LSW, lesser sphenoid wing. Courtesy of Mayfield Clinic, Cincinnati, OH.
Extradural anterior clinoidectomy technique and section of the orbitotemporal periosteal fold (OTPF) using the right frontotemporal approach. A, OTPF incision should be made at the level of the sphenoid ridge to avoid injury to the CN coursing through the SOF. B, temporal fossa dura is elevated from the contents of the SOF. C, optic canal is identified and unroofed. D, ACP is freed from the optic strut and the clinoid tip is removed. LSW, lesser sphenoid wing.

Images

  • (A) Right temporal tip view for MOB detachment.
  • (B) Right subfrontal view in extradural anterior clinoidectomy. The superior wall of the SOF, optic canal roof, and optic strut are shown as three feet to connect the ACP to the frontal and sphenoid bones.
  • FR: foramen rotundum, GWS greater wing of sphenoid, LWS lesser wing of sphenoid, SOF superior orbital fissure, ACP: anterior clinoid process
 
A) LWS Line C' SOF Line D i ACP superior medial Line B GWS _ ine A inferi (B) oc SOF os— ACP
  • A) Schematic drawing of the skin incision and craniotomy of the pterional approach. Care should be taken to avoid injuring the anterior branch of the middle meningeal artery and temporal branches of the facial nerve.
  • B) The blue shaded area shows the part of the optic canal roof that must be removed if an extension of drilling the lesser wing of sphenoid or extra-dural anterior clinoidectomy is necessary. OC, optic canal; SOF, superior orbital fissure.
  • C) Intraoperative view after the pterional craniotomy. The blue shaded area (part of the optic canal roof) must be removed for further medial exposure. ON, optic nerve; SOF, superior orbital fissure.
  • D) Intraoperative view after part of the optic canal roof is removed. The meningo-orbital band (MOB) connects the periosteal layer of the frontotemporal basal dura to the periosteal layer of the periorbita and demarks the transition between the medial and lateral portions of the middle fossa. By partially removing part of the optic canal roof and separating the dura propria of temporal lobe from the inner cavernous membrane, the MOB can be safely detached from the periorbita to expose the middle cranial fossa, including the anterior clinoid process.
  • ACP, anterior clinoid process; MOB, meningo-orbital band; ON, optic nerve; SOF, superior orbital fissure.
Reference
Schematic-drawings-of-a-right-pterional-approach-with-extra-dural-removal-of-the-anterior-clinoid-process-
 
  • (A) Retraction of the basal dura revealed the MOB.
  • (B) Partial unroofing of the lateral SOF, exposure of the periorbita and Line A (dotted line).
  • (C) Retraction of the temporal base dura revealed a divided dura propria and inner cavernous membrane. The stump of Line A is shown (arrows).
  • (D) Peeling off the dura propria superiorly showed the lateral edge of the lesser wing of the sphenoid and the ACP covered with a thin pericranial layer (Line D, arrows).
  • (E,F) Views of the SOF and ACP before (E) and following (F) MOB detachment; ACP is widely exposed.
  • MOB, meningoorbital band; GWS, greater wing of sphenoid; LWS, lesser wing of sphenoid; PO, periorbita; ICM, inner cavernous membrane; DP, dura propria. anterior clinoid process (ACP), the superior orbital fissure (SOF)
GWS GWS 't.ÂoB. GWS GWS (0) GWS po łcM..
 
  • After standard frontotemporal craniotomy, the middle fossa dura is dissected until the foramen rotundum, and superior orbital fissure are exposed (a).
  • Skeletonization of the foramen rotundum is not needed because this junction is naturally exposed at the foramen rotundum (a, arrow).
  • The roof of the superior orbital fissure is skeletonized and opened to expose the junction between the dura propria of the temporal lobe and the periosteal dura (b, arrowheads).
  • The bone around the meningo-orbital band is drilled and incised to a length of 4 mm (c).
  • Peeling of the dura propria is started from the foramen rotundum to the lateral wall of the superior orbital fissure (d).
  • V2: Second division of the trigeminal nerve.
Figure I: After standard frontotemporal craniotomy, the middle fossa dura is dissected until the foramen rotundum, and superior orbital fissure are exposed (a). Skeletonization of the foramen rotundum is not needed because this junction is naturally exposed at the foramen rotundum (a, arrow). The roof of the superior orbital fissure is skeletonized and opened to expose the junction between the dura propria of the temporal lobe and the periosteal dura (b, arrowheads). The bone around the meningo-orbital band is drilled and incised to a length of 4 mm (c). Peeling of the dura propria is started from the foramen rotundum to the lateral wall of the superior orbital fissure (d). V2: Second division of the trigeminal nerve