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Olfactory Groove Meningioma: Eyebrow Incision

July 01, 2015


Let's review techniques for resection of large olfactory groove meningiomas via the supraorbital eyebrow craniotomy. This is an 85-year-old female with progressive confusion. MRI evaluation demonstrated a sizeable olfactory groove meningioma with evidence of edema along the basal frontal lobe on the right side. A supraorbital craniotomy was completed. You can see the incision. The supraorbital and supratrochlear nerves were carefully protected during the planning of the incision by palpating the supraorbital groove. The incision extended slightly beyond the edges of the eyebrow to avoid adequate exposure of the keyhole. This case a lumbar drain was also used. You can see the area of the keyhole, the orbital rim, the frontal process of zygoma. Supraorbital groove is situated at the tip of my arrow. A generous burr hole was completed at the level of the keyhole. The frontal dura was identified. The periorbital was dissected away from the inner aspect of the roof of the orbit. A supraorbital craniotomy and osteotomy of the rim of the orbit were completed to remove the frontal bone and the rim of the orbit on one piece. You can see the frontal process of zygoma was transected. More medially, the rim of orbital roof was also disconnected and essentially a small modified orbitozygomatic craniotomy was completed. Here you can see the removal of the roof of the orbit. Removal of the rim provides a more expanded trajectory toward the anterior cranial base. Here's the periorbita and the orbital fat. The dura was opened in a curvilinear fashion. Despite removal of the bone and the removal of the orbit, you can see the exposure is very limited. Retention sutures were used on the dura to mobilize the periorbita inferiorally. I use a piece of rubber dam to slide around the base of the frontal lobe. You can see the bone along the lateral aspect of the orbital roof interfered with my visualization. This is not an uncommon finding, especially exaggerated in this patient because of the very prominent bony gyrations over the roof of the orbit. Here's the sphenoid wing. Again, you can see the carotid artery just behind the capsule of the tumor. Here's the posterior capsule. I felt that removal of the bone of the roof of the orbit was necessary for adequate visualization of the optic nerve, carotid artery, and removal of this tumor. So I released the retention sutures, dissected dura from the lateral roof of the orbit, and performed additional osteotomies and removal of the bone over the area seen here. Since only a small part of the roof of the orbit is being removed, replacement of the bone, or use of the prosthesis to reconstruct this part of the roof is not necessary. And the risk of enophthalmus is very minimal. Now the dura was again placed under additional tension. You can see the operative corridor is much more expanded. I can see their carotid artery, the posterior capsule of the tumor, the olfactory nerve. The optic nerve should be just a little bit more medial, hiding behind the poster capsule of the tumor. Early identification of the neurovascular structures behind the tumor is important so that these structures can be protected during tumor devascularization. So I continued to devascularize the base of the tumor followed by its debulking. The olfactory nerve was intimately involved with the tumor. Here's the optic nerve that is evident upon slight decompression of the tumor capsule more posteriorly. Again, it's really important to identify the optic nerve as early as possible so that devascularization and decompression can proceed efficiently without the surgeon always worrying about injuring the nerve during every maneuver. Now that all the important neurovascular structures are mapped, I aggressively devascularized the base of the tumor. This patient suffered from anosmia before surgery, and therefore preservation of the olfactory nerves was not necessary. Here's the dissection over the superior pole of the tumor. Again, tumor has to be debunked so that its mobilization is facilitated without undo retraction on the basal frontal lobes. Again, further disconnection of the tumor capsule from the basal frontal lobe. Here's the optic nerve, carotid artery. Dissection of the posture capsule of the tumor using micro scissors. The optic foramen does not appear to be affected by the tumor. Some of the frontal polar branches were carefully protected and dissected from the tumor capsule. Covered with a piece of cotton. Tumor was relatively large; therefore, ultrasonic aspirator was used to debulk the tumor so that the tumor can be removed and delivered through such a small opening within the cranium. Here again is the dissection along the posterior capsule of the tumor, away from the basal frontal lobe. Now here's delivery of the large piece of the tumor through this small opening. Ultimately the tumor was delivered. Inspection reveals preservation of both optic nerves. Both foramina appear unaffected. Basal frontal lobe looks relatively healthy. Hemostasis was secured. Here's the third cranial nerve, posterior communicating artery, internal carotid artery. Again, the panoramic view of the basal cisterns via the supraorbital craniotomy. And the closure was performed in standard fashion. And the postoperative MRI immediately after surgery confirmed gross total resection of the mass without any untoward effects. Thank you.

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