The endoscope provides a unique view of intracranial structures. In many ways, this view is liberating, as it allows one to look around corners and to work at angles not safely obtainable with the microscope. On the other hand, this view can be disorienting to the inexperienced. The views are at different angles than traditional microsurgeons are accustomed to (how often do you get a good view of the underside of the optic nerve with the microscope?), the structures are bigger, the colors are somewhat different, and there is a fish-eye effect, a feature of the endoscope which distorts proportions somewhat. For this reason, this chapter provides an atlas of endoscopic images we have obtained over the years. This is not the first atlas of its type; however the images are from real surgery, not cadavers, and are therefore similar to what you will see intracranially. The atlas illustrates the anatomy of both endonasal and transcranial approaches, and should provide a useful supplement to the numerous endoscopic videos and images of varied pathology in other chapters.
Fig. 5.1 Key demonstrating the color coding of various structures used throughout this atlas.
5.2 Parasellar Endoscopy
Fig. 5.2a, b At the conclusion of a right supraorbital craniotomy for a craniopharyngioma, endoscopic inspection revealed an olfactory tract severed from the olfactory bulb. 1, L optic nerve; 2, R olfactory tract; 3, falx cerebri; 4, orbital gyrus; ASB, anterior skull base; CG, crista galli.Fig. 5.3a, b Moving the endoscope more posteriorly, the right optic nerve and internal carotid artery are seen. The oculomotor nerve is also seen here piercing the dura to enter the cavernous sinus. 1, R optic nerve; 2, R internal carotid artery; 3, R oculomotor nerve.Fig. 5.4a, b Placing the endoscope through the prechiasmatic space one sees the infrachiasmatic structures and the large vessels within the interpeduncular cistern. 1, L internal carotid artery; 2, L posterior communicating artery; 3, L oculomotor nerve; 4, L superior cerebellar artery; 5, optic chiasm; 6, pituitary stalk; 7, basilar artery; 8, R oculomotor nerve.Fig. 5.5a, b The endoscope has been turned 180 degrees about the camera allowing the angled tip to look down at the pituitary gland through the opening in the diaphragma sellae. 1, L internal carotid artery; 2, L oculomotor nerve; 3, optic chiasm; 4, pituitary stalk; 5, pituitary gland; 6, R optic nerve; 7, R internal carotid artery; DS, dorsum sellae; TS, tuberculum sellae.Fig. 5.6a, b Moving the endoscope past the dorsum sellae, the basilar artery bifurcation can be seen. The floor of the third ventricle has been opened up due to retrochiasmal invasion of the craniopharyngioma and hence the left and right hypothalami (LT, RT) can be seen. 1, L oculomotor nerve; 2, basilar artery bifurcation; 3, L superior cerebellar artery; 4, basilar artery;5, R oculomotor nerve.Fig. 5.7a, b The endoscope has been inserted into the cranial vault. The anterior skull base (ASB) can be seen forming the top of this image. In the midline the crista galli (CG) can be seen, and laterally, the lesser wing of the sphenoid bone (LSW) is visualized. 1, L optic nerve; 2, L internal carotid artery; 3, L frontal lobe.Fig. 5.8a, b A left supraorbital approach was used to resect a chordoma. The left opticocarotid window is seen here. The internal carotid artery is seen here leaving the cavernous sinus via the upper dural ring. The ophthalmic artery is seen through the falciform ligament. 1, L oculomotor nerve; 2, L ophthalmic artery; 3, L optic nerve; 4, L internal carotid artery. ACP, anterior clinoid process.Fig. 5.9a, b Moving the endoscope further medially, the optic chiasm comes into view, with the pituitary stalk, infiltrated with tumor, visible through the prechiasmatic window. 1, pituitary stalk; 2, R internal carotid artery; 3, R optic nerve; 4, optic chiasm; 5, L optic nerve.Fig. 5.10a, b Over to the contralateral side the right optic nerve can be seen exiting the optic foramen. 1, R ophthalmic artery; 2, R optic nerve.Fig. 5.11a, b Retracting the endoscope along the skull base, the olfactory bulb comes into view over the cribriform plate. 1, L olfactory bulb; 2, branch of the anterior cerebral artery.Fig. 5.12a, b Laterally, the lesser sphenoid wing (LSW) becomes visible. The temporal lobe (TL) can also be seen filling the middle cranial fossa. 1, superficial middle cerebral vein.Fig. 5.13a, b A view of the optic chiasm from a right supraorbital craniotomy. The olfactory tract is also seen running in the olfactory sulcus between the gyrus rectus and the orbital gyri; 1, R olfactory tract; 2, R optic tract; 3, R optic nerve; 4, R internal carotid artery; 5, optic chiasm; 6, L optic nerve.Fig. 5.14a, b The right ophthalmic artery is seen here, originating within the subarachnoid space. Due to retrochiasmatic and third ventricular extension of the craniopharyngioma, the thin lamina terminalis was opened (indicated with *) to assist with the resection. 1. R optic nerve; 2, optic chiasm; 3, L optic tract; 4, R optic tract; 5, R ophthalmic artery; 6, R internal carotid artery; ACP, anterior clinoid process.Fig. 5.15a, b In this image the pituitary gland can be seen, after moving the endoscope through the opticocarotid window. 1, pituitary stalk (attenuated by tumor); 2, pituitary gland.Fig. 5.16a, b Angling the endoscope posteriorly, the basilar artery bifurcation comes into view. The Liliequist membrane is also seen. 1, L internal cerebral artery; 2, pituitary gland; 3, L posterior communicating artery; 4, P1 segment of the L posterior cerebral artery; 5, P1 segment of the R posterior cerebral artery; 6, basilar artery; DS, dorsum sellae.Fig. 5.17a, b The Liliequist membrane is a sheet of arachnoid separating the interpeduncular from the suprasellar cistern.Fig. 5.18a, b Taking the endoscope out of the opticocarotid window, the pituitary gland can be seen here through the infrachiasmatic window. 1, L anterior cerebral artery (A2); 2, L optic nerve; 3, optic chiasm; 4, L internal carotid artery; 5, pituitary gland; 6, R optic nerve; 7, L olfactory nerve; TS, tuberculum sellae.Fig. 5.19a, b The dorsum sellae and interpeduncular cistern can be seen through the gap where the anterior wall and the floor of the third ventricle once were. The right anterior cerebral artery n also be seen in this image 1. Right anterior cerebral artery (A1 segment); 2. Pituitary stalk; 3. Posterior edge of the optic chiasm; 4. Pituitary gland; 5. Left posterior communicating artery; 6. Left posterior cerebral artery (P2 segment); 7. Right posterior cerebral artery (P1 segment).Fig. 5.20a, b A view from a right supraorbital craniotomy shows residual craniopharyngioma posterior to the optic chiasm, after microsurgical removal. The endoscope has been inserted to assist in removing the remaining part of the tumor. The middle cerebral artery can also be seen entering the sylvian fissure. 1, L internal carotid artery; 2, L optic nerve; 3, residual tumor; 4, optic chiasm; 5, R optic nerve; 6, R internal carotid artery; 7, R anterior cerebral artery (A1); 8, R middle cerebral artery (M1).Fig. 5.21a, b Moving the endoscope tip closer to the chiasm, the tumor can be seen surrounding the pituitary gland and infundibulum. This component of the tumor is not directly in the surgeon’s line of sight since it is hidden under the chiasm and is only approachable and resectable under endoscopic visualization. 1, L internal carotid artery; 2, L optic nerve; 3, anterior cerebral arteries; 4, optic chiasm; 5, residual tumor; 6, pituitary stalk.Fig. 5.22a, b A right supraorbital craniotomy was used for the removal of a craniopharyngioma. This view is looking under the optic chiasm. The pituitary stalk has been severed in removing the tumor. 1, L oculomotor nerve; 2, L optic nerve; 3, R optic nerve; 4, opening in the diaphragma sellae (DS) for the pituitary stalk. Fig. 5.23a, b A view through the opticocarotid window, with the angled tip facing the base of the optic chiasm (OC). The third ventricular cavity (TV) can be seen after resection of the craniopharyngioma. 1, L internal carotid artery; 2, L posterior communicating artery; 3, L oculomotor nerve; DS, dorsum sellae; TV, third ventricular cavity.Fig. 5.24a, b Looking further back, the interpeduncular region can be seen. 1, L oculomotor nerve; 2, L posterior communicating artery; 3, L posterior cerebral artery (P1); 4, L superior cerebellar artery; 5, basilar artery; 6, R posterior cerebral artery (P1); 7, mammillary bodies; DS, dorsum sellae; TV, third ventricular cavity.Fig. 5.25a, b The endoscope is introduced via a right supraorbital craniotomy. The craniopharyngioma (CP) can be seen here adjacent to the mammillary bodies. C, clivus. 1, basilar artery and perforators.Fig. 5.26a, b After resection of the tumor, the endoscope is reintroduced. Here, the right opticocarotid window is seen. 1, R olfactory tract; 2, R optic nerve; 3, R internal carotid artery.Fig. 5.27a, b Moving slightly deeper, the recurrent artery of Heubner comes into view. The recurrent artery originates from the anterior cerebral artery and doubles back toward the sylvian fissure to supply the anterior perforated substance. 1, R optic nerve; 2, R olfactory tract; 3, R recurrent artery of Heubner; 4, R anterior cerebral artery.Fig. 5.28a, b In this patient, a small craniopharyngioma was removed and the floor of the third ventricle (FTV) is still intact. 1, basilar artery; 2, R posterior cerebral artery (P1); 3, L posterior cerebral artery (P1); 4, L superior cerebellar artery; 5, L oculomotor nerve.Fig. 5.29a, b Looking medially, the chiasm and pituitary gland can be seen, as well as the contralateral olfactory tract. 1, L olfactory tract; 2, L optic nerve; 3, optic chiasm; 4, R optic nerve; 5., Pituitary glandFig. 5.30a, b This is a view of the right opticocarotid window after resection of a sphenoid wing meningioma. 1, R oculomotor nerve; 2, R posterior communicating artery; 3, R middle cerebral artery (M1); 4, R anterior cerebral artery (A1); 5, R internal carotid artery; 6, R ophthalmic artery; 7, R optic nerve; 8, R olfactory tract; ACP, anterior clinoid process.Fig. 5.31a, b The oculomotor nerve can be seen here piercing the dura in the oculomotor trigone to enter the cavernous sinus. The anterior petroclinoid ligament makes up the lateral margin of the oculomotor triangle. 1, R internal carotid artery; 2, R posterior communicating artery; 3, R oculomotor nerve; 4, R anterior petroclinoid ligament.Fig. 5.32a, b This is the view from a left supraorbital craniotomy of the left cranial nerves II and III. 1, temporal uncus; 2, anterior petroclinoid ligament; 3, L oculomotor nerve; 4, L optic tract; 5, L middle cerebral artery (M1); 6, L internal carotid artery; 7, L optic nerve. Fig. 5.33a, b The lamina terminalis and anterior cerebral arteries with a relatively prefixed chiasm can be seen in this image. 1, R optic nerve; 2, optic chiasm; 3, lamina terminalis; 4, R anterior cerebral artery (A1); 5, L anterior cerebral artery (A1); 6, anterior communicating artery; 7, R anterior cerebral artery (A2); 8, L anterior cerebral artery (A2). Fig. 5.34a, b A right supraorbital craniotomy has been performed for resection of a hypothalamic hamartoma. The third ventricle can be seen through an opening created in the lamina terminalis. There is a small piece of Gelfoam in the prechiasmatic space. 1, R olfactory tract; 2, gyrus rectus; 3, L optic nerve; 4, optic chiasm; 5, third ventricle; 6, R optic tract; 7, R optic nerve; 8, R internal carotid artery; 9, R anterior cerebral artery.Fig. 5.35a, b The pituitary gland can be seen below the prefixed optic chiasm. 1, pituitary gland; 2, L optic nerve; 3, optic chiasm; 4, L anterior cerebral artery (A1).Fig. 5.36a, b This image shows the bifurcation of the right internal carotid artery. 1, basilar artery; 2, R internal carotid artery; 3, R middle cerebral artery; 4, R anterior cerebral artery; 5, R optic tract; 6, optic chiasm; 7, L anterior cerebral artery.Fig. 5.37a, b Looking into the opening in the lamina terminalis, the third ventricle can be seen. The third ventricle is compressed due to the hypothalamic hamartoma. 1, infundibular recess; 2, massa intermedia; 3, foramen of Monro; LT, RT, left and right hypothalami.Fig. 5.38a, b Through the opticocarotid recess, the interpeduncular region is seen with a prominent exophytic component of the hamartoma (EH). 1, L posterior communicating artery; 2, L oculomotor nerve; 3, L posterior cerebral artery; 4, L superior cerebellar artery; 5, R posterior cerebral artery; 6, R superior cerebellar artery; 7, basilar artery.
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2 Cognitive Principles of Planning Keyhole Approaches
3 Technical Principles of Operating in Keyhole Craniotomies
12 Keyhole Approaches to Tumors of the Middle Fossa, Cavernous Sinus, Tentorium and Lateral Midbrain
15 Keyhole Surgery of the Tectum and Pineal Region
13 The Cerebellopontine Angle
8 Keyhole Surgery for Supratentorial Intra-Axial Tumors
