46 Endoscopic Endonasal Transmaxillary Approach to the Vidian Canal and Meckel’s Cave

46.1 Indications

•Tumors isolated to the Meckel’s cave.

•Tumors with middle fossa–extracranial extension.

•Tumors with pure extracranial involvement along the second (V2) and third (V3) branch of the trigeminal nerve.

46.2 Patient Positioning

•Position: Supine with the head fxed with a Mayfeld head holder.

•Body: The body is placed horizontal or in slight reverse

Trendelenburg position (15-30°).

•Head: The head is slightly extended and rotated to the right.

•Abdomen and contralateral thigh are prepped and draped in a sterile fashion in case a fat graft or fascia lata are needed.

46.4 Nasal Stage (Figs. 46.2, 46.3)

•A contralateral nasoseptal fap must be harvested

(see Chapters 38 and 39).

•Complete a septectomy by resecting the posterior nasal septum.

•Introduce the endoscope from contralateral nostril.

•Sphenoidectomy is performed.

•Uncinectomy is carried out.

•Middle turbinate is resected.

•Maxillary sinus ostium is identifed.

•Ethmoidectomy is performed: the ethmoidal bulla and su- pra-bulla cells are both removed.

•Removing the ethmoidal bulla does facilitate the removal of the posterior wall of the medial junction of maxillary sinus.

46.3 Surgical Approach (Fig. 46.1)

•Start with a rigid 0° endoscope.

•1% lidocaine with 1:100,000 epinephrine is used to vasoconstrict the sphenopalatine artery (SPA) at the sphenopalatine foramen, in addition to infltrating the uncinate process and vertical lamella of the ipsilateral middle turbinate.

•Resection of the posterior third of the septum allows for a binostril, 4-handed surgical technique and greater maneuverability of surgical instruments.

46.3.1 Critical Structures

•Middle turbinate

•Uncinate process

46.4.1 Critical Structures

•Middle turbinate.

•Uncinate process.

•Ethmoidal bulla.

•Maxillary sinus ostium.

46.5 Maxillary Sinus

Stage (Fig. 46.4)

•A wide maxillary antrostomy is carried out.

•The infraorbital neurovascular bundle is identifed.

•Sphenopalatine artery is cauterized and divided.

Fig. 46.1 Endoscopic view of the middle turbinate and uncinate process.

Abbreviations: NS = nasal septum; RMT = right middle turbinate; TMT = tail of the middle turbinate; UP = uncinate process.

Fig. 46.2 Probe in the maxillary sinus.

Abbreviations: MO = maxillary ostium; NS = nasal septum;

P = probe; RMT = right middle turbinate; TMT = tail of the middle turbinate; UP = uncinate process.

Fig. 46.3 After septectomy and uncinectomy, the maxillary sinus ostium and the ethmoidal bulla come into view.

Abbreviations: EB = ethmoidal bulla; P = probe; MS = maxillary sinus; MSO = maxillary sinus ostium.

Fig. 46.4 View after maxillary osteotomy showing the sphenopalatine artery and the infraorbital neurovascular bundle. Abbreviations: CS = cavernous sinus; FP = fat pad; ICA = internal carotid artery; IMA = internal maxillary artery; IOB = infraorbital nerve and vessels; OF = orbit ; PSC = parasellar ICA; SD = sellar dura; SPB = sphenopalatine branches.

•The posterior wall of the maxillary sinus is removed by drilling the vertical and orbital processes of the palatine bone (i.e., anterior wall of the sphenopalatine foramen).

•The periosteal layer covering the pterygopalatine fossa is opened.

46.5.1 Critical Structures

•Maxillary sinus ostium.

•Sphenopalatine artery.

•Infraorbital neurovascular bundle.

•Pterygopalatine fat and underlying blood vessels.

Fig. 46.5 Contents of pterygopalatine fossa: the vidian nerve, the pterygoid wedge, and V2.

Abbreviations: CP = carotid prominence; ION = infraorbital nerve; OF = orbit ; OP = optic prominence; OPB = orbital process of the palatine bone; PMS = posterior wall of the maxillary sinus; SPB = branches of the sphenopalatine artery crossing the sphenopalatine foramen; SS = sphenoid sinus.

Fig. 46.6 Contents of PPF: the vidian nerve, the pterygoid wedge, and V2.

Abbreviations: B = bone over the quadrangular space; CS = lateral wall of the cavernous sinus; GPN = greater palatine nerve over the pterygoid process; MPP = medial plate of the pterygoid process; P = pituitary; PC = paraclival carotid; PG = pterygopalatine ganglion; PSC = parasellar ICA; VN = Vidian nerve.

46.6 Exposure of the Pterygopalatine Fossa (PPF) (Figs. 46.5, 46.6)

•The contents of the pterygopalatine fossa are laterally retracted.

•The inferior portion of the medial pterygoid plate is drilled.

•The vidian nerve at the junction of the sphenoid sinus foor and medial pterygoid plate is identifed.

•The pterygoid wedge (anterior junction of the medial and lateral pterygoid plates).

•The foramen rotundum and the maxillary nerve (V2) at the superior margin of the fossa are identifed, by travelling laterally and superiorly toward the inferior orbital fssure.

•The maxillary nerve can be traced posteriorly to identify the foramen rotundum.

•Arachnoidal layer: Trigeminal cistern.

•Cranial nerves: Motor and sensory roots of the trigeminal nerve, the trigeminal ganglion.

•Arteries: Internal carotid artery.

•Veins: Cavernous sinus.

46.6.1 Critical Structures

•Vidian nerve.

•Maxillary nerve (the neural structures of the PPF lie deep to the vascular structures).

46.7 Accessing Meckel’s

Cave (Figs. 46.7,46.8)

•The medial and lateral pterygoid plates are drilled back

(Fig. 46.7).

•The vidian nerve is exposed back to the junction of the paraclival and lacerum segment of the internal carotid artery (ICA).

•The quadrangular space is exposed; it is defned by the carotid artery medially and inferiorly, by the maxillary nerve laterally and superiorly by the sixth cranial nerve and the frst branch of the trigeminal nerve (V1).

•The dural opening is tailored with respect to the prominence of the tumor within Meckel’s cave.

46.7.1 Critical Structures

•The ophthalmic branch of the trigeminal nerve (V1) and the abducens nerve, which both traverse along the superior aspect of the quadrangular space.

46.8 Meckel’s Cave

Exposure (Figs. 46.9, 46.10)

•Parenchymal structures: Dura of the medial middle cranial fossa.

Fig. 46.7 Boundaries of the quadrangular space.

Abbreviations: B = bone over the quadrangular space; CD = clival dura; CS = lateral wall of the cavernous sinus; P = pituitary;

PCJ = petroclival junction of the ICA; PMS = posterior wall of the maxilla; PSC = parasellar ICA; VC = Vidian canal.

46.9 Pearls

•The Vidian nerve is a crucial landmark for locating the lacerum segment of the ICA.

•Dissection should not cross the superior margin of V2 to avoid injury to the abducens nerve.

Fig. 46.8 Boundaries of the quadrangular space. The limits of the quadrangular space are shown: paraclival carotid (medially), petrous carotid and petrous bone (inferirorly), V2 and foramen rotundum (laterally), VI and V1 nerves (superiorly). Abbreviation: GG = Gasserian ganglion; OF = orbit ; P = pituitary; PB = petrous bone over the petrous carotid; PC = paraclival carotid; PCJ = petroclival carotid junction; PSC = parasellar

carotid; VI = sixth cranial nerve; VN = Vidian nerve and canal; V1 = ophthalmic nerve; V2 = maxillary nerve; V3 = mandibular nerve.

Fig. 46.9 Meckel’s cave exposure (wide view).

Abbreviations: GG = Gasserian ganglion; ION = infraorbital nerve;

OF = orbit ; P = pituitary; PC = paraclival carotid; PCJ = petroclival carotid junction; PMS = posterior wall of the maxilla; PSC = parasellar carotid; VI = sixth cranial nerve; VN = Vidian nerve and canal; V1 = ophthalmic nerve; V2 = maxillary nerve; V3 = mandibular nerve.

Fig. 46.10 Meckel’s cave exposure (ma iew). Abbreviations: GG = Gasserian ganglion; P = pituitary; PB = petrous bone over the petrous carotid; PC = paraclival carotid; PSC = parasellar carotid; VI = sixth cranial nerve; V1 = ophthalmic nerve; V2 = maxillary nerve; V3 = mandibular nerve.

References

1.de Lara D, Ditzel Filho LF, Prevedello DM, et al. Endonasal endoscopic approaches to the paramedian skull base. World Neurosurg 2014;82(6, Suppl)S121–S129.

2.Hofstetter CP, Singh A, Anand VK, Kacker A, Schwartz TH. The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave. J Neurosurg 2010; 113(5):967–974.

3.Raza SM, Amine MA, Anand V, Schwartz TH. Endoscopic

Endonasal Resection of Trigeminal Schwannomas. Neurosurg Clin N Am 2015;26(3):473–479.

4.Simal Julián JA, Miranda Lloret P, García Piñero A, Botella Asunción C. Full endoscopic endonasal suprapetrous approach to Meckel’s cave. Acta Neurochir (Wien) 2014;156(8):1623–1626.

PartXXXXVI

Vascular Proceduresxxxx

Mario Teo, Jeremiah Johnson, and Gary K. Steinberg

47.1  Indications

•Symptomatic Moya-Moya disease. To supplement cerebral blood fow due to ongoing poor cerebral perfusion.

•Complex aneurysm. To replace native cerebral blood fow when intracranial vessel sacrifce is necessary.

47.2  Patient Positioning (Fig. 47.1)

•Position: The patient is positioned supine with the head fxed with a Mayfeld head holder.

•Body: A shoulder roll is placed under the ipsilateral shoulder.

•Head: The head is rotated 60° to the contralateral side, ensuring that venous return is not compromised due to excessive neck rotation.

•The Sylvian fssure has to be the highest point in the surgical feld, and the operative feld is parallel to the foor.

•Linear incision

○A superfcial skin incision is made over the STA.

○Starting point: Incision starts just anterior to the tragus (posterior to the hairline).

○Course: It runs along the course of the donor STA.

○Ending point: The incision line ends at about 9 cm length of the STA.

•Curvilinear incision

○To harvest the frontal STA branch, a curvilinear incision behind the hairline is performed.

○Starting point: The incision starts just anterior to the tragus (posterior to the hairline).

○Course: It runs superiorly, then curves forward to the anterior frontal line.

○Ending point: Incision line ends at the mid-pupillary point at the hairline.

47.3  Skin Incision (Figs. 47.2, 47.3)

•From the preoperative angiogram, the most suitable superfcial temporal artery (STA) branch (frontal vs parietal branch) is chosen as the donor.

•The donor STA branch is transduced using a small Doppler probe above the zygoma, and followed to the convexity for a length of about 9 cm.

•The parietal branch is preferred as it is well behind the hair line, has a straighter course, with less risk of damage to the frontal nerve during dissection.

•Minimal hair shave.

47.3.1  Critical Structures

•Frontal and parietal branches of STA.

•Frontal branch of the facial nerve.

47.4  Soft Tissues Dissection

•Myofascial level

○The initial incision is made through the epidermis and partial thickness of dermis along the Doppler-defned projected course under microscopic examination.

Fig. 47.1 Patient positioning.

Abbreviations: SI = skin incision.

Fig. 47.3 The c ation of the frontal and parietal STA branch on a skull model.

Abbreviations: CS = coronal suture; FB = frontal branch; PB = parietal branch; SS = squamosal suture; STA = supe al temporal artery.

○A blunt tip and fne curve scissors have to be used to perform the dissection through the remaining dermis and subcutaneous tissue to avoid damage to STA (Fig. 47.4A).

○After STA vessel is visualized, dissection proceeds along the loose areolar plane around the STA vessel with a Bovie tip or microscissors (Fig. 47.4B), preserving a cuf of perivascular tissue, and free it from the underlying temporal fascia

(Fig. 47.4C, Fig. 47.4D).

Fig. 47.2 Skin incisions are outlined. In blue over the parietal STA branch, in red a curvilinear incision to harvest frontal STA branch. Abbreviations: SI = skin incision.

○For dissection of the frontal STA branch, the vessel is dissected from the underside of the scalp fap.

•Muscle

○The STA is retracted laterally, and protected with a vein retractor (Fig. 47.5A).

○The temporal fascia and muscle are incised in line with the long axis of the STA, then perpendicular to this at the proximal and distal ends (in an H-shaped fashion).

○The muscle is retracted after freeing it from the underlying bone (Fig. 47.B).

•Bone exposures

○Subperiosteal dissection of the temporal muscle attachment is as wide anteriorly and posteriorly as allowed by the scalp incision, also from the superior temporal line superiorly to above the zygoma inferiorly.

47.5  Craniotomy (Fig. 47.6)

•Burr holes

○I: The frst burr hole is made just under the superior temporal line.

○II: The second one is placed above the zygomatic process.

•Craniotomy landmarks

Anatomic landmarks which have to be considered in performing the craniotomy are as follows:

○Superiorly: The superior temporal line.

○Inferiorly: The area just above the zygomatic process.

○Anteriorly and posteriorly: Anterior and posterior limit

of the craniotomy are determined by the wideness of scalp exposure. A 6 cm diameter craniotomy is created to maximize the distal peri-Sylvian and recipient vessel exposure, as well to maximize the area for associated indirect revascularization to occur.

47.7  Dural Opening (Fig. 47.8)

•Dura is opened in a multiple leafets stellate fashion.

•Dural tack-up sutures are used to obliterate epidural space.

•Large middle meningeal artery (MMA) vessels are preserved.

47.6  Preparing Donor Artery  (Fig. 47.7)

•Donor artery preparation should be performed under microscopic guidance.

•A segment of 1–2 cm of distal STA is dissected free of all soft tissue.

•Soft tissue is also dissected of a cuf of the proximal STA for the placement of a proximal temporary clip.

•The ideal site for temporary clipping is distal to the take-of of the unused (frontal or parietal) branch of STA.

47.7.1  Critical Structures

•Large MMA with extensive extracranial to intracranial collateralization [determined preoperatively on the cerebral angiography, external carotid artery (ECA) injection].

47.8  Intradural Stage (Figs. 47.9–47.11)

•The arachnoid over the potential recipient middle cerebral artery (MCA) vessel is opened (Fig. 47.9A).

tissue to avoid damage to STA. (B) After the STA vessel is visualized, dissection along the loose areolar plane around the STA vessel is carried out, leaving a c ivascular tissue. (C) STA is freed from the underlying temporal fascia. (D) STA is fully dissected with a thin c t tissue. Abbreviations: LAP = loose areolar plane; ST al temporal artery; TMF = temporal muscle fascia.

Fig. 47.5 Muscle dissection. (A) STA is retracted laterally, protected with a vein retractor. The temporal fascia and muscle are incised in an H-shaped fashion. (B) Subperiosteal muscle dissection is performed to free the temporal muscle from the underlying bone.

Abbreviations: ST al temporal artery; TMF = temporal muscle fascia; TS = temporal squama.

Fig. 47.8 Dural opening. Stellate dural opening, preserving the STA vessel. Abbreviations: CC = cerebral cortex; DM = dura mater;

•A segment of 7 mm of M4 branch of MCA is prepared for temporary clipping and anastomosis.

•The minimum diameter for the recipient vessel is 0.7 mm, but ideally at least 1 mm (Fig. 47.9B).

•High visibility background material is passed beneath the recipient vessel.

•Before temporary clipping, blood fow is measured in the MCA branch using a Charbel Transonics ultrasonic fow probe

(Fig. 47.9C).

•The temporary clip is applied to the proximal STA and the distal STA is divided at a 45°angle (Fig. 47.9D). The distal stump of the STA in the scalp is coagulated to occlude it.

•The “cut fow” in the donor artery is measured using a Charbel Transonics ultrasonic fow probe.

Fig. 47.6 Craniotomy. (A) The location of craniotomy on a skull model. (B) Craniotomy is performed preserving the STA. Abbreviations S = coronal suture; FB = frontal branch; PB = parietal branch; SS = squamosal suture; STA = super-

al temporal artery.

Fig. 47.7 Preparation of donor vessel.

(A) Dissection of distal STA. (B) Proximal STA dissected of soft tissue for temporary clip application.

Abbreviations: B = bone; DM = dura mater;

•The cut STA segment is fushed with heparinized saline solution (Fig. 47.10A).

•Prior to applying the temporary clips to the MCA vessel, MAP > 90 mmHg, hypothermia of 33–34°C and burst suppression using propofol are achieved.

•Arteriotomy is made in the recipient MCA (Fig. 47.10B), and the lumen is fushed with heparinized saline solution.

•The donor and recipient vessels are tinted with indigo-car- mine or a sterile marking pen to better visualize the arteries during the microanastomosis.

•Monoflament sutures (10–0) are used to anchor the apices of the incision, toe stitch frst (Fig. 47.10C), followed by the heel stitch (Fig. 47.10D).

•The side walls of the anastomosis are sutured in an interrupted fashion, also using 10-0 monoflament sutures.

•Sutures should be passed from outside the donor to inside the recipient or outside the recipient to inside the donor, and then tied on the outer surface of the anastomosis.

•Great care must be taken not to catch the back wall of the vessel while suturing the anastomosis.

•Once the anastomosis is complete, the temporary clips on the recipient artery are released, and then the proximal clip on the STA is removed (Fig. 47.11A).

•Occasionally additional sutures need to be inserted to control blood leakage at the anastomosis.

•Blood fow in the STA, proximal and distal MCA to the anastomosis is measured with a Charbel Transonics fow probe, and intraoperative indocyanine green (ICG) is performed to confrm patency and function of the bypass graft (Fig. 47.11B). Intraoperative Doppler of the proximal STA is also used to verify graft patency during the entire closure, including replacement of the bone fap.

•The inferior burr hole on the bone fap is enlarged appropriately to prevent compromise of the proximal STA by the replaced skull fap.

47.9  Pearls

•Successful STA-MCA bypass is a technically challenging operation, requiring operative skill, patience, and attention to detail at every stage of the operation.

•An experienced anesthetic team and specialized neurological intensive care unit (ICU) are imperative to achieve low rates of morbidity.

•For the early career neurosurgeon, laboratory microanastomosis practice and mentorship are essential for good outcomes.

References

1.Chang SD, Steinberg GK, eds. Superfcial temporal artery to middle cerebral artery anastomosis. In: Techniques in Neurosurgery. Philadelphia: Lippincott Williams and Wilkins;2000; No. 6.

2.Gooderham PA, Steinberg GK, eds. Intracranial-Extracrani- al Bypass Surgery for Moyamoya Disease. In: Spetzler RF, Kalani Y, Nakaji P, eds. Neurovascular surgery. 2nd ed. ed: Thieme;2015.

3.Guzman R, Lee M, Achrol A, et al. Clinical outcome after 450 revascularization procedures for moyamoya disease. Clinical article. J Neurosurg 2009;111(5):927–935.

4.Miyamoto S, Yoshimoto T, Hashimoto N, et al; JAM Trial Investigators. Efects of extracranial-intracranial bypass for patients with hemorrhagic moyamoya disease: results of the Japan Adult Moyamoya Trial. Stroke 2014;45(5): 1415–1421.

5.Qian C, Yu X, Li J, Chen J, Wang L, Chen G. The Efcacy of Surgical Treatment for the Secondary Prevention of Stroke in Symptomatic Moyamoya Disease: A Meta-Analysis. Medicine (Baltimore) 2015;94(49):e2218.