15 Frontotemporal and Pterional Approach
Cristian Gragnaniello, Nicholas J. Erickson, Filippo Gagliardi, Pietro Mortini, and Anthony J. Caputy
15.1 Indications
•Aneurysms.
○All aneurysms of anterior circulation.
○Basilar tip aneurysms.
•Parasellar lesions.
•Meningiomas involving the sphenoid wing and the anterior clinoid.
15.2 Patient Positioning
•Position: The patient is positioned supine with torso fexed slightly downward and knees slightly fexed to improve venous drainage. Soft gelatin roll placed under the ipsilateral shoulder can be used to reduce neck rotation.
•Head: The head is fxed in a Mayfeld 3-point head holder. It is rotated to contralateral side such that the pterion area is at
12 o’clock, elevated and slightly extended so that the vertex tilts toward the foor.
•The ipsilateral zygoma is the highest point in the surgical feld.
•The single pin of the head holder should be placed on the ipsilateral side superior to the mastoid process. On the other arm, one pin is placed superior to the mastoid process on the contralateral side.
15.3 Skin Incision (Fig. 15.1)
•Starting point: The incision begins at the zygoma (1 cm anterior to the tragus to avoid damage to frontotemporal branch of facial nerve and frontal branch of superior temporal artery).
•Run: The incision extends cephalad crossing the superfcial temporal artery while coursing posterior to the hairline.
•Ending point: The incision terminates at widow’s peak.
•The base of the skin incision should equal its height to avoid necrosis of the margin. Hemostatic clips are attached to skin edge and galea to keep vascularity.
•The superfcial temporal artery is preserved in every case, especially if the surgeon anticipates the potential for bypass.
15.3.1 Critical Structures
•Frontal branch of the facial nerve.
•Superfcial temporal artery.
15.4 Soft Tissue Dissection
•Myofascial level (Fig. 15.2)
○Yasargil frst described the interfascial dissection of the temporal muscle that serves to preserve the frontotemporal
Fig. 15.1 Skin incision. The incision begins at the zygoma, 1 cm anterior to the tragus and extends cephalad posterior to the hairline ending at the widow’s peak.
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15 Frontotemporal and Pterional Approach
branch of the facial nerve and minimize postoperative cosmetic changes (see Chapters 6 and 8).
○The temporal muscle is covered by a superfcial fascia. This dissection should be made vertically starting from the superior temporal line, 1.5 to 2 cm from the superior rim of the orbit to the posterior portion of the zygomatic arch using a cold scalpel and Metzenbaum scissors.
Fig. 15.2 |
Soft tissue dissection. After the |
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sk |
icranium and fa |
t- |
ed anteriorly, the frontal bone along with |
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the temporal fascia and its insertion at the |
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superior temporal line are visualized. Abbreviations: E = ear; FB = frontal bone; FP = fat pad; PC = pericranium; STL = superior temporal line; TF = temporal fascia.
Fig. 15.3 Temporal muscle detachment. The temporal muscle is elevated away from the squamous portion of the temporal bone and ted in the same manner as the skin
ascia is left along the superior temporal line.
Abbreviations: E = ear; FB = frontal bone; PC = pericranium; STL = superior temporal line; TM = temporal muscle; TSq = temporal squama.
○The refection of the skin and superfcial fascia along with its underlying fat pad is completed with the use of hooks or sutures and elastic bands as per surgeon’s preference.
•Muscles (Fig. 15.3)
○The dissection and detachment of the temporal muscle is done in two stages. A vertical incision is made perpendicularly to the zygoma posteriorly and a transverse incision
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parallel to the superior
temporal line, leaving a superior strap attached to the skull.
○Using a Cushing’s elevator, the detachment of the deep muscular fascia of the skull is started on its posterior superior portion using horizontal movements with the tip of the elevator.
○Using three hooks or elastic bands, the temporal muscle is refected anteriorly and inferiorly.
15.4.1 Critical Structures
• Frontal branch of the facial nerve.
15.5 Craniotomy/Craniectomy (Figs. 15.4, 15.5)
•Burr holes
○Usually two burr holes are sufcient, placed at points
A and B to easily cross the sphenoid wing.
○Point A is located in the squamous portion of the temporal bone just above the posterior root of the zygoma.
○Point B is called “keyhole” and is located at the intersection of the zygomatic bone, the superior temporal line and the supraorbital edge. The drill must be positioned posteriorly and inferiorly to prevent entering the orbit.
○A third burr hole at point C is recommended in older patients where the dura mater is frmly attached to the bone.
•Cuts
○A pneumatic craniotome with continuous irrigation is then used to cut a bone fap starting at point B and extending anteriorly across the anterior margin of the superior temporal line and then following it posteriorly to the extent of the bony exposure ending at point A.
Fig. 15.4 Craniotomy. After the keyhole (B) is made, a second burr hole is made posteriorly in the squamous portion of the temporal bone just above the posterior root of the zygoma (A). In older patients, a third burr hole (C) may be necessary as strenuous attachment of the dura to the bone is
expected |
zes of the craniotomy |
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are shown, tailoring for t |
ypes of |
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exposure that may be needed. Abbreviations: FTC = fronto-temporal craniotomy; PTC = pterional craniotomy; SON = superior orbital notch; STL = superior temporal line.
○It is important to stay as low as possible on the orbit to avoid having to rongeur bone, which can be cosmetically unappealing as will be covered by thin skin and reconstructed by large burr hole cover that could further create issues over time.
○Starting again at point B, the craniotomy is taken posteriorly across the sphenoid wing until the drill hangs up due to the presence of the greater wing of the sphenoid.
○Starting at point A, the craniotomy is taken anteriorly across the sphenoid wing until the drill hangs up.
○The bone between the two points, where the drill hangs up, is then drilled with a large burr.
○The length and height of drilling and resulting size of the bone fap will vary depending on the aim of surgery.
○The bone fap is removed using periosteal elevators and holes are drilled in the bone and bone fap for placing dural retention sutures.
○The sphenoid ridge is removed with a high-speed drill to the lateral margin of the superior orbital fssure. The
temporal bone is removed with a rongeur so that it is fush with the foor of the middle fossa. These steps are crucial to achieve adequate intradural exposure.
15.5.1 Variants (See Chapter 17)
• Orbitozygomatic osteotomy
15.6 Dural Opening (Fig. 15.6)
•A curvilinear incision in the dura and the fap is pediculated towards the greater sphenoid wing.
•The dural fap is sutured to the base of the temporal muscle.
15.6.1 Critical Structures
• Middle meningeal artery.
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Fig. 15.5 Superior view of the craniotomy in place.
Abbreviations: E = ear; FB = frontal bone; PC = pericranium; STL = superior temporal line; TM = temporal muscle; TSq = temporal squama.
Fig. 15.6 Dural exposure. The frontal and temporal dura delineated by the middle meningeal artery.
Abbreviations: E = ear; FB = frontal bone; FD = frontal dura; MMA = middle meningeal artery; PC = pericranium; TD = temporal dura; TM = temporal muscle.
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15.7 Intradural Exposure (Figs. 15.7, 15.8)
•Parenchymal structures: Sylvian fssure, inferior frontal gyrus, superior temporal gyrus and middle temporal gyrus are exposed.
•Arachnoidal layer: Optic and carotid cisterns.
•Cranial nerves: Second and third cranial nerves, optic chiasm.
•Arteries: Internal carotid artery, M1 segment of middle cerebral artery, A1 segment of anterior cerebral artery, basilar artery.
•Veins: Superfcial Sylvian veins, vein of Labbè.
•Two 15-mm retractors are placed on the frontal and temporal lobes, each covered with a protective coating of non-adher- ent dressing.
•The surgeon will section veins of the temporal lobe that enter the sphenoparietal sinus as necessary to open the
Sylvian fssure and gain subfrontal and pre-temporal exposure.
•The arachnoid of the optic and carotid cisterns is incised and CSF is aspirated.
•The two 15-mm retractors stretch the arachnoid of the Sylvian fssure such that it can be cut and the Sylvian fssure opened.
•Brain relaxation techniques and patience are important to prevent retraction-induced venous stasis and arterial compression.
Fig. 15.8 Intradural exposure after dissection of the Sylvian
sure. The internal carotid artery (ICA) is seen with its bifurcation and anterior cerebral artery (ACA) running antero-medially to cross the optic nerve (ON) and the middle cerebral artery (MCA) that bifurcates to give rise to the two M2 segments. It can be appreciated that the superior division of M2 bifurcates soon after the MCA bifurcation to give rise to an anterior branch. Abbreviations: ACA = anterior cerebral artery; ICA = internal carotid artery; IFG = inferior frontal gyrus; III CN = third cranial nerve; MCA = middle cerebral artery; OCT = oculomotor-carotid triangle; ON = optic nerve.
Fig. 15.7 Intradural exposure. The dura has been opened in a semicircular fashion, with t ted anteriorly. The middle frontal gyrus, inferior frontal gyrus and superior temporal gyrus along with the middle cerebral artery are visualized upon
tion of the dur |
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Abbreviations: DF = dur |
ar; FB |
= frontal bone; IFG = inferior frontal gyrus; MCA = middle cerebral artery; MFG = middle frontal gyrus; PC = pericranium; STG = superior temporal gyrus; TM = temporal muscle.
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References
1.Fossett D, Caputy AJ. Operative neurosurgical anatomy. New York, NY: Thieme Medical Publisher; 2002
2.Greenberg MS. Handbook of neurosurgery. New York, NY: Thieme Medical Publishers; 2010
3.Sekhar LN, Fessler RG. Atlas of neurosurgical techniques.
Brain. Volume 1. New York, NY: Thieme Medical Publishers; 2016
4.Yasargil MG, Antic J, Laciga R, Jain KK, Hodosh RM, Smith RD. Microsurgical pterional approach to aneurysms of the basilar bifurcation. Surg Neurol 1976;6(2):83–91
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