Indications

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  Surgical approach for clipping aneurysms of the anterior and posterior circulation (upper basilar and its proximal branches)

  
  
• •
  

  Surgical approach for tumors of the anterior and middle cranial fossa, including sphenoid, parasellar, and cavernous sinus regions

  
  
• •
  

  Resection of arteriovenous malformations of the perisylvian frontal and temporal regions

Contraindications

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  High-riding basilar aneurysms with the aneurysm neck significantly above the posterior clinoid are not amenable from this approach because the rostral angle is insufficient.

  
  
• •
  

  Large parasellar or sellar tumors with significant superior extension are not amenable from this approach because the rostral angle is insufficient.

Planning and positioning

• •
  

  Before initiating a surgical procedure, the patient should have had all the appropriate imaging studies, blood tests, and medical and cardiac clearance.

  
  
• •
  

  The anesthesia team should have adequate peripheral or central access.

  
  
• •
  

  Additional operative equipment (e.g., microscope) should be properly set up before beginning the surgery to reduce delay at critical points during the operation.

  
  
• •
  

  Antibiotics are given to all patients before skin incision, and repeat doses are given as appropriate. Depending on the case, steroids, antiepileptics, and mannitol are also used.

Positioning the patient and head. The patient is placed supine on the operating table with the ipsilateral shoulder elevated as needed to facilitate head rotation toward the contralateral side. The skull clamp is fixated with the paired posterior pins at the equator in the occipital bone and the single anterior pin at the equator in the contralateral frontal bone superior to the orbit. The head is positioned by first elevating the head above the heart in the “sniffing” position. Second, the head is rotated up to 60 degrees to the contralateral side depending on the intended operation. Third, the neck is extended so that the vertex is angled down 10 to 30 degrees, allowing for self-retraction of the frontal lobe off the anterior cranial fossa floor. When the head is ideally positioned, the malar eminence of the zygomatic bone should be the highest point in the operative field.

Planning and marking the incision. Before drawing the incision, the midline is identified and marked. The incision for a pterional craniotomy is curvilinear and courses from the root of the zygoma to the anterior midline. The incision is divided into two segments. The first segment starts at the root of the zygoma (1 cm anterior to the tragus of the ear) and extends to the linea temporalis. This section can be angled anteriorly or posteriorly for varied exposure. The second segment extends anteriorly and superiorly from the linea temporalis to the midline just behind the hairline.

Procedure

Elevation of the skin flap. Starting at the anterior, midline portion of the marked incision and extending to the linea temporalis, the scalp is cut full-thickness (including galea aponeurotica and pericranium) down to the bone with a No. 10 blade. Raney clips are applied to the scalp edges for hemostasis. Plastic and towel drape edges are included in the applied Raney clip when possible to secure the drapes in position; this maneuver also helps hold the clip in position when the scalp is thin. After Raney clips are applied to this section, the next section of the incision is addressed. Before making a cut, the remaining scalp is bluntly dissected from the temporal fascia with an instrument (e.g., fan-shaped periosteal elevator). The skin is incised down to the level of the temporal fascia, using blunt dissection when necessary to preserve the superficial temporal artery, and Raney clips are applied.

Preservation of the frontalis branch of the facial nerve. The frontalis branch of the facial nerve is found in the fibrofatty tissue (“fat pad”) deep to the superficial temporalis fascia. The scalp flap is reflected anteriorly until the fat pad is visualized, at which point the fascia is incised and the frontalis branch is elevated via the interfascial dissection of the skin flap ( A ). The scalp flap is wrapped in a moist gauze sponge and anchored anteriorly by suture retraction ( B ).

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