6.1 Introduction

Temporal lobe resection is still the gold standard for treatment of refractory temporal lobe epilepsy, but newer, less invasive techniques such as responsive neurostimulation and laser interstitial thermal therapy are challenging the role of the resective technique. Nonetheless, anterior temporal lobectomy and amygdalohippocampectomy remain useful in cases of failed laser interstitial thermal therapy or responsive neurostimulation and patients with temporal lobe tumors.

6.2 Layout of the Operating Room and Positioning the Patient

A multidisciplinary team is required for epilepsy surgery and includes the anesthesiologist, circulating nurse, scrub nurse, surgical assistant or resident, neurophysiologist or neurologist, patient, and surgeon. The team uses several workstations that occupy floor space in the suite. They include the anesthesia apparatus, instrument tables, neurophysiology platform, navigational equipment, cautery machines, microscope, and operating table.

Walls support large format monitors for viewing films, navigational data, suction canisters, and electricity. The ceiling delivers anesthesia gases, general and task lighting, and sometimes a microscope. Adequate space and thoughtful placement of these items are necessary to minimize clutter and to maintain a safe environment for patient and personnel. An example of an operating room arrangement in shown in ▶Fig. 6.1. However, the arrangement ultimately depends on the location of utilities, anesthesia, doors, lighting, and even the occasional window.

6.3 Surface Anatomy and Designing the Incision for Right Temporal Lobectomy

Place the patient in the supine position on the operating table and secure him or her in the Mayfield headrest (Integra LifeSciences Corp., Plainsboro, NJ). There are two pinning options: (1) single pin in the forehead and two posteriorly and (2) single pin at the root of the mastoid process, one pin in the forehead, and one just behind the hairline. The head is turned at least 45 degrees to the left. A shoulder roll may be necessary. Turn the bed as necessary to accommodate the various work zones. If surgical navigation is planned, attach the arm that holds the reference array. It goes contralateral to the operating side. Take care that the arm will not interfere with any retractor apparatus. Once this is done, then register the head into the surgical navigation software.

The temporal lobe is contained by the middle fossa. It is bounded above by sphenoid bone and sylvian fissure, and below by the temporal bone and the tentorium. Anteriorly, it is bounded by lateral orbital wall. Posteriorly, it is bounded by the parietal lobe. Several surface landmarks reveal the location of the middle fossa (▶Fig. 6.2). A typical temporal skin incision accomplishes several tasks while providing exposure to the temporal lobe and associated structures, including (1) be mostly concealed by hair; (2) preserves blood supply to scalp and temporalis muscle; (3) avoids the facial nerve; and (4) avoids the ear canal. Its boundaries are determined by the root of the zygoma, superior temporal line, and, on the face, the amount of anterior temporal exposure required.

For epilepsy surgery, a fair amount of anterior exposure is necessary, so the scalp and temporalis muscle are often dissected separately.

The incision is in the form of a question mark (▶Fig. 6.2). With a marking pen, start just below the root of the zygoma, and just in front of the ear, curve posterior to the ear, then superiorly and anteriorly. Note that the incision may be different on the nondominant side, compared with the dominant side. In some dominant temporal lobe resections, language mapping may be necessary, and this requires greater surface exposure. If you begin the incision more than 1 cm in front of the ear, you are likely to encounter the facial nerve and the superficial temporal artery. The incision will show prominently as well. Try to follow the hairline to its most facial extent. Extend the mark onto the face by 1 to 2 cm in case extra exposure is needed. Prepare the skin and drape. Preplace the Greenberg or Budde retractor clamps so that no extra time is spent once the dura is open. Infiltrate local anesthetic into the wound. Epinephrine helps with hemostasis. Do not inject the superficial temporal vessels.

6.4 Incision and Extracranial Dissection

Begin the incision rostrally and open the scalp down to the bone until you reach the temporalis fascia. At that point, slide an elevator under the scalp to define a plane, then open sharply. Just open the skin for the last 2 cm of incision above the zygoma. Use Metzenbaum scissors to dissect in layers to the temporalis fascia, so that the superficial temporal vessels may be identified, secured with bipolar cautery, and cut. Cauterize any arteries in the scalp. Venous bleeding may be secured with Raney clips.

Once this is done, then separate the galea from the temporalis fascia by finger or sharp dissection or cautery. You will need to identify the frontal process of the zygoma. This marks the frontal extent of the craniotomy. The pterion is just behind it.

Open the temporalis fascia sharply and curvilinearly from the frontal part of the zygoma to the root of the zygoma (▶Fig. 6.3). Leave a minimal 1 to 2 cm cuff of fascia to which to sew. Some surgeons prefer monopolar cautery to elevate the temporalis; others prefer to use periosteal elevators. Try to advance as anteriorly as possible along the lateral temporal bone.

Drill two bur holes (▶Fig. 6.3) with either an acorn bit or a perforator, one at the pterion and the other at the root of the zygoma. Use a no. 3 Penfield dissector or an Adson periosteal elevator to elevate the dura in the epidural space. You may drill a third burr hole at the posterior edge of the craniotomy, if desired.

Use a craniotome to make the long cuts first (▶Fig. 6.3). There will be two short cuts. First, advance anteriorly from the root of the zygoma along the middle fossa floor. Turn superiorly toward the pterional bur hole. The craniotome will be blocked by the wing of the sphenoid bone. Make a short cut (usually ~1 cm) from the pterion to the sphenoid wing. Score the remaining sphenoid segment with a craniotome bit without the footplate.

Use a no. 3 Penfield dissector to elevate the bone. The sphenoid part will crack. Carefully dissect the bone away from the dura with a periosteal elevator. Do not allow the bone to lever into the brain.

Obtain hemostasis. The middle meningeal artery may require attention at the sphenoid wing. There is often venous bleeding, which responds either to bone wax or to thrombin-soaked Gelfoam sponge (Pfizer Inc.) or FloSeal (Baxter).

Continue the bony dissection by using a rongeur to remove 1 to 2 cm more of squamous temporal bone anteriorly and inferiorly toward the floor of the middle fossa (▶Fig. 6.3). Reserve the chips for closure. Note whether there are any opened mastoid air cells along the floor. Wax these thoroughly. It is often helpful to drill some of the sphenoid wing. You do not need to go to the superior orbital fissure. Once you obtain hemostasis, it is time to open the dura.