Preop

Look up the MEPMC note in epic for epileptologist evaluation

Medications

• Ancef
• Home AEDs (they should have taken them the morning of surgery)
• 10 mg IV dexamethasone
• Mannitol can be given if there is concern that the brain will be very full (i.e. patient is young or obese) but is not always given
• End-tidal CO2 should be kept at 25. 

Monitoring

Dependent on pathology. Usually just ECOG if the epileptogenic zone is reasonably non-eloquent (i.e. not near motor). If it is near motor or sensory then maybe SSEPs and tcMEPs but it would be reasonable to ask Dr. Gonzalez in this setting.

Pinning and Positioning

Turn the bed 90 degrees with the side of pathology opposite anesthesia. Place a large foam bump longitudinally under the ipsilateral torso. The arm may be tucked or simply placed on an arm board. 

Attach the Layla bar attachment.  

Take the head of the bed off to pin. Two pins go in the back in the axial plane, low, just above the superior nuchal line. The single pin goes in the forehead at the junction of the mid-pupillary line and hairline. Be sure to study the preop CT to know the size of the frontal air sinus and avoid pinning in it. Pin to 70 lbs. Image guidance goes on the inside (but he won't use it).  

Turn the head into a "backstroke position": 

1. Extend the neck, a lot
2. Rotate to the side opposite the pathology by about 45 degrees
3. Laterally flex towards the floor
4. The ipsilateral maxillary eminence, or cheekbone, should be the highest point in the field

Incision

Shave liberally. Dr. Gonzalez does not do a "hair sparing" incision and is okay with the resident shaving. 

This is a small reverse question mark centered on the approximate location of the Sylvian fissure as below. Note that Dr. Gonzalez will curve the top of the question mark (the part nearest the apex of the head) downwards a little (towards the feet). 

As an exercise, Dr. Gonzalez may mark the expected locations of the Sylvian fissure, central sulcus, inferior frontal gyrus, amygdala and hippocampus on the skin. 

Infiltrate the skin with 1% lidocaine with epinephrine 1:100,000. 

Draping

In the standard fashion. Blue towels, Ioban, crani drape. Cut holes for the Layla bar and image guidance arm. 

Approach

Skin

Cut skin with a 10 blade through galea. Be aware that there is temporalis under all parts of the incision, so do not go straight down to bone. Once through galea, develop the subgaleal plane with a large scissor and cut skin on top of the scissor. You may use the scissor or Bovie to complete the cut through the galea. 

Dissect the scalp flap off of the muscle with Metzenbaum scissors then secure to the Layla bar with fish hooks. 

Verify that the skin exposure is adequate to reach the root of the zygoma and that the eventual craniotomy will show the inferior frontal lobe, Sylvian fissure, and superior and middle temporal gyri. 

Muscle

Use a Bovie to cut through temporalis fascia and muscle to the bone in a C shape, leaving it pedicled at its inferior and anterior attachment. 

Elevate the temporalis from the temporal fossa. Dr. Gonzalez uses a Bovie for this. Move the fish hooks from the scalp flap to the muscle flap to secure it back. 

Verify that you have exposed the root of the zygoma and the depression for the sphenoid ridge and that your craniotomy will have sufficient exposure of the frontal and temporal lobes. 

Bone

Use a perforator to make burr holes. Dr. Gonzalez usually uses only one burr hole at the mid-posterior border of the planned craniotomy but will be okay with you making up to three. He does not irrigate away the bone dust and chips because he believes they have hemostatic properties. After the burr holes, he takes two bites with the Kerrison rongeur along the planned path of the craniotomy to "start it off." He does not use the Penfield 3 or the Woodson to develop the epidural plane. Use the B1 with the footplate to turn the craniotomy. 

Use a Leksell rongeur (with the tips pointed away from the brain) to bite away as much of the squamous temporal bone covering the temporal pole as possible. You do not have to bite towards the floor of the middle cranial fossa or expose inferior temporal gyrus. This gyrus will likely be resected but can be visualized under the edge of residual squamous temporal bone. 

Dura

Before opening the dura, place 4-0 Nurolon dural tackups  along the edges of the craniotomy and tie them to the cut edge of the temporalis. These tackups are permanent and persist through closure. 

Open the dura in a C shape with the flap pedicled on the middle meningeal artery. 

Fold the flap in half then secure to the muscle flap with 4-0 Nurolon suture passed through the folded dura. 

Tack the cut edge of the dura to the skin edge. These tackups are temporary and will be removed prior to closure. 

Place four 4x4 pieces of gauze in a square around the perimeter of the exposure. Then, place four blue towels in a square on top of the 4x4s and staple in place. Irrigate the field to wet the towels and gauze. 

Lateral temporal lobectomy

Lateral temporal lobectomy begins with two corticectomies. The first is along the superior temporal gyrus and the second starts at the posterior border of the STG cut and extends towards the floor of the middle cranial fossa, often at an oblique angle (i.e. the bottom of the corticectomy is more posterior than the top). 

The posterior limit of the STG cut is defined by either the vein of Labbe or the position on STG that is across the Sylvian fissure from pars triangularis of the inferior frontal gyrus. Pars triangularis can often be identified by the presence of a small pocket of CSF below the arachnoid. 

Take the STG cut as far anteriorly as you can. You will need to peek under the bony edge of the remaining squamous temporal bone. Once the pia is coagulated and cut with microscissors, use a 7 mm Rhoton suction and Penfield 1 to dissect towards the Sylvian fissure in the subpial plane. Once separated from the pia, the STG can be pulled into the suction and destroyed. 

Carry the subpial dissection superiorly towards the Sylvian fissure and follow the pia as it curves over the top of the STG then back inferiorly. Through the translucent pia, you will see the M2s as they course over the face of the insula. Now, carry the subpial dissection inferiorly to expose the entire face of the insula. Again, this is all subpial, so you may see the insular cortex between branches of the MCA, but it will be behind a thin layer of pia. Carry this dissection inferiorly to the inferior limit of the insula. The plane of the insula will define the trajectory of approach to the temporal horn of the lateral ventricle. This is your next goal. 

Continue dissection inferiorly in the same plane as the insula through the white matter. As you move inferiorly, you will begin to encounter small blood vessels in the white matter. These vessels will lead you to the temporal horn. Once you find it, open the temporal horn. You will encounter a rush of CSF and see the pearly white convexity of the head of the hippocampus. It is a very distinct appearance. This completes the STG dissection. 

Now, return to the surface of the brain and turn your attention to the superior-inferior corticectomy that cuts across the superior, middle, and inferior temporal gyri. Carry this corticectomy medially to the level of the temporal horn and inferiorly to the floor of the middle cranial fossa. Suck the white matter and coagulate and cut the pia and pial vessels when they are encountered at the sulci and underside of the temporal lobe. 

At this point, you should have deepened both corticetomies to the level of the plane of the insula and have exposed the temporal horn of the lateral ventricle. Now you will carry this dissection plane anteriorly, towards the temporal tip. The trajectory of this dissection is in parallel to the trajectory of the hippocampus. Carry this plane anteriorly to the temporal tip and coagulate and cut the pia to remove the lateral temporal lobe. This completes the lateral temporal lobectomy. 

Meidal Temporal Lobectomy

Closure

Position supine with a bump oriented longitudinally. He doesn't care much about pinning if it makes sense in some way. We did two pins on the contralateral side, oriented right to left, one pin on the frontal boss at the mid pupillary line. He does not care about pins in the forehead. The neck should be extended and turned, not quite fully horizontal, what JGM calls the "backstroke" position, looking towards the back corner of the room. 

He used the position of the sEEG leads to localize the location of the craniotomy. In this case, the epileptogenic zone was the superior temporal gyrus. So we did a small reverse question mark incision with a small leg going down in front of the ear. He raises the skin and temporalis as two separate flaps. Make skin incision just through skin then take a Metzenbaum scissor to go through galea. Open the whole incision this way. Use Metz to separate the loose areolar tissue from the temporalis. Next, use a Bovie to go straight down to bone through the fascia and muscle, expose the root of the zygoma. Dissect periosteum and muscle away from the incision line on both sides of the incision, i.e. down towards the floor of the middle cranial fossa and up onto the frontal bone. One burr hole is placed at the root of the zygoma and the other at the posterior limit of the craniotomy. He does not use a 3 Penfield or Woodson to dissect the dura and instead just goes straight into the B1 with the footplate. He does take a cranial Kerrison to start the craniotomy tract on either side of each burr hole. The craniotomy should go up past the Sylvian fissure to expose the bottom edge of the frontal lobe and down to the floor of the middle cranial fossa. The posterior limit is determined by the last positive sEEG lead and the anterior limit is the sphenoid wing. Elevate the bone flap. To stop bleeding from the cut edge of the sphenoid wing he stuffs NuKnit against it until it stops. He tacks up the dura all the way around before opening it with a pickup and Metz. He then tacks up the cut edge of the dura over the prior tackups. Be aware that the dura will be adherent to the surface of the brain at the site of the prior sEEG leads. He does not use SurgiFoam! 
Once the bone flap is off, define the limits of the cortisectomy. If there is a Sylvian vein that makes it easy to find the fissure. In our case, there was no vein so we relied on the arterial vasculature to define the fissure. Veins will cross fissures but arteries will not. There is also a small cistern just inferior to pars triangularis that can be used to find that structure. Also, Heschel's gyrus will be along a vertical line passing through the EAC. Make the cortisectomy with bipolar and microscissor. Once the cortisectomy was done, he used a suction and Pen 1 to peel the temporal lobe away from the Sylvian fissure using subpial dissection. This plane came away very nicely. He started at the midpoint of the Sylvian fissure and worked backward until he saw Heschel's gyrus which was the first transverse gyrus. It is oriented obliquely where it heads more posteriorly as you follow its course medially towards the brain stem. We cut across Heschel's gyrus at its midpoint, sparing the mesial portion of the gyrus. Loss of the mesial Heschel's gyrus is associated with Cocktail Syndrome, where patients are unable to localize sounds and feel very disoriented. We then took the superficial dissection down towards the floor of the middle cranial fossa. Since we were removing STG alone and no mesial structures, the deep limit of the resection was the bottom of the superior temporal sulcus. Venous bleeding is encountered at the bottom of a sulcus, which also helps to define the deep limit. We stopped before hitting temporal horn, which was evident based on the surrounding white matter. Once we had made cuts from superficial to deep straight into the brain we started dissecting in the sagittal plane, from the Sylvian fissure to the floor of the MCF.