Minimally Invasive Thumb-sized Pterional Craniotomy for Surgical Clip Ligation of Unruptured Anterior Circulation Aneurysms

The overall goal of this procedure is to isolate an intracranial aneurysm from the normal circulation by a surgical clip ligation, using a less invasive surgical approach. This is accomplished by first prepping the patient in a Mayfield head holder and then dissecting the scalp to ultimately expose the ion. The second step of the procedure is to drill and remove a thumb sized craniotomy centered around the ion.

The third step is to reach the aneurysm by a bimanual dissection of the sylvan fissure without the use of brain retractors, and then secure the aneurysm. The final step is to use intraoperative doppler of the aneurysm dome and surrounding vessels to confirm normal circulation before performing. A standard closing use of this protocol can result in shorter hospital stays at lower costs and fewer complications than the national average.

The main advantage of this technique over existing techniques like the standard TER onal craniotomy, is that patients can have shorter hospital stay at a lower cost Position the head and neck for maximal venous drainage with the ipsilateral zygoma positioned at the highest point, expose and sterilize the dermis and drape the surgical area. Begin the surgery with a standard curved scalp incision for a AL approach extending from the midline of the scalp behind the hairline. Gently curve the incision towards the tragus.

Complete the incision three millimeters anterior to the tragus level. With the superior edge of the zygoma above the superior temporal line, the incision should penetrate to the skull and at the level of the temporalis muscle, the incision should penetrate to the muscle facia. Use bipolar electrocautery to acquire scalp homeostasis as needed.

Next, with a Bovie monopolar electrocautery device, cut the temporalis muscle down to the skull directly beneath the scalp incision. Now raise a myocutaneous flap anteriorly using a periosteal elevator and use electrocautery to elevate the temporalis muscle. Then using fish hooks avert and secure the myocutaneous flap starting at the undersurface of the flap.

Use metson balm scissors to make an inverse subfascial dissection in the vascular plane. Keep the facia and sub fat pad attached to the scalp to avoid injuring the frontalis branch of the facial nerve. Use starfish hooks to secure the temporalis muscle posteriorly and inferiorly exposing the AL region going forward.

It is important to always keep the entire scalp flap and temporalis muscle moist with wet GREs. Using the drill, make a three to four millimeter bur hole of the most inferior temporal location of the planned craniotomy. Using a two milliliter cutting bur to start the hole, then use the foot plate of a side cutting drill to widen out the hole into a thumb sized craniotomy about three by four centimeters based around the ion.

Drill out the ion to complete the craniotomy and save the bone flat. Use a number one Penfield to separate the dura from the lateral sphenoid wing. An assistant must gently retract the dura away from the bone wall drilling so the dura is not injured with the drill in the next step.

Now use the two millimeter burr to drill out the lateral sphenoid wing and the superior and lateral orbital walls until only the outer cortical table of bone remains. Do not enter the orbit medially drill until the lateral aspect of the superior orbital bone fisure is exposed. Is the drill or a handheld lepert bone cutter to remove any small pieces of bone that would interfere with medial exposure after they're dissected from the dura?

Now, before opening the dura, use bipolar electrocautery and bone wax to ensure excellent hemostasis of all the soft tissue and bone surfaces. This will prevent blood from oozing into the intradural space and hindering visualization. Gently elevate the dura and open using a number 15 scalpel.

Using dural scissors, create a CS shaped opening from the frontal dura extending inferiorly to the temporal dura with the base of the dural flap opening centered around the tarion. Using four zero sutures, take the dura to the soft tissues more superficially, making sure that the dural flap lies flat against the alter cortical bone of the orbit. Do not let the dural flap obscure the view of the proximal sylvan fissure or the sub frontal region.

We suggest using a six French Fukushima suction tip for the superficial sylvan fissure dissection in a four French Fukushima suction tip for the deeper dissection around the optic nerve, the arteries, and the aneurysm itself. These tips have good suction strength and can easily be adjusted with the thumb during dissection. Hold the suction in the non-dominant hand in the bipolar device or micro dissecting instruments in the dominant hand.

Then make certain the surgeon's forearms are resting comfortably at the desired height to minimize upper body fatigue. Initially, the surgeon's hand will have a projection nearly parallel to the floor during a superficial dissection of the sylvan fissure. Later, the hands turn more perpendicular to the plane of the floor as the dissection deepens into the sylvan fissure.

Throughout this angle, change the flat edges of the instruments are able to maintain gentle retraction as needed. Now, LA moist telfa strips on the brain surface perpendicular to the sylvan fissure at the site of manipulation, so they follow the angle of the retraction instrument and the telfa do not obscure the fissures content. Using the telfa strips to stabilize the instruments edges start the next phase of the surgery.

First, further relax the brain evacuate the cerebral spinal fluid by opening the YL vian fissure and the three arachnoid sters, the inter optic, carotid optic and carotid ocular motor. With these subarachnoid spaces opened patiently suction the cerebral spinal fluid. This avoids having to place a lumbar drain in the patient preoperatively.

Then to open the arachnoid corridors, gently hold the brain tissue aside with the edge of the instrument handles or with a suction device. Now perform the sylvan fissure dissection less than one centimeter. Proximal YL and fissure dissection is required to expose the internal carotid artery terminus, the posterior communicating and anterior choroidal arteries, the A one and M1 origins and the proximal A two and M two segments for aneurysms.

Other than of the anterior communicating region, the Sylvan fisheries dissected about one centimeter posterior to its anterior most extent. To expose the supra glenoid ICA, its branches, the A one and M1 origins and the A two and M two segments. In the case of anterior communicating artery aneurysms, Sylvan fisher dissection is rarely required, and little to minimal gyrus rectus resection is needed.

Depending on how high the anterior communicating segment is positioned. Sub frontal dissection underneath the frontal lobes alone is usually adequate to access the anterior communicating region. Once proximal and distal controller obtained, the aneurysm is identified and dissected out from surrounding structures.

It can be secured in the standard fashion using the four French Fukushima tip to maintain mild retraction and optimize visualization during clip application. After clipping the aneurysm, perform an intraoperative doppler of the aneurysm dome to confirm cessation of flow. Also, check the inflow and outflow zones to confirm patency.

Once the occlusion is confirmed, acquire excellent hemostasis and prepare for closure. Re approximate the native dura with four zero sillon and cover with a synthetic dural substitute. If a watertight closure is not able to be obtained adequately secure the bone plate with a metal plating system per standard of care first, but the frontal edge of the bone flap flush to the native bone, so there will be no unsightly space between the two plates after healing.

Depending on the residual bony defect, a small wire meash can be contoured and secured behind the orbit to reconstruct the terone region. Next, re approximate the temporalis muscle fascia posteriorly with interrupted two zero vicral sutures and superiorly to the frontal metal plate. Secure it anteriorly minimizes cosmetic defect anteriorly.

When temporalis muscle atrophy occurs, then rear approximate the G using three zero Vicryl sutures and lastly, close the scalp in a standard fashion using either staples or sutures. In 22 elective aneurysm clippings on patients less than 55 years of age performed by the developer of the technique, only one patient who had a right MCA aneurysm experienced postoperative complications. In 18 patients follow-up imaging showed no occurrences through an average duration of 22 months.

Compared to the nationwide inpatient sample data, the hospital stay and expenses for such patients undergoing the procedure from 2008 to 2010 was significantly reduced non-inclusive of patients with subarachnoid or intra cerebral hemorrhage. After watching this video, you should have a good understanding of how to isolate an intracranial aneurysm from the normal circulation via surgical clip ligation using a less invasive surgical approach. Thank you for watching this video.