June 02, 2014
Let's review patient positioning for retromastoid craniotomy as well as alternative skin incisions. This is a 61 year old male who presented with gait imbalance and ultimately was diagnosed with a CP angle ependymoma. A very unusual location for such a tumor without a clear connection to the fourth ventricle. A retromastoid craniotomy was completed. Let's go ahead and review patient positioning. The lateral position is ideal. Neurophysiological monitoring was implemented. You can see immobilization of the shoulder, anteriorly and inferiorly so that the suboccipital area can be exposed. You can see the use of pillows to buttress the pressure points. Here, placement of a tape to immobilize the shoulder anteriorly. I usually use an inverted horseshoe incision. However, some of the colleagues use a C incision as demonstrated here. You can see the mastoid groove in the middle of the incision. Here's additional view of the final patient positioning. You can see the mobile position of the shoulder. The incision is injected with local anesthetic and epinephrine. Here is mobile position of the shoulder anteriorly and inferiorly. The angle between the shoulder and suboccipital is expanded. The scalp flap is reflected anteriorly. The mastoid groove is palpated. Although the scalp is reflected anteriorly, the periosteum and the suboccipital muscles are reflected inferiorly. This maneuver moves the suboccipital muscles out of the working zone of the surgeon. Part of the pericranium here can be harvested for closure of the dura. Monopolar cautery is used to dissect the muscle away from the suboccipital bone. Here's the mastoid groove. We'll go ahead and dissect the muscle more inferiorly. The muscle is immobilized all the way to the level of the posterior fossa floor. The emissary vein is controlled using bone wax. Fish hooks are used to immobilize the muscle inferiorly. Effective immobilization of the muscle is mandatory for adequate visualization through the posterior fossa. A burr hole's placed at the junction of the transverse and sigmoid sinuses. A generous one is necessary so that the dura can be stripped away from the inner surface of the calvarium, and the edges of the dural venous sinuses is exposed. Here's the craniotomy. You can see the junction of the transverse and sigmoid sinuses. The mastoid aerosols are well waxed. The dura is incised along the border of the dural venous sinuses. In this case, following completion of the retro mastoid craniotomy and intradural dissection, it goes to removal of the mass was accomplished. Thank you.
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