The transoral robotic surgery is done under general anesthesia. The surgery starts with an examination of the throat, called direct laryngoscopy, by both palpation and careful visual inspection. This is intended to both assess the suspected tumor and double-check that no other suspicious lesions are present. Following this, the surgical exposure of the throat is established, with a mouth retractor device, referred to as a mouth gag. There are various types, differing in shape and utility. It is necessary for both the tongue and jaw to be stably positioned. The pressure applied to the tongue and jaw can sometimes lead to discomfort appreciated after the surgery, and also temporary bruising/swelling/loss of sensation at the tip of the tongue. With the retractor creating exposure of the throat, the robotic instrumentation is positioned. The DaVinci SP is a robotic surgical system with four flexible instruments entering the surgical field through a single 25mm access port. This point of rotation remains just outside of the mouth, and the instruments are advanced to the oropharynx space. The instruments include an endoscope, two forceps (which also deliver bipolar energy for hemostasis), and a spatula or scissors which delivers monopolar cautery energy for cutting tissue and hemostasis.
The surgeon controls the instruments from a nearby console, with 3-dimensional magnified view. An assistant can place two additional instruments through the mouth, typically two suctions, though at times additional forceps or hemoclips are needed. The tumor is resected en bloc, which means incisions are made in the normal tissue surrounding the cancer, so that a normal margin of tissue is completely surrounding the tumor. This normal margin is critically important to ensuring that the tumor is completely removed. It is definitively assessed once the tissue has been fixed in formalin and thin cross-sections evaluated by the pathologist under the microscope, which takes a couple of days following the surgery to be completed. If certain margins are concerning during the surgery, these can be sampled and checked by freezing the tissue and examining under the microscope intraoperatively; the assessment of margins during surgery can not be as comprehensive or definitive as the assessment of the whole surgical specimen following fixation on permanent sections. Close and concerning margin edges recognized during surgery will be re-excised to more confidently ensure the margin is clear. At the end of the TORS surgery, our expectation is that the tumor is completely removed from the oropharynx.
The wound in the throat will heal by secondary intention. This means that the body forms a healing scab in the wound, and the edges of normal tissue gradually migrate across the surface and close up the wound. For an average size wound in the oropharynx, this will take approximately 4 to 6 weeks to granulate and then epithelialize. In the early part of this phase, there is a very fresh wound bed which has a risk of bleeding if traumatized or irritated. If bleeding occurs, it is most often mild bleeding from a wound edge, which will stop or resolve on its own. More uncommonly, major bleeding could occur, particularly from a small arterial vessel, if exposed in the wound bed. This risk is decreased by ligating the branches from the external carotid artery at the time of the neck dissection portion of the surgery.
The surgical treatment also includes a neck dissection. This is to remove the involved and at risk lymph nodes from the neck. This is done through an incision in the neck skin, and the lymph nodes from along the carotid sheath and internal jugular vein are removed. The lymph nodes are dissected while preserving the surrounding structures, including muscles, nerves and blood vessels, as long as they are not directly invaded by the cancer. It is expected that the skin of the neck will be numb following the surgery. Other nerves, such as those that move the tongue, vocal cords, and trapezius muscle should be functioning well following surgery. Of these, the trapezius is most likely to be affected with temporary dysfunction, which can appear as weakness in lifting the arm past 90 degrees at the shoulder. Overall, the neck dissection surgery is well-tolerated with mild side effects.
The significant part of recovery following the surgery is related to the throat surgery. There is pain and swallowing dysfunction, which very gradually improves. Initially, the recommended diet is full liquids, including calorie-dense shakes and puréed foods. It is very uncommon for a feeding tube to be needed. It is common for there to be 10lbs of weight loss in the post-operative period. Throat pain following surgery is controlled with hydration, active swallowing, and analgesics including acetaminophen, celecoxib, gabapentin, and hydrocodone if needed.
The tissue at surgery is removed and examined carefully by a pathologist. The findings are reported several days after surgery. Significant factors include the margins, size of the tumor, number of lymph nodes involved, extension outside of the lymph node, perineurial invasion, and lymphovascular invasion. The combination of these factors will guide recommendations regarding any adjuvant treatments with radiation or chemotherapy following the surgery. It is possible that following surgery the risk of recurrence is low enough that no additional treatment is recommended. If there is an intermediate risk, then a reduced dose course of adjuvant radiation is recommended. If the risk is in the higher range, then traditional adjuvant radiation with concurrent chemotherapy is still recommended. The goal for starting adjuvant treatment is 6 weeks following surgery.
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