Tuesday, June 17, 2008

manage carotid body tumor

fromClinical Neurology News:

Resection Remains Best Treatment for Carotid Body Tumors
Article Outline
Skip Angiography, and Other Surgical Pearls
CHICAGO — Surgical resection remains the treatment of choice for carotid body tumors, as presented in a review of 88 patients at one center.
Radiation therapy and chemotherapy are unsuitable alternatives because these rare tumors are too slow growing, and radiation exposes the carotid arteries to radiation arteritis, accelerated atherosclerosis, and even necrosis, Dr. Thomas A. Whitehill said at a vascular surgery symposium sponsored by Northwestern University.
Preoperative percutaneous tumor embolization has been tried with mixed results, but can be an important adjunct when treating select patients with large tumors (greater than 6 cm). There has been one report of a successful use of covered stents to facilitate resection (J. Vasc. Surg. 2003;38:389–91).
The malignancy rate for carotid body tumors is hard to define because there are no reliable histologic markers, but is thought to range from 2% to 5%, he said. Even if benign on histologic exam, all tumors, once discovered, should be surgically removed because they will ultimately wrap around the internal and external carotid arteries, erode into the base of the skull, and entrap neighboring cranial nerves. Increasing size also can interfere with speech, swallowing, and respiration, said Dr. Whitehill of the vascular surgery division of University of Colorado Health Science Center, Denver.
From 1993 to 2007, Dr. Whitehill and colleagues surgically resected 88 Shamblin classification II or III carotid body tumors, with an average diameter of 10.4 cm (range 5–16 cm). The patients ranged in age from 30 to 40 years.
Surgery time ranged from 4 to 14 hours, with an average blood loss of 375 mL (range 50–1800 mL). An internal carotid artery (ICA) resection bypass was performed in three patients, and ICA ligation in none.
Complications were relatively low, Dr. Whitehill said, and included cranial nerve IX neuropraxia (4%) or injury (1%), cranial nerve XII neuropraxia (30%), and superior laryngeal nerve injury (10%). There were no strokes or deaths.
Surgical advances and the widespread use of CT and MRI have decreased the overall risk of postoperative stroke over the past 25 years from about 30% to less than 2%, although the incidence of cranial nerve injury remains high at 15%–35%, he said.
Skip Angiography, and Other Surgical Pearls
Dr. Thomas A. Whitehill offered tips for carotid body tumors.
▸ Skip the angiography suite when making the diagnosis, and focus on CT imaging, preferably axial cuts rather than reconstructions. MRI may be slightly better at evaluating distant, metastatic deposits at the skull base.
▸ A nerve stimulator may be useful for preoperative identification of the cranial nerve.
▸ Do preoperative vocal cord and speech evaluations.
▸ Consider serial embolization in patients who are too old or have too many comorbidities to tolerate surgery.
▸ On a side CT view, draw a line between the mastoid tip and the angle of the mandible to get an idea of how high an exposure is needed and to help with preoperative planning.
▸ Utilize nasotracheal intubation in most patients, as it provides greater mobility with the mandible when resecting large tumors.
▸ In high access cases, mobilize the parotid gland anteriorly, up to the level of the facial nerve.
▸ Gain vascular control, if possible, and mobilize the tumor circumferentially to assess the extent of disease.
▸ Resect the tumor from proximal to distal.
▸ Fine mosquito clamp dissection and 3–0 or 4–0 silk ligation can give the best hemostasis.
▸ Send all suspicious lymph nodes for frozen permanent sections.
▸ Rather than using maxillomandibular arch bar fixation to obtain mandibular subluxation, consider interdental cross-wiring between the maxilla and mandible using bicuspids in dentate patients and Steinmann pins in patients with no teeth.
▸ For very distal tumors, cutting the digastric muscle will get you within 2 cm of the skull base.
▸ For large tumors, ligating the external carotid artery near its takeoff provides greater mobility.
▸ Avoid ligation of the internal carotid artery.
▸ If a tumor is 6 cm or more in diameter, consider preoperative embolization.
▸ Pushing the tumor completely through the bifurcation or pulling it anteriorly through the bifurcation may improve exposure angles and ease dissection.
▸ Take your time after the tumor is cleared of the two carotid arteries. The posterior surface and medial side of the tumor still must be separated from the deeper parapharyngeal tissues. Haste at this stage can result in the superior or inferior laryngeal nerves being transected or medial pharyngeal injuries, causing substantial swelling and neck pain in patients.

No comments: