Tolerance of the carotid-sheath contents to brachytherapy: an experimental study.

Tumor invasion of the carotid artery is a potential indication for brachytherapy, which delivers a high dose of irradiation to residual tumor while limiting the dose to adjacent healthy tissues. The tolerance of carotid-sheath contents to varying doses of brachytherapy, however, has not been clearly established. In order to evaluate brachytherapy effects on carotid-sheath contents, after-loading catheters were implanted bilaterally in 3 groups of 6 rabbits each (18 rabbits). Iridium 192 brachytherapy doses of either 5000 cGy (rad), 9000 cGy, or 13,000 cGy were delivered unilaterally, with the contralateral neck serving as a nonirradiated control in each animal. There were no carotid ruptures and wound healing was normal. Two animals from each group were killed at 6, 20, and 48 weeks. Even at the highest dose (13,000 cGy), nerve conduction studies performed on the vagus nerve prior to sacrifice revealed no increased latency, histologic changes were minimal, and carotid arteries were patent. These observations suggest that the carotid-sheath contents in healthy rabbits could tolerate high doses (up to 13,000 cGy) of low-dose-rate interstitial brachytherapy without complications.

Oropharyngeal angioedema associated with the use of angiotensin-converting enzyme inhibitors.

Angioedema that occurs in the head and neck may be a serious and possibly life-threatening condition. We present two cases of oropharyngeal angioedema associated with the use of angiotensin-converting enzyme inhibitors in patients with no underlying renal failure. Angiotensin-converting enzyme-inhibiting agents are now commonly used to control hypertension. Treatment of acquired angioedema is directed first at protecting the airway by careful observation, intubation, or if necessary, tracheostomy. The causative agent is withdrawn, and the patient is treated with antihistamines and steroids until the acute episode resolves. Although not used in our patients, the treatment of angioedema with subcutaneous epinephrine has been described. As more patients are treated with angiotensin-converting enzyme inhibitors, it becomes essential for the otolaryngologist to become aware of this potentially life-threatening complication.

5-Hydroxytryptophan and carbidopa in spontaneously hypertensive rats.

Serial measurements of blood pressure, body weight, food and water intake, and salt and water excretion were compared in two groups of spontaneously hypertensive rats (SHR) over a 12-day period: control SHR (n = 11) and a group (n = 9) which received supplementary 5-hydroxytryptophan (5-HTP; 2 mg/ml) in its drinking water. During the final 4 days of study, both groups received additional oral carbidopa (50 mg/kg twice a day) to inhibit peripheral, but not brain aromatic L-amino-acid decarboxylase (LAAD), an enzyme necessary to the formation of 5-hydroxytryptamine (5-HT, serotonin) from 5-HTP. 5-Hydroxytryptophan increased urinary 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) markedly; following carbidopa, urinary 5-HT, and to a lesser degree urinary 5-HIAA, decreased, whereas brain 5-HT and 5-HIAA increased. Spontaneously hypertensive rats treated with 5-HTP plus carbidopa had significantly lower blood pressure levels, lower pulse rates, reductions in food and water intake, salt and water excretion, and a loss of body weight, when compared with the control SHR. These data indicate that enhanced brain formation of 5-HT can give rise to metabolic and circulatory responses with a resultant lowering of blood pressure.

Computed tomography in patients with laryngeal carcinoma: a clinical perspective.

Among the various diagnostic modalities that have been recommended for preoperative assessment of the patient with laryngeal carcinoma is computed tomography. While good overall correlation between CT findings and operative findings has been noted, a significant number of false positives and false negatives have been found, particularly with regard to cartilage invasion and lymphadenopathy. We compared the findings of direct laryngoscopy, palpation of the neck, and CT with pathologic specimens in 29 patients who underwent surgery for carcinoma of the larynx. We found that CT scanning underestimated the extent of neoplastic involvement in over half the cases. With respect to cartilage invasion we determined a significant number of false-negative findings. Computed tomographic scanning was equivalent to palpation in predicting cervical metastasis. Our findings indicate that the role of CT scanning may be more limited than previously acknowledged, particularly in patients for whom nonconservation surgery is planned.