Radiation-related cranial nerve palsy in patients with nasopharyngeal carcinoma

Cranial nerve palsy is a rare complication after patients with nasopharyngeal carcinoma (NPC) receive radiotherapy using a technique that delivers 180-200 centigrays (cGy) per day. Cranial neuropathy is of particular clinical interest in terms of making a differential diagnosis, because it is also a common presenting manifestation in patients with NPC. Cranial neuropathy may lead to distressing signs and symptoms in these patients, and their treatment has not been addressed in previous reports. This article presents the authors' experience with radiotherapy-related cranial nerve palsy in patients with NPC.

Nineteen patients were diagnosed with radiation-related neuropathy. Patients with recurrent tumors or with a suspicion of persistent or recurrent tumors were excluded. Most patients were treated using 180 cGy or 200 cGy per fraction per day. The total dose was 7000-13,000 cGy to the nasopharynx and 5000-9000 cGy to the neck. Unilateral vocal cord paralysis alone and hearing loss were not included in the analysis.

There were 15 male patients and 4 female patients. The latency before palsy occurred was 12-240 months. Single nerve palsy developed in four patients, including two patients with hypoglossal palsy and two patients with recurrent laryngeal palsy. Two patients had three nerve palsies each. The other 13 patients presented with 2 nerve palsies each. Vagus and hypoglossal palsy appeared to be a frequent combination and occurred in 11 patients. Overall, there were 17 patients with hypoglossal palsy (7 bilateral, 8 left-sided, and 2 right-sided), 11 patients with vagus palsy (2 bilateral, 7 left-sided, and 2 right-sided), 6 patients with recurrent laryngeal nerve palsy (5 bilateral), and 2 patients with accessory palsies (all bilateral). Marked neck fibrosis was present in 12 patients. Patients who had vocal cord paralysis suffered from easy choking and hoarseness. Severe respiratory difficulty occurred in two patients who had bilateral vocal cord palsy. Surgical procedures included laryngoplasty, tracheostomy, and gastrostomy. Quality of life improved considerably after patients underwent surgery.

Radiotherapy-related cranial nerve palsy may occur in patients with NPC after they receive conventional radiotherapy. Hypoglossal nerve palsy was found the most frequently in this series, followed by vagus nerve palsy and recurrent laryngeal nerve palsy. Neck fibrosis and the course of the three nerves through the neck may be important risk factors for the development of palsy. The diagnosis must be made only after the possibilities of tumor-induced palsy and idiopathic palsy are excluded. Surgery is helpful in improving the quality of life in many patients.