Predictive factors and radiological features of radiation-induced cranial nerve palsy in patients with nasopharyngeal carcinoma following radical radiotherapy.

OBJECTIVES To identify the key predictive factors of radiation-induced cranial nerve palsy in patients with nasopharyngeal carcinoma (NPC). METHOD AND MATERIALS From November 1998 to December 2007, all consecutive patients with newly diagnosed NPC who were curatively treated with radiotherapy and subsequently developed radiation-induced cranial nerve palsy (RICNP) were included in our study. Patients with cranial nerve palsy due to disease recurrence were excluded. Their records were retrospectively reviewed. RESULTS Amongst 965 patients with NPC treated with radical radiotherapy, 41 developed new cranial nerve palsy. After exclusion of 5 patients with cranial nerve palsy due to recurrence, 36 (3.7%) developed RICNP. The median follow-up was 8.9 years (range, 3.2-11.3 years). Ten of the 36 patients had cranial nerve palsy at presentation. Twenty-seven patients had single cranial nerve palsy and 9 patients had multiple cranial nerve palsy. The most commonly involved cranial nerve was cranial nerve XII, with 30 patients having palsy of cranial nerve XII and 6 of them having bilateral cranial nerve XII palsies. Magnetic resonance imaging features of radiation-induced hypoglossal nerve palsy were demonstrated in our study. Multivariate analysis revealed that cranial nerve palsy at presentation was an independent prognostic factor for the development of RICNP. Other factors including T staging, N staging, gender, age, radiotherapy technique and the use of chemotherapy have no significant relationship with the risk of developing RICNP. CONCLUSION RICNP in patients with NPC is not a rare complication, and cranial nerve palsy at presentation is an important prognostic factor.