New Onset Diplopia in Patients with Nasopharyngeal Carcinoma following Concurrent Chemoradiotherapy: Clinical Features and Etiology

Purpose. To investigate the clinical features and etiology of nasopharyngeal carcinoma (NPC) patients with new onset diplopia after concurrent chemoradiotherapy. Methods. We retrospectively reviewed the medical records of NPC patients with new onset diplopia after concurrent chemoradiotherapy from 1998 to 2012 in a cancer center. Their clinical manifestations of ocular motor dysfunction in relation to etiology were investigated. Results. Twenty-three NPC patients with diplopia after concurrent chemoradiotherapy were enrolled in this study. Unilateral cranial VI palsy (91%) was the most common ocular motor dysfunction in these patients. The new onset diplopia in these patients was secondary to tumor recurrence in 12 cases (52%), radiation neuropathy in 8 cases (35%), and skull base osteoradionecrosis in 3 cases (13%). Patients with tumor recurrence and skull base osteoradionecrosis tended to present a rapid progression of the nerve palsy or severe ocular duction deficit. Patients with radiation neuropathy were often manifested by incomplete nerve palsy with insidious onset and slow progression. Patients with osteoradionecrosis were associated with poor prognosis. Conclusions. A new onset diplopia in NPC patients could be caused by tumor recurrence or treatment complications such as radiation neuropathy and osteoradionecrosis, and they show diverse clinical symptoms, course, and outcome.