Sixth cranial nerve palsy in isolated sphenoid sinusitis: a case report

Abstract

In January 2013, a 78-year-old woman presented with diplopia due to a left abducens nerve palsy. She also mentioned a progressive left retro-orbital pain since 2 weeks, which she had already experienced 4 months earlier but resolved after steroid therapy for 10 days. She was known with diabetes mellitus type two and was treated with oral antidiabetics. Further neurological examination was normal. Fundoscopic examination could not reveal papillary edema. Magnetic resonance imaging (MRI) of the brain, orbits and sinuses demonstrated no parenchymatous or orbital pathology, but revealed an isolated sphenoid sinusitis (ISS), probably due to a fungal infection. The fungus seemed to have invaded the clivus at the site where the left abducens nerve enters Dorello’s canal (Fig. 1a–c). An urgent endoscopic sphenoidotomy was performed. Cultures showed growth of Scedosporium Apiospermum, a common soil fungus. Biopsy excluded malignancy. The patient was treated with intravenous voriconazole for 3 weeks. One month after surgery, her complaints had resolved. Clinical and ophthalmological examination revealed a complete recovery of the left abducens nerve palsy. Subsequently performed cone-beam computed tomography evaluation of the paranasal sinuses in March and April 2013 showed a progressive resolution of the sphenoid sinusitis with only some residual mucosal thickening in June. At that moment, she was still being treated with oral voriconazole 200 mg twice daily. In October 2013 voriconazole was stopped without clinical or radiological signs of disease recurrence up till now.