Orbital apex syndrome secondary to acute invasive fungal rhinosinusitis diagnosed by transnasal endoscopic biopsy of the optic canal:A case report.

Orbital apex syndrome (OAS) is a complex condition characterized by visual loss, diplopia, and eye pain that occurs secondary to several pathological processes involving the orbital apex. We report a case of acute invasive fungal rhinosinusitis (AIFRS) associated with OAS. A 76-year-old man with left-sided visual loss, diplopia, palpebral ptosis, and headache was diagnosed with OAS secondary to Tolosa-Hunt syndrome and received systemic corticosteroid therapy from his neurologist. Owing to persistent symptoms, we opened the optic canal using a transnasal endoscopic approach for a surgical biopsy of the orbital apex lesions. Histopathological evaluation revealed numerous Aspergillus organisms in the biopsied granuloma. After surgical debridement, he received a 12-month course of voriconazole, and no recurrence of AIFRS occurred during 8-year follow-up. Patients with OAS may occasionally be prescribed corticosteroids because the clinical manifestations of AIFRS-induced OAS are similar to those observed in OAS secondary to Tolosa-Hunt syndrome, especially no nasal symptoms which is known to respond to corticosteroid therapy. Because both AIFRS-induced OAS and OAS secondary to Tolosa-Hunt syndrome induce ophthalmoplegia, proptosis, eye pain, it is sometimes difficult to differentiate these two diseases in early stage. However, corticosteroid therapy causes exacerbation of fungal infection in patients with AIFRS-induced OAS resulting in delayed accurate diagnosis and poor prognosis. AIFRS is associated with a high mortality rate ; therefore, transnasal endoscopic biopsy of orbital apex lesions before corticosteroid administration is recommended in patients with OAS. J. Med. Invest. 71 : 310-313, August, 2024.