To describe a case of clival osteomyelitis presenting with facial droop, direction-changing nystagmus, and gait instability, and to highlight the diagnostic and treatment challenges for invasive fungal disease.

Invasive mucormycosis skull base osteomyelitis is a rare condition with incidence of 1.7 per 1,000,000 that has a wide range of neurological manifestations and can become rapidly fatal if not diagnosed and treated promptly.

A 50-year old male with type 1 diabetes mellitus and Marfan syndrome presented with headache and jaw pain and was initially diagnosed with acute sinusitis and temporomandibular joint arthritis. Six days later, he returned with facial droop, direction-changing nystagmus and gait instability. Initial contrasted CT revealed sinus disease; however, MR showed clivus and basilar artery enhancement. Sphenoidotomy revealed large fungal hyphae, and empirical therapy with vancomycin, meropenem, posaconazole and amphotericin B was started. His hospital course was complicated by recurrent strokes, cerebral abscess formation, infectious vasculitis and basilar pseudoaneurysm. Endoscopic clivectomy was considered but he was a poor candidate. Culture eventually grew Rhizopus arrhizus, and he was transitioned to triple antifungal therapy and hyperbaric oxygen. After several months of treatment and clinical stability he was transitioned to posaconazole monotherapy. Six months after discharge, the patient remained stable both symptomatically and radiographically.