A Diagnostically Challenging Case of Fisher Syndrome in a Patient with Symptoms Resembling Rhinogenic Intracranial Complications

Abstract

Fisher syndrome is an autoimmune disorder characterized by an acute onset of external ophthalmoplegi, ataxia, and decreased tendon reflexes. It is a subtype of Guillain-Barré syndrome (GBS). We herein report the case of a patient who initially presented with acute sinusitis and was subsequently diagnosed to have Fisher syndrome after undergoing a challenging diagnostic process. The patient was a 33-year-old man who exhibited extraocular muscle paralysis that had progressed from the initial sinusitis. Imaging findings led to the suspicion of partial thrombosis in the cavernous sinus and narrowing of the internal jugular vein, thus leading to a diagnosis of cavernous sinus thrombosis complicated by Lemierre’s syndrome. The administration of antibiotics and thrombolytic therapy were initiated. The patient’s extraocular muscle paralysis was resistant to treatment, and his complaints of unsteadiness persisted. We considered Fisher syndrome in the differential diagnosis and performed a test for anti-GQ1b IgG antibodies in the blood serum. The blood test results were positive for anti-GQ1b IgG antibodies, thus leading to the patient’s diagnosis of Fisher syndrome. In cases presenting with refractory extraocular muscle paralysis and ataxia, it is extremely important to conduct a thorough examination while carefully considering Fisher syndrome in the differential diagnosis, including testing for anti-GQ1b IgG antibodies in the blood serum.