RESUMEN
Ophthalmoplegia without ataxia has various etiologies. An atypical Miller Fisher syndrome implies an ophthalmoplegia without ataxia, areflexia or both. The presence of anti-GQ1b antibody supports the diagnosis of an atypical Miller Fisher syndrome. A 4-year-old Russian girl visited our hospital because of acute bilateral abducens nerve palsy and mydriasis. Although the muscle power of extremities was normal and she didn't show an ataxia, the deep tendon reflex of both knees and ankles was absent. The results of nerve conduction study and cerebrospinal fluid analysis were normal. Magnetic resonance imaging (MRI) showed an enhancement of the bilateral abducens nerve. The anti-Gq1b antibody titer was elevated. The diagnosis of atypical Miller Fisher syndrome was made and a therapy with intravenous immunoglobulins led to the clinical recovery. We report a girl with atypical Miller Fisher syndrome with acute bilateral abducens nerve palsy and mydriasis, diagnosed by of anti-GQ1b antibody positivity.