Understanding the diagnostic challenges of Miller Fisher syndrome in children: a case report from an ophthalmological perspective

We report a case of a 6-year-old boy with autism spectrum disorder presenting with new-onset squint and 'ptosis' following a recent infection. Clinical examination revealed ataxia and areflexia alongside a dilated pupil poorly reactive to light. Subsequently, his eye movements deteriorated to near-complete ophthalmoplegia at 1-week review. Further investigations inclusive of a magnetic resonance imaging (MRI) brain scan, a computed tomography (CT) venogram and a lumbar puncture were conducted to consider and rule out differential diagnoses. Cerebrospinal fluid analysis revealed an albuminocytologic dissociation. The clinical triad of progressive ophthalmoplegia, areflexia and areflexia alongside albuminocytologic dissociation led to the diagnosis of Miller Fisher syndrome. The patient was commenced on intravenous immunoglobulin and his symptoms showed significant improvement. We use this interesting case to provide context for key learning points about diagnosing Miller Fisher syndrome in children.