RESUMEN
RATIONALE: Miller Fisher syndrome (MFS) is a rare variant of Guillain-Barre syndrome, classically diagnosed based on the clinical triad of ataxia, areflexia, and ophthalmoplegia. MFS is usually preceded by viral infections and febrile illness; however, only a few cases have been reported after vaccinations. PATIENT CONCERNS: A 53-year-old hypertensive male presented with a 2-day history of progressive ascending paralysis of the lower limbs along with diplopia and ataxia, 8 days after the first dose of the Sinovac-Coronavac coronavirus disease 2019 (COVID-19) vaccination, with no prior history of any predisposing infections or triggers. DIAGNOSES: Physical examination showed moderate motor and sensory loss with areflexia in the lower limbs bilaterally. Routine blood investigations and radiological investigations were unremarkable. Cerebrospinal fluid analysis showed albuminocytologic dissociation and nerve conduction studies revealed prolonged latencies with reduced conduction velocities. The diagnosis of MFS was established based on the findings of physical examination, cerebrospinal fluid analysis, and nerve conduction studies. INTERVENTIONS: A management plan was devised based on intravenous immunoglobulins, pregabalin, and physiotherapy. However, due to certain socioeconomic factors, the patient was managed conservatively with regular physiotherapy sessions. OUTCOMES: Follow-up after 6 weeks showed remarkable improvement, with complete resolution of symptoms 10 weeks after the discharge. LESSONS: This case suggests that MFS is a rare adverse effect after COVID-19 vaccination and additional research is required to substantiate a temporal association. Further studies are needed to understand the pathophysiology behind such complications to enhance the safety of COVID-19 vaccinations in the future.