COVID-19-Associated Miller Fisher Syndrome With Long Latency Period: A Case Report.

Coronavirus disease 2019 (COVID-19) has been known to affect multiple organ systems, aside from the respiratory system. Increasing reports of post-infection neurological complications have been reported. Miller-Fisher syndrome, a rare variant of Guillain-Barré syndrome (GBS), has been reported after COVID-19 infection. We present the youngest known adult (26-year-old male) reported to have had COVID-19-associated Miller Fisher syndrome (MFS) with also the longest reported latency period (10 weeks) between infection and development of neurological symptoms (including dysphagia, horizontal diplopia, facial weakness, upper and lower extremity weakness, paresthesia). This is currently the second youngest reported case after the case of a seven-year-old child. The patient was treated with intravenous immunoglobulin and was ultimately transferred to a different facility for higher level of care. Most symptoms were resolved within four days. The patient reported resolution of neurologic symptoms with the exception of left-sided facial weakness at the one-year follow-up. As more reports of COVID-19-associated GBS and MFS appear in the future, we are likely to discover more variability than was previously known in GBS and MFS. With COVID-19 potentially affecting multiple systems, there could be increased variability to previously known conditions. Future studies may need to closely examine long-term follow-ups of patients previously diagnosed with COVID-19 as post-COVID complications become more prevalent.