A case report of thrombocytopenic COVID-19 and Miller-Fisher syndrome on a concurrent chronic immune neuropathy.

Rationale: Miller-Fisher syndrome (MFS) is a rare subtype of Guillain-Barre syndrome with classic features of ataxia, areflexia, and ophthalmoplegia that can be caused by a preceding infection including COVID-19. We present a current, asymptomatic thrombocytopenic COVID-19 infection as a cause of MFS in a 60-year-old male with a concurrent chronic immune neuropathy.

Patient Concerns: A 60-year-old male presenting with acute symptoms of MFS including ataxia, areflexia, and ophthalmoplegia on a chronic immune neuropathy for at least 1 year and concurrent asymptomatic COVID-19 positive infection.

Diagnosis: MFS suspected secondary to a current thrombocytopenic COVID-19 infection.

Interventions: Five days of intravenous immune globulin with continued monthly intravenous immune globulin as an outpatient, follow-up long-term in a neuromuscular clinic, electromyography as an outpatient, and continued physical therapy.

Outcomes: The patient significantly improved after initial treatment.

Lessons: The full effect of COVID-19 on the various Guillain-Barre syndrome subtypes is unknown, although it clearly can be a cause of the various variants including being caused by a current, asymptomatic infection.