Author response: COVID-19 presenting with ophthalmoparesis from cranial nerve palsy

We appreciate Dr. Machado's insightful comments regarding our case series1 describing cranial neuropathies in 2 patients with COVID-19. The triad of progressive ophthalmoplegia, ataxia, and areflexia in our first case suggested Miller Fisher syndrome (MFS), despite the negative ganglioside panel, although we were surprised by the short interval of 4 days between respiratory and neurologic symptoms. However, in 2 cases of COVID-19-associated MFS, latencies were similar (5 and 3 days),2 suggesting that the postinfectious interval is shorter for COVID-19 than for other infections. In fact, in a recent case of Guillain-Barre syndrome associated with COVID-19, neurologic symptoms preceded the respiratory symptoms by 1 week.3 The authors noted that lymphopenia was present on admission, indicating the presence of COVID-19 long before systemic symptoms began. This is in line with recent observations that 10/13 nursing home residents only developed symptoms 7 days after testing positive.4 Our second case may reflect direct viral invasion because there were no signs of MFS. Transfer of the virus through the olfactory bulbs is supported by recent evidence of olfactory bulb edema5 and hyperintensity of the adjacent gyrus rectus6 in patients with COVID-19-associated anosmia, although our patient never developed anosmia. The rapid recovery of anosmia observed in most COVID-19 cases argues for olfactory epithelial dysfunction as opposed to olfactory nerve damage, and we agree with Dr. Machado that hematogenous spread of virus may also play a role in CNS disease.