Isolated Sixth Nerve Palsy and COVID-19: A Recurrent Case in a 7-Month-Old Child and Analysis of Reported Cases

With the SARS-CoV-2 pandemic (COVID-19), data on central and peripheral nervous system involvement, including those causing cranial nerve 6 (CN6) palsy, have been limited to case reports. To extract clinically relevant features of COVID-19-related CN6 palsy, we report on a recurrent pediatric case and analysis of reported cases associated with infection or immunization.

A PubMed search revealed 18 cases of isolated CN6 palsy in addition to the index case (n = 19). Clinical characteristics, workup, and temporal associations between systemic symptoms onset or vaccination, symptoms onset, and resolution were compiled and analyzed.

The median age of CN6 onset was 43 years (interquartile range [IQR]: 28-52). Sixteen cases (84.2%) were associated with COVID-19 illness and 3 (15.8%) were associated with COVID-19 vaccination. Four cases (23.5%) had positive neuroimaging findings. The median latency from first COVID-19 symptoms or vaccination to onset of CN6 palsy was 6 days (IQR: 2.3-16), and the median time from onset to resolution was 30 days (IQR: 14-60). Latency to onset of CN6 palsy was significantly and directly associated with time to resolution (R 2 = 0.401, P = 0.010). Patients who had a positive SARS-CoV-2 antibody test had significantly longer days from symptoms to onset (6.0 vs 24.5, P = 0.030), and patients with a positive SARS-CoV-2 polymerase chain reaction test had a significantly shorter time to resolution (17.50 vs 90, P = 0.042).

Isolated CN6 palsy from COVID-19 is rare, can occur in infants as young as 7 months, and can be recurrent. Longer latency from systemic symptoms onset portends greater recovery times, and this relationship may reflect multiple mechanisms by which COVID-19 (and/or an immune response thereto) causes cranial neuropathies with direct clinical relevance.