Isolated cranial sixth nerve palsy after COVID-19

(Image Credit: AdobeStock/JeromeCronenberger)

Isolated cranial sixth nerve (CN6) palsy from the COVID-19 virus is rare, can occur in infants as young as 7 months, and can be recurrent. Longer recovery times were found to be associated with longer latency from the onset of systemic symptoms,¹ according to study authors Grace Baldwin, MD, Eric Gaier, MD, PhD, and Lauren Hennein, MD.

Baldwin is from Harvard Medical School, Boston; Gaier from Harvard Medical School; Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School; and Massachusetts Institute of Technology, Cambridge, MA; and Hennein from Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Department of Ophthalmology, Rady Children's Hospital—San Diego, and The Viterbi Family Department of Ophthalmology, University of California San Diego, San Diego, CA.

The investigators conducted a PubMed search to identify cases of CN6 palsy that were related to the COVID-19 virus. The data on central and peripheral nervous system involvement have been limited to case reports, they explained.

They experienced a recurrent pediatric case of CN6 palsy in a 7-month-old child and identified 18 additional cases that were associated with infection or immunization in the literature search.

Baldwin and colleagues collected data on the cases that included the clinical characteristics, workup, and temporal associations between systemic symptoms onset or vaccination, symptoms onset, and resolution.

Analysis of the collected data showed that the median patient age at the onset of CN6 onset was 43 years (interquartile range [IQR]: 28–52 years).

Sixteen cases (84.2%) were associated with COVID-19 and 3 (15.8%) with the COVID-19 vaccination. The investigators reported that 4 cases (23.5%) had positive neuroimaging findings.

“The median latency from the first COVID-19 symptoms or vaccination to onset of the CN6 palsy was 6 days (IQR: 2.3–16), and the median time from onset to resolution was 30 days (IQR: 14–60).

They pointed out that latency to onset of CN6 palsy was significantly and directly associated with the time to resolution (R2= 0.401, P = 0.010). “Patients who had a positive SARS-CoV-2 antibody test had significantly more 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),” they reported.

In commenting on the finding of longer latency from the onset of systemic symptoms in association with longer recovery times, they hypothesized that this may reflect multiple mechanisms by which COVID-19 (and/or an immune response) causes cranial neuropathies with direct clinical relevance.

Reference:

1. Baldwin GE, Gaier ED, Hennnein LM. Isolated sixth nerve palsy and COVID-19: a recurrent case in a 7-month-old child and analysis of reported cases. J Neuroophthal. 2024;44:301-307; DOI:10.1097/WNO.0000000000001989