A new paper in Brain, published by Oxford University Press, indicates that a COVID-19 infection may prompt Guillain-Barr syndrome.

Since early 2020, the COVID-19 pandemic has affected the entire world, either by direct infection or through its social and economic consequences. Besides the well-known severe respiratory signs, and the risk of long-term complications, researchers and public health officials have also reported both central and peripheral neurological complications.

Guillain-Barr syndrome is an autoimmune disorder in which a person's immune system attacks the nerves, causing muscle weakness and occasionally paralysis. The disease can last for weeks or several years. The disease is relatively rare (In the United States 3,000-6,000 people develop the condition every year) but can be severe.

The condition is triggered by an acute bacterial or viral infection. Since the beginning of the pandemic, doctors have reported over 90 Guillain-Barr diagnoses following a possible COVID-19 infection. However, whether COVID-19 is another potential infectious trigger or whether the reported cases are coincidental is unclear.

Using an international collection of Guillain-Barr syndrome patients known as the International GBS Outcome Study (or IGOS), researchers studied patients from January 30^th until May 30^th 2020. Some 49 Guillain-Barr syndrome patients were added to the study during this period from China, Denmark, France, Greece, Italy, the Netherlands, Spain, Switzerland, and the United Kingdom.

In this cohort study, 22% of the Guillain-Barr syndrome patients included during the first 4 months of the pandemic had a preceding COVID-19 infection. These patients were all over 50 years of age and patients frequently (65%) experienced facial palsy (64%) and had a demyelination form of GBS. At hospital admission, 73% of the Guillain-Barr patients with a COVID-19 infection had increased inflammatory markers. All these patients fulfilled the diagnostic criteria for both Guillain-Barr syndrome and COVID-19.

Researchers here emphasized, however, that they did not find more patients diagnosed with Guillain-Barr syndrome during the first four months of the pandemic compared to previous years. This suggests that while a strong association between a COVID-19 infection and Guillain-Barr syndrome is not likely, a COVID-19 infection may sometimes lead patients to develop Guillain-Barr syndrome.

"Our study shows that COVID-19 may precede Guillain-Barr syndrome in rare cases, said Bart C. Jacobs, one of the paper's authors, "but the existence of a true association or causal relation still needs to be established".