Although Guillain-Barré syndrome may rarely follow a recent infection with SARS-CoV-2, a strong relationship of GBS with the novel coronavirus is unlikely, say researchers with the International GBS Outcome Study (IGOS) consortium.
“Our study shows that COVID-19 may precede Guillain-Barré syndrome in rare cases, but the existence of a true association or causal relation still needs to be established,” Bart Jacobs, MD, PhD, department of neurology and immunology, Erasmus Medical Center and University Medical Center, both in Rotterdam, the Netherlands, said in a statement.
The study was published online in the journal Brain.
No uptick in pandemic cases
Since the beginning of the pandemic, there are reports of more than 90 GBS diagnoses following a possible COVID-19 infection. However, it remains unclear whether COVID-19 is another potential infectious trigger or whether the reported cases are coincidental.
To investigate further, Dr. Jacobs and the IGOS consortium reviewed 49 patients (median age, 56 years) with GBS who were added to their ongoing prospective observational cohort study between Jan. 30 and May 30, 2020.
The patients came from China, Denmark, France, Greece, Italy, Japan, the Netherlands, Spain, Switzerland, and the United Kingdom.
Of the 49 GBS patients, 8 (16%) had a confirmed and 3 (6%) had a probable SARS-CoV-2 infection; 15 had possible SARS-CoV-2 infection, 21 had no suspicion of SARS-CoV-2 infection, and 2 were “unclassifiable.”
Of the 11 patients with confirmed/probable SARS-CoV-2 infection, 9 had no serological evidence of any other recent preceding infection known to be associated with GBS.
The other two had serological evidence of a recent Campylobacter jejuni infection, which could have played a role in GBS onset, the researchers noted.
Most patients with a confirmed/probable SARS-CoV-2 infection had a sensorimotor GBS variant (73%), although Miller Fisher syndrome–GBS overlap (18%) and an ataxic variant (9%) were also found.
All patients with a confirmed/probable SARS-CoV-2 infection had a severe form of GBS. Common early neurologic features were facial weakness (64%), sensory deficits (82%), and autonomic dysfunction (64%), although not significantly different, compared with the other patients.
All eight patients who underwent nerve conduction study had a demyelinating subtype, which was more frequent than in the other GBS patients (47%; P = .012) as well as historical region and age-matched controls included in the IGOS cohort before the pandemic (52%, P = .016).
The median time from the onset of SARS-CoV-2 infection to neurologic symptoms was 16 days and ranged from 12 to 22 days.
More research needed
The researchers noted that the 22% frequency of a preceding SARS-CoV-2 infection in this study population was “higher than estimates of the contemporaneous background prevalence of SARS-CoV-2, which may be a result of recruitment bias during the pandemic, but could also indicate that GBS may rarely follow a recent SARS-CoV-2 infection.”
Importantly, however, they did not find more patients diagnosed with GBS during the first 4 months of the pandemic, compared with previous years, “suggesting that a strong association between SARS-CoV-2 and GBS is unlikely.”
“Should SARS-CoV-2 indeed be able to trigger GBS, our data are consistent with a postinfectious disease mechanism rather than direct viral invasion,” they noted, adding that the study was not designed to quantify a causative link between GBS and SARS-CoV-2.
“An unbiased multicenter, international, case-control study is needed to determine whether there is an association or not,” they wrote.
The IGOS is financially supported by the GBS-CIDP Foundation International, Gain, Erasmus MC University Medical Center Rotterdam, Glasgow University, CSL Behring, Grifols, Annexon and Hansa Biopharma. Dr. Jacobs received grants from Grifols, CSL-Behring, Annexon, Prinses Beatrix Spierfonds, Hansa Biopharma, and GBS-CIDP Foundation International and is on the global medical advisory board of the GBS CIDP Foundation International.
A version of this article first appeared on Medscape.com.