Guillain-Barré syndrome: what it is and what causes it

Guillain-Barré syndrome is an autoimmune disease that causes damage to peripheral nerves, i.e. thosenerves that connect the central nervous system (brain and spinal cord) to the peripheral one, which branches out into the rest of the body.

In short, the immune system mistakenly attacks themyelin sheathsthat line the nerves, resulting in disruption of nerve signals, the development of numbness and muscle weakness. It is not a contagious disease, given itsautoimmune nature. In about14% of cases the syndrome manifestsitself with very mild symptomsthat do not require too urgent treatment, although it is equally recommended to monitor the patient very carefully.

Currently, 6 variants of the syndrome have been classified, the most common of which are:

• Acute inflammatory demyelinating polyradiculoneuropathy: the most common form in the USA and in most cases (about 40%) was found in those who had been infected withCampylobacter jejuni (bacterium responsible for gastroenteritis);
• Acute motor axonal neuropathy: very common in Asia, it occurs especially in pediatric age with respiratory symptoms. The course is generally positive;
• Acute axonal sensory and motor neuropathy: the most severe and extremely rare form in non-adult subjects. Can cause considerablemuscle atrophy;
• Encephalitis of the brainstem of Bickerstaff: the patient manifests a total lack of reflexes, despite this the therapies usually have a good outcome;

The causes of this disease are stillunknown, although in66% of cases it was detected in individuals who had contracted lung or gastrointestinal tract infections.

Among the bacteria that could play a role in triggering the disease are;

• Campylobacter jejuni (in the United Kingdom and the Netherlands at least 25% of cases of Guillain-Barré syndrome are preceded by infection with this bacterium);
• Hepatitis E virus (source)
• HIV I and HIV II (source);
• Influenza A virus (source);
• Salmonella virus;
• Herpesviruses such as Cytomegalovirus and Epstein-Barr Virus (EBV))

It would also seem that those suffering from diseases such as lupus erythematosus or sarcoidosis are also at risk of developing this syndrome.

The annual incidence rate of Guillain-Barré syndrome increases with age (0.6 per 100,000 per year in children and 2.7 per 100,000 per year in older adults 80 years and older), and the disease is slightly more frequent in males than in females ( Source). Those over the age of 50 are most at risk (Source ).

What are the most common symptoms of this disease?

The disease manifests itself with a progressive weakness of The Lower Limbs(more rarely the upper limbs), often also accompanied by pain. Contrary to what one might think, total paralysis of all limbs (paraparesis) occurs only in rare cases, while fatigue of the facial muscles may be more widespread (if the antibodies have attackedthe cranial nerves ).

The progressive progression of the paralysis from the lower limbs upwards (ie ” ascending paralysis “) also causes the following symptoms:

• Speech disorders ( Dysarthria );
• Difficulty swallowing ( Dysphagia );
• Hypotonia (reduction of nervous activity of an organ);
• Hypoesthesia (lack of reaction to stimuli);
• Cardiac arrhythmiasandblood pressure changes changes ;
• Alterations inbody temperature ;
• Breathing disorders ;

The last symptom listed tends to occur in about 25% of ascertained cases and in 30%of cases mechanical ventilation must be provided. Most of those who undergo artificial ventilation (6 out of 10 patients ) have a high probability of experiencing very serious complications such as:

• Pneumonia;
• Pulmonary embolism;
• Thromboembolism;
• Urinary retention;
• gastrointestinal bleeding;
• Permanent paralysis (if the patient is not treated in time).

After  4 weeks , when symptoms have peaked, they remain stable for some time and the nerves gradually heal.

What is the treatment for Guillain-Barré Syndrome?

Since this is a pathology that develops very rapidly, healthcare personnel must immediately implement treatments a few hours after the onset of symptoms. There is still no targeted therapy against the reference syndrome, although two treatments that can benefit healing stand out:

• Plasmapheresis: with this treatment, the antibodies responsible for attacking the myelitic sheath are eliminated. The patient’s blood undergoes plasma removal and subsequent re-infusion of the organism;
• Immunoglobulin injection : This therapy consists of injecting healthy antibodies from donors. These new antibodies do not attack the peripheral nervous system;

Other therapies used to alleviate complications of the syndrome include:

• Monitoring and prevention of venous thrombosis (for example by administering anticoagulants );
• Management of possible intestinal and/or urinary dysfunctions;
• Assistance for artificial respiration;

Guillain-Barré syndrome and vaccinations: a precedent with the flu vaccine

On the CDC website it is reported that in 1976 there was a small increase in the risk of GBS after vaccination against swine flu, a special flu vaccine for a potential pandemic strain of the influenza virus. The National Academy of Medicine, formerly known as the Institute of Medicine, conducted a scientific review of this issue in 2003 and found that people who received the 1976 swine flu vaccine had an increased risk of developing GBS. The increased risk was about one additional case of GBS for every 100,000 people who received the swine flu vaccine. Scientists have several theories as to the cause, but the exact reason for this link remains unknown.

There have been several studies on the risk of GBS after the flu vaccine during each flu season. Data on an association between seasonal influenza vaccine and GBS varied from season to season (see, for example, the meta-analysis evaluating the association between the occurrence of Guillain-Barré syndrome with monovalent influenza vaccine A(H1N1) of 2009 ).

However, studies suggest that a person is more likely to contract Guillain-Barré Syndrome after contracting the flu than after vaccination , still making vaccination preferable in terms of risk / benefit especially for those at risk .

What is the link with viral vector COVID-19 vaccines?

Studies aimed at demonstrating the correlation between vaccination with some viral vector anti-COVIDVaccines (Vaxzevria and Janssen) and the onset of the disease are still ongoing. In the USA, theFood and Drug Administration  had raised a first alarm in mid-July , after 100 individuals subjected to the inoculation of Johnson & Johnson’s Janssen vaccine had manifested this disease (compared to 12.2 million total doses administered).

Only on that occasion was the death of a patient recorded ( the mortality rate was therefore equal to 1%among the affected). On July 22, the EMA included the syndrome as a very rare adverse event in the Johnson & Johnson vaccine leaflet (Source). As regards theAstraZeneca vaccine , on 9 July the EMA recommended the introduction of a warning regarding the possible manifestation of the syndrome, although it was not possible to prove or deny a correlation relationship.

The EMA data updated to June 27 reported 223 confirmed cases of Guillain-Barré syndrome against 54 million doses of Vaxzevria vaccine inoculated.

• The rare cases of Guillain-Barré syndrome have been observed only following vaccination with viral vector vaccines, while no cases following vaccination with mRNA vaccines have been observed .
• Healthcare personnel must continue to monitor the onset of this syndrome, also paying close attention in recognizing the first symptoms of the disease.
• Those who receive the Janssen or Vaxzevria vaccine must be very attentive to the possible symptoms of the reference syndrome and, if suspicious symptoms appear, it is advisable to go to a health facility.
• Pharmacovigilance studies will continue in order to prove or disprove the correlation as rare side effects of these vaccines.
• At the moment, the COVID vaccines in question have even greater health benefits compared to the risks.