Cra­nial nerve throm­bo­sis is a rare con­di­tion in which nerve cells be­come oc­clud­ed as a re­sult of a blood clot caused, for ex­am­ple, by el­e­vat­ed blood pres­sure. This dis­ease par­tic­u­lar­ly af­fects younger peo­ple be­tween the ages of 25 and 45. They have typ­i­cal head and neck pain, im­paired vi­sion and speech pro­cess­ing (but not with re­spect to speech pro­duc­tion). In ad­di­tion, there are symp­toms that are sim­i­lar to a stroke, such as spas­mod­ic sig­nal trans­mis­sion to the cor­re­spond­ing or­gans (e.g., there is an in­creased risk of dis­trac­tion, de­creased con­cen­tra­tion, de­creased vi­sion, hear­ing or dex­ter­i­ty in the form of brief paralysis).

Clos­er look at the disease

Blood from the brain is con­duct­ed back to the heart via cere­bral veins and via blood ves­sels (si­nus­es) run­ning in the hard meninges. Like oth­er blood ves­sels, the veins and si­nus­es in the brain can al­so be af­fect­ed by a block­age (throm­bo­sis). When blood can­not drain, it backs up. The in­creased pres­sure in the area in front of the drainage ob­struc­tion caus­es flu­id to leak in­to the brain tis­sue (cere­bral ede­ma), and in­tracra­nial pres­sure in­creas­es. Of­ten, the in­creased pres­sure in the af­fect­ed ves­sels al­so leads to con­ges­tive hemorrhage.

There is al­so a risk of re­duced blood flow (is­chemia) to sec­tions of the brain. This oc­curs when the small­est ar­te­r­i­al ves­sels, the cap­il­lar­ies, are lit­er­al­ly “squeezed” by the in­creased pres­sure in the brain and the blood can no longer flow through them.Depending on the lo­ca­tion of the throm­bo­sis, we can dis­tin­guish be­tween the fol­low­ing forms:

• Si­nus throm­bo­sis (iso­lat­ed oc­clu­sion of one or more blood vessels)
• Cere­bral vein throm­bo­sis (iso­lat­ed oc­clu­sion of one or more cere­bral veins)
• Si­nus vein throm­bo­sis (com­bined throm­bo­sis of veins and sinus)

What might be the risk factors?

In many cas­es, the cause of cere­bral ve­nous and cere­bral si­nus throm­bo­sis can­not be found. Some­times se­vere, spread­ing in­flam­ma­tions from the ear or fa­cial area are be­hind it. More of­ten, how­ev­er, throm­bo­sis is the re­sult of pre­vi­ous­ly un­known in­creased blood clot­ting or dis­eases that cause the blood to clot more than nor­mal. Fe­male sex hor­mones al­so in­crease blood clot­ting. There­fore, preg­nant women and women tak­ing the pill or hor­mone re­place­ment ther­a­py have an in­creased risk of throm­bo­sis, es­pe­cial­ly if they smoke at the same time. In some cas­es, blood dis­or­ders al­so lead to throm­bo­sis in the brain. For ex­am­ple, throm­bo­sis-pro­mot­ing clumps and blood flow dis­tur­bances oc­cur when red blood cells are in­creased, as in poly­cythemia ve­ra, or de­formed, as in sick­le cell anemia.

Can vac­ci­na­tion against Covid-19 ac­tu­al­ly lead to such neu­ronal disease?

No, it is one hun­dred per­cent cer­tain that no vac­cine can cause cra­nial nerve throm­bo­sis or any oth­er neu­ronal dis­ease (in­ci­den­tal­ly, nei­ther can any oth­er drug that is sup­posed to have a neu­ronal ef­fect). How­ev­er, we have not yet been able to rule out one hun­dred per­cent that, in com­bi­na­tion with oth­er risk fac­tors (e.g. drink­ing al­co­hol, reg­u­lar smok­ing or an un­bal­anced di­et), it can stim­u­late neu­ronal de­gen­er­a­tion in the medi­um or long term. In the short term, how­ev­er, it nev­er will be able to — nei­ther As­traZeneca, nor any oth­er vac­cine that has been ap­proved so far by health au­thor­i­ties in the U.S. or the EU, or that is still in the works.