Cerebral venous sinus thrombosis is a cerebrovascular disorder that has an incidence of 1-1.3 cases / 100,000 inhabitants per year.

A toilet holds a dose of AstraZeneca.

The European Medicines Agency (EMA) confirmed this Wednesday that there is a “possible link” between the administration of the AstraZeneca vaccine against Covid-19 and the rare (and very rare) cases of cerebral sinus thrombosis detected in different countries of Europe. According to the opinion of the European body, which has analyzed 86 of these cases among millions of administered doses, the benefits of the drug outweigh the risks. Therefore, its possible occurrence should be listed as a “very rare” side effect of the vaccine.

But what is cerebral venous sinus thrombosis? What symptoms do you usually have this disorder that appears in one of every million vaccinated? A thrombosis, in general, is the appearance of a clot that prevents normal blood circulation. In the case of cerebral venous sinus thrombosis, as explained by the Spanish Society of Neurology (SEN) in an informative note, it is so named because this strange clot appears in the venous system of the brain.

“Cerebral venous sinus thrombosis is a rare cerebrovascular disease that represents less than 0.5% of the total cases of cerebrovascular diseases that occur”, says the SEN, which estimates that the incidence is 1-1.3 cases / 100,000 inhabitants per year.

As the president of the Spanish Society of Thrombosis and Haemostasis Joan Carles Reverter explained to EL ESPAÑOL, most cases of cerebral venous sinus thrombosis associated with the AstraZeneca vaccine have occurred in women under 60 years of age (a fact which could be explained because the two majority populations that have been immunized with this drug are health workers and teachers). However, in his latest opinion, the EMA has not been able to establish specific risk factors.

The main symptoms that appear when this rare disorder occurs resemble those of a stroke. “The most frequent symptom is headache,” explains José Miguel Láinez, president of the Spanish Society of Neurology. “But also, in the vast majority of patients, this headache is accompanied by other symptoms similar to those of a stroke (focal deficits, loss of strength or sustained sensitivity, gait disturbance or language or speech disturbance, confusional episodes, loss of vision…) that helps to differentiate this headache from a conventional headache ”, he adds. “It can also be accompanied by other symptoms such as vomiting, seizures or cervical stiffness.”

From the SEN they point out that the headache of one of these thromboses is very peculiar: it appears suddenly, “it can occur on only one side of the head, it worsens when the patient is lying down or exercising, interrupts the night’s rest and, in addition if it does not respond to the usual treatments for headaches, it progressively worsens ”. According to Láinez, most patients with this disorder have a favorable prognosis, although its evolution will depend on the urgency with which it is treated.

“Only in severe cases where treatment is delayed, it can lead to disability or a fatal outcome. In addition, in recent years, thanks also in part to the fact that most cases of cerebral venous sinus thrombosis reach hospitals through the Stroke Code, the speed in the care of these patients is increasingly rapid and the prognosis of this disease is increasingly favorable ”, concludes the also head of the Neurology service of the Hospital Clínico Universitario de Valencia.