The veins of the brain, both the superficial veins and the deep<unk>  system, empty into the dural<unk>  sinuses, which carry blood back to the jugular vein and thence to the heart. In<unk><unk><unk> , blood clots usually form both in the veins of the brain and the<unk>  sinuses. The<unk>  of the veins themselves causes<unk>  infarction (damage to brain tissue due to a congested and therefore insufficient blood supply). This results in<unk>  edema (both vasogenic and cytotoxic edema), and leads to small petechial haemorrhages that may merge into large haematomas.<unk>  of the sinuses is the main mechanism behind the increase in intracranial pressure due to decreased resorption of cerebrospinal fluid (CSF). The condition does not typically lead to hydrocephalus, however, because there is no difference in pressure between various parts of the brain. Any blood clot forms due to an imbalance between coagulation (the formation of the insoluble blood protein fibrin) and fibrinolysis. The three major mechanisms for such an imbalance are enumerated in Virchow's triad: alterations in normal blood flow, injury to the blood vessel wall, and alterations in the constitution of blood (hypercoagulability). Most cases of<unk>  are due to hypercoagulability. The inflammatory response and prolonged immobilization of patients with COVID-19 may also help explain the formation of<unk> . It is possible for the clot to break off and migrate (embolise) to the lungs, causing a pulmonary embolism. An analysis of earlier case reports concludes that this occurs in about 10% of cases, but has a very poor prognosis. Central<unk> <unk>  usually involve the dural sinuses with or without involvement of the cortical veins; isolated cortical<unk> <unk>  are extremely rare with only about 100 cases reported.
Cerebral venous sinus thrombosis
Subarachnoid hemorrhage
Brain abscess
Cavernous sinus thrombosis
Amoebic brain abscess
Subdural empyema
Arachnoiditis
Pseudosubarachnoid hemorrhage