Asubdural hematoma is swelling that occurs underneath the dura mater. this type of swelling would also put direct pressure on the

This type of swelling would also put pressure on the skull and develop the pressure that can cause the brain to malfunction. When it forms, growing blood clots occupies space within the skull and damages the brain tissue. A subdural haematoma is a collection of clotting blood that forms in the subdural space a space between two of the meninges which form the protective lining that covers the brain. It usually occurs because of a head injury and a serious condition that emergency treatment may be needed. A CT scan can show a subdural haematoma and an operation to remove the haematoma.  The brain and the meninges covering it fit tightly within the skull. 

They include lobsters and crabs