Some patients report a numb sensation in their head .
Others have reported blurred vision caused by hypotension behind the eye due to a lack of oxygen and pressure ; these patients have also reported severe head pains , many of which lead to permanent brain damage .
Some patients report a numb sensation in their head , and others have reported blurred vision caused by hypotension behind the eye due to a lack of oxygen and pressure ; these patients have also reported severe head pains , many of which lead to permanent brain damage .