Hemorrhoids are classified into two general categories: internal and external. Internal hemorrhoids lie far enough inside the rectum that you can't see or feel them. They don't usually hurt because there are few pain-sensing nerves in the rectum. Bleeding may be the only sign that they are there. Sometimes internal hemorrhoids prolapse, or enlarge and protrude outside the anal sphincter.
Cerebrospinal fluid (CSF) collection is a test to look at the fluid that surrounds the brain and spinal cord. CSF acts as a cushion, protecting the brain and spine from injury. The fluid is normally clear. The test is also used to measure pressure in the spinal fluid. See also: CSF culture.
Normal pressure hydrocephalus is a brain disorder in which excess cerebrospinal fluid accumulates in the brain's ventricle, causing thinking and reasoning problems, difficulty walking and loss of bladder control. About.PH is called normal pressure because despite the excess fluid, cerebrospinal fluid pressure as measured during a spinal tap is often normal. As brain ventricles enlarge with the excess cerebrospinal fluid, they can disrupt and damage nearby brain tissue, causing symptoms of NPH.