An orthostatic A symptom is anything of which a patient complains with respect to his or her own body. It may also be obvious to an observer, for example a rash, but it may be entirely subjective, such as a pain somewhere or an emotional feeling. is one that develops when the affected person stands up. They are sometimes but by no means always the result of This clear, water-like fluid forms, for the most part, within the brain, more specifically inside the ventricles of the brain. Blood flows through structures inside the ventricles, called the choroid plexuses, and clear fluid is produced as a result, passing into the ventricle. This process is akin to blood flowing through the kidneys and urine being produced as a result. An important difference is that, unlike urine, the cerebrospinal fluid is not passed out of the body periodically. Instead, the fluid is re-absorbed back into the blood stream, mostly via the arachnoid granulations, into the cerebral venous sinuses. In the course of a 24-hour period, most healthy adults will produce about 500mls (or a pint) of cerebrospinal fluid, although at... leakage from the spine. The commonest cause of such leakage is a A long needle is passed into the lower part of the spine, in order to remove some cerebrospinal fluid. This may be to reduce pressure within the head or to obtain a sample of the fluid for laboratory analysis..