A minimally invasive operation (“keyhole surgery”) performed upon the brain, through a single hole drilled in the skull. Through this is passed an instrument called an endoscope – sometimes referred to, in lay terms, as a “telescope”. A camera, attached to the endoscope, displays images on a television screen, enabling the operator to see the internal anatomy of this part of the brain. Instruments are passed down the working channels of the endoscope and are then used to burn an internal bypass channel, between one part of the cerebrospinal fluidThis 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... channels and another, thereby by-passing a blockage that has been detected on magnetic resonance imagingA highly sophisticated form of obtaining images (pictures) of the internal structures of the body. Unlike some other forms of imaging, magnetic resonance imaging does not involve the subject being exposed to ionising radiation, which can be harmful if used to excess. Magnetic resonance imaging can reveal not just structures but information about how well or otherwise body parts are functioning. and which is causing hydrocephalusMeaning “water on (or in) the brain”, this word refers to an anatomical state in which there is an abnormally large volume of cerebrospinal fluid within the head. Most often this excess fluid accumulates within the ventricles of the brain and the word ventriculomegaly may be used synonymously. Some authorities teach that the word ventriculomegaly simply describes large ventricles and that the word hydrocephalus should be reserved to indicate that the enlarged ventricles are generating symptoms. Cerebrospinal fluid may also accumulate over the surface of the brain but inside the dura, in which case the term “external hydrocephalus” is sometimes used. Read more.