This article is written by a Registered Nurse with Intensive Care training and describes how brain surgery is possible in some cases without anaesthesia.
We all know that our brains are made up of grey and white cells which are made up of neurons and glial cells. The grey matter is for thinking and the white matter is generally for autonomic processes. The Brain located in the skull, medically referred to as the cranium. The total number of neurons is estimated to be about 100 billion in a healthy adult brain. The glial cells are much more and their function is to support and act as scavengers for the dead neurons.
Tag words: Awake surgery, glial cells, brain, schwann’s cells, microglia, oligodendroglia, astroglia, neurones, myelin, motor neurones, interneurones
GLIAL CELLS constitute 90% of the brain’s cells. Glial cells are “glue cells” which perform the following functions:
- digest dead neurons.
- Manufacture myelin for neurons
- Provide physical support and deliver nutrition.
Examples of glial cells are Microglia, Oligodendroglia, Astroglia and Schwann’s Cells.
During fetal development, a special type of brain cell called Neuroglia guides the neurons.
The brain is made up of many different types of neurons which vary in size from 4 microns (.004 mm) to 100 microns (.1 mm) in diameter. In length these cells can measure from a fraction of an inch to a few feet.
Neurons are not capable of regeneration after damage. The only cells (neurons) which are capable of regeneration are the neurons from the hippocampus.
Special Note: Skin cells and liver cells (if more than one quarter of liver is functional) are the other human cells which are capable of regeneration.
Below is a brief description of the different types of Neurons in the human body. The main function of neurons is to carry electro-chemical nerve signals. The different types of neurons have different structures and are found in different parts of the body. The structures – processes, or axons originating from the cell body.
- Sensory neurons transmit impulses from the body’s sense receptors like the eyes and ears to the CNS. Sensory neurons have 2 processes. Sensory neurons constitute 0.9% of all neurons. Sometimes called bipolar neurons. Examples: retinal cells, olfactory epithelium cells.
- Motoneurons carry signals from the CNS, muscles and body glands. These motoneurons have many processes which originate from the cell body. Motoneurons make up 9% of all neurons. Sometimes called Multipolar neurons Example: spinal motor neurons, pyramidal neurons, and Purkinje cells.
- Interneurons have two processes and form all the neural wiring within the CNS. These have two axons (instead of an axon and a dendrite). One axon communicates with the spinal cord; one with either the skin or muscle. These neurons have two processes. Sometimes called Pseudopolare or Spelling cells. Eg. dorsal root ganglia cells.
Diagram 1: Representation and distribution of nerve pathways.
Our Brains do not have pain receptors! So what? So – Brain surgery can be performed without anaesthesia, when the patient is awake. Read the conclusion.
Conclusion: The brain is a complex organ but is itself not supplied with sensory neurons which are designed to pick up sensation of pain. Since there are no sensory neurons in the brain, it is theoretically possible to do brain surgery without anaesthesia. The meanings and blood vessels are supplied with sensory neurons so they are sensitive to pain. Some intestines in the abdomen are not supplied with sensory neurons and hence some abdominal surgery can also be performed without anaesthesia. The following is a quote from the web site of a major brain surgery unit, “in awake brain surgery. Neuroscientists at ____ developed many of the awake brain surgery procedures that have been adopted by medical centres around the world. This brain surgery team has performed hundreds of awake surgeries, with a high success rate in extending patients’ lives and improving their quality of life.” It is interesting that they do not mention that this is possible because there are no pain receptors in some parts of the brain.