It is estimated that there are up to 30 strokes every minute throughout the world
A stroke can be fatal or disabling, while others are purely temporary with a recovery time of less than 24 hours. Whatever the case, a stroke is always serious and, as well as having physical and mental consequences for the sufferer, it can also have a significant effect on other family members. This book gives the basic information needed to understand what a stroke is, how to spot the risk factors that may contribute to a stroke, and how to take steps to deal with the repercussions, including details on what happens in a stroke, the different types of stroke, stroke recovery and rehabilitation, and medication and aids and equipment for independent living.
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Understanding and Dealing with Stroke
By Keith Souter
Summersdale Publishers LtdCopyright © 2013 Keith Souter
All rights reserved.
Understand the brain
The brain is the most important organ in the body; it controls movement and is the organ which perceives all of the information that is transmitted from the sense organs through touch, vision, hearing, smell and taste. It is also where you perceive pain. You might say that the brain is the essence of the individual, since it is where all of our thought processes and emotions seem to take place; that is, the brain seems to be the seat of the mind. This is a very interesting point, which has been widely debated by philosophers and scientists almost since the beginning of human consciousness. We will come back to this later in the chapter, since it is important in our understanding of the brain.
Basic brain facts
The average adult brain weighs about 3 lb.
The brain has a texture like firm jelly.
The brain is made up about one hundred billion cells.
About a quarter of the blood pumped out by the heart with every heartbeat goes to supply the brain.
The brain uses about 20 per cent of the body's oxygen.
The brain needs a continuous supply of oxygen. A few minutes of oxygen deprivation will lead to irreversible damage.
The brain looks wrinkled and not unlike a walnut. Those wrinkles are called convolutions and they are where you do your thinking.
The nervous system
The nervous system is the body's main communication system. It is customary to consider it as having two parts – the central nervous system, consisting of the brain and spinal cord, and the peripheral nervous system, consisting of the nerves to the various parts of the body.
The nervous system controls every aspect of your bodily function, ranging from the involuntary processes like breathing to the voluntary processes of moving. The brain, of course, is the great computer of the body where all the information from sensory nerves is transmitted and where thoughts and decisions are made, and it is from there that nerve impulses are transmitted down motor nerves to make muscles move.
This next section considers the brain in a little more depth and shows how we have come to build up a picture of the brain. If you simply want to quickly get an idea of the basic structure of the brain then you can skip ahead to The basic brain structures in medicine on page 34. You can of course return later if you want to gain a deeper understanding.
What the ancients thought about the brain
We know that our early ancestors recognised that the head was often the site of illness. In a time when the world and the universe seemed to be under the control of gods, people understandably thought that illness and disease resulted when the gods were angry or when spirits possessed an individual.
Archaeological evidence shows that the practice of trephination, the boring of a hole in the skull, was used in early tribal societies. It was presumably thought that this would let out evil spirits. Examination of many skulls which had been trepanned in this way shows that healing of bone around the site of the boring often took place, indicating that in many cases the operation was a success. Incredibly, they used three distinct methods – cutting, scraping and drilling.
The reason that the procedure could have helped some people with head injuries or certain other conditions was because it would have released pressure upon the brain; a head injury could have caused a rise in pressure, resulting in bleeding inside the skull. Unfortunately, for those people who were not suffering from a rise in pressure, the trephination may have done actual harm.
The ancient Egyptians had developed a quite sophisticated system of medicine and surgery with doctors who specialised in one area of the body. Thus, they had eye doctors, stomach doctors and head surgeons. The Edwin Smith Papyrus, written in about 1500 BC, is essentially an Egyptian textbook of surgery. It describes surgical instruments and techniques and discusses 48 cases of injuries, including head injuries.
A beautiful description of ancient Egyptian surgery is given in the 1945 historical novel The Egyptian by the Finnish writer, Mika Waltari, which became an international bestseller, and later a Hollywood blockbuster in 1954. In the novel, the main character, Sinuhe, who would become the royal physician to Pharaoh Akhenaten, is apprenticed to Ptahor, the 'opener of heads'. Ptahor shows him how to examine a patient and diagnose where there may be a problem in the head from an assessment of the state of consciousness and the use of the limbs. He then shows him how to remove a piece of skull and replace it with a silver plate which is bound with bandages while the patient awaits recovery.
The Greeks abhorred the thought of anatomical dissection, so most of their theories about brain function came through simple observation. The great philosopher and scientist, Aristotle, incorrectly taught that the heart was actually the organ that controlled thought and emotions. He described the way that people with heavy upper bodies were often slow witted, as a result of the drain on their heart.
In about 450 BC, the ancient Greek physician, Hippocrates, known as the father of medicine, described the condition of stroke. He called it apoplexy, which literally meant 'struck down by violence'. This archaic term was used right up until the twentieth century.
The rise of anatomy
In the second century the Greek physician Claudius Galenus of Pergamum (AD 131–201), better known as Galen, performed several dissections on animals and accurately described many of the organs of the body. He described the function of the nerves, and examined the structures of the eyes, ears, larynx and the reproductive organs. He taught that psychic gases and humours flowed through the body into the ventricles of the brain, thereby allowing the development of mental functions.
After that, the Church banned the anatomical dissection of the body and it was not until the sixteenth century that further advances in knowledge about the brain were made. Andreas Vesalius (1514–1564) was a Flemish anatomist who demonstrated that Galen and other early anatomists had been incorrect in some of their conclusions. In 1543, he wrote the first anatomically accurate medical textbook, De Humani Corporis Fabrica (On the Fabric of the Human Body), which was complete with precise illustrations.
One of King Charles II's physicians was Dr Thomas Willis (1621– 1675). He was an anatomist who was deeply interested in the blood supply of the body. He published several books in the 1660s, the most significant being a work about the brain. In it, he described the circle of blood vessels at the base of the brain, which was formed from major arteries travelling up the front of the neck and joining with ones from the back of the neck, to produce an arterial circle which gave off branches to supply blood to the various areas of the brain. This is called the Circle of Willis. We shall look at it in more detail in the next chapter.
Contemporary with Willis was Johan Jacob Wefner (1620–1695), a Swiss physician who discovered that some patients who died from apoplexy had actually had a bleed into the brain. He also concluded that blockage of one of the main blood vessels in the brain could produce apoplexy. In 1658, he published a great treatise, Historiae apoplecticorum, or History of Stroke. It is one of the classic texts on strokes.
The nineteenth century – major advances
The Victorian era saw an explosion in knowledge in all areas of science, medicine included. It was not always a straightforward progression of knowledge, however, as was shown by the development of a pseudo-science called phrenology. This was an idea introduced by an Austrian physician called Franz Gall, who suggested that the brain consisted of a collection of individual faculties, each of which was associated with a different mental function, character quality or emotion. Phrenologists 'read' the lumps and bumps on people's heads in order to read their characters. You can still see phrenological busts and maps of the head with all of these 'faculties' outlined and numbered in a network over the head in various textbooks of psychology. The theory has died out, yet the iconic image lives on.
Yet this misconception that specific functions could be localised was taken up by many doctors and led to further misconceptions about the brain and the mind. Gradually, it became clearer that, while there were some parts of the brain that seemed to have specific roles, by and large the brain worked as a single organ – so that if damage or injury occurred in one part, other parts could eventually take over that function.
There are three major discoveries that we should consider:
The speech centre
In the mid-nineteenth century, the French surgeon and anthropologist Pierre -Paul Broca (1824–1880) discovered that the left hemisphere of the brain was dominant in speech production. He localised this to a very specific area in the frontal lobe of the dominant hemisphere. It was named after him as Broca's area.
Not long after Broca's discovery, Carl Wernicke (1848–1905), a German anatomist and psychiatrist, discovered another area of the brain associated with the way that we understand language and writing. This was also found in the dominant hemisphere, but is towards the back of the temporal area: it is known as Wernicke's area.
The Russian psychiatrist Sergei Korsakoff (1854–1900) studied the effects of alcoholism. He found that in advanced cases patients became paranoid, developed memory problems and could eventually manifest a type of movement disorder or stagger that is called ataxia. From anatomical examination of the brains of people with such problems he found that they had developed a specific nutritional deficiency (later found to be vitamin B1 or thiamine), which caused structural changes in areas of the middle of the brain. He deduced that these areas were associated with the ability to remember. As a result, we now know that the temporal lobes of the brain are associated with memory function.
The parts of the brain
We are now in a position to have a look at the different parts of the brain, in order to see what parts control which aspects of our body functions.
Please note that in this section we are going to discuss the brain in a logical manner from a biological sense, to give you an understanding of how the brain works functionally. Later, in the section on the basic parts of the brain, we consider the parts in a slightly different way, as we do in medicine. This will be helpful in distinguishing how different types of stroke cause different clinical patterns of symptoms.
The evolved brain Human beings are the most evolved creatures on the planet in terms of brain function. Our brains are similar to other primates, all of which are more evolved than other mammals. In turn, all mammalian brains are more evolved than the brains of birds or reptiles.
When we look at the brain in this sense we can see how our brains have evolved, for we have three parts that reflect the advance up the evolutionary tree.
If you scale mammals, birds and reptiles to the same body size, the mammal would have a brain twice as large as a bird and ten times as large as a reptile's. A mammalian brain is twice as large as a bird's brain.
Here we need to look inside the brain, so take a look at Figure 2 which shows a section through the brain from front to back. This shows the three main parts of the brain. They reflect the development of the brain up the evolutionary tree.
This part of the brain is sometimes called the 'reptilian brain', because it is present in reptiles. It evolved hundreds of millions of years ago. It is the part of the brain that takes care of our basic life functions, such as control of our heartbeat, our breathing. It is also our instinctive brain which controls our survival need, our sexual desires and our basic needs.
It consists of:
The spinal cord – which relays information to and from the brain to the rest of the body.
The medulla oblongata – which controls all the autonomic functions. These are the involuntary functions of the body like the heartbeat, breathing and digestion.
The pons – which regulates sleep and controls one's level of consciousness.
The cerebellum – the large structure at the back and the bottom of the brain, which controls movement and balance. It has a right and a left hemisphere.
This part of the brain is present in all mammals and is sometimes called the 'old mammalian brain', or the 'emotional brain'. It evolved about 150 million years ago. This is the part that controls emotions and stores memories. Nowadays we mainly refer to it as the 'limbic system'.
It consists of:
The amygdala – an almond-shaped structure (its name being the Latin for 'almond'), which has a role in storing deep emotional memories. It seems to control fear and is responsible for activating all the unpleasant sensations we experience when frightened, such as palpitations, butterflies in the stomach, sweaty hands and shivers. There is also mounting evidence that it is associated with addictive tendencies.
The hippocampus – which is involved in memory-storing and memory -processing. It is shaped a little like a seahorse, hence its name, which comes from the Greek.
The hypothalamus – is the workhorse of the brain, in terms of regulating many of our internal functions, such as thirst, appetite, internal balance of metabolism, temperature control and circadian rhythms such as the sleep cycle.
The thalamus – which is the great signal box of the brain. It relays information from all of the sense organs to the higher parts of the brain where the information is processed and the experiences of the senses are perceived. It has a large part to play in pain perception as well as being the relay centre for movements.
The forebrain is also called the neocortex, or the neomammalian brain, or the 'rational brain'. It is the last part of the brain to have evolved and is found in other primates as well as in highly intelligent mammals like dolphins.
It makes up two thirds of the whole brain and it is where we think, perceive, create and plan. It is where we organise thoughts to produce language, solve problems, philosophise and experience life.
It is also where we perceive all the information from our sense organs and control our body movements.
There are two halves of the neocortex, called hemispheres. Certain functions of the mind seem to be associated with either the right and left hemispheres of the brain. This has become known as the 'right brain v. left brain' theory of mind. It was based on the work of psycho-biologist Robert Sperry (1913–1994), for which he received a Nobel Prize in 1981.
Sperry's work gave us some very good insight into the brain–mind connection and delineated functions that seem more associated with one hemisphere than the other. It does not mean that they are exclusively associated in that way, for other work indicates that, in many ways, the brain is holographic. This means that all parts of the brain have the potential to operate the mind, so that if there is injury to one part of the organ other parts may be able to take over function. So it is more an order of pre-eminence of associations rather than exclusive association.
Its significance is that some people seem to be more one-sided than the other; in other words, the operation of their brains and minds seems to be biased towards one hemisphere. Thus, we talk about right-hemisphere dominance or left-hemisphere dominance. Once again, it is important to appreciate that this does not mean that only one side works, but that the functions of one side seem to be most to the fore in the way that these people think and live.
The two hemispheres are connected by a part of the brain called the corpus callosum. This is a bridge where nerve pathways pass over from one hemisphere to the other side of the body. This results in the left side of the brain controlling the right side of the body, and the right hemisphere controlling the left side of the body.
Each hemisphere of the neocortex has four lobes, each of which has a different function (see Figures 3(a) and 3(b)).
The frontal lobe – where reasoning, calculation, problem solving and judgement take place. Broca's area is usually in the frontal lobe.
The parietal lobe – where pain and touch are processed.
The temporal lobe – which is mainly concerned with memory, although it is also associated with emotions and speech. Wernicke's area, which controls language recognition, is located in the temporal lobe in the left hemisphere. Sound is also perceived in the temporal lobes.
The occipital lobe – at the back of the brain, is associated with visual perception. This may be the most surprising finding, since one would expect visual perception to occur near to the eyes, but in fact quite complex pathways are involved. We shall consider these when we come to the section on visual problems in Chapter 8, Complications after a stroke.
Excerpted from Understanding and Dealing with Stroke by Keith Souter. Copyright © 2013 Keith Souter. Excerpted by permission of Summersdale Publishers Ltd.
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Table of Contents
Part One: Understanding Stroke,
Chapter 1: Understand the brain,
Chapter 2: What happens in a stroke,
Chapter 3: The different types of stroke,
Chapter 4: Risk factors for having a stroke and how to reduce your risk,
Chapter 5: When a stroke strikes,
PART 2: DEALING WITH STROKE,
Chapter 6: Stroke recovery and rehabilitation,
Chapter 7: Medication,
Chapter 8: Complications after a stroke,
Chapter 9: Aids and equipment for independent living,
Chapter 10: Life after a stroke,
Chapter 11: On becoming a carer,
Chapter 12: Coming to terms with a stroke – using the Life Cycle,