The Four Ss – Understanding Damage to the Brain

Letter S in glass. Damage to the brain

Image from Pixabay

The four S’s

Size, Site, Source, and Stage.

A way to help understand the outcomes, and level of injury, that might occur after damage to the brain.


 Why bother understanding more about the brain and its function?
  • To better understand the likely outcomes of damage to the brain.
  • A reminder that the brain controls everything we do and therefore anything we do can be affected by damage to the brain.
  • A reminder it is the damage to the brain causing difficulties, not the person.
  • Help you work out ways to overcome, or work around the changes and difficulties that result.

If you know someone is eating excessively because of damage to their limbic system you know that just saying “Don’t eat” is not going to be helpful. You know you will need quite strong strategies to overcome the strong urges being generated.


Four S’s. A Way to Consider How Damage to the Brain Affects the Outcome.

Size – How much of the brain is damaged?

Site – Where in the brain has the damage occurred?

Source – What is the cause of the damage to the brain?

Stage – What age and life stage the person is at?

Baby elephant with mother. Size damage to the brain

Image from


The number of cells affected, and the size of the area damaged, will impact on the type and severity of outcomes.

If a small haemorrhage occurs, the damage may be limited to the functions of those cells immediately surrounding the haemorrhage.

If a stroke affects one whole hemisphere (side) in the brain you would expect more extensive damage on the affected left or right side . You would expect a greater range of outcomes and difficulties than from a small haemorrhage.

The brain is compact, complex yet vast:

“…100 billion cells,each with 1000 to 10,000 synapses, the neocortex makes roughly 100 trillion connections and contains 90 million metres of wiring packed with other tissue into a one-and-a-half- -litre volume in the brain.” Blakeslee. Sandra, The Age 06 01 04

That size again:

100 billion cells that enable our brains to function in a complex, systematic and efficient way.

Each cell works with 10,000 to 20,000 other cells

Cells are the building blocks of the brain and nervous system.


  • If cells are damaged then the part they are responsible for cannot function as it used to.
  • The number of cells damaged will determine the extent of damage and outcomes.
  • The function of cells that link to the damaged cells will also be affected.

Colourful map. Site damage to the brainSite

The part, or parts of the brain that are damaged.

Lobes and major structures of the brain are thought to have specific functions which mean that where the damage occurs will influence the kind of outcomes.

While key functions are allocated to different parts of the brain ALL parts of the brain work closely together and inter-relate. So damage in one part can affect another function elsewhere.

Understanding the functions of each lobe you would then expect a person with damage mainly in the occipital region to have difficulties with aspects of vision. If damage was in the frontal lobe  then you could expect more difficulty with areas such as behaviour, thinking, decisions making.



The source or cause of damage to the brain will impact both the Size and Site and therefore the outcomes of brain injury.

A person who has a deteriorating condition such as dementia or Parkinson’s disease might have a slow onset of brain injury and will have changes with time as the disease progresses.  A person traumatic brain injury will have a sudden onset and then is likely to have a more stable outcome that will hopefully improve with time.

Damage caused by loss of nutrition or oxygen to the brain such as Hypoxia  can cause damage throughout the brain and therefore have significant impact on all areas of a persons life. Whereas damage caused by a blow to the head might affect a more localised area of function that relates to where the person’s head was hit.



The age and stage of life a person is when damage occurs will impact on the outcome.

A child, an adolescent, adult and an older person even with similar size, site and source of brain damage may still have different outcomes.

It was once thought that children recovered from brain injury better than adults, because their brain was still growing. It is now more commonly reported that children do less well because they have not had the time and practice to learn the social behaviours, the rules of life, and how to do things, as well as mature adults.

An adolescent may find it harder to manage the ups and downs of puberty along with a brain injury. In addition outcomes may become more pronounced. Puberty may increase difficulties with behaviour.

The incidence of brain injury tends to change with age with some causes more common depending on the age of the person.

And Finally

To understand more about what happens when damage to the brain occurs, it can be helpful to understand more about the functions of the brain. More information can be found:

In “Your Marvellous Brain Part 1: User Manual”

And ‘Your Marvellous Brain. Part 2: Through Paparazzi Eyes

Also this interactive presentation of the brain gives an overview of brain functions.

More on site and outcomes when we looked at damage to major structures of the brain next week.

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