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Concussion is the most common form of traumatic brain injury (TBI), affecting around 42 million people worldwide each year. It is the result of a physical blow or sudden jolt that forces the brain to move within the skull. The cerebrospinal fluid that usually protects the brain is not enough to stop it from hitting the skull and causing neuron damage.

Most people will make a quick and complete recovery after concussion. However, neurosurgeons and other brain experts stress that there is no such thing as a minor concussion. The effects can be significant, especially when a person suffers concussion a second time before they have had a chance to recover from the first injury. Contrary to popular belief, you don’t have to lose consciousness (pass out) to have concussion and even mild forms should be taken seriously.


The effects of concussion are:

  • a rapid (usually immediate) but temporary loss of normal brain function
  • a change in mental state or level of consciousness, but not necessarily a loss of consciousness
  • a wide range of signs and symptoms, including headache, confusion, nausea
  • no obvious damage to the physical structure of the brain
  • a gradual improvement of symptoms for most people, and prolonged symptoms for

Immediate signs of concussion to look for include:

  • upper limb muscle rigidity or spontaneous movement
  • loss of overall body tone
  • loss of control of the neck (“rag doll effect”)
  • lack of co-ordination, such as stumbling, or an inability to walk a straight line
  • a fit/seizure
  • balance difficulty
  • slow responses
  • vacant stare or appearing dazed
  • confusion
  • disorientation – not sure of the time and place
  • no memory of events immediately before or after the injury
  • holding the head
  • facial injury
  • inability to speak coherently or slurred

After the initial injury people describe the following symptoms:

  • headache or a feeling of pressure in the head
  • nausea or vomiting
  • confusion or difficulty concentrating
  • memory loss or difficulties
  • poor attention & concentration
  • dizziness or difficulty balancing
  • tiredness and fatigue
  • changes in vision, such as double or blurry vision, or ‘seeing stars’
  • ringing in the ears
  • sensitivity to light
  • loss of smell or taste
  • trouble falling asleep
  • intolerance of bright light & loud noise
  • mood disturbances, including feeling sad, irritable, and frustrated
  • sleep difficulty
  • lethargic, low motivation
  • slow reaction


Because the damage caused by concussion is too small to show up on imaging tests like CT and MRI scans, a doctor will make a diagnosis based on neurological and cognitive examinations. CT or MRI scans can be used to detect bleeding on the brain.