Pain Problems in Whiplash Injury
After a neck injury or more general pain problems, disturbances in the feelings experienced from the body (sensory aspects) may occur in the arms and legs although there are no pain symptoms in these areas. Local hyperalgesia may occur in the neck area which is an increased pain response to a normally painful stimulus, so the joints or muscles are much more sensitive to being stretched. This may be due both to local inflammation exciting the nerves in the damaged areas and changes in the reaction of the central nervous system.
But if the sensory reactions are more widespread this may indicate more strongly that the central nervous system is processing these sensory inputs abnormally. A locally increased pain reaction may occur both in patients who have whiplash and general neck pain but more widespread sensory upsets may help tell whiplash from less severe neck problems. People who have suffered whiplash have generally higher levels of disability and pain and demonstrate more widespread pain on clinical examination.
Patients who have nerve root problems in the neck (a form of sciatica like pain in the arm) and those with whiplash associated disorder (WAD) both share abnormal ways of processing sensory information which may mean there is a similar underlying change in pain processing. One other thing that occurs does point to the role of the central nervous system in whiplash and other injuries is the development of allodynia. Allodynia is a technical term in pain descriptions and refers to a person suffering pain in response to a normally non-painful stimulus such as touching, brushing or wearing clothes.
The kinds of abnormality in the way feelings are processed in chronic whiplash patients have been found to be present from just after the time of injury, in other words they develop very quickly after the insult. Everybody who suffers whiplash, no matter how severe or mild it is, develops some increased pain reaction (hyperalgesia) to local mechanical stimuli such as movement. In milder injuries and in those who recover well this settles over two or three months.
People who have higher levels of pain and more long term symptoms have been shown to have persisting hyperalgesia symptoms which may not change from early on after the injury. This can include what is called cold hyperalgesia where cold causes an exaggerated pain reaction and this problem is a negative sign for full recovery from the whiplash injury.
Author: Jonathan Blood-Smyth