After neck injury or generalised pain problems, the disturbances in sensory aspects may occur in the arms and legs even though there are no symptoms in these areas. Local hyperalgesia in the neck, an increased pain response to normally painful stimuli, may be due to the local nerve systems being abnormally sensitised to incoming stimuli. But these more widespread reactions can be indicative of altered processing in the central nervous system. Locally increased pain reactions in the neck can be present in whiplash and general neck pain sufferers but the more widespread sensory upsets may help distinguish whiplash from less severe neck problems.
Whiplash patients have generally higher levels of disability and pain and show more widespread pain on clinical examination. Patients with nerve root problems in the neck and those with whiplash associated disorder (WAD) both share features of sensory abnormality which may indicate that the underlying changes in the processing of pain are similar in both conditions. Another piece of evidence which may back up the role of central systems in these presentations is the occurrence of allodynia. Allodynia is the presence of pain in response to a normally non-painful stimulus such as touching, brushing or wearing clothes.
At the time of the injury the abnormal pain processing mechanisms are set up in the nervous system and the same abnormalities have been shown to be present in patients with chronic whiplash pain. Whatever the severity of the whiplash injury, all sufferers seem to have some degree of pain overreaction to inputs, with this typically settling down in two or three months in less severe cases. Those patients who suffer from chronic neck symptoms and increased levels of pain will also likely have continuing mechanical overreaction which may persist rather than reduce with time. The levels of mental distress also affect pain thresholds.
Psychological distress is commonly present in patients who have whiplash associated disorder and if a patient has higher levels of pain and disability they are also likely to have elevated amounts of mental distress. The increased pain sensitivity that patients exhibit is not thought to be the result of psychological distress but the underlying pain reaction mechanisms in the central nervous system might be responsible for both the hyperalgesia and the psychological distress. Along with these findings, cold hyperalgesia (an increased pain reaction to cold) and abnormalities of circulatory function can occur.
If a peripheral nerve is injured in the body then patients can develop the pain of cold overreaction and as this occurs in whiplash this may imply that some nerve injury is involved in both cases. A lesion of one of the cervical nerve roots can also cause the cold overreaction response and this again could link it to the same symptom presentation in whiplash. An overreaction to cold, cervical burning pain and sudden electric shock are all neuropathic pains, pains caused by abnormal responses in the nervous system, and have been identified in groups of patients with acute whiplash syndrome.
While the findings of sensory abnormalities in the neck are important it is hard to relate them realistically into effective physiotherapy. The local neck anatomy may be overreacting from its injury if there is hyperalgesia only locally to mechanical stimuli and this type of localised problem can be affected by manual therapies such as physiotherapy. Reducing this nerve over reactivity and improving muscle co-ordination and overall neck pain management may also be effected by exercise regimes.
It takes much more careful judgment and planning to treat a patient who has the added symptoms of neuropathic pain, the allodynia, the widespread sensitivity and the cold overreaction. Stirring up the pain and other symptoms in treatment will only reinforce the abnormal neural processing and worsen the pain. Manipulative and manual techniques need to be much more gently applied and there is some evidence that physiotherapy can be useful in the overall management of whiplash disorder.
However if the patients do exhibit neuropathic symptoms such as overreaction to cold stimuli then the therapeutic approach is much less clear, with much higher levels of pain and disability reported. With about 30 percent of patients being helped by drug therapy, the role of physiotherapy in these cases has not been established.
Tags: abnormal pain, central nervous system, neck pain sufferers, nerve root, nerve systems, painful stimuli, painful stimulus, sensory aspects, share features, whiplash injury