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.
Chronic whiplash sufferers have been found to have the same abnormal mechanisms present in their sensory systems as at the time of the precipitating event. There is some mechanical hyperalgesia to local inputs present in all patients with whiplash injuries, however over 2 to 3 months this will settle down in mild cases. Patients who have more long term neck symptoms or higher pain levels will tend to suffer from ongoing hyperalgesia which may not settle down as in milder cases. Pain thresholds in patients with musculoskeletal pain can also be changed by the levels of psychological distress such as anxiety.
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.
Many of the sensory findings in the neck may not easily translate into ways of managing whiplash by physiotherapy. However, if there is only local hyperalgesia in response to mechanical inputs and no other sensory abnormalities, then the local neck structures may be oversensitive due to the injury to the neck tissues. This kind of local abnormality has been shown to react favourably to physiotherapy or other manual therapies. Exercise may also reduce this type of increased nerve reactions and also improves the ways the muscles coordinate, improving the management of neck pain.
The presence of the allodynia, the overreaction to cold and the wider spread sensitivity to mechanical inputs means that the treatment needs to be approached with much greater care. It is very easy to stir up the symptoms in this condition and this merely increases the abnormal nerve processing. Manual and manipulative techniques must be applied with care and if this is done then there is some expectation that physiotherapy can be of some use in the management of this kind of disorder.
The presence of the neuropathic symptoms such as overreacting to cold inputs means that there are typically much higher levels of disability and pain and the likelihood of physiotherapy being an effective management is uncertain. Medication for these pains is useful for about 30 percent of patients.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapist, back pain, orthopaedic conditions, neck pain, injury management and physiotherapists in Reading. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
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Tags: back pain, injury management, Pain Management, Piriformis Syndrome, Sciatica