Cervical Pain and Disability – Part One
People with neck pain syndromes may present with a large variability in their disability and pain. Very small amounts of pain and very little disability may be present in some whilst others report the opposite with high disability and pain. The pathologies and the nerve mechanisms which exist in these cases are likely to be different in different neck problems. Investigation of the anatomical explanations for neck pain has been performed but has been unable to satisfactorily explain clinical neck syndromes. Increasingly attention has shifted towards looking at the mechanisms of pain which might be responsible.
The first step towards targeting more specific and accurate e.g. whiplash treatment at someone with neck pain is to understand which neck pain syndrome is dominant in the patient’s presentation. Repetitive minor events, sustained postural stresses or a defined incident such as a whiplash injury may all contribute to trauma suffered by the neck. If inflammatory changes are present due to these factors then this is understood to have profound effects on the way pain is processed in the local area of tissue damage and in the spinal cord and brain, the central nervous system. Animal research work provides most evidence but can be interpreted to understand human pain.
A whole series of chemical and neurological processes are set off by an injury and its following inflammation, all of which makes the central nervous system develop an increased response to all feelings coming in. Patients with whiplash and those with standard neck pain where the diagnosis is not clear have both been shown to have reduced tolerances to pain and a reduced threshold to pain. This reaction is termed hyperalgesia which is used to describe an increased pain response to a stimulus which is normally painful.
Hyperalgesia in the neck occurs in all whiplash injuries to some degree, whatever the severity, but settles over two to three months in those who recover or only have mild symptoms. Hyperalgesia has been found to persist in those with ongoing and more severe pain symptoms. The nerves in the local areas of damage may be sensitised and patients with whiplash have been shown to have damaged structures in cases where pain and disability has continued. Another argument is that the nerves in the central nervous system become sensitised by the pain inputs and this is responsible for ongoing pain.
While neurological mechanisms in the central nervous system may be responsible for some of the pain problems it is important not to forget that damaged neck structures may exist and be sources of pain. The neck facet joints have been shown to be ongoing pain sources in a percentage of patients with chronic whiplash. Referred pain may also occur and this is pain felt in an area away from the presumed region of damage or difficulty. The nervous system may interpret incoming pain from internal structures such as discs and facets as being in areas who share close neurological links with them.
The neck segments from cervical vertebra three upwards can refer head pain whilst those from there down to the first thoracic can give arm pain. There can be an increased pain response on testing in parts of the body where there are no reports of pain symptoms from the patients. Hyperalgesia, an increased response to mechanical inputs, is common to both whiplash patients and those with general neck pain. Whiplash patients however, may exhibit more complicated neurological disturbance with increased reactions to cold, heat and pressure but these results are not well explained.
A more widely occurring sensitivity response to incoming signals is present in patients with higher pain reports and who have more widespread symptoms. These findings are typical of syndromes such as whiplash and cervical nerve root disorder (radiculopathy, where the nerve root which is on its way out of the spinal canal towards the body is compressed or otherwise compromised along its route), both perhaps triggering a complicated change in the excitatory responses of the central nervous system to arriving pain inputs. However, this central mechanism might be kept going and sensitised by pain coming in continually from altered tissues in the neck.
Jonathan Blood Smyth is the Superintendent of Physiotherapists at an NHS hospital in the South-West of the UK. He writes articles about back pain, neck pain, and injury management. If you are looking for physiotherapists in Oxford visit his website.