Neck Pain and Disability – Part One

The amount of neck pain and disability suffered by patients varies greatly from very low pain levels and virtually no disability to high pain levels which interfere significantly with activities of daily living. The underlying reasons for this are likely to be related to the pathological and neurological mechanisms at work in the differing neck pain syndromes. Initial focus was on identifying pathology in the cervical spine which could be responsible but this approach has not led to a complete understanding. Attention has moved towards the underlying pain mechanisms potentially responsible.

One way to allow more accurate whiplash treatment to be identified is to clarify which diagnosis and which pain syndrome in present in an individual patient’s neck pain problem. Neck injury can consist of long term postural abnormality, repeated small trauma in activity or an obvious event such as whiplash injury. Any inflammation which is present in these cases in known to significantly change the ways pain is processed both in the central nervous system of the brain and the spinal cord and in the locally damaged area. Even though most research has been performed on animals this can be taken seriously when considering pain in humans.

An injury sets off a chain of events in the local area, the spinal cord and in the brain which leads to the central nervous system developing increased sensitivity to all incoming stimuli, making it react more strongly. A reduction both in the pain threshold and the tolerance to pain in the neck has been found in patients with generalised neck pain of unknown origin and in those who have suffered whiplash. This is known as hyperalgesia which is defined as an exaggerated painful response to a normally painful stimulus.

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.

The internal nerve mechanisms of the central nervous system are very likely important in neck pain problems but there is evidence of ongoing pain sources in the shape of damaged neck structures. Investigation of the facet joints of the neck by injection blocks has indicated they are a pain source in some chronic whiplash pain patients. Referred pain is also a typical phenomenon, with pain being perceived away from the site of its generation. This may be because the nervous system interprets pain inputs from bodily structures such as joints and discs as related to other areas linked with the same sensory nerve pathways.

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.

If there is greater pain and it is more widespread then the amount of wider sensitivity to sensory inputs is also increased, which is generally found in whiplash patients and also in sufferers from chronic nerve root pain in the neck. Both these conditions, cervical radiculopathy (where one of the exiting nerve roots from the spinal cord is compromised by for example compression) and whiplash may initiate complicated changes in the processing of pain information within the central nervous system. However, these changes in the central processing may be maintained by some pain inputs from the injured or altered disc, neck muscle, joint or ligament.

Jonathan Blood Smyth is the Superintendent of Physiotherapy 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 Bolton visit his website.

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Filed under back pain by Jonathan Blood Smyth on Dec 29th, 2009.

Neck Pain and Disability – Part One

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