Getting To A Diagnosis of Back Pain
The diagnosis of lumbar back pain is difficult and uncertain due to the various conditions which can present with this problem. Effective back pain management depends on identifying what kind of back pain problem is present, and many people have suggested that there are many back pain subtypes which need to be identified before treatment can be well targeted. The variations in diagnoses for low back pain and related symptoms include: postural pain; trigger point pains; nerve root compression; neuropathic pain; facet joint pain; disc related pain and lumbar stenosis.
One of the most important distinctions is between mechanical low back pain, secondary to changes which may have occurred in the discs, joints, ligaments or muscles and neuropathic pain. Neuropathic pain is quite different to tissue based pain and is generated by the nervous system itself, usually after injury or damage. Phantom pain, diabetic neuropathic pain, post shingles pain and pain after nerve root damage are all examples of neuropathic pain. Neuropathic pain is particularly unpleasant and difficult to treat. Diagnosing it correctly from all the other pain types is the first step.
Researchers from Addenbrooke's Hospital in Cambridge UK and Massachusetts General Hospital in Boston have investigated the diagnostic difficulty stated above. The pain processes which are occurring in many cases are very complex and this is not reflected in the assessment process of merely investigating the area of pain and its intensity. They attempted to design a tool for assessment which would recognise the complexities, narrow the options for a diagnostic decision and perhaps lead to more appropriate management. A standardised tool was developed to assess chronic back pain so that the underlying pain subtypes could be identified.
The researchers took 130 patients with peripheral neuropathic pain and 57 with standard back pain and tested them in a standardised manner. They gave them an interview which consisted of 16 specific questions and put them through a specific list of 23 physical tests. The researchers provided a list of words which could describe pain and the patients were asked to choose what was most appropriate for them. Sensibility tests of the ability of a person to discriminate light touch, pinprick and vibration stimuli were also included as these can be altered in chronic pain.
Identification was possible of six subgroups of neuropathic pain patients and two subgroups of patients with non-neuropathic pain. The researchers were also able to identify the six questions and ten physical tests which did the best job of making the discrimination between these various types of pain. They then tested the revised diagnosis tool on another group of 137 patients and reported it worked well and patients found it acceptable. They found that a small number of symptoms and signs can distinguish a distinct set of subtypes of neuropathic pain but that these types were not determined by the underlying condition which caused the pain.
The recording of the symptoms was less sensitive in distinguishing the neuropathic nature of the pains than the physical examination. The pain quality was less important than often noted and the pinprick testing more helpful. The researchers tried to link the pain subtypes with specific underlying biological mechanisms, with spontaneous pain of a burning nature linked to spontaneous discharges in heat sensitive pain nerves and pain from brushing related to increased sensitivity of cells in the dorsal horn of the spinal cord.
Patients with neuropathic pain are generally diagnosed as to the causal disease they exhibit, but the researchers did not find a connection between the diseases patients had and the types of neuropathic pain they showed. Several underlying mechanisms of pain production may occur in patients with the same disease and the same pain production can occur in patients across several diagnoses. The types of pain mechanism producing pain in individuals may also vary over time. The tests help to distinguish between nerve root involvement and segmental spinal pain. This can be difficult as nerve root pain can present with minor sensory or motor changes and segmental pain can refer to the limbs.