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Discogenic Pain

- Discussion:
    - when the innervated ligamentous layer of the outer annulus fibrosis is stretched because of segmental instability, pain results;
    - acute sprain probably represents partial tearing of annular tissue;
    - if annular tissue becomes weakened to the point of allowing nucleus to protrude beyond the normal confines of the annulus, it may actually
            be a prelude to subsequent episodes of frank disc herniation;
    - if rent develops in annulus becomes complete tear to point of allowing nuclear liquid to escape, it may lead to a frank annular tear;
    - instability or chronic ligament stretch produces discomfort ranging from mild and intermittent to persistent and disabling;
    - mild discomfort compels us all to reduce lumbar lordosis inorder to ease the discomfort;
    - more persistent variety can be recognized by strengthening spine flexors and correcting lordotic postures;
    - pain from ligament stretch is midline & worse w/ lordotic postures;
    - like most other mechanical back pain it is worse w/ bending & lifting;
    - on PE, these pts also lack features identifying other pain syndromes;
    - any diagnositic features to be found are in positive instability sign or a positive wt relief flexion test;

- Instability:
    - instability test is performed with the patient prone w/ arms at sides;
    - examiners thumbs finds interspace and exerts sharp downward pressure seeking a reproduction of pain;
    - several interspaces are tested to find levels that are not painful for comparison;
    - if no interspace is found or if all are painful, the test cannot be performed;
    - if one or two levels are painful, the patient is asked to lift his head, shoulders, and arms and the downward pressure is repeated;
    - if pain is greater when pt is prone & relaxed than when extended with paravertebral muscles tight, the test is positive;
    - test stresses painful annulus in relaxed position, but contracted muscles stabilize segment, reducing stress & pain from pressure;
    - if pain is greater w/ muscles contracted or pain is equal with both maneuvers, the test is negative;
    - wt relief flexion is performed w/ pt supine, hips & knees flexed;
    - examiner places one arm under pts knees and lifts pt's buttocks up from the examination table;
    - if the pain is decreased with this maneuver, the test is positive;
    - x-rays may show a narrowed disc space or a spondylolysis or spondylo-lithesis corresponding with the painful interspace - or interspace may be normal;

- Treatment Considerations:
    - initial treatment is conservtive (as in most forms of low back pain);
    - in the study by Suseki K, et al (1998), the authors used a rat model to demonstrate that sensory information from the
            lumbar disc is conducted through rami communicantes;
            - the authors point out that if the same non segmental pattern is found in man, then simple decompression of the nerve root would not
                    be expected to relieve discogenic pain

Sensory nerve fibres from lumbar intervertebral discs pass through rami communicantes. A possible pathway for discogenic low back pain