The Association Between Proinflammatory Cytokines, Microbial Infection and Clinical Manifestation in Sciatica Patients

The clinical manifestation of disc degeneration and/or disc herniation can be low back pain and/or sciatica. The patterns of sensory and motor signs and symptoms that develop after neuropathy vary between individual patients with disc degeneration and/or disc herniation. The expression of these sensory signs (hyperalgesia, allodynia, and sensory loss), which we call the individual somatosensory profile, reflects pathophysiological mechanisms in damaged and surviving afferent nerve fibers such as conduction block, ectopic impulse generation, peripheral sensitization, and central sensitization. In addition, studies have been conducted in search of a microbial origin responsible for the observed inflammatory reaction in discogenic low back pain and sciatica. However, the studies tested mixed cohorts of patients in terms of clinical symptoms (low back pain alone, sciatica, both), length of symptoms (acute and chronic), and tissue cultured (disc, bone). We hypothesize that the possible infectious etiology of the observed inflammatory reaction seen in acute disc herniation and sciatica may be different from that of chronic low back pain due to disc degeneration.

We further suspect that the immununogenicity of an acute disc herniation causing neurological deficit may be different from a similar disc herniation not causing a deficit, and still different from chronic degenerated discs without herniation or neurological deficit. Despite the frequent occurrence of low back pain and sciatica in the general population their underling mechanisms are poorly understood.

Aims and hypotheses of study

(1) To test the differences in disc microbial cultures and in levels of disc and blood cytokines, between patients suffering disc degeneration / herniation and spinal stenosis (controls), and (2) to assess the relationship between clinical manifestations and sensory profiles of these patients and levels of cytokines found in disc tissue and blood.

Ouer hypotheses are: (1) patients suffering from disc degeneration / herniation or spinal stenosis will differ in microbial culture and cytokines levels, with higher levels of positive microbial disc culture and cytokines in the disc herniation group, (2) proinflamtory cytokines levels will correlate with hyperalgesic (rather than hypoalgesic) sensory profiles.