P 172 Endogenous pain modulation in patients with syringomyelia

Introduction Syringomyelia is a rare disease affecting the spinal cord. Some patients have no symptoms, but often dissociated sensory disturbances and neuropathic pain can be found. Aim of this study was to analyse endogenous pain modulation and stress-induced analgesia in patients with syringomyelia. Method We investigated 19 syringomyelia patients (11 with and 8 without neuropathic pain) in comparison to 15 healthy control subjects. Conditioned pain modulation (CPM) was tested with cold pressure test (CPM). Test stimuli were electrical stimuli with a frequency of 1 Hz, conditioned stimulus was forehead cooling using a cold pack. For comparison stress-induced analgesia was investigated with Stroop-test (color-word-interference test). Result All 3 groups had significant endogenous pain modulation in the cold pressure test, which did not differ between groups. Stress-induced analgesia could be found in all 3 groups as well, without any group differences. Conclusion Despite syringomyelia endogenous pain modulation and stress-induced analgesia were preserved. Therefore syringomyelia is not associated with a lesion of the descending pain-inhibitory pathways, but more likely by direct lesion of the spinothalamic tract.