Decreased cutaneous sensory axon-reflex vasodilatation below the lesion in patients with complete spinal cord injury.
The histamine-induced skin flare response has been considered of practical value in determining the level of a spinal cord lesion, but clinical observations have varied widely with regard to the nature and degree of change below the lesion. We have quantified cutaneous sensory axon-reflex vasodilatation in patients with complete spinal cord injury (SCI) above and below the lesion, and compared the findings with normal subjects. Axon-reflex vasodilatation was induced by intradermal histamine injection, and measured by (a) laser Doppler fluxmetry and (b) tracing the surface area of the flare. Axon-reflex vasodilatation was present in all SCI patients above and below the lesion, but was significantly diminished below the lesion by both measures (pflux rise = 0.0008; pflare = 0.023), and in comparison with controls (by 39%). The flux increase was significantly correlated with the area of flare (r = 0.82; p = 0.02). Axon-reflex vasodilatation and visual analogue scale (VAS) pain scores on histamine injection were not significantly different above the lesion in SCI patients from controls. Baseline laser Doppler flux was not different at any test site in SCI and normal subjects. The cutaneous sensory axon-reflex is thus significantly diminished in SCI patients below the level of the lesion, but the underlying mechanism is unclear. A possible explanation under investigation is that increased basal or reflex sympathetic vasoconstriction mediated via the isolated spinal cord may counteract the vasodilatation produced by the cutaneous sensory terminals.
Kuesgen
B
B
Division of Neuroscience and Psychological Medicine, Imperial College School of Medicine, Hammersmith Hospital, London, UK.
Frankel
H L
HL
Anand
P
P
D000328:Adult; D001369:Axons / Q000502:physiology*; D005260:Female; D006632:Histamine; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009475:Neurons, Afferent / Q000502:physiology*; D010147:Pain Measurement; D012018:Reflex / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply* / Q000294:innervation*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D014664:Vasodilation / Q000502:physiology*
D006632:Histamine