Diminished skin vasodilator response to local heating in patients with long-standingsubacute myelo-optico-neuropathy

BackgroundLocal heating of non-glabrous skin increases skin blood flow (SkBF) in two phases: the initial peak (P1) is mediated by sensory axon reflex, and the plateau phase (P2) is thought to be mediated by local production of substances including nitric oxide. We evaluated P1 and P2 responses in subacute myelo-optico-neuropathy (SMON).MethodsSkBF response to local heating from 32 °C (5 min of baseline) to 42 °C (at least for 30 min) of the dorsal surface of the hand skin were measured in 7 SMON patients (67.6 ± 10.0 years) and 7 normal control volunteers (65.0 ± 7.4 years) participated.ResultsMean values of SkBF at P1 (SkBFP1) and SkBF during P2 (SkBFP2) were significantly lower in SMON patients than in controls (p < 0.05, p < 0.05). Mean SkBFP1/SkBF at baseline (SkBFbase) and SkBFP2/SkBFbase ratios were significantly lower in SMON patients than in controls (p < 0.01 and p < 0.05, respectively).ConclusionsThe SkBF response to local heating was diminished in SMON patients. This may reflect the involvement of the spinal cord, peripheral sensory nerves, and sympathetic post-ganglionic nerves in SMON.