We studied the clinical symptoms in nine children (seven females and two males; mean age 11.6 years) with severe but transient acute secondary erythermalgia. The classical symptoms at presentation were episodic attacks of painful burning hands and feet which felt warm with congested appearance of the feet. Each attack lasted for a mean period of 25 days (range from 6 to 56 days). The blood pressure was elevated in seven patients.
Labetalol, a combined alpha1, beta1, and beta2 adrenoceptor-blocking drug, has been shown to have analgesic properties in vivo. To determine the underlying mechanisms, we examined its effects on GABAA receptor-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) and spontaneous firings of rat ventrolateral periaqueductal gray (PAG) neurons, either mechanically dissociated, or in acute brain slices. These PAG neurons mediate opioid-mediated analgesia and pain transmission and are under tonic control of GABAergic interneurons.