No abstract

In conclusion, the treatment modality described may be a new approach to the treatment of wrinkles.

We have determined the depth and duration of analgesia to needle insertion after topical application of EMLA cream (Eutectic Mixture of Local Analgesics). EMLA was applied for 30, 60, 90 and 120 min and the sensory and pain threshold depths were determined before analgesia (1.0 and 1.9 mm, respectively) and up to 4 h after the cream was removed from the skin. The maximal depth of analgesia (approx. 5 mm) was observed 30 min after a 90-min application and during the 60-min period after a 120-min application of EMLA cream, for both sensory and pain thresholds. For application times shorter than 120 min, the depth of analgesia increased during the period after removal of the cream. This suggests new guidelines for the use of this topical analgesic.

Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) receptor channel blocker known to inhibit "wind-up" and hence central hyperexcitability of dorsal horn neurons. We sought to assess the effect of ketamine on single and repeated nociceptive stimuli. A placebo-controlled, human (12 volunteers) experimental study was conducted in which several psychophysical (pain detection and tolerance thresholds, magnitude ratings) and electrophysiologic (withdrawal reflex) techniques were used 1) to investigate whether a ketamine (0.5 mg/kg) bolus followed by a 20-min infusion (9 micrograms.kg-1.min-1) inhibits central temporal summation to repeated nociceptive electrical stimuli, and 2) to assess quantitatively the hypoalgesic potency using several experimental nociceptive stimuli (argon laser, pressure, electrical). Facilitation of the withdrawal reflex to and pain rating of repeated electrical stimuli (five pulses at 2 Hz) were inhibited by ketamine. Reflex and pain rating to a single stimulus did not change. The pressure pain detection and tolerance thresholds were increased significantly by ketamine, whereas the laser heat pain and tolerance thresholds remained stable compared with placebo. The stimulus response function showed that ketamine reduced the responses to the highest electrical stimulus intensities (1.4, 1.6, and 1.8 times the reflex threshold). We conclude that ketamine inhibits central temporal summation in humans and has a marked hypoalgesic effect on high intensity nociceptive stimuli.