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Keywords:

  • diabetic neuropathy;
  • sensibility;
  • somatosensory cortex;
  • touch thresholds;
  • vibrotactile sense

Diabet. Med. 27, 823–829 (2010)

Abstract

Aims  Impaired sensory function in the sole of the foot in diabetic patients is a substantial problem caused by unknown mechanisms. Hand or foot sensibility can be improved by cutaneous anaesthesia of the forearm or lower leg, respectively, in healthy subjects. Hypothetically, cutaneous anaesthesia induces a silent area in the primary somatosensory cortex, allowing adjacent cortical areas to expand; thus, resulting in enhanced sensory processing. Our aim was to improve sensory function in the foot in Type 1 and Type 2 diabetic patients by application of an anaesthetic cream to the lower leg.

Methods  In a double-blind study, 37 patients with Type 1 or Type 2 diabetes were randomly assigned to cutaneous application of either an anaesthetic cream (EMLA®) or a placebo cream to the skin of the lower leg for 1.5 h. Sensibility at five points of the sole of the foot was assessed before and after 1.5 and 24 h. Vibrotactile sense was also assessed. Primary outcome was change of touch threshold at the first metatarsal head from pretreatment to 1.5 h assessment.

Results  Anaesthetic cream on the lower leg resulted in a significant improvement of touch threshold at the first metatarsal head after 1.5 and 24 h. In addition, improvement of touch thresholds was also observed at the other four assessment sites, together with a decreased vibration threshold at 125 Hz.

Conclusions  The findings of improved touch thresholds open up new possibilities in treatment of sensibility disturbances in the diabetic foot, using a simple and non-invasive method.