Brain Vol. 127 No. 12 © Guarantors of Brain 2004; all rights reserved
Letter to the Editor |
Reply to ‘Skin denervation in type 2 diabetes: correlations with diabetic duration and functional impairments—a comment’
Department of Neurology, National Taiwan University Hospital, Taipei 10002, Taiwan; Department of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei 10018, Taiwan
Sir,
We appreciate the interest of Dr Aprile and colleagues in our work on skin denervation in diabetes (Shun et al., 2004
). There are two important issues in their comments. Dr Aprile and colleagues previously demonstrated double peak sensory action potential probably originating from receptors or nerve terminals (Aprile et al., 2003). They further showed preliminary data of double peak action potential on diabetic patients. In their analysis, sensory thresholds and stimulus intensity needed to obtain double peak potential were different between diabetic patients and control subjects. Hence, Dr Aprile and colleagues drew the conclusion that there was a functional impairment of receptors or nerve endings in the skin of diabetic patients. Although the origin of double peak action potential requires further investigation, the study did suggest the possibility of early changes in functional impairment of sensory nerves in diabetes. A further issue is that nerve terminal changes could potentially be an early event of diabetic neuropathy. Mackel developed the technique of percutaneous microneurography with intradermal stimulation to study cutaneous afferents (Mackel, 1988). There were significant abnormal excitation properties in diabetic nerves compared with normal cutaneous nerves (Mackel, 1989), probably related to disturbances of the recovery process (Mackel and Brink, 2003). All these studies suggested the importance of evaluating nerve terminals in diabetic neuropathy, and the combination of these approaches is necessary to address these issues.
References
Aprile I, Stalberg E, Tonali P, Padua L. Double peak sensory responses at submaximal stimulation. Clin Neurophysiol 2003; 114: 256–62.[CrossRef][Web of Science][Medline]
Aprile I, Stalberg E, Caliandro P, Pazzaglia C, Tonali P, Foshini M, Trotta E, et al. New neurophysiological findings on skin receptors or intradermal nerve endings after repetitive capsaicin application. J Periph Nerv Syst 2004; 9: 109–10.
Mackel R. Conduction of neural impulses in human mechanoreceptive cutaneous afferents. J Physiol 1988; 401: 597–615.
Mackel R. Properties of cutaneous afferents in diabetic neuropathy. Brain 1989; 112: 1359–76.
Mackel R, Brink E. Conduction of neural impulses in diabetic neuropathy. Clin Neurophysiol 2003; 114: 248–55.[CrossRef][Web of Science][Medline]
Shun CT, Chang YC, Wu HP, Hsieh SC, Lin WM, Lin YH, et al. Skin denervation in type 2 diabetes: correlations with diabetic duration and functional impairments. Brain 2004; 127: 1593–605.
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