The Usefulness of Cutaneous Silent Period in Diabetic Polyneuropathy

OBJECTIVE: To evaluate the usefulness of cutaneous silent period(CSP) in assessing the pain sensory function mediated by the Adelta fiber in diabetic polyneuropathy and to define the proper CSP parameter and method. METHOD: We studied 18 diabetic polyneuropathy patients and 20 age-matched healthy subjects. CSPs were recorded in the abductor pollicis brevis muscle and soleus muscle with the surface electrodes and a painful electrical stimulation was given to the mixed nerves(median and tibial nerve) and cutaneous nerve(ulnar and superficial peroneal nerve). Onset latency, end point and duration of CSP were compared between two groups. CSP parameters correlated with the motor and sensory nerve conduction parameters in diabetic polyneuropathy patients. RESULTS: CSP onset latency and end point were significantly delayed in diabetic polyneuropathy patients for both mixed nerve and cutaneous nerve stimulations. There was no difference in CSP duration between two groups. CSP onset latency was shortend and duration was prolonged in mixed nerve stimulation due to an antidromic collision, which showed a cutaneous nerve stimulation as the propor method. There was no correlation between the CSP parameters and motor and sensory nerve conduction parameters. In 3 cases, the CSPs were unable to the evoked despite the sensory nerve action potential was normally evoked. This suggests that the CSP would give an information about the Adelta fiber function than the large myelinated fiber. CONCLUSION: This study indicates that the CSP is a useful supportive electrophysiologic study to assess the Adelta fiber function in diabetic polyneuropathy. The CSP onset latency and cutaneous nerve stimulation are the useful parameter and method for the CSP.

The Changes in Cord Dorsum Potential after Spinal Cord Stimulation / 대한마취과학회지

BACKGROUND: Spinal cord stimulation(SCS) evolved as a direct clinical application of the famous gate-control theory, the idea of activating the central collaterals of large afferent fibers contained in the dorsal column. It is well known that the cord dorsum potential(CDP) evoked by stimulation of dorsal roots or peripheral nerves can be recorded from the cord surface in spinal animals. However, there have been no data about the changes in CDP after SCS. METHODS: Using ball-type electrode, CDP was recorded at the dorsal root entry zone of lumbosacral enlargement in anesthetized cats. The dorsal root was stimulated electrically to activate Adelta-fiber(single pulse of 0.2 ms duration and 1 mA intensity) and C-fiber(single pulse of 0.2 ms duration and 10 mA intensity). Potentials were averaged 10 times and measured before(control) and immediately after, and 10, 20, 30, 40, 50, 60 min after SCS for 20 min. RESULTS: CDP elicited by dorsal root stimulation consisted of the characteristic waves of Adelta-fiber and C-fiber with different time latency. CDP showed significant decrease in the amplitude of C-fiber wave immediately after SCS(75.0+/-8.8%), and 20 min(69.0+/-7.9%), 30 min(75.1+/-4.4%), 40 min(75.4+/-4.4%), 50 min(78.3+/-5.9%), but not 10 min and 60 min, after SCS. However there were no statistically significant decrease in the amplitude of Adelta-fiber wave after SCS. CONCLUSIONS: The above results indicates that SCS suppresses the transmission of nociceptive electrical stimuli via C-fiber, while SCS has little influence on the transmission of electrical nociceptive stimuli via Adelta-fiber.