15. Paroxysmal pain is mediated by non-nociceptive large myelinated fibres: A neurophysiological study in normal humans

Abstract

In this neurophysiological study we aimed at verifying whether high frequency, low intensity electrical stimulation, selectively activating non-nociceptive large myelinated fibres, can produce a painful paroxysmal sensation resembling the electrical shock-like pains typically occurring in neuropathic pain conditions. In 10 healthy subjects high frequency (100 Hz), low intensity (2–5 mA) electrical stimuli producing a painful paroxysmal sensation were delivered to the fifth finger. After lidocaine block of the ulnar nerve at the wrist the painful sensation persisted, while pinprick and thermal threshold significantly increased ( P < 0.05, paired t -test). Because tactile sensation remained unchanged we conjecture that the painful sensation is mediated by non-nociceptive large myelinated fibres. This finding supports previous data showing that in patients with different neurological diseases paroxysmal pain is associated to large myelinated fibre dysfunction.