Figure 4.

Recording from the right superficial peroneal nerve of a CRPS II patient (#15, Table 1) with a painful neuropathy, ongoing pain and both heat and mechanical hyperalgesia. Left panel: Initial recording of 5 units, three (a,d,e) had abnormal bursting discharge (arrows); one fiber (b) was as a sympathetic efferent with natural on-going discharge. The fifth fiber (c) behaved as a normal CMH. The fastest conducting unit (0.9 m.s⁻¹, (a)) with the abnormal discharge was a mechano-sensitive nociceptor. The slowest conducting unit (0.63 m.s⁻¹, (e)), classified as a mechano-insensitive nociceptor (based on slowing after “pause”), also engaged in abnormal bursting discharge of two or more action potentials (arrow). The nociceptor with the longest latency (e) and an unidentified unit (d) with pronounced bursting (arrows) were lost. Right panel: Response to the classification protocol (2 Hz electrical stimulation) of the CMH (a), MIA (c) and sympathetic efferent (b).