Electrophysiological evidence of "nerve entrapment syndromes" and subclinical peripheral neuropathy in progressive systemic sclerosis (scleroderma).

We report the electrophysiological findings and the management of 5 subjects with progressive systemic sclerosis (PSS) and clinical evidence of nerve entrapment. Three had carpal tunnel syndrome (CTS), 1 bilateral CTS and right tarsal tunnel syndrome (TTS) and 1 Guyon's canal syndrome. Only 1 patient (with CTS) showed significant clinical improvement after surgical decompression; the other 4 demonstrated a slight recovery of conduction without lasting clinical relief after conventional treatment. To explain these failures we hypothesized that these entrapment syndromes were the clinical expression of underlying diffuse damage to the peripheral nervous system (PNS). The conduction values of nerves unaffected by entrapment syndromes were within normal limits, but almost all distal velocities were below the mean of controls. Such subclinical distal peripheral neuropathy was also verified in a selected sample of 17 patients with PSS, without clinical symptoms or signs of PNS involvement. In these 17 cases the mean distal sensory and motor conduction findings of the median, ulnar, sural and tibial nerves were significantly lower than those of a control group, while no significant differences were found in the more proximal tracts of the same nerves. Furthermore, 3 of the 17 patients showed classical electrophysiological evidence of TCS and TTS without any clinical symptoms. We conclude that the subjects with PSS had subclinical polyneuropathy which may become plain polyneuropathy or nerve entrapment syndromes perhaps induced by other risk factors.