PERIPHERAL NERVOUS-SYSTEM INVOLVEMENT IN SYSTEMIC-SCLEROSIS - THE MEDIAN NERVE AS TARGET STRUCTURE

Objectives. To investigate the frequency and the main electrophysiolog ical characteristics of the canalicolar passage nerve involvement in p atients with systemic sclerosis (SSc). Methods. Thirty-two SSc patient s were enrolled in the study, classified according to the type (diffus e or limited) and the duration (>/< 5 years) of the disease. Sensory-m otor nerve conduction studies (NCS) of the upper and lower limbs, in p articular at the critical canalicolar points, were conducted by record ing the Compound Muscular Action Potential (CMAP) and the Sensory Acti on Potential (sNAP). The following parameters were evaluated: Motor Ne rve Conduction Velocity (MNCV) and Sensory Nerve Conduction Velocity; distal and proximal latency of the CMAP and the onset and peak latency of the sNAP; peak-peak amplitude and negative-peak area of the CMAP a nd sNAP; and the Terminal Latency Index(TLI) (Terminal Distance/MCNV x Distal latency). Results. Four (12.5%) patients had a distal neuropat hy of the upper limbs (one with monolateral and two with bilateral inv olvement of the median nerve and one bilateral involvement of the ulna r nerve). Fourteen (43.7%) patients showed a decrement of the median n erve TLI and seven (21.8%) of either the median or the ulnar nerve (Ta ble I). Motor and sensitive conduction velocity and latency studies di d not show a statistical difference between SSc patients and controls. The amplitude and area of the CMAP (distal and proximal), sNAP and of the median nerve TLI were significantly decreased in patients with re spect to controls. Conclusion. Distal mononeuropathy of the median ner ve was the most frequent result in our patients. The involvement of th e peripheral nervous system seems to be strictly topographical, follow ing the modifications of the tissues and vascular tone (Raynaud's phen omenon) at the upper acral level. The neurophysiological alterations d etected in our study at the wrist level may not be linked merely to a compressive event but also to microvascular involvement Nerve involvem ent closely connected with the pathogenesis and distribution of SSc sh ould be considered when peripheral nervous system involvement is the i nitial symptom of the disease.