CMAP SCAN analyse after periferal nerve transecti̇on

Objective: Waller degeneration (WD) involves complex physiological changes in the distal axon after nerve transection. The aim of this study was to advance our previous observations with MUNE studies during early stages of WD by using CMAP Scan and MScanFit MUNE studies. Materials and Methods: Twelve patients (7 median, 5 ulnar) with acute nerve transection at the forearm were included in the study. The first electrophysiological studies were performed between 9-72 hours after injury. Investigations were repeated at intervals of 1-2 days until compound muscle action potential (CMAP) amplitudes were reached at zero. CMAP Scan curves are recorded in each session; their quantitative parameters; MUNE and MU sizes were calculated with MScanFit method. Results were grouped according to recording time after injury (before and the after 48 hour, post- injury ). Results: Excitability threshold of axons in the cases with nerve transection were higher than healthy controls and ALS patients, irrespective of the recording time. While CMAP amplitudes decreased steeply (<48 hours: 6.6 ± 4.0mV; > 48 hours: 2.5 ± 2.5mV), MU sizes and MScanFit values (<48 hours: 80 ± 33.4;> 48 hours: 55.1 ± 34.8) showed a more moderate decline. While steps occurred in eight patients, D50 remained unchanged during the follow-up. Discussion: In this study, there were a more clear decrease in MScanFit MUNE values during the progression of WD, as compared to our previous observations with other MUNE methods. This finding suggests that MScanFit MUNE has more ability than other MUNE methods in compensating errors related to functional instability in the neuromuscular junction. Some of the potential mechanisms that might lead to the presence of steps in CMAP Scans identified in the early stage of WD deserve to discuss. Key Words: Wallerian Degeneration, CMAP Scan, MScanFit Mune, peripheral nerve transection