gms | German Medical Science

Objective: The prognosis after severe traumatic brain injury is difficult to determine. The purpose of this study was to examine the prognostic value of a present single parameter in early somatosensory (SSEP) and acoustic (EAEP) evoked potentials in order to predict long-term clinical results.

Methods: This is a retrospective analysis of 100 patients (age 14-85 years, mean age 43,8 years) who suffered from severe traumatic brain injury grade III or IV. On these patients SSEP and EAEP were recorded and the following single parameters examined: Latency and amplitude of N20, latency of N13, central conduction time, amplitude ratio of N20/N13, amplitude difference of N20, amplitudes of peak I-V, absolute latencies of peak I-V, interpeak latencies I-III and III-V and amplitude ratio V/I. The patients were divided into different outcome groups according to the Glasgow outcome scale (GOS) and re-evaluated after 1,3 – 3,9 years (mean 2,65 years) post trauma. Each parameter of the evoked potentials was correlated to the later outcome and the predictive value calculated.

Results: There was no statistical difference between the different mean values of the central conduction time of the N20 (p=0,14). The amplitude ratio of N20 left / N20 right was 1,12 (GOS 1) and 0,98 (GOS 5) with no statistical difference between the different groups (p<0,05). The mean latency of peak V was 6,15 ms (GOS 1) and 5,82 ms (GOS 5). A statistical difference was not evident (p=0,214). The interpeak latency I-V was 4,31 ms (GOS 1) and 4,17 ms (GOS 5) with no statistical difference (p=0,39). The amplitude ratio of peak V/I was 1,57 (GOS 1) and 1,78 (GOS 5). Again, no statistical differences between the single outcome groups could be found (p<0,21).

Conclusions: All examined parameters could not be used alone to predict a long-term clinical result. To achieve this purpose specific combined parameter systems like the Riffel score are necessary.