Article
The predictive value of combined and single parameter analysis of evoked potentials after head injury
Der prädiktive Wert kombinierter und Einzelparameter-Analyse evozierter Potentiale nach Schädel-Hirn-Trauma
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Authors
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Matthias Hubert Morgalla
- Neurosurgical Department, University of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen
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J. Bauer
- Neurosurgical Department, University of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen
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M. Tatagiba
- Neurosurgical Department, University of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen
| Published: | April 23, 2004 |
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Outline
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Objective
In patients with head injuries sustaining severe brain damage the prediction of later outcome is often very difficult. Somatosensory (SEP) and acoustic evoked potentials (AEP) have proven to have predictive benefit for these patients. The use of evaluation scores for evoked potentials seems to allow prediction. Single parameter analysis however is difficult and rarely used. It was our objective to to correlate the Riffle score with the later outcome after head injury and define the predictive value of SEP and AEP. We also wanted to perform a single parameter analysis of SEP and AEP for outcome prediction.
Methods
A retrospective study was performed on comatose patients after head injury. The inclusion criterias were: head injury °III or worse, post injury follow-up had to be possible and the disability was related to the head injury only. For analysis the first (day 0-3) and last examination before discharge from the intensive care unit were used. We also performed a single parameter analysis of SEP and correlated them with the Glasgow outcome score (GOS). The patients were re-evaluated for late outcome after discharge. Statistical analysis: the prediction of different outcomes was evaluated by the Riffle score. Single parameter analysis was performed by Wilcoxon test. Statistically significant differences were calculated by the Kruskal-Wallis test.
Results
We included 100 patients in the study. The age ranged from 14 - 85 years, the mean age was 43.8 years. The patients were re-examined after 1.3years - 3.9 years. Prediction of death at Riffle score 1: the sensitivity was the highest at the measurement of the AEP (0,8). Only 80% of the patients who died had a Riffle score of 1. Prediction of good outcome at good Riffle score: most patients with good outcome were predicted by a good Riffle score. The differences of the SEP results between the Riffle groups 1,2 and 5 were statistically significant (p=0.001). The highest predictive value was obtained by the combination of SEP and AEP. The difference was significant when the Riffle groups 4 and 5 were compared with group 1 (p=0.001). Single parameter analysis: several models were used without specific statistical differences. Differences of amplitudes of N20 did not have predictive value.
Conclusions
The predictive value of SEP and AEP regarding late outcome can be assessed best by using the Riffle score. Single parameter analysis of SEP or AEP seems difficult and does not allow outcome prediction.
