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Stability of auditory event-related potentials in coma research

An Erratum to this article was published on 17 April 2015


Patients with unresponsive wakefulness syndrome (UWS) or in minimally conscious state (MCS) after brain injury show significant fluctuations in their behavioural abilities over time. As the importance of event-related potentials (ERPs) in the detection of traces of consciousness increases, we investigated the retest reliability of ERPs with repeated tests at four different time points. Twelve healthy controls and 12 inpatients (8 UWS, 4 MCS; 6 traumatic, 6 non-traumatic) were tested twice a day (morning, afternoon) for 2 days with an auditory oddball task. ERPs were recorded with a 256-channel-EEG system, and correlated with behavioural test scores in the Coma Recovery Scale-revised (CRS-R). The number of identifiable P300 responses varied between zero and four in both groups. Reliabilities varied between Krippendorff’s α = 0.43 for within-day comparison, and α = 0.25 for between-day comparison in the patient group. Retest reliability was strong for the CRS-R scores for all comparisons (α = 0.83–0.95). The stability of auditory information processing in patients with disorders of consciousness is the basis for other, even more demanding tasks and cognitive potentials. The relatively low ERP-retest reliability suggests that it is necessary to perform repeated tests, especially when probing for consciousness with ERPs. A single negative ERP test result may be mistaken for proof that a UWS patient truly is unresponsive.

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On behalf of all authors, the corresponding author states that there is no conflict of interest.

Ethical standard

This study has been approved by the ethics committee of the University of Munich and has, therefore, been performed in the accordance with the ethical standards laid down in the 1964 Declaration of Helsinki.

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Correspondence to Barbara Schorr.

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Schorr, B., Schlee, W., Arndt, M. et al. Stability of auditory event-related potentials in coma research. J Neurol 262, 307–315 (2015).

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  • Disorders of consciousness
  • Minimally conscious state
  • Unresponsive wakefulness syndrome
  • P300
  • ERPs
  • EEG