Risk, diagnostic error, and the clinical science of consciousness

• Studies suggest the rate of misdiagnosis of the vegetative state/unresponsive wakefulness syndrome is between 30–40%.
• Novel neuroimaging techniques may offer ancillary diagnostic evidence that reduces diagnostic error.
• In some cases, a patient's true condition may be underdetermined by the evidence, which may lead to inconsistent diagnoses.
• If evidence fails to determine a diagnosis, investigators may appeal to the risks of diagnostic error to guide research.
• Future research should make explicit the risks of diagnostic error when comparing or deploying novel neuroimaging methods.

In recent years, a number of new neuroimaging techniques have detected covert awareness in some patients previously thought to be in a vegetative state/unresponsive wakefulness syndrome. This raises worries for patients, families, and physicians, as it indicates that the existing diagnostic error rate in this patient group is higher than assumed. Recent research on a subset of these techniques, called active paradigms, suggests that false positive and false negative findings may result from applying different statistical methods to patient data. Due to the nature of this research, these errors may be unavoidable, and may draw into question the use of active paradigms in the clinical setting. We argue that false positive and false negative findings carry particular moral risks, which may bear on investigators' decisions to use certain methods when independent means for estimating their clinical utility are absent. We review and critically analyze this methodological problem as it relates to both fMRI and EEG active paradigms. We conclude by drawing attention to three common clinical scenarios where the risk of diagnostic error may be most pronounced in this patient group.