fMRI - A more balanced perspective

In November 2012 BBC Panorama showed a research team using functional Magnetic Resonance Imaging (fMRI) to detect hidden awareness amongst patients who may be deemed vegetative by observational assessments. This is something I consequently wrote about here.

The programme claimed 20% of patients in a vegetative state show cognitive responses to fMRI however this isn’t strictly true. In addition, around one in five normal volunteers cannot generate fMRI activity on motor imagery tasks so negative results in patients do not necessarily indicate a lack of awareness.

One thing which wasn’t stressed in the programme was the important difference between patients in a ‘vegetative state’ and those who are ‘minimally conscious’. ‘Patients in a vegetative state have no discernible awareness of self and no cognitive interaction with their environment.’ Whereas patients in a minimally conscious state ‘show evidence of interaction through localising or discriminating behaviours although these interactions occur inconsistently.’

The two patients shown in the programme responding to the fMRI techniques may have been minimally conscious rather than vegetative. The reason for this being that one of the patients was filmed responding to a question from his mother by raising his thumb and the other seemed to turn his head purposefully in response to having his earphones put on.

More than 40% of patients in a minimally conscious state are misdiagnosed initially as being in a vegetative state. Currently in the UK the Wessex Head Injury Matrix (WHIM) and the sensory modality rehabilitation assessment technique (SMART) are used to assess disorders of consciousness.

So again, to finish I ask the same question; In the future will scans such as the one using fMRI be used in addition to observational assessments to decide if someone is in a vegetative state?

The possibility that fMRI might open up potential avenues of interaction with patients with these conditions still exists and the findings are still important however the way in which the tests should be delivered and interpreting the findings still needs to be determined and may not be as significant as originally thought.

Source: Student BMJ