Home / Insight / Utmost severity traumatic brain injury cases: Is the claimant likely to emerge from a permanent vegetative state (PVS)?

Utmost severity traumatic brain injury cases: Is the claimant likely to emerge from a permanent vegetative state (PVS)?


Amongst the most tragic cases we handle are those where claimants are rendered PVS or minimally conscious (MC). As we all know, claimants in a vegetative state can exhibit spontaneous movement, may have an awake/asleep pattern and so on but will have no awareness and no meaningful response to stimuli. In a minimally conscious state the claimant, whilst in a severely reduced state of consciousness, will demonstrate definite, albeit minimal, evidence of awareness. 

Treatment regimes, including whether a claimant should be cared for in an institution or at home in expensive adapted accommodation with home based care,  may depend on the degree of sentience and prognosis in terms of improvement in awareness and life expectancy. However, identifying the difference between the PVS claimant and the MC claimant may be very subtle and depend on careful observation of a claimant’s behaviours, over a long period of time. 

Interestingly, it was reported this week in the Times that research scientists from Cambridge University have found that a  “sniff test” is surprisingly accurate (100%) in the absence of other indicators (so where we would generally have to wait and see) at predicting whether unresponsive patients with the most serious brain injuries are likely to regain at least some level of consciousness  by measuring the volume of air they inhaled through their nostrils when presented variously with pleasant and unpleasant smells.  

The scientists reportedly found that if patients in a vegetative state had a sniff response, they later transitioned to at least a minimally conscious state. In the study, 43 severely brain-injured patients were presented with a jar containing either a pleasant smell of shampoo, an unpleasant smell of rotten fish, or no smell at all for five seconds. Each jar was presented ten times in a random order, and a measurement was made of the volume of air sniffed by the patient. A follow-up three and a half years later found that more than 90 per cent of the patients who had a sniff response shortly after their injury were still alive, while 63 per cent of those who had showed no response had died.

Managing expectations around the prospect of a claimant regaining awareness is often a difficult issue in maximum severity brain injury cases and, whilst the “sniff test” study may be small, any tool that better assists the family and ourselves could be an important development for us in the management and resolution of these claims and is something we may want to explore with our experts in appropriate cases.



Victoria Coleman

Victoria Coleman


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