AS MANY as 40 per cent of patients diagnosed as being in a vegetative state may in fact have some level of awareness. A test designed to discern subtle signs of consciousness could, if used routinely, change the treatment many patients receive.
At worst, such misdiagnoses could influence the decision to allow a patient to die. They may also be depriving patients of measures that make them more comfortable, more likely to recover or allow them to communicate with family.
鈥淲e may have become much too comfortable about our ability to detect consciousness鈥�
Advertisement
In a vegetative state (VS), a person鈥檚 reflexes are intact and they can breathe unaided but there is no awareness. A minimally conscious state (MCS) is a twilight zone, only recently recognised, in which patients may experience physical pain, some emotion and communicate to an extent. However, this state tends to arise only intermittently, so it is hard to discern whether this is a significant feature of a patient鈥檚 existence.
In 2002, at the JFK Johnson Rehabilitation Institute in Edison, New Jersey, and colleagues developed a set of diagnostic . Two years later they released the (CRS-R) to enable clinicians to distinguish between MCS and VS. It is still the only tool for this purpose, and consists of a series of behavioural tests repeated a specific number of times.
To assess whether current diagnoses might be missing MCS, Giacino, together with Caroline Schnakers at the University of Li猫ge in Belgium and colleagues, carried out a two-year study using the CRS-R to 鈥渞e-diagnose鈥� patients in Belgian intensive care units and neurology clinics with VS.
The patients were all diagnosed initially via a 鈥渃linical consensus鈥� of assessments by several specialists. Some used qualitative, 鈥渂edside鈥� observation, others an older quantitative scale designed to measure consciousness. Of the 44 patients they studied, the researchers re-diagnosed 18, or 41 per cent, as being in an MCS, using the CRS-R (BMC Neurology, ). 鈥淲e may have become much too comfortable about our ability to detect consciousness,鈥� says Giacino. 鈥淚 think it鈥檚 appropriate for there to be some level of alarm about this.鈥�
Giacino concedes he can鈥檛 exclude the possibility that the CRS-R is over-diagnosing MCS. But Schnakers argues that CRS-R should be more accurate than other methods because it specifies how many times to repeat tests to avoid missing any brief spells of awareness.
So why do clinicians still use bedside diagnosis? 鈥淭heir focus is more typically on death or survival,鈥� says of the Moss Rehabilitation Research Institute in Philadelphia, Pennsylvania, and on biological factors that need treatment. 鈥淔or their purposes the distinction [between MCS and VS] doesn鈥檛 matter much.鈥�
But for the patient and their family and friends, the difference between MCS and VS can make all the difference.