Is It Even Possible to Accurately Measure Physical Pain?

Pain is obviously one of the most important symptoms with which doctors deal, but measuring its severity objectively is difficult. Some people turn a twinge into agony, while others raise not a murmur in the last extremities of torture. And it is universally accepted that a person’s psychological state or disposition has a profound effect on his perception of pain.

Philosophers, indeed, have used the phenomenon of pain to debate what seemed to them an important question, namely whether there were such things as private languages or inner states inaccessible to others.

Clever experiments reported in a recent issue of the New England Journal of Medicine offer the hope, perhaps illusory, that brain imaging techniques might one day distinguish between real and severe pain on the one hand from exaggerated or false pain on the other (people may exaggerate or lie about pain for a variety of reasons).

The experimenters took young adult volunteers and subjected an area of their skin to increasing levels of heat until it became painful, all the while scanning their brains. In another experiment they compared physical pain with social pain: the experimental subjects had recently had a broken relationship and their brain scans when being showed pictures of their late sexual partners were compared with those when subjected to painful warmth on their skins. They also studied the effect of painful stimuli when the patient had been administered a powerful analgesic.

The subjective feeling of physical pain correlated with activity in certain areas of the brain with considerable consistency. This, the authors stated, raises the hope that brain scans might be able to tell doctors when patients who are unable to express themselves for one reason or another are suffering pain, and thus treat their suffering.

The study has its limitations, however. It is an elementary logical error to say that because part x of a person’s brain lights up on a scan when he is suffering pain he must be suffering pain when part x of his brain lights up. This might be so, but it has to be shown to be so. In fact, it is prima facie rather unlikely, given the immense complexity of the brain and its vast numbers of interconnections. Furthermore, one must remember that the experiments were performed in a very simple situation, quite unlike the real-life situations that doctors actually face. Still, one cannot but admire the accumulated human ingenuity that made these experiments possible.

Against is the argument from the slippery slope. Not only might doctors start taking matters into their own hands (in some jurisdictions it seems that they have), but the category of unbearable suffering is an indefinitely expansible one. In non-discriminatory times, why should only the terminally ill have the benefit of physician-assisted suicide?

On the other side is the cruelty of prolonging unavoidable and useless suffering. There are many horrible ways to die and they could be easily avoided. As I approach death – or is it the other way round, as death approaches me? – I pray that mine will not come in the horrible ways I have seen as a doctor. I think, though I cannot be sure, that I would like to choose my moment if one of those horrible ways were mine.

Will brain scans one day help us decide the dilemma? Just pop the applicant for assisted suicide in the scanner and see which parts of his brain light up? If he fails the test he lives; if he passes it he dies. No more ethical agonizing.

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