The brain's pain centre: How we turn sensation into suffering

The pain is always there,” she told me. “Even when I am asleep, I think it waits for me to wake up.” She was 54 and had lived with severe burning pain down her right leg for almost seven years, beginning after an injury and persisting despite surgeries, injections, physiotherapy, medications and enough medical opinions to constitute a small conference.

By the time she came to see me, the original injury had healed. Her scans showed nothing sinister pressing on a nerve. Yet the pain had acquired a life independent of whatever had first caused it. She stopped travelling, meeting friends and sleeping properly. “The worst thing,” she told me, “is not that it hurts. It is that I am always thinking about how much it hurts.” That distinction is one of the most profound things neuroscience has taught us about pain. There is the sensation of pain, and then there is the suffering created by it. Somewhere between the two lies a remarkable strip of brain called the anterior cingulate cortex.

The anterior cingulate cortex, or ACC, curves along the inner surface of the brain, just above the corpus callosum. Its job is difficult to fit into a single sentence. It participates in attention, motivation, decision-making, emotion, empathy and, importantly, the emotional experience of pain. Put your hand on a hot stove and several parts of the brain tell you where the pain is, how intense it is and that withdrawing your hand would be an excellent idea. The cingulate adds something more personal: ‘I really dislike this.’ It helps transform sensation into suffering. Intriguingly, parts of the same network are recruited when we watch someone else suffer. The circuitry that allows us to hurt overlaps with the circuitry that allows us to care. There is something rather beautiful about that. Evolution could have made pain a simple warning light on a dashboard. Instead, it made it emotional.

Philosophers understood this distinction long before neuroscientists put people inside scanners. Buddhist thought has long explored how physical pain can acquire another layer through fear, resistance and anticipation. Modern neuroscience, in its considerably less poetic fashion, has arrived at something similar. The brain does not passively receive pain. It interprets it, remembers yesterday’s pain and anticipates tomorrow’s. It asks whether something terrible has been missed and whether life will always be this way.

Austrian neurologist Viktor Frankl wrote, “When we are no longer able to change a situation, we are challenged to change ourselves.” That is not to suggest chronic pain can simply be thought away. Anyone who has experienced it knows how insulting that idea can be. But it does remind us that suffering is shaped not only by the intensity of a signal, but by what the brain believes that signal means. The nervous system is not merely a telephone cable carrying pain upwards. It is also an editor, historian, critic and, on particularly bad days, an enthusiastic catastrophist.

The extraordinary role of the cingulate became apparent when surgeons began performing cingulotomy in a small number of carefully selected patients with otherwise unbearable, treatment-resistant pain. The aim was not to abolish pain but to interrupt part of its emotional circuitry. What followed was one of the strangest observations in medicine. Some patients could still identify the pain. They knew where it was and could describe its intensity. But it no longer dominated them in quite the same way. The sentiment was essentially: ‘It still hurts, but I don’t mind it as much.’ Think about how astonishing that is. The signal remains, but its tyranny diminishes.

Today chronic pain treatment is broader, combining medication, rehabilitation, psychological strategies, neuromodulation and, only exceptionally, procedures targeting specific circuits. For my patient, a combination of targeted treatment and rehabilitation gradually returned what seven years of suffering had taken away. First she slept. Then she walked farther. Then she travelled. Eventually she went out to dinner without first calculating how quickly she could escape.

Months later, she returned looking different. Not because the pain had disappeared completely. “It’s still there,” she said. For a moment, I felt that familiar disappointment doctors experience when the enemy refuses to surrender. Then she smiled. “But now the pain has me less.” I wrote that sentence down after she left. Perhaps healing is not always the elimination of everything that hurts us. Sometimes it is reclaiming the territory suffering has occupied: a night’s sleep, a walk, a dinner, a holiday, a laugh.

The anterior cingulate reminds us that the brain does not merely experience the world; it helps decide what the world means to us. Pain and suffering live close together, but they are not identical. Somewhere in that small distance lies the possibility of freedom. As she got up to leave, her husband, who had remained admirably silent through our philosophical discussion, finally spoke. “So, doctor, does this mean she won’t complain about pain anymore?” She looked at him and lamented, “You, unfortunately, are chronic.”

The author is consultant neurosurgeon at Wockhardt Hospital, Mumbai.

mazdaturel@gmail.com @mazdaturel