Hell-Bent (18 page)

By the twentieth century, specific pain receptors called nociceptors were found. Just as taste buds are specialized to detect a distinct flavor, these receptors fired only in the presence of a distinct type of pain. When activated, they sent electrical energy up the nerve to the brain. Using tiny probes, researchers found that firing a single nociceptor, like a tiny tug on the rope, wouldn’t generate much of a response in the brain. But when hundreds of receptors were fired at once, as in the smashing of a toe, the bell in the brain would start to ring.

Three and a half centuries later, this basic Cartesian description still
dominates how we treat pain. From mothers on the playground to doctors in the ER, if someone runs up to us in pain, we immediately and reflexively search for a source. If we notice a twinge in our thigh when stretching, we scan back in our memories, searching for a moment we might have pulled something. A feeling of pain always results in a search for the injury pulling the bell.

But pain is tricky. And although the dominant Cartesian description may be helpful, it is decidedly inaccurate. This became apparent even in the early days of pain research to those who were watching. Researchers noted a “volunteer effect” in their pain labs, whereby first-time volunteers who were asked to undergo a procedure (like a precise shock to their fingers) reported experiencing a higher level of pain than the subjects who had volunteered many times before. Similarly,
in experiments where subjects were
lucky enough to self-administer pain, they ended up demonstrating a far higher pain tolerance than those where the patient sat passively watching as someone else ratcheted up their dose.

But these observational asides didn’t make much of an imprint. After all, the actual results of the experiments all still supported the Cartesian hypothesis. It wasn’t until scientists stepped out of the laboratory and began studying what the pain response looked like in practice that the metaphorical rope began to fray and its bell began to crack.

Consider, for example, the fifty
-two-year-old machine shop foreman cited by Ronald Melzack and Partick David Wall in their study of pain in a Canadian emergency room. A piece of heavy machinery had collapsed in his shop and landed on his boot, severing the entire front half of his foot. The wound was gruesome; his toes were gone, the remainder of his foot mangled. A Cartesian would expect every nociceptor in the neighborhood to be ringing its corresponding bell at top volume. Yet, when asked by the attending physician whether he would like anesthesia, the foreman demurred, stating he was in no pain. In the words of Wall, the foreman with his mashed foot “was coherent, sad, and thoughtful.” Instead of moaning or complaining, he would softly murmur regrets like “What a fool they will think I am to let this happen” and “There goes my holiday.” The only time pain did come up was when the foreman complained about
a small pain in his
uninjured leg,
which he hoped would go away with a light massage.
¹⁷

What makes the foreman interesting is that his reaction, while certainly unexpected, is not some freakish exception. In fact, Melzack and Wall were conducting research in that ER precisely because of a previous observation indicating that the foreman’s reactions might actually have been normal.

This was the experience of
Dr. Henry Beecher during World War II. Dr. Beecher was manning a care unit one station removed from the front lines. The men he received had devastating injuries—bones shattered by gunshot, limbs torn free from explosions—and with their survival in question, Dr. Beecher’s first instinct was humanitarian: to ask these soldiers if they were suffering pain and determine whether they required anesthesia. During the frenzy of triage, he was surprised by how many men calmly rejected his offer. But when he looked back over his notes, he became astonished. Almost 70 percent of the severely traumatized soldiers had rejected his offer of anesthesia, describing themselves as
feeling only slight pain at the
sight of their massive wounds.

Weirder, Beecher remembered many of these soldiers wincing, yelping, and cringing when he approached them to insert intravenous needles to supply fluids.

The image of a solider with his leg blown off wincing as he was approached with a tiny needle stayed with Beecher after he returned to civilian life. And together with Melzack and Wall, he ushered in a new theory that changed the course of pain research.

The new theory, known as
the gate control theory, proposed pain, as it travels up the rope to the bell, hits a checkpoint (or gate), which acts a bit like a Ma Bell operator in the spinal cord. At this checkpoint, the pain signal is evaluated. Depending on the circumstances, it is allowed to progress upward intact, dialed up (as in an extremely powerful reaction to an unexpected paper cut), dialed down (as in our stoic wartime heroes), or stopped completely. Even more fascinating, when researchers began looking for the
physiological mechanisms behind the gate control theory, it turned out there was a host of signals traveling
down
to the checkpoint from the brain. Meaning the decision to allow a pain to progress upward is active: as if the brain can tell the Ma Bell operator which calls to let through.
Factors such as emotions
, memories, beliefs, mental suggestions are all channeled to the checkpoint, mediating our experience of pain.
Finally and most important
—actually overthrowing the gate control theory itself—researchers discovered there are pains that exist
only
in the brain. Phantoms. Bells that ring without a rope being pulled. Neural routines that misfire.

In this new era, instead of a straightforward transmission—from injury to rope to bell—pain exists on a continuum. On one extreme, there are classic Cartesian pains tied directly to an injury; on the other end, there is the entirely psychogenic pain that lives in the brain, disconnected from any physical injury. And in the vast blurry middle where we spend most of our lives, we have pains mediated by factors in both directions: connected to the flesh but controlled by the brain.

In this context, the pain-aware yoga of Backbending no longer seems an unreasonable method of retraining the mind. Might the repetitive deep spinal bends provide an opportunity to explore pain perception? Might the overwhelming—but voluntary—pain rewire otherwise damaged neural pathways?

It’s not as crazy as you might think.

One of the extremely helpful qualities
of neural networks is that they get stronger the more often they are activated. This efficiency through repetition is one of the reasons a black belt in karate or a concert pianist has such blinding speed where the rest of us experience routine clumsiness: Their motor neurons have practiced the same sequence so many times, the paths have become etched into their brains. Or as the neurological ditty goes: “Neurons that fire together, wire together.”

The same understanding means that the longer the pain pathways relay messages, the more efficient those pathways become. In chronic pain patients, this means greater pain is transmitted quicker and deeper into the spinal cord the longer the pathways are activated.

It also explains why hanging out in a deep backbend, focusing on exploring
and observing those pain pathways, might weaken those connections. In a backbend, the pain is initially intense, but you learn to actively move that focus elsewhere. You start down one pain pathway, but then divert those neurons elsewhere. You pull the rope, watch it travel to the checkpoint, and then practice reconnecting it elsewhere. You take ownership over Ma Bell: from stabbing burn to deep breathing.

Five years after Mary’s desperate self-experiments at home, in 1999, the Physicians Neck & Back Clinic in Minnesota began thinking along similar lines. The clinic conducted a study in which sixty patients whose doctors had recommended back surgery delayed the surgery to first participate in a ten-week program focused on strengthening the key muscles that support the spine.
Of the forty-six members who completed
the study, only three decided to continue with the surgery; the rest were able to significantly reduce their pain. Within the world of rehab, the results were exceptional.

But that was because the Physicians Neck
& Back Clinic in Minnesota was pioneering a new type of rehab. When I talk to Dr. Brian Nelson, founder and medical director of the Physicians Neck & Back Clinic, he speaks of four ways the clinic bucked the conventional wisdom in back pain. Each resonated with a lesson I’d learned from the yoga.

First, they avoided surgery. “We found that 85 percent of the time, we couldn’t determine the exact cause of pain,” Dr. Nelson tells me. “Yes, a CT scan will show areas of abnormality in patients. And lots of doctors will interpret those abnormalities as the cause of the pain. But when you look at the CT scans of patients without injury, people who have no back pain, they will often show identical types of abnormalities.” And because the clinic couldn’t link the pain to a discrete injury, they believed surgery should be a last resort rather than a default option.

Second, they believed in a different kind of rehab. “We believe in an intensive rehab. You need to overload the muscle, work it to failure,” Dr. Nelson explains. “At failure, there are neural muscular channels that get activated, the muscle adapts. The patient will experience soreness and may believe that is damage … but it also promotes healing.” This was a big departure from the prevailing wisdom of the time, which essentially taught patients in pain to take it easy.

Third, to complement the intensity, they believed in precision. “Chronic back pain typically involves the weakening in very specific muscle groups. These can be very difficult to isolate because many other muscle groups protect them.” To target these muscles, very carefully prescribed strengthening exercises were needed. At the Physicians Neck & Back Clinic, these are done using precisely adjusted Nautilus machines rather than precise alignments prescribed by an expert teacher/guru, but both the principle and the muscles involved are strikingly similar. “It turns out that by avoiding those muscles—which often can be quite painful to exercise—the muscles atrophy. You get patients who are extremely good at compensating, but are in actuality making their recovery more difficult,” Dr. Nelson says.

Finally, they accepted that to complete these exercises, patients would experience pain, even deep pain. “One hundred years from now, they are going to laugh at how we understand pain,” Dr. Nelson tells me. “Pain actually changes the pain. The perception, the experience of pain, alters the way the brain reacts to the pain. Patients need to be retrained so that hurt does not equal harm.” In many cases, even if a patient’s back pain originally sprang from a physical cause, the pain signals became lodged in the higher recess of the central nervous system. The Cartesian bell was ringing out of control regardless of rope. In these cases, spinal surgeries devoted to burning nerves or fusing discs were futile. To dislodge the pain, nerve fibers need to be “reeducated.” “We’ve found that trying to live without back pain is exactly the wrong idea. Patients need to see that this pain—precisely delivered to the correct muscles—is a good thing. It changes the way they perceive all pain,” Dr. Nelson tells me. “You can see this effect on an fMRI, by the way. You can see the parts of the brain light up handling the pain, and you can see that explaining the significance of pain shifts the parts of the brain lighting up.”

Listening to Dr. Nelson discuss the chemistry of a vertebral disc produces another lightbulb. “The disc,” he explains, “is living tissue, but it has almost no blood supply.” This lack of blood flow means that getting nutrients and healing agents into it, especially when damaged, can be very difficult for the body. Instead the body relies on relatively huge blood flow to
the vertebral body located directly above and below the disc. Nutrients circulating in the vertebral body diffuse through to the disc itself. When the muscles of the back atrophy, the discs compress down, reducing diffusion even further, making it even more difficult for nutrients to penetrate and for the damaged disc to repair itself.

And what enhances diffusion? The backbend! “Backward bending creates a huge pressure differential,” Dr. Nelson tells me, “which has a corresponding huge positive effect on diffusion. It gives nutrients a chance to slip in there.” Not surprisingly, the deeper the backbend, the larger the pressure differential. I find it impossible not to think of Mary gingerly placing herself into a backbend off the corner of her bed, her body sensing that it was doing something necessary. “In fact,” Dr. Nelson tells me, “backward bending and forward bending are probably the only ways we know of to increase diffusion to the disc.”

And the Rest Is Reefer Madness

Descartes’s interest in the pathways of the body was actually only a side project in a larger obsession. Descartes was intent on solving the problem of dualism. Dualism in Western philosophy asks us to reconcile the idea that man occupies both a spiritual and a physical place on the planet. By tracing the physical pathways of pain, Descartes hoped to find the intersection point where they mediated with the soul. In this way, Descartes was on a very similar quest to that of our sages from the Vedas. Yoga is after all concerned with the yoking between man’s primary dualities: the immediate physical reality of his senses and the expansive immortal reality of the universe.

And although dualism has never been terribly successful in locating a plausible gateway for the soul in the physical body,
¹⁸
thinking about pain provides another, slightly more materialistic way to think about this union. Yoga
can be seen as an attempt to unify the rope and bell. To create a consciousness that is not divided with one part located in the raw material world of our surroundings and one part located in the messy interior world of our brains.

Instead of pain being some exceptional
outlier, the more modern neuroscience probes the workings of the brain, the more it appears all perception operates within the anti-Cartesian principles of pain and the gate control theory:
Our reality is created by the brain as much as it is perceived by the brain.
Vision, our bedrock sense, can be lost to people with perfectly functional eyes, or deconstructed so that patients lose isolated aspects: Men and women who are suddenly without the ability to sense motion, recognize a particular shape, or see texture. Perception of our body parts can be altered, famously in disorders like phantom limb syndrome, where amputees continue to feel sensation from appendages that no longer exist, or more wildly in disorders like Apotemnophilia where people with perfectly functioning limbs suddenly disown them, fail to recognize them as their own, or become filled with an intense desire for amputation. Our most private intense sensations like orgasm can be stimulated without pleasure during seizures, or on the flipside, generated without any physical stimulation, by thought alone. Even belief itself—spirituality—can be elicited in atheists by stimulating specific areas of the left prefrontal cortex. The more we learn, the more it appears our experience of the world is built out of fragments cobbled together like a tile mosaic,
our consciousness only an interpretation
, minimally corresponding to the stimulus external to our brains.