work, and so on. They then try to piece it all together to form a diagnosis. When a cause is detected, the patient is either sent to a specialist (e.g., a urologist to treat a kidney stone) or treated on the spot (e.g., with antibiotics for a urinary tract infection). In cases of pathological pain, however, test results may show nothing abnormal. Such perplexing cases usually require the intervention of a pain specialist like me.
Beyond inflammatory, nociceptive, and pathological pain, there is the realm of psychological pain. Both physical and psychological pains require a diagnostic workup to get to the underlying cause. There are parallels in the diagnostic processes of a psychologist or psychiatrist: “I see you are anxious and depressed. Can you describe the sensation of your anxiety? Do you know what kinds of situations trigger your depression?”
Anxiety, with or without pain, can be adaptive. For example, if you’re worried about an upcoming test, your anxiety may push you to study. As you firm up your knowledge of the test material, your anxiety should fade. Anxiety can also be maladaptive. If you suffer from an anxiety disorder like agoraphobia, the irrational fear of open spaces, it can prevent you from even holding a job that requires leaving the house. This would require proper psychiatric treatment to regain normal function. (We discuss psychological pain further in Chapter 3.)
Pain is unpleasant; it needs to be. If it weren’t, we’d ignore it. Think about that time the low-fuel indicator came on in your car and you kept driving. (How did you like that walk to the gas station in 90-degree heat?) Pain is painful precisely because it needs to jolt us into action.
***
Let’s return to the garage on that Sunday afternoon when I was moving beer into the fridge. The gash on my leg was starting to throb and burn. I tried unsuccessfully to bandage it; it was bleeding too profusely. It looked like stitches would be necessary, given the size and depth of the laceration. Reluctantly, I told my wife and daughter that I’d be missing the family trip to the neighborhood pool. Instead, I hopped in the car, saw and ignored the low fuel indicator, and drove to the nearest emergency room.
“Insurance card and ID please?”
After filling out the forms, feeling a bit sheepish considering how minor my injury was compared to those I saw around me, I buried myself in an outdated magazine and tried to get comfortable.
Physical pain helps us survive life-threatening situations by activating our fight-or-flight system. When it detects danger, our body releases adrenaline and other chemicals to help us run faster, jump higher, and focus more clearly on the threat at hand—our survival depends on it. So when the smoke detector is going off for no reason, as it does with maladaptive pain, it can’t simply be ignored. Chronic pain gnaws away at you because millions of years of evolution have designed pain to command your attention. This wears you down quickly and adds a component of psychological pain to the picture.
As a pain specialist, I seek to diagnose the root cause of adaptive or maladaptive pain from a constellation of symptoms. I order laboratory tests, perform clinical examinations, and use every other tool at my disposal to confirm or refute a list of possible diagnoses until I’ve narrowed it down to the most likely culprit. While there’s no doubt that pain exists when a patient reports it, I have to keep the subjective experience of the patient in mind as I look for a possible physical source.
When the source of pain is hard to identify, people become desperate. This is natural, but their despair can actually amplify their pain sensation. No matter how unpleasant the pain, it isn’t wise to seek to turn the sensation off entirely. One of my patients, Mark, suffered from severe complex regional pain syndrome (CRPS), a painful condition of sharp, shooting, burning pain in the arms or legs. This syndrome can occur after an injury. The nerves get stuck in a circular feedback loop: The pain produces inflammation, then the inflammation produces more pain. The sympathetic nervous system, which controls a person’s fight-or-flight response, facilitates something we call wind-up. The pain in the affected area worsens and worsens.
To understand this phenomenon, think of the volume control on your stereo. You turn the knob up and the “volume” of the music is increased—and each note is amplified many times higher. In the nervous system, the pain signal is progressively turned up many times higher through wind-up. In a pain circular feedback loop, the nervous system continues to wind up, so the intensity of the pain increases over time.
By the time of his appointment, Mark was experiencing extraordinarily severe pain in his leg.
“Can’t you just cut the leg off?” Mark asked. That question should give you some sense of the desperation chronic pain patients experience.
Mark isn’t my only patient with nerve damage to have asked about surgically removing a limb. I empathize deeply with anyone whose suffering has reached the point where amputation seems like a feasible alternative. Unfortunately, as I tell my patients, severing the limb in question would actually make the pain much worse due to central sensitization, a phenomenon where pain sensation actually increases due to the nervous system’s sensitivity going into overdrive. Think of central sensitization as the end result of wind-up. It is the new set point for your nervous system. Going back to the volume control example, your centrally sensitized nervous system is now where the volume has been turned up on your body’s stereo.
To give you a sense of how bad pathological pain can feel, here’s an excerpt from The Story of Pain by Joanna Bourke, quoting physician Valentine Mott:
I have seen the most heroic and stout-hearted men shed tears like a child, when enduring the agony of neuralgia. As in a powerful engine when the director turns some little key, and the monster is at once aroused, and plunges along the pathway, screaming and breathing forth flames in the majesty of his power, so the hero of a hundred battles, if perchance a filament of nerve is compressed, is seized with spasms, and struggles to escape the unendurable agony.
Mott puts it more poetically than I ever could, but his description resonates with what I’ve witnessed as a pain specialist.
Pain and the Withdrawal Reflex
But pointless suffering is only part of the picture. Pain is essential in helping us process and interpret our environment. It is no understatement to say that pain is vital to life and to our survival as a species.
We have many reflexes that help us adapt and survive, and pain plays a part in many of them. The withdrawal reflex, triggered by pain, drives us to unconsciously pull back from potentially damaging situations. When our eyes dry out or come in contact with dust or a foreign object, the trigeminal nerve detects this discomfort and signals our brain, which in turn tells the facial nerve to tell our eyelid to blink. This blink reflex helps lubricate the eye to keep the cornea from drying out.
You can override the blink reflex, but it’s uncomfortable. Think of your last staring contest, or of the effort of keeping your eyes open during the flash of a family photo. Both of these are examples of how you can modulate the blink reflex by focusing on and inhibiting it. Overriding the blink reflex for too long is not only uncomfortable, but it can also result in damage to your eye. To an extent, the same is true for the adaptive side of pain. We can modulate its actions and severity, but in the end we need it to survive.
Other common reflexes include the cough reflex, which might be triggered when food goes down your windpipe, and the itch reflex, which alerts you to scratch when mosquitoes are making unsanctioned withdrawals from your blood supply. These involuntary actions are common, protective responses that are usually adaptive. While they each have the potential to become maladaptive in certain situations—a chronic cough after a cold, the ceaseless itch of an allergic reaction—we have to keep their protective qualities in mind as we cope with
