Understanding pain management
Pain is unique among all sensations in that it is designed by nature to protect the body. Unlike other sensations, it has another unique feature – the ability to influence the mind to produce suffering.
Just imagine 3 scenarios:
A little child fascinated by the wavering flames touches it. But the moment the hand touches the flame the child snatches it back because of the burning pain that sears the hand.
A young man who has never experienced any pain in his life suddenly wakes up in the middle of the night clutching his abdomen. An inflamed appendix is asking for attention through pain.
An extremely fit athlete jumps to kick a football into the goalpost but lands awkwardly on his ankle that twists under him. If it were not for pain from the ankle he would just continue to play and damage his ankle beyond repair. It is pain that prevents him from damaging his body.
Thus, pain is our friend, a vital sensation essential for survival, for protecting us from a continuous series of damages that could harm us irredeemably as we go through life.
All the above instances refer to acute pain, which comes on to protect the body. Acute pain may warn us of an external or internal danger.
However, there is another kind of pain – chronic pain, defined as any pain that has persisted for more than 3-6 months. There are various types of chronic pains – simple pains from ageing like arthritic pains or spondylosis of neck or back etc.; complex pains where the sensation becomes autonomous as it were; a self-sustaining torment that has the potential to rob you of your personality. Some of these complex pains like pain after herpes, or after a stroke or after an amputation can be very severe. When chronic pain has also got severe intensity, it can be devastating.
How does a protective sensation become a rogue rampaging out of control?
To understand this, we have to look into the details of this vital sensation. Pain has dual connotations in the nervous system.
1. Mechanism 1: Imagine that you have to confront a wild animal. You have to run away to escape it whatever the level of pain. This is a survival instinct inbuilt into every living being. The body has 2 mechanisms to allow this. One is the secretion of endorphins (morphine like substances produced in the nervous system), which suppress the pain immediately after an injury. We see this in soldiers who are shot but will continue to fight without feeling any pain but once they have escaped to safety the same bullet wound becomes excruciatingly painful, Also, in burn victims, the initial pain is severe but soon enough they don’t feel any pain till after a few hours. However, in chronic pain there is no immediate imminent threat to get the endorphins flowing. So this inbuilt relief of pain is non functional.
2. Mechanism 2: Imagine that there is a gate in the spinal cord. When there is an injury there are pain impulses that have to go past the spinal cord to reach the pain for one to feel pain. At the spinal cord there is a gate, which is usually kept semi closed. There have to be enough pain impulses to push the gate open. Unless this threshold is reached the gate remains closed and pain is not felt. But when pain becomes chronic, barrages of impulses bombard the gate for long periods of time. This keeps the gate open and later the gate assumes a semi open or wide-open position. So that even a pain impulse that would not be felt will become a severe pain in chronic pain patients. It is like a radio without volume control. The moment it is put on it blares at its loudest.
3. Because pain has a protective role the body has put several failsafe mechanisms in the nervous system. These failsafe mechanisms have the ability to multiply pain so that it will be responded to be mandatory. In fact, in certain types of pains non-painful sensations will be felt as pain.
Since many of the intricacies of chronic pain lie in the nervous system, chronic pain is actually a disease of the nervous system. Unfortunately many of these changes in the nervous system are so subtle that they cannot be picked up by even the most sophisticated investigations available today like the CT, PET or simple MRI scans or any blood tests. However, a new investigation called functional MRI promises to pick up some of these subtle changes in function of nervous system. Brain-imaging studies and research in genetic and molecular biology, for example, suggest that a brain in chronic pain looks and acts differently from a normal brain and that the phenomenon can even run both ways: haywire circuits cause the brain to register persistent pain, which in turn leads to changes — perhaps permanent — in the way the brain and body work.
In addition to all these mechanisms of chronic pain at the body level pain has the ability to influence the mind to produce suffering, depression and anxiety, which can, in their turn, influence the physical pain. So, it can spiral into a vicious cycle of pain, suffering and more pain.
There are several types of chronic pain as enumerated below.
1. Backache (lumbago sciatica, disc problems)
2. Persistent pain after back surgery (failed back surgery, post laminectomy syndrome )
3. Neck pain (spondylosis, repetitive strain injury, post laminectomy syndrome)
4. Shoulder pain (frozen shoulder, tennis elbow)
5. Knee pain (arthritis,, muscular pains around the knee)
6. Heel pain (calcaneal spur)
7. Coccidynia (pain in the tail bone)
8. Sports injuries (after gym exercises, yoga or any unaccustomed activity)
9. Cancer pain (because of cancer itself or after surgery, chemotherapy or radiotherapy)
10. Headache and migraine
11. Neuralgias (trigeminal, occipital etc.)
12. Neuropathic pains
13. Crps1 &2 RSD (reflex sympathetic dystrophy) causalgia
14. Abdominal pain (chronic pancreatitis, after TB or any other cause)
15. Post surgical neuropathic pains
16. Male pelvic pains (interstitial cystitis, chronic prostatitis etc)
17. Female pelvic pains (interstitial cystitis, chronic vulval, vaginal pains dyspareunia (pain during sexual intercourse) etc.
18. Pains persisting after any surgery (hernioplasty, knee replacement and any other surgery)
19. Pains after stroke
20. Pains after amputation of any part of the body.
21. Vascular pains (vascular insufficiency, burgers’ disease)
RSI – repetitive strain injury particularly in people with sedentary work style particularly computer professionals
But, recognizing a disease is but an acknowledgement that it needs to be treated. Modern pain management is pretty good at relieving the acute pain that occurs immediately after surgery or an injury. This is, of course, provided that pain is monitored as other vital signs are monitored.
However, chronic pain is a very different entity to treat. As with acute pain, the prerequisite is recognition. But even after this acknowledgement, chronic pain is tricky to treat probably because of the extensive changes in the nervous system wrought by the chronic nature of pain.
In general, since chronic pain is a complex entity, he treatment also requires many modalities involving many disciplines .
The multidisciplinary treatment has the following guidelines:
1. Recognition of the pain generator.
2. Treatment of the primary condition if any, causing the pain
3. Investigations to detect any deficiencies, particularly those of vitamin B12, D3, calcium, hypothyroidism etc., particularly for RSI patients
4. Medication – often a combination of painkillers, drugs that have actions on the nerves like anticonvulsants antidepressants, muscle relaxants, anesthetic agents (local and general), etc.
5. Physical therapy – electrical modalities, exercises, manipulations, etc.
6. Referral to psychologist, dietician and other specialists as needed.
7. Interventions of various kinds. These can include:
a) Dry needling of muscles, trigger injections or nerve blocks particularly for RSI
b) Nerve blocks – can be a one shot injection into the epidural space or near the nerves carrying the pain as well as the nerves that sympathetically influence pain. The nerves may be blocked as they leave the spinal cord or at more distal areas.
c) In some types of chronic pain a single shot block may not be effective in the long term and may require continuous blocks which are accomplished by placing a special fine catheter near the nerves . This is a highly skilled technique where a special needle incorporating electrical stimulations locates the nerve. Once the needle has located the nerve transmitting the pain a special stimulating catheter is passed through the needle.
d) Radiofrquency ablation: A special insulated needle with a bare tip is placed near a nerve which is located by passing an electric current through the needle. Once the nerve is located the needle tip is heated to 80-90 degrees with a thermocouple control by a custom designed generator. This burns the nerve transmitting the pain so the pain is effectively controlled .
e) Implantation of devices like intrathecal pump for longstanding delivery of powerful pain killer drug like morphine, muscle relaxants like baclofen or midazolam into the water surrounding the spinal cord. The pump placed in the abdominal fat delivers the medicine to the spinal canal through special tubing.
f) Implantation of spinal cord stimulators into the epidural space surrounding the spinal cord. These deliver a micro current to the pain carrying nerves in the spinal cord to replace the pain sensation with a pleasant tingling sensation.
With modern pain management there is no pain that cannot be treated. Every pain has some treatment and nobody needs to suffer unnecessarily. 100% reduction of pain is an unrealistic goal but most pains can be reduced by 50-60% because there are always individual factors that influence the outcome of treatment. The treatment may vary depending on the cause of the pain and from patient to patient.
Text: Dr Lakshmi Vaz, Pain Management Consultant
Image: Flickr Creativecommons Stevendepolo