Pain reception is transmitted to the brain in a complicated process along nerves and through the spinal chord. But there are different kinds of nerves, which enable different types of pain transmission and different types of pain experience.

The first type of pain receptors are so called A Delta fibers. They measure temperature and pressure. These fibers are myelinated, which means electrically isolated somehow in the way of an electric cable and due to this isolation react very fast. A Delta fibers trigger the pull away reflex that every human being shows when suddenly hurt i.e. by a pinprick. A Delta fibers are responsible for the sensation of first, sudden sharp pain.

The second type of pain receptors is C fibers. They react about ten times slower than A Delta fibers and are not myelinated. This lack of isolation causes signals running along C fibers to give pain information to other cells along its way. C fibers react to all kinds of stimuli – thermal, mechanical and chemical – and create the sensation of slow, dull, deep and lasting pain.

This allows for pain information sent to the brain to be qualified. If we are stung by a bee we immediately react, but if a tooth suddenly revolts, we don’t: we know instinctively from the type and origin of pain that it would not help in this case. So basically there are three types of pain information sent to our brain according to the pain receptors involved:

The first type of pain is called cutaneous pain, “skin pain”. Skin pain comes from the density of fast reacting nerve ends right under the skin. Skin pain is sharp, short, localized and very well defined.

The second type of pain is called somatic pain, “bodily pain”. This pain stems from the relatively lower distribution of nerve receptors deeper inside the human body that are located around tendons, bones, ligaments, blood vessels, tendons and muscles. Somatic pain is dull, slowly increasing, not precisely localized and of longer duration. We feel somatic pain after injuries like sprains or broken bones.

The third type of pain is called visceral pain, “organic pain”. Inside the organs and body cavities nerve ends are very scarcely distributed, and they produce a very slow, deep and lasting pain that in many cases is difficult to localize at all or even located at the wrong place, in a phenomenon that is called referred pain and that is explained by C fibers transmitting pain signals and on their way triggering reactions from other pain receptors that are not actually activated by the original pain signal.

According to the gate control theory these nociceptors do interact with other nerves – so called nonnociceptors – and that pain is “modulated” in the process. This pain modulation is one of the main reasons why different individuals frequently experience the “same” pain differently.

One of the main active nerves in this process are large diameter A beta fibers. A beta fibers obviously have the ability to reduce the signals of the A delta fibers and C fibers while moving towards the brain. Based on this gate control theory it can be explained how certain non-painful physical stimuli on nonnociceptor nerves will reduce pain.

In practice we can see that the theory works when we feel pain and rub the affected area and by this reduce the pain. This very same principle applies to other, more refined types of therapy like massage or acupressure. All these techniques obviously activate nonnociceptor nerves and stimulate them to suppress or inhibit pain information before it reaches the brain.

As a consequence we can finally state: pain is exclusively “produced” in the brain. If the brain for whatever reason “decides” that a certain pain sensation is “unwanted” or “unwarranted” the brain is able to activate the large nonnociceptor nerves in the spine and inhibit pain signals coming up there accordingly.

So this way the gate control theory finally provides us with a model to understand why people from various cultures are able to perceive different kinds of pain in a different way. It also explains in a straightforward medical way why mental techniques like meditation or yoga indeed can help to suppress pain.

In all these cases it seems we have people who either have a different conception of pain, have learnt to control certain brain functions or both. As soon as pain signals set in they can command parts of their brain to produce pain-suppressing signals.

The gate control theory finally even explains why also hypnosis – recently very much in demand for anesthesia – really does work: it activates brain functions that usually are not submitted to an individual’s own will.

We all know that treatment of pain by getting rid of its causes is the best way, but it is not always possible and especially it does not always work fast enough. Half of the patients in US consultation rooms come for the treatment of pain, and no part of pharmacology is better researched than pain treatment.

But we have to differentiate between several forms of pharmacological pain management:

Anesthesia describes the suppression of all kinds of sensations including pain by inducing a state of reduced awareness. If this reduction is complete and pharmacologic we speak of general anesthesia.

Local anesthesia can either be achieved by certain drugs that are locally applied – the classical case being the injections of a dentist – or by acupuncture or hypnosis and even combinations of two or all three of these techniques.

In all cases anesthesia is a procedure of invasive medicine and reserved for the clinical practitioner and thus not a part of our own treatment of regular pain.

This treatment is called analgesia. The body produces its own painkillers with the very same effect. They are called endorphins. These endorphins are emitted to reduce pain after the brain first allowed it to be registered. Unlike under anesthesia, under analgesia consciousness and awareness are not directly altered or affected. The same applies to endorphins. So basically analgesia does nothing else but reinforcing the bodies own endorphin emissions.

There are several fundamentally different types of analgesic drugs though, which we will describe on the following pages.

Their use however is limited by some side effects.

First of all they paralyze the human respiration center. Overdosing can mean death, but individual tolerances for these drugs are extremely variable and therefore the effects of opiates and opiods not well predictable.

Second they are addictive.

Third they invariably induce heavy constipation.

Fourth they frequently cause nausea and vomiting.

Besides opiates and opioids for unknown reasons are not very effective in suppressing several types of pain, i.e. spasms or toothaches.

So these are quite a couple of good reasons why the prescription of opiates and opiods in pain management today is restricted to rather few and rather specific cases.

They are however still the drugs of choice for pain management in advanced cancer cases, palliative medicine and acute trauma.

All the NSAID’s do have very similar effects and properties. They all inhibit certain enzymes that are part of the complicated systems responsible for transmitting pain and inflammation signals.

NSAID’s are effective against almost types of pain. At the same time they lower fever (antipyretic) and in addition at higher doses reduce inflammation, which frequently is part of painful conditions.
Besides they are not narcotic and leave our mental capacities unaffected.

Due to these properties they are permanently in very high demand. The massive consumption of NSAID’s in recent years however has shown that NSAID’s just like other drugs can and do sometimes will have side effects. NSAID’s are not recommended for people with gastrointestinal ulcers and it seems that they also increase the risk of myocardic infarctation.

Low prices, easy availability, high efficiency and the lack of narcotic effects have seduced many people into indiscriminate long term consumption of NSAID’s against hang over, untreated tooth problems and so on, and many of the side effects have been observed due to overdosing or permanent abuse of NSAID’s.

Another very popular painkiller is Paracetamol. It is often mistaken as a NSAID, but it does not belong to this group and its pharmacological mechanism is still debated. It is however widely accepted as a low risk, high effect painkiller. Unlike the NSAID’s it does not influence fever or inflammation, but is a “pure” painkiller.

In many states of the US and many countries in Europe THC was recently established as an alternative painkiller. Clinical studies have proven beyond doubt that THC, the active ingredient in certain hemp species, has a strong painkilling effect. The exact pharmacological mechanisms of THC are still researched, but could be similar to certain antidepressants, which also in some cases have strong painkilling effects.

Classical herbal household remedies like essential oils, cloves and especially capsaicin, the ingredient in cayenne pepper, recently enjoy increased and undebated popularity. They have the great advantage that they can be applied topically (right on the affected area) and have no systematic (on the whole body) effects at all.

A newcomer finally is Kratom , the leaf of South East Asia’s mitragyna speciosa tree. Kratom has been used as a painkiller for centuries in Asia and now slowly gains reputation in western countries as an alternative low risk painkiller. Until now it is not recognized by the FDA but widely available in the Internet trade. Kratom leaves contain up to 25 different alkaloids, some of which are very effective painkillers.

The exact properties of these alkaloids have been intensively researched during the laqst years especially in Japan. There seems to be a chance that a whole new generation of various drugs could be synthesized on the base of this Kratom research.