How can it hurt here, yet be coming from somewhere else? The mystery of referred pain!

This is a very common question that I get asked all the time. It is very easy to assume that if you have pain in your foot then you have a problem with your foot but actually you could be wrong.



In this example pain in the foot could actually be referred from multiple regions in the body and it could even be originating from a nerve root compression in your lower back.

It is important to know that your internal organs can also refer pain to other parts of your body, which can be misleading but very important to know. For example shoulder pain can actually be coming from your diaphragm, which is innervated by the left and right phrenic nerves. These nerves come from spinal cord levels C3, C4, and C5 and these spinal levels also supply sensation to the shoulder. So shoulder pain can actually be coming from your diaphragm and the same misleading pain signals can come from other organs too. We wouldn’t get very far treating your shoulder when the pain is actually coming from an internal organ!

Here is an obvious one:  Heart attack, the pain from your heart can radiate into your arm and even your jaw.

Below is a diagram of visceral pain referral:


So how does referred pain occur?

Well truthfully it isn’t fully understood but there are some theories on the subject but all have flaws in their logic:

The Convergent-projection theory:

This theory is very old but makes sense. It was first thought up in the 1800’s, which in itself is pretty amazing. Basically the gist of it is as follows:

Where nerves get lots of high sensory input, which the skin does, and where nerves get minimal sensory input, which the organs do, they converge at the same place in the spinal cord. The central nervous system expects lots of signals from the skin, but not many from the organs. So when an organ is at fault the high input it generates makes the brain assume that the signals must be coming from the skin, as pain from an organ is unusual. So the skin area supplied by the same spinal level as the organ, will be where the brain assumes the pain is coming from. 
You could also use this theory with any internal structure such as cartilage in the knee, intervertebral discs in the spine etc. etc.

Dermatomal rule:

This theory suggests that pain will refer into a structure that originated from the same embryonic segment as the pain provoking structure.

Other theories are:

Axon Reflex theory, Convergence-facilitation theory, Hyperexcitabillity theory and the Thalamic convergence theory.

What types of referred pain are there?

Visceral pain, which originates from your internal organs

Somatic pain, which originates from the other tissues of your body, for example muscle, joint etc.

Neuropathic pain, which originates from the nerves, for example a nerve root compression.

Basically visceral and somatic pain tends to be dull and non-specific and Neuropathic pain tends to be sharp, shooting or burning and it will follow a dermatomal pattern.

What does getting referred pain mean?

If the area of referred pain is larger, then this correlates with a more painful origin problem and often denotes that the pain has been there for longer. This is also shown in chronic pain sufferers who tend to get an awful lot of referred pain. This also has something to do with central sensitisation in chronic pain sufferers. Mostly the pain will be on the same side of the body that the problem is coming from but in neuropathic pain, the pain can refer bilaterally if the origin is in the central nervous system.

Here is a diagram of referred neuropathic pain or dermatomal pain:


Here are two diagrams of pain referred from muscle: 

The infraspinatus muscle:


The Peroneals:



Here is a diagram of pain referred from facet joints in the neck:


So pain in your arm doesn’t mean that there is a problem in your arm, nor does it necessarily mean that you have a ‘trapped nerve’ in your neck it could mean you have an issue with an internal organ. So don’t just assume what it is because you never know where it is truly coming from. As a Physiotherapist I can often find out what the origin is and then sort it out by assessing you thoroughly.

If you need any further information or would like to book an appointment then call Hawkes Physiotherapy on 01782 771861 or 07866195914

WWW.HAWKESPHYSIOTHERAPY.CO.UK


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