Referred Pain From The Back To The Leg

Pain messages get to the brain along nerves. If there are no nerves to a bit of the body then no pain messages can get to the brain from it.

So what bits of the spine have nerves going to them? I will come to that shortly but first I want you to realise that not all pain which is felt in the back actually comes from the back. It's important to understand the concept of Referred Pain


Referred pain and lower back pain

Sometimes the brain gets confused. Parts of the body can send messages to the brain in such a way that the brain thinks the pain is in the lower back. This often happens in the area of the back we call the thoracic area - in other words the bit behind our ribcage. It can also occur in the lower back or the neck but this is less common.

This kind of pain is called referred pain and disease in the heart, the lungs, the kidneys or the stomach and gullet can all cause it. Some infections or blood cell diseases can cause it too. This is one reason why you might want to see your doctor before going to another type of therapist. Many well trained chiropractors, osteopaths, physiotherapists and others have some knowledge of diseases in the inner parts of the body but if you are at all worried then it is best to speak to a doctor first.



So - Which parts of the spine can hurt?
Almost all of the component bits of the spine have a nerve supply. They get it from two different kinds of nerve fibre. One is called the peripheral nervous system and the other is called the autonomic system. Don't worry about what these names mean. The main reason to mention them is that they produce different effects in the brain when a bit of the spine sends a message along them.

Messages along the peripheral nerves get translated by the brain as pain. Those signals which come up the autonomic fibres are felt by the brain in different ways - some of them quite bizarre. For example I have known people feel creepy-crawly sensations in the skin or funny feelings of heat or cold when these nerves are activated. One man I remember described a sensation like running water down his legs. All quite strange.

People sometimes think they are going a bit mad when this happens to them. Sadly, their doctors sometimes think this too. If you have had sensations like this along with lower back pain then don't despair. They often vanish away after simple manipulation type treatment. Medicines are rarely needed. In very troublesome and persistent cases then injections can be given to switch off these nerve pathways. New medications such as Gabapentin can also help with this type of pain.

Many bits of the spinal sandwich have nerves going to them. The discs, the joints, the ligaments and muscles are all places where pain signals can arise. Although it may seem strange, even the nerves have nerves of their own. Each nerve as it comes out of the back bone is covered in a thin sleeve of stuff called dura. This dural sleeve is full of little nerve endings. It is very sensitive to being irritated by chemicals or to being squeezed by things around it.

The type of low back pain you have, where it is and where it goes to can give clues to which bit of the spine is unhappy. As you now know, other bits of the body can send or 'refer' pain to the spine. Well the same is true in reverse. The spine can refer pain to other bits of the body - often to the arms in the case of the neck or to the legs when it is the lower back which is irritated. This knowledge helps us work out which bit of the spine is causing your pain. It's not foolproof because the nerve pathways are very complicated but it does help in planning the best treatment.

We know for example that if the spinal cord is inflamed then pain is not usually the problem. It is more likely that pins and needles or numbness in the arms or legs will occur. Often in both legs at the same time. Sometimes the legs or arms feel restless. Occasionally the muscles can be weak. This can make the limb feel heavy or as if it is not working properly.




Pain From Nerves

Inflamed nerves behave in a very typical way. If something irritates the dura sleeve of a nerve in the low back then the person usually feels the pain more in their leg than in the lower back. Usually only one leg will be painful and the pain is typically sharp and shooting in nature. If nerve pain is felt in both legs then something serious could be going on in the back and this would be a reason to see a specialist urgently.

Pain from nerves runs like a hot needle shooting down the leg. It goes along a narrow band of skin and often has pins and needles or numbness along with it. A cough or a sneeze will make the leg pain worse.

If the nerve is very inflamed then the muscles which that nerve goes to may become weaker or softer than normal and the kind of reflex that a doctor checks by hitting your knee or ankle with his little hammer may be harder to produce. 


Some people like to call this kind of pain sciatica but I don't like the term. In the dictionary sciatica simply means pain in the leg caused by something wrong in the back - but not all such pain is caused by irritated nerves. Inflamed joints and ligaments can also cause leg pain which is nothing to do with nerve irritation. Terms like lumbago and sciatica are more confusing than helpful and I always try to avoid using them. Nerve pain or neurogenic pain is a more helpful term for this kind of lower back and leg pain


REFERRED PAIN FROM JOINTS AND MUSCLES

So what else can give pain in the leg apart from inflamed nerves. Well almost every other component of the spine can but they all do it in much the same way - that's why it can be hard to tell if a disc or a joint or a muscle is causing the pain. The term "Somatic Pain" is normally given to the kind of pain that arises in this way.

All these structures tend to produce lower back pain and leg pain in roughly equal proportion - unlike the nerve which makes more leg pain than back pain. The leg pain associated with somatic pain is usually hard for the sufferer to pin down and they are only able to say where it is in a vague general manner. It often seems to be "just inside somewhere." It may be felt in both legs - again unlike nerve or neurogenic pain which is usually in one or the other leg but not both at the same time. Lastly it is very rare for pain from joints, discs or muscles to cause numbness, weakness or pins and needles.

The only clue to which of these three structures is at fault comes from some recent research which shows that pain from an inflamed or degnerate lumbar disc is felt in the middle of the back and may go to either side. Pain from a joint or muscle is always to one side or the other and never moves over to the other side of the back bone. If it starts on the left it should stay on the left and vice versa for the right.

For most back pain sufferers we can't properly identify the bit of the spine causing the problem. These people may be seen by different doctors, physios, osteopaths and chiropractors and given a completely different "diagnosis" each time. This can be very frustrating and confusing and really stems from the fact that nobody really knows what bits of the spine are causing which patterns of pain.

Many therapists really do think that they know and they are not trying to mislead anyone, but there's no proper research to prove it either way. It might all become clear in the fullness of time but until then an honest therapist will admit that they can't be absolutely sure what's really going on in your spine. Treatment can still be given and very often it will work but don't get too obsessed with the name your therapist gives to your problem - it won't affect the outcome of your treatment. 


Referred pain in reverse

Before leaving the subject you should know that referred pain can go in reverse.

Pain from the limbs can be felt in the spine area. For example someone with arthritis in the hip joints can start off by feeling pain in the lower back and not in the hip area at all. The sacro-iliac joints can behave in the same way and the shoulder can send pain to the neck. A good doctor or therapist will always examine these joints when first assessing back or neck pain.



Pain caused by serious disease

What pattern of lower back pain might point to cancer?

Lower back pain caused by serious underlying disease such as cancer is very rare but this site would not be complete without some discussion of it.

What clues are there in the pain that might lead us to suspect that there was something seriously wrong? Are there any patterns which should ring the alarm bells in the mind of the doctor or, for that matter, the patient? The answer to this is yes.

•  Lower back pain that is not changed by movement?
Low back pain from discs, joints, muscles and nerves is always changed in some way by the movements the sufferer makes. Changes in posture or activity will alter the pain. In other words the pain varies if you lie down to rest, move around, avoid sitting too long in the one place or go for a swim once a day. Lower back pain that does not vary with movement or activity could point to a serious underlying disease and you should arrange to have a check up from your doctor.

•  Low back pain which is with you no matter what you do - which never gives you a comfortable position or that keeps you awake all night is always a worrying sign.

•  How did your lower back pain start?
Can you clearly remember roughly how or when it started? This is nearly always the story in pain which is a nuisance but not due to serious disease. If the pain just seemed to come on very gradually over a long period of time and for no very obvious reason then you should seek a doctors opinion. Probably further tests need to be done.

•  Rib area pain?
Pain in the area of the back behind the rib cage can be caused by simple problems in the joints but should be checked out for you by an experienced doctor or therapist.

•  Lower back pain with weight loss or ill health?
Have you lost weight for no very clear reason? Have you had a disease such as cancer somewhere else in your body previously? Are you unwell as well as being in pain? If you are then be honest with yourself and seek your doctors help.

These things do not always mean you have a life-threatening illness but they may do. Please don't just keep your worries to yourself - see your doctor. He may be able to reassure you and prevent needless worry. On the other hand if you are unlucky and it is something like cancer then the earlier you go to the doctor the better. No more than one person in every two hundred with lower back pain has a serious cause for it. Don't get obsessed by the worry of cancer but if you do think you fit into the danger category then do go to your doctor - today please!




Lower back pain
What causes back pain
How the spine nerves work
Facet Joint Pain - Sacroiliac Joint Pain
Back pain, disc pain and disc degeneration
lower back pain and the lumbar facet joints
What is Lower Back Pain
Why is my back sore?
Lower Back Pain Treatment and Referred Pain
First aid treatment measures for a low back pain attack
Manipulation Treatment for Back Pain
Acupuncture treatment for lower back pain 

Back Pain Treatment 

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Doctor Cameron also provides online information about other joint pain topics including shoulder pain, frozen shoulder and about how joint injections can help to treat pain or stiffness. If you browse around his other sites you will find lots of related health information - much of it also dealing with joint pain, muscle pain and sports injury.