What is referred pain? This is a question often asked to Osteopaths. Referred pain is a term which relates to pain felt in an area which is not the actual location producing the problem - the origin of the pain.
It is caused by the network of interconnecting sensory nerves which converge in the spinal cord effectively getting confused and linking areas which are supplied by the same nerves resulting in pain and other symptoms. A good example is headaches, in which pain caused by problems in the joints and muscles of the neck or jaw lead to referred pain in the base of the skull and in many areas over the head, forehead, around the eyes or into the temple areas.
What is viscero-somatic referred pain? The viscera are the internal organs of the body and the word somatic refers to the musculo-skeletal part of the body. One of the most common pain referral patterns occur during a heart attack where nerves from the heart convey pain to the spinal cord of the upper back (T1 - 4 vertebral levels). As these levels also supply sensation to the left arm, left side of the chest and, less frequently, up towards the left shoulder and neck people can experience pain, tingling and numbness in these areas when having a heart attack. The brain is not used to receiving such strong signals from the heart and perceives them to be originating from the left arm and chest. A similar referral pattern can happen between the gall bladder and the right shoulder as an inflamed and irritated gall bladder can prompt a pain impulse in the diaphragm which has a nerve supply from the same level as the right shoulder.
In all cases, referred pain is often felt as quite a constant, dull ache which is difficult to locate and may vary in severity. For example, clear sciatic nerve root impingement (originating from the lower back) often creates pain or sensory symptoms like tingling or numbness as a fairly clear line down the back of the leg possibly past the back of the knee towards the calf and ankle. Another case of peripheral nerve entrapment is commonly felt at the wrist (carpel tunnel), where the median nerve gets trapped as it passes through a small tunnel in the wrist, giving symptoms into the hand.
Referred pain, say from the lumbo-sacral joint (base of the spine), may cause only diffuse achy pain in random locations in the buttocks and into the back of the thigh and possibly calf. Local assessment of the thigh muscle may result in no abnormal findings however if the symptoms have been prolonged, the patient may experience tenderness, tightness or weakness in the back of the thigh.
It is very important that a thorough examination is to be carried out by the Osteopath to establish whether the symptoms you are experiencing are referred or local to the site where the pain is being experienced. Then, the best course of action can be determined.