Arm pain or neck pain – where is the source?
Have you ever experienced pain in the arm, but the movements of the shoulder and elbow do not seem to aggravate the pain? Or found pain on the side of your thigh or knee, but there is nothing wrong with your knee? Are you imagining the pain? Where is the pain coming from?
These pains are real. Pain in the arm can be referred from the neck and similarly the source of pain in the leg can be from the lower back.
Types of referred pain from the spine
- The most common is a deep dull ache in certain parts of the affected limb. See image below. These areas of pain correspond to where the nerves in the spine supply sensation to. There are 7 vertebrae in the neck. Depending on the level, nerves exit from the vertebra and travel to specific areas of the scalp, shoulder, arm, forearm and hand. Similarly nerves exiting between the 5 vertebra of the lower back travel to the bottom, thighs, legs and feet. These nerves supply sensation to these particular areas and are called dermatomes. So if the exiting nerves are mildly irritated, it can refer pain to its specific dermatome. Therefore, if the structures surrounding the nerves are inflamed, immobile, strained or somehow affect the exiting nerves, pain can develop in the extremities.
- The second type of referred pain is sharper, more acute and often described as pulling, stabbing and severe pain. However, the site of pain remains the same. In these cases, the nerves exiting the vertebra are not only irritated but usually impinged or compressed. The cause of the impingement is usually severe degeneration in the vertebrae, disc prolapse and swelling which reduces the canal space, for which the nerves to exit. These types of pain can be accompanied by loss of strength of muscles in the arm and leg as well as decrease sensation as the compression affects the conduction within the nerve fibres. The impinged nerve essentially is less able to send its usual amount stimuli to the muscles it excites.
Treatment of referred pain
The treatment for referred pain is simple. Find the cause of the irritation or compression and remove or reduce the cause as much as possible within the realm of physiotherapy.
- Type 1 Dull achy pain is usually due to poor posture, excessive mechanical loading on the spine, i.e. tight muscles, stiff and or mal-positioned facet joints.Once the mechanical fault is corrected, the structures offloaded, through manual therapy, the symptoms tend to promptly reduce.
- Type 2 Pain which is more acute, it is more difficult to treat. As the source of pain is from the compression /impingement of the nerve, the cause of the impingement is usually structural. This means that the existing degeneration of the spine and the significant disc protrusion are the main reasons for the impingement. Therefore unless that is addressed, often the pain is not completely resolved.
The role of physiotherapy in this intance is to reduce the non structural causes such as excessive vertical loading, the narrowing of the canal and pain reduction. These non structural causes could be the result of swelling, poor posture, muscle spasm. Traction and specific exercises are therefore taught to open the canal space and reduce disc protrusion and impingement.