Chronic Pain – is it all in my head?

Many people suffer from chronic pain but few of us understand exactly what it is. Chronic pain is difficult to define but is often thought to be consistent pain which lasts in excess of 3-6months. When the body is exposed to a painful stimulus for a long period of time, changes within the brain, spinal cord and cells lead to an increased perception of pain.

Two phenomena occur when chronic pain is experienced.

  1. The threshold for detecting pain is reduced resulting in an exaggerated response to a painful stimulus. This is known as hyperalgesia.
  2. Non pain sensitive structures suddenly become pain sensitive, and stimuli which would not normally evoke pain, do. This is known as allodynia.

In order to understand these processes we must outline the Pain Pathway…

  1. A stimulus causes damage to the tissue, e.g. a tear occurs in the calf muscle
  2. Damage to the tissue (calf muscle) results in the release of neurotransmitters (chemical messengers)
  3. These chemical messeners then activate the nerve endings (nocioceptors) found within the muscle
  4. The nerve endings transport the signal to the spinal cord, where they then communicate with an interneuron (the middle man)
  5. The middle man has the ability to increase or decrease the intensity of the signal before it then communicates with a secondary nerve
  6. This secondary nerve sends the signal up the spinal cord to the brain where pain is perceived

Along this six step pathway, a number of changes can occur which heighten the detection and perception of pain.

Firstly, when exposure to a stimulus is prolonged, the increased release of chemical messengers makes the nerve endings more sensitive. Second, the middle man fails to regulate the incoming pain signals and thus increases the input being sent to the brain via the secondary nerve. Third, within the brain, MRI and EEG studies show that the area of the brain that detects pain becomes larger, with areas of the brain not normally designed to detect pain becoming active.

It can be very difficult to break this pain cycle. Due to the complex nature of chronic pain and the involvement of the nervous system (brain and spinal cord) best practice involves the implementation of a pain management team. Your Physiotherapist or Doctor may refer you to a Pain Management Clinic. These clinics have highly qualified staff across a number of disciplines which aim to give you strategies to manage your pain and promote independence.