Mechanisms of Pain Production

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Definitions

Posture
Postural pain occurs when normal tissue is held at end range for prolonged periods of time.
No tissue damage needs to exist but pain is a warning of potential damage. Pain goes when the tissue is taken away from end range.

Dysfunction
Dysfunction pain occurs when abnormal or shortened tissue is taken to end range. Pain goes when the tissue is taken away from end range.

Derangement
Derangement pain occurs when a tissue is distorted in a particular direction. Derangement pain can be variable but always follows a particular pattern. 

Disc Protrusion
Disc protrusion pain can occur when the gel like centre of a disc creates a bulge, usually in the back wall of the disc. This has also been called a prolapse or herniation. Back pain is the typical feature, leg pain may be present.

Disc Extrusion
Disc extrusion pain occurs when the gel like centre of a disc ruptures, usually through the back wall of the disc. Back pain may go but now leg pain is the typical feature.

Disc Sequestration 
Disc sequestration pain occurs after a piece of disc material breaks away from the disc and moves to interfere with normal joint or tissue function. Symptoms can be variable and can come and go in an instant

Radiculopathy
Refers to pain originating from nerve root irritation, typically caused by a disc bulge. Pain can extend below the knee or elbow. Radicular pain must have other associated neurological features

Cauda Equina Pressure
Cauda equina symptoms are a medical and surgical emergency. This is a result of a major disc rupture with the gel like centre being blasted backwards into the bunch of nerve roots called the Cauda equina. Loss of bladder or bowel function and other neurological signs are present.

Trauma 
Pain from trauma will vary depending on the extent and type of tissues damaged. A typical inflammatory process occurs usually followed by a typical healing process. 

Spinal Canal Stenosis
The hole running down through the back of each vertebrae that contains the spinal cord is known as the spinal canal. Stenosis means the hole has narrowed for some reason, so the spinal cord or the descending nerve roots may become pressured with certain activities such a walking. Symptoms usually start with back pain but may progress into leg pains. 

Foraminal Stenosis
The hole formed between two vertebrae where the nerve exits the spinal canal is called the foramen. Stenosis means the hole has narrowed for some reason, so the nerve has less room to move and may get jammed or pinched with certain movements producing pain in the area the nerve supplies.

Adherent Nerve Root
Adherent usually means scar tissue has formed following trauma or surgery and anchored the nerve root to another structure limiting its movement. Pain occurs in the distribution of the nerve root only when the adherent nerve root is put under tension and at no other time.

Spondylolisthesis
Usually a defect in the bone at the rear area of the vertebrae called the 'pars interarticularis' can potentially allow the whole spinal column to slip forward on that vertebra. Symptoms arise due to the movement producing local mechanical trauma. There are five types of Spondylolisthesis and if active symptoms are usually worse with upright activities. Five to six percent of painfree people have a spondylolisthesis on x-ray. An x-ray finding is not the diagnosis but it merely supports the diagnosis made in the clinic.

Ankylosing Spondylitis
A sero negative systemic rheumatic disorder causing inflammation and pain in spinal joints and large joints of the limbs. Often has a positive HLA-B27 tissue antigen with blood testing. Typically has back pain and early morning stiffness. Will begin to demonstrate decreased chest expansion may have a low-grade fever and feels fatigued. Occurs three times more often in men than in women.

Cancer 
Pain from cancer can vary between individuals but is typically worse at night being quite severe and unremitting. Other clinical mechanical findings may or may not be present.

Psychogenic 
Refers to pain originating in the mind either consciously or subconsciously. A real spinal condition may or may not exist but psychological factors make symptoms appear worse. Secondary gain is a common cause of psychogenic pain.

Fracture 
Various spinal fractures are possible from sudden trauma like in a car accident or diving into shallow water. Fractures can also be caused by internal pathology such as cancer. Spinal cord damage is one of the greatest fears with spinal fracture and if suspected every care must be taken to minimize movement of that area.

Degeneration
Pain from spinal degenerative changes (also called arthritis) not as common as most people believe and x-ray findings showing degeneration DO NOT confirm that is the cause of the symptoms. Clinical findings must be matched to the behaviour of the symptoms. There are plenty of people with very degenerative (or arthritic) spines and no pain.

Neurogenic Claudication
The hole running down through the back of each vertebrae that contains the spinal cord is known as the spinal canal. Stenosis means the hole has narrowed for some reason, so the spinal cord or the descending nerve roots may become pressured with certain activities such a walking. Symptoms are commonly felt in both calves and known as neurogenic claudication.

Instability
Instability means joints between vertebrae have lost their natural passive restraints to movement, so uncontrolled movement may occur causing mechanical deformation and pain. An apparent decrease in active or muscular strength and endurance around the spine has also been called instability. In any case pain will only be felt in the presence of mechanical deformation of tissue not by the movement itself. Surgeons tend to fuse vertebrae together when they believe they are unstable.

Arthritis
Pain from spinal degenerative changes is not as common as most people believe and x-ray findings showing degeneration DO NOT confirm that is the cause of the symptoms. Clinical findings must be matched to the behaviour of the symptoms. There are plenty of people with very degenerative/arthritic spines and no pain.

Other
There are other mechanisms of back-related pain which will not be covered here in these brief definitions.

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Last Modified: August 17, 2001