TERMINOLOGY

• Disc extrusion
• Intravertebral disc herniation
• Free fragment
• Sequestered disc
• Herniated nucleus pulposis

INTRODUCTION

A potential cause of neck or back pain is a herniated disk, sometimes referred to a disc protrusion. The spinal column is made up of bones (vertebrae) that are stacked upon one another and separated by a cushion referred to as an intervertebral disc. A disc consists of an outer layer of tough supportive fibers called annular fibers. The annular fibers wrap around a soft gel like center called the nucleus pulposis. The discs absorb shock and allow for movement. They also serve as spacers creating height between vertebrae providing space for spinal nerves to exit on either side of the spine through openings called neuroforamen.

When a disc herniates, disruption of the annulus allows the gel like center to take the path of least resistance and migrate through the tears. In some cases this causes the disc to protrude into the spinal canal. With more serious annular disruption the gel like center of the disc may extend beyond the outer annular fibers. When this occurs it is called a disc extrusion. If a piece breaks off of the disc extrusion this is referred to as a sequestered disc fragment. A disc herniation can directly put pressure on the adjacent spinal cord and/or spinal nerve. This can cause pain, numbness, tingling or weakness in the back, legs or arms, depending on the location of the disc herniation.

Classification of Disc Disorders

It is important that physicians of various disciplines agree and understand the use of common terminology to describe different disease processes. Standardization of language or terminology is often a challenge. IN 1995 the North American Spine Society (NASS) initiated efforts to standardize the use of terminology as it applies to various disorders of the intervertebral disc. They received assistance from the American Society of Spine Radiology (ASSR) and the American Society of Neuroradiology (ASNR). The efforts lead to the development of recommended classifications, definitions and criteria for different disc disorders at various stages of development. The use of commonly accepted and understood terminology helps physicians accurately communicate with their patients and with each other. It influences the type of care recommended to patients with spine disorders.

The following disc disorder classifications and their descriptions are derived form the nomenclature and classification of lumbar disc pathology, recommendations of the combined task forces of the North American Spine Society, American Society of Spine Radiology and American Society of Neuroradiology.