A median herniated disc is also known by many similar diagnostic terms including medial herniation, medial bulging disc, medial disc prolapse and central herniated disc. Median or medial are location-specific terms used to designate the herniation as occurring in the center of the posterior space behind the disc, as opposed to the posterolateral or far lateral variety of herniated discs. Medial bulges are less common than posterolateral bulges by a significant percentage. Since medial bulges face directly towards the center of the spinal canal, they have a good chance of affecting the spinal cord if they are severe and deep.
This discussion will focus on central herniated discs and provide details about the various profiles of central disc prolapses.
Broad based medial bulging discs demonstrate more than 25%, but less than 50% percent, of the total disc size being accounted for by the herniated portion. In other terms, the circular flat map of a disc surface is comprised of 360 degrees and the herniated portion is comprised of 90 to 180 degrees and is focused towards the middle of the spinal canal.
Often, mild to moderate central bulges are said to efface the thecal sac and some particularly large or severe protrusions even actually impinge upon or compress the spinal cord itself.
Focal medial disc bulges also face into the spinal canal directly, rather than to either side, but are smaller in size than broad based bulges. Focal medial bulges are defined as direct posterior herniations in which the size of the herniation is 25% or less of the overall surface area of the disc.
In a flat circular disc map, the herniation of a focal medial bulge would account for less than 90 degrees of the total possible 360 degrees. This sounds better than a broad based bulge and in some cases, it may truly be. However, large focal bulges can actually extend further and possibly influence nerve tissues worse than broad based bulges which consist of width of herniation, rather than penetrating depth.
Medial disc conditions are less prevalent when compared to paramedial herniations. Typically it is far less likely that the disc will bulge or rupture directly on the center line of the posterior side. Regardless of what type of herniation you may demonstrate on diagnostic testing, the terminology used is more of a medical nomenclature application than it is indicative of any particular symptomology. Remember that most mild to moderate herniations are not symptomatic in any way and many do not require aggressive treatment or any treatment at all.
Some herniations can be pain-generating, when nerve structures are affected, but the majority implicated in dorsopathy syndromes are clearly misdiagnosed as the actual source of symptoms, as supported by the abysmal curative statistics of common therapy options.