So you have a disc bulge…., what does it mean for you? 

If you have had back pain for a while, it is likely someone has ordered imaging of your back. Typically, the report will report all sorts of findings. Many of these findings are present without causing symptoms. Often one or more lumbar discs are reported as “bulging”. Maybe you were told you had a bulging disc and now you are concerned with what this might mean for you. So, read on….., this primer will give you an overview on understanding disc injuries. (There are supporting research references if you really want to dig deeper). 

INSIGHT: A major consideration in the discussion of disc injuries, is to ask why your back pain is present (or “why do I have a disc injury”). Keep in mind that focussing on a disc injury is only part of the process of understanding why you have back or neck pain. Identifying movement, posture, strength and overloading issues are the main areas that drive treatment strategies and recovery, including when discs are “bulging”.

Firstly, lets’ start with the ‘language’ of disc injuries. Terms like disc herniation and disc prolapse are generic terms that cover all disc injuries. A more exact method of describing disc injuries is to classify them into three main types; bulges, protrusions and extrusions. Each type of disc injury has a wide range of clinical implications that vary all the way from ‘no effect on you’ to the need for surgery. I’ll describe each type of disc injury below. But firstly, understanding the basic anatomy is helpful. The image below will show you the basic structure and terminology.

Disc bulges

Disc bulges are the most common finding seen on imaging. They are are commonly found in people with and without back pain. Some people who are known to have disc bulges have never experienced back pain. A disc bulge might be associated with pain but this will depend a number of things such as if a sudden tear has occurred, if there is inflammation, if the bulge combines with other components to narrow spaces for nerves, if there is damage to the ‘endplates’ that are on the top and bottom of the disc etc. It’s important to understand that pain intensity does not directly relate to the size of the bulge. This means that you could have strong pain with only a minor disc bulge. 

Annular tears

Small disruptions to the outer fibrous ring of the intervertebral disc (known as the the annulus fibrous) can occur and these are called ‘annular tears’. They can be present with or without pain and do not require surgical intervention. Annular tears may be associated with pain and annecdotally, seem to take several weeks to settle. During the recovery time it is not uncommon to have flare-ups of pain followed by further recovery. The two images below show small white (bright) areas at the back of the disc that indicate annular tears.

Disc protrusions

Disc protrusions are asymmetrical disc bulges that usually affect one side of the disc, with the possibility (but not always) of compressing nerve tissue. People often describe their pain as a “pinched nerve” but true symptoms of nerve compression include sensory changes such as ‘pins and needles’ (paraesthesia) or numbness (anaesthesia), loss of strength and reduced reflexes. Pain is often present but pain alone does not always indicate nerve entrapment.

Disc extrusions

A disc extrusion occurs with a tear in the annulus that allows gel-like material to emerge from the disc, similar to a disc protrusion but with the disc material extending vertically past the upper or lower endplate of the vertebrae. Extrusions may extend in any direction, and can be quite large. If the extrusion is directly in the midline it may not cause nerve compression but if it occurs either side of midline nerve compression may occur. The nerve that is getting ready to exit the spinal canal (the traversing nerve) can be compressed in the region known as the lateral recess (in the posterolateral aspect of the spinal canal). In recent studies, extrusions were more commonly associated with signs of nerve root compression (often know as a radiculopathy).

However, disc extrusions are an example of size not meaning everything.  A number of studies have shown that large disc extrusions shrink (regress) over time. Some types of disc injuries such as protruded and extruded discs may do better with surgical decompression, but the natural history of recovery will mean that many people with significant disc injuries do not need surgery.

 

 

Recovering from a disc injury

As a general rule, recovery strategies will include activity and movement while respecting nerve sensitivity. Typically, many people show slow but steady recovery over a three month period. Some people who have significant nerve damage, high levels of pain and/or slow recovery may require earlier surgical intervention. Physiotherapy, exercise and gradual return to activity are usual first line strategies of management.

References for further reading:

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