Dr David McGrath

Dr David McGrath

Dr David McGrath

Spine Physician

MB BS (Hons) FAFOM, RACP, FAFMM
Master of Pain Medicine


A Bulging Disc

This is a common stement and often given as the "diagnosis".
The problem is, the observation is unreliable and non valid as a diagnosis. Firstly, the inter-observer reliability is low for modern imaging methods such as CT and MRI. That is, radiologists don't always agree that the bulge exists. Secondly, the probability of having pain, is no greater than stastistical average. ie invalid as a diagnostic sign.
With the advent of dynamic MRI, active flexion and extension views, are also possible. Scientists, utilising these machines, as a research tool, have shown that discs can bulge backwards into the intervertebral canal on both flexion and/or extension, but not at every level, and not with any predictability. In other words, discs bulge with different dynamic forces. A persistant bulge, may be an indicator of abnormal physiology, and may be the source of pain, but by itself,has no accuracy as a painful diagnosis.
The high frequency of reporting from radiologists, is probably due to their desire to find a cause for sciatica, not simple back pain. Physical pressure against spinal nerves, along with chemical irritation, can lead to severe leg pain and dysfunction of bladder and bowell. For many years, this diagnosis (disc prolapse) was looked for as "the only cause of back and leg pain " and traditional was treated with surgery.
We have advanced considerably, from this simple viewpoint. An isolated significant loss of disc height, and some other MRI findings have greater significance than a simple bulge.

A disc bulge is NOT a diagnosis.

©Copyright 2007 Dr David McGrath. All rights reserved