Investigation of the Lower Spine

Introduction

An accurate diagnosis is always important in managing any clinical problem. When treating problems in the lumbar spine, clear and detailed information is an absolutely key factor in success.

With different structures and different levels of the spine being affected to varying degrees by a range of degenerative processes, getting this wrong can have serious consequences. With reliable and complete diagnostic information, an appropriate surgical strategy can be tailored to the specific problems affecting an individual's lower back. The wear and tear processes that can occur certainly do not always cause problems and a key question to be answered is: where is the pain coming from? This is one of the most important questions we will attempt to answer, using the most up-to-date and detailed spinal imaging techniques.

X-rays (Radiographs)

X-rays have been used for almost a century and are still the first line investigation of the lower back. Standard front and side views provide a great deal of information about the bony anatomy of the spine and a wide range of conditions which affect the bones, facet joints and intervertebral discs. Degenerative changes cause well recognised features. The intervertebral discs themselves can not be seen but much can be learned about the condition of the discs from what is termed the 'disc space' (the gap on x-rays between the vertebrae occupied by the disc) and the bony features around this.

Side views of the spine taken in positions of forward bending and in extension, called dynamic radiographs, can provide additional information about movement in the spine and areas of instability.

MRI (Magnetic Resonance Imaging)

It is no exaggeration to say that MRI has revolutionised our management of conditions affecting the spine and it is really impossible to do justice, in a few short paragraphs, to this truly amazing form of imaging. MRI provides highly detailed pictures of the spine, including vitally important information about structures such as the intervertebral discs, the spinal cord and nerves in the spine. The quality of the various discs can be assessed. Scans reveal, for example, the early breakdown of the central nucleus in mild degeneration. Problems affecting the discs such as tears or protrusions can be seen very clearly together with any compression of the nerve roots these might be causing. The space available within the spinal canal can be evaluated accurately and any narrowing or stenosis shown. Other causes of nerve compression, such as cysts from facet joints or scarring from previous surgery, can all be distinguished using modern techniques. MRI is also highly sensitive in detecting abnormalities such as infection or tumours within or around the spine.

This technology has seen significant improvements over the past few years. Not all MRI scanners are the same. At The Spine Clinic we have the best quality imaging available and, even more importantly, highly experienced radiologists who are experts in their field, conducting and reporting on the scans.

Having an MRI Scan

CT Scans (Computerized Tomography)

Whereas an x-ray effectively provides a two dimensional 'shadow' of the spine, perhaps with views from the front or from the side, CT scanning uses views taken from every angle around the spine, either in a full circle or in a helix. Sophisticated computer hardware and software can then analyse and reassemble the radiographic information to provide sectional slices in any plane through the body. The equipment can even reconstruct three dimensional views of the spine from any angle.

CT scanning is often the best way to show abnormalities of the bones themselves such as fractures or other bony defects, some of which will not show up very clearly on MRI scans. X-rays of course show bone very clearly but soft tissue can also be seen, casting a softer shadow on plain x-rays. CT scanning will also show soft tissues such as the intervertebral discs and nerve roots, although not with quite the same qualitative detail that can be achieved with MRI scans. Nonetheless, with CT scanning, soft tissue components of the spine, as well as structures close to the spine such as blood vessels, can be shown in beautiful detail (see the picture). CT scanning can therefore offer a very good alternative for discs and nerve roots if for some reason MRI cannot be used.

At The Spine Clinic we have available the very best in CT scanning equipment, able to provide very sophisticated imaging with very low radiation exposure, similar to that used with plain x-rays of the spine.

Having a CT Scan

Provocative Discography

Although investigations such as x-rays and MRI scans provide extremely detailed information about the spine they do not actually show us pain. Very often the painful problem is clear from the clinical assessment and from the scans and x-rays. Sometimes, however, further information about the contribution coming from different levels in the spine can be important, affecting our approach. This is where provocative discography can be so helpful.

The investigation involves carefully positioning needles in the suspicious discs and one normal disc, which is used for comparison. A small amount of special fluid visible on x-ray screening (called contrast media) is injected into the disc. This gives useful information about the disc's internal structure. However, the really useful part of the investigation comes from any symptoms that the injection of the fluid might cause. In a normal healthy disc the injection does not cause any discomfort, but if we find that, when injecting an abnormal disc, the patient's typical symptoms of back pain are provoked, then clearly we have found the problem area. The combination of provocative discography and MRI allow us to identify the source of a patient's back pain as accurately, and with as much confidence, as possible.

Local anaesthetic and sedation are used during the procedure, but it is important that the patient is able to report what they are feeling at the time. The results of provocative discography are absolutely dependent upon the skill and experience of the operator. Madeleine Sampson has provided a dedicated discography service for many years, providing reliable results upon which important decisions about further care can be based.

Having Provocative Discography

Bone Scans

Bone is a living tissue which experiences a constant turnover, with certain cells absorbing old bone and other cells laying down new bone. This process allows bone to respond to changing stresses and to repair any damage which might occur. Bone scanning allows this process to be monitored. A radioisotope is used which is taken up by the bone cells involved in the process of bone turnover. A special camera enables the distribution and degree of activity to be assessed throughout the skeleton. Any areas where there is increased activity will be seen as 'hot spots,' while reduced activity will be seen as a void in the normal background level of activity.

A typical example of how bone scanning can be helpful is seen in certain fractures such as stress fractures or osteoporotic micro-fractures in the spine. These may not be evident on x-rays. However, the healing response to a fracture, which starts quite quickly, involves a considerable increase in bone turnover and will be seen as a very apparent 'hot spot' on a bone scan.

The radioisotope is injected and a period of time is allowed for this to be taken up by the skeleton. The isotope gives off a very low level of background radiation which can be detected by a special camera. The images can give a broad 'wide-angle' view of the whole skeleton or, with a special technique called SPECT bone scanning, can give very detailed images, for example showing precisely where in a vertebrae a focus of activity is located. CT scanning can further enhance SPECT bone scans, by showing for example that a localized area of intense activity is precisely located at the site of a bony abnormality.

Having a Bone Scan

 

 

 

back to top