Founders Statement
Patient evaluation and diagnosis is pivotal to the success of keyhole treatment. More important than finding the correct segmental level is the precise definition of the painful structure out of many that can exist at that index level. In this unit patients complete an extensive obligatory questionnaire incorporating the Oswestry Disability Index score split to assess the individual roles of back, buttock and leg pain in their presentation. Similar substratification is applied to the Visual Analogue Pain scale. We use indexes of depression and the DRAM score, pain mannikins, and data required for the Macnab score and the General Health Questionnaire.
Patient participation is essential if we are to meaningfully assess the true benefits of intervention. Our patients complete a "patient satisfaction and recommendation score" as well as a "patient achievement score" based upon 100 target activities from which the patient may choose 25 targets which they seek to have improved by surgical intervention. Subsequently they judge our performance on our ability to restore these qualities of life and activity.
Patients are analysed with our physiotherapy team to etablish the inherent malposture present in each individual, their clinically evoked pain sources and their neurological status. The malposture is then addressed by means of advanced spinal physiotherapy based upon the Muscle Balance approach. After 3 months of this rehabilitation approximately 50% of patients no longer require surgical intervention. Those patients not responding are submitted to an MRI scan with and without gadolinium enhancement and compression.The final arbiter in defining the index level is Spinal Probing and Discography. Much emphasis has been placed upon discography evoked pain and intradiscal pressure traces. In our experience of over 4,500 spinal probings and discography, we find that it is the probing which more accurately defines the source of the pain and allows distinction between annular, foraminal and external foraminal sources. In our hands whilst the specifity of both discography and probing is approximately 95%, discography is only accurate in 60% whilst probing is 95% accurate as judged by the outcome to subsequent successful treatment or therapeutic instillation of steroid in to the index disc (Therapeutic Discogram).
Interpretation of spinal probing must distinguish radicular pain from pain produced by the inflamed disc wall or adjacent tissues. During probing, radicular pain must be avoided. Annular or peri-annular structures will reproduce back pain, buttock pain, groin pain and pain arising from the posterior longitudinal ligament which radiates to the level of the knee, proximal calf or shin or radiates superiorly up the spine over several segments.
Probing often confirms the genuine nature of symptoms manifested by patients and which all too often have been dismissed by specialists as "over distressed" behaviour or "failed back" syndrome. These symptoms may have been present for decades despite the received wisdom that such symptoms will settle spontaneously.
In this unit the presence of a large disc protrusion fitting with clinical findings is a misleading finding in 4% of cases. MRI scans miss the presence of a leaking disc in 65% of cases. Leaking discs may be depicted on the MRI scan as merely a "black" desiccated disc and one among many.
Some radial tears may indeed disappear. Rather than resolution this occurs because the remaining annular integrity disrupts, the inflammatory fluid escapes thus collapsing the high intensity zone (HIZ) on the T2 scan.
Probing reveals that annulae that contain an HIZ or leak are associated with symptom reproduction in over 90% of cases at probing. In many such cases symptoms associated with the HIZ or leak have been present for many years. The longest enduring symptomatic annular collection in our unit persisted for 26 years with identical symptoms during this period and resolved with laser treatment.
Endoscopic visualisation provides yet more accurate definition of the source of pain and is especially useful in patients with long standing degeneration following previous intervention or in cases with perineural scarring. The MRI scan underestimates perineural scarring and fails to reveal tethering to the ascending facet joint, the detrimental role of the foraminal ligament and shoulder osteophytes, infolding of the ligamentum flavum in the foramen and hypervascularity in the tissues in and adjacent to the foramen, and fibrotic engorgement of the posterior longitudinal ligament on the dorsum of the vertebralbody. In these circumstances the nerve may be trapped by these structures and tissues, flattened and reddened over a specific section in the foramen or extraforaminal region. On occasion the disc wall is quiescent and the redundant bulge is not contributory to the painful symptoms.
The importance of accurate symptom reproduction in the planning of subsequent treatment means that the surgeon should carry out the spinal probing and discography in every instance.