What is Degenerative Disc Disease?
Oddly enough, this condition is not really degenerative and is not really a disease. More correctly it is a condition that results from ageing and its effects vary considerably in their nature and severity and should be referred to as disc degeneration (Spondylosis). However, the term Degenerative Disc Disease is generally used to define a number of natural processes and conditions brought about by the general ageing and wear and tear upon the spinal discs and the secondary effects that this has upon associated spinal structures.
What are the symptoms?
Frequently symptoms are triggered by a simple twisting injury such as swinging a golf club. Whilst the symptoms vary considerably from person to person, in many cases the sufferer will experience continuous low-level pain centred on the lower back and occasionally in the hips, groins and legs. From time to time, this will flare up in intensity for a few days and then subside. The pain is often worse in a seated position and is frequently exacerbated by lifting, bending or twisting movements. Pain levels can vary from mostly nagging to intermittently severe and disabling. In addition, there may be pain, numbness or tingling in the legs, muscle weakness and foot drop.
What causes the pain?
The perceived wisdom is that back pain in particular arises from the disc itself. Therefore it is thought that over time, the pain will gradually decreases as the degenerating disc stops causing pain. However aware state endoscopy allows us to see where the pain is arising. This shows us that only 11% of patients have symptoms arising from the disc itself. The medial border of the nerve when palpated is the actual cause of the back pain and the core of the nerve is the cause of the referred pain down the arm or leg.
The pain may arise from multiple origins. The pain may derive from damage, irritation or pressure upon nerves within and around the spinal area. There are actually few nerves in the disc itself, but any injury to the disc can cause these nerves or those in the Posterior Longitudinal Ligament to become sensitised and cause pain. In addition, the disc in some patients may contain inflammatory proteins which can leak and irritate the exiting nerve in the foramen or the descending nerves in the spinal canal at that level causing pain for the sufferer. Moreover, when the disc becomes damaged or worn down loosing tension and height, it can permit micro-movements of the vertebrae which can lead to painful reflex muscle spasms because the facet joints and ligaments in the foramen impact upon the nerve and irritate or compress the nerve causing back and leg pain.
Why does the disc degenerate?
There is only a very limited blood supply to the disc because the disc contents are highly irritant and need to be kept isolated from the body. Since blood brings only limited healing nutrients and oxygen to the damaged disc it is slow to repair itself after suffering damage or injuries. Despite this, the painful aspects of the condition are actually common in younger age groups (30-50). Over time the inflammatory proteins within the disc burn out, the disc loses its water content, becomes stiffer thus limiting painful micro-movements and irritating the nerve in the foramen. However repetitive micro-trauma and bleeds lead to scarring around the nerve in the foramen and persistent back and or leg pain which continues to afflict older patients. A myth has arisen that back/leg pain is less common in the elderly. In fact many older patients drastically reduce their activity levels to reduce their symptoms and because they expect to have age related pain complain less about these symptoms.
How is the condition diagnosed?
MRI & CAT scans enable the surgeon to image good anatomical detail and definition of pathological changes. But because pathology becomes prevalent with increasing age even in patients without symptoms MRI images cannot be used as the sole diagnostic tool. This means that clinical examination and consideration of the patient’s history must also be taken into account. However whilst the loss of disc height and dehydration which results from disc degeneration can result in exiting nerve roots becoming nipped by the vertebrae and so causing irritation and pain such changes may be evident at several disc levels in the same patient. The distribution of the pain is supposed to guide the surgeon as to the disc level causing the symptoms but these distribution patterns may be in error for instance in the lumbar spine in excess of 15% of patients. So a more accurate method of diagnosis is called for hence our development of aware state diagnosis.
How is the condition treated?
In many cases management of the condition is encouraged using pain medications, physiotherapy, osteopathy and chiropractic techniques including ultrasound and electrical stimulation. The use of these thus enables the sufferer to engage in exercise regimes and rehabilitation. The aim of the treatment is to re-train the body to adopt better posture and optimised intersegmental load transmission. Overall, management of the condition seeks to minimise or prevent the application of excessive stress upon the disc through better ergonomics and posture.
As symptoms persist then increased medication and injections of steroid are employed to reduce pain and inflammation of the nerve using facet joint injections, root blocks or epidural injections.
Is conventional surgery appropriate?
Most types of conventional surgery for this condition are fairly extensive which is why management of the condition is the preferred treatment. However, in cases where management is not appropriate or possible and where the disc bulge is squeezing the nerve the bulge is taken away through a microscope (Microdiscectomy). Where back pain is predominant artificial disc replacement and/or spinal fusion are frequently recommended. However, these carry with them a number of potential risks and disadvantages that are common in all types of multi-level open back surgery as detailed below.
Why is aware state diagnosis better?
Conventionally the cause of the pain is diagnosed from the pattern of the pain and MRI scans but these techniques are inaccurate. However, the causal pain sources can now be accurately defined through aware state surgical examination, during which the surgeon seeks to replicate the pain by spinal probing. When this provokes a response, the patient, who is protected by circulating intravenous pain killers, offers feedback to the surgeon regarding the type and distribution of the pain produced. Sometimes, when the response is only partially akin to the presenting symptoms or when the response is at more than one spinal level, additional techniques such as Differential Discography are used. These techniques enable the surgeon to determine the relative importance of each site in the totality of the patient’s pain and condition, and that the symptoms can be modified by Endoscopic Minimally Invasive Spine Surgery.
Why is this better than conventional diagnosis?
This ‘live’ approach to diagnosis means that causes of pain can be defined and ultimately confirmed and also that misdiagnosis due to strange nerve anatomy can be avoided. Subsequent endoscopic examination with the patient awake then leads the surgeon to the precise source of pain at the specified intervertebral level. This is in complete contrast to conventional diagnostic techniques which rely upon pre-operative ‘guesstimation’ based upon X-rays, MRI scans and CAT scans and often results in the “overkill” of multiple level surgery performed to attempt a treatment “catch all”.
Why is this better than conventional surgery?
The benefit of Endoscopic Minimally Invasive Spine Surgery is that it enables the surgeon to treat the condition specifically, precisely and with minimum collateral damage to tissues, reduced risk to the patient and enhanced long-term outcomes. This is in contrast to conventional surgery, especially where multi-level conditions are suspected. Under these circumstances, the surgeon will treat all the involved levels using ‘overkill’ multi-level surgery with its problems including blood loss, potential nerve and tissue damage, extended post-operative care and unnecessarily operating on non-causal levels. Minimally invasive techniques can be used in all age groups but offer treatment for the frail, the infirm and the elderly because they avoid the use of General Anaesthesia. They also open up the opportunity to treat effectively and definitively, long term symptoms where the diagnosis is in question to the conventional surgeon and where the patient is therefore referred for palliative Chronic Pain Management.