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Spine "Instability"

What causes Spinal “Instability”?

Spinal Instability is a term coined to describe abnormal movement between one vertebra and another. As a disc degenerates it loses tension or ‘turgor’ which allows the disc to bulge and permits increasing movements to take place between the vertebrae. The loss of disc height causes the facet joints to displace and override beyond their correct congruent alignment. This overriding and abnormal slipping of the facet joints induces arthritic overgrowth of the joints and the production of bone spurs around the joint margins.

What are the symptoms?

Abnormal sliding between vertebrae may occur during flexion, lifting or extension and cause pain. This produces significant back pain, attended by a ‘catch’ sign where the patient is suddenly startled by a stabbing pain. This usually occurs when the sufferer is halfway through getting out of a chair and standing upright. It is often associated with a spasm and sometimes locking up of the back.

What actually causes the pain?

The pain is caused when movement such as flexion or extension causes the vertebrae to slide forward and backward or rotate abnormally. This directly irritates the nerve which has become tethered to the disc, vertebra, facet joint margin and ligaments in the foramen. Since the nerve cannot move freely to accommodate these abnormal movements, it becomes irritated causing back and/or leg pain. The abnormal movements cause arthritic overgrowth of the joints and bone spurs to develop. The ‘catch’ occurs when the facet joint bone spurs dig into the nerve.

What is wrong with conventional diagnosis?

Conventional diagnosis relies upon the ‘catch’ sign and also the ‘apprehension’ test, so called because when the surgeon presses upon the patient’s head, the patient will exhibit a sense of apprehension for any movement likely to cause displacement of the facet joints in the lumbar or cervical spine and irritation of the nerve and pain. Clinical examination as a means of identifying the causal segment is also unreliable, although the use of weight bearing X-rays in flexion and extension, both standing and sitting, does demonstrate the way in which each patient individually moves their back. MRI and CAT scans demonstrate the presence of pathology e.g. degenerate disc bulges etc, as well as overgrown facet joints, bone spurs and swelling of the nerve. However this can grossly underestimate the presence of the essential tethering which is causal.

What is the conventional treatment?

Conventional wisdom deems that the problem lies in the disc itself (discogenic pain) and is a mechanical dysfunction best treated by fusion, removing movement at that segment and, where possible, re-aligning the vertebrae to a normal position and disc height, preferably with undercutting (opening the doorway) of the foraminal spaces. However these techniques fail to liberate the tethered nerve root and symptoms may persist.

How should the condition be diagnosed?

MISS surgeons recognise that the spine is inherently unstable, being minutely controlled by ligaments and muscles, and therefore abhor the term ‘instability’. The symptoms are not due to instability in itself but to irritation or impingement on the nerve occasioned by the abnormal micro-movements. Indeed, aware state diagnosis and endoscopic live surgery have shown that it is not the disc that is the cause of so-called ‘discogenic pain’ but the nerve which is responsible for the symptoms of “instability”. The nipping noted in spinal instability arises from the nerve itself, because it is tethered to the disc, the facet joint and the superior foraminal ligament. Also nipping is caused by bone spurs projecting from the vertebra in front of the nerve and from the facet joints behind the nerve, both of which put pressure on the nerve when the sufferer moves.

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 to determine the relative importance of each site in the totality of the patient’s pain and condition.

Can the diagnosis be confirmed?

This can be achieved by the use of spinal probing of the nerve, contents of the foramen and epidural space to determine contributory levels. Hydraulic discography can be used to determine levels causing compression of the nerve exiting the spinal space. This procedure enables the surgeon to re-tension the disc and ligaments, restore disc height, realign the facet joints and restore the volume of the foramen at the suspected level. These techniques, which include the injection of an X-ray visible liquid into the disc, open up the ‘Foramen’ or spinal spaces and effectively liberate the nerve temporarily. Where pain rather than compression is the predominant symptom then insertion of anaesthetic or steroid in to the disc (Differential Discography) can be used to distinguish the role played by each level in the symptom complex. If these studies transiently reverse the symptoms, then the specific causal segment can be identified without having to open the back at several levels. This will demonstrate whether or not the original surgery addressed the causal segment in the first instance or whether it addressed the correct level but failed to correct the effects of the pathology at the operated level.

Why is this better than conventional surgery?

The benefit of Endoscopic Lumbar Decompression & Foraminoplasty (ELDF) 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 outcome. This is in contrast to conventional fusion 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. The success rate is about 60% for single level fusions and less the more levels that are involved. Complications occur in 12 – 17% and this limits the age group of patients that can be offered such treatment ELDF 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 long term symptoms where the diagnosis is in question to the conventional surgeon and where the patient would otherwise be referred for palliative Chronic Pain Management.

Is there a better alternative treatment?

Having determined the causal level, Endoscopic Lumbar Decompression & Foraminoplasty (ELDF) enables the surgeon to ‘walk up’ the exiting nerve root, ‘liberate’ it to allow for movement, and remove the factors such as bone spurs which are causing the pain. The great benefit of MISS 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 outcome. In addition, ELDF preserves muscle power, maintains integrity of disc and joints, and can be followed by e.g. rehabilitation, physiotherapy, postural control and restoration of muscle function.

What proof is there of successful treatment?

Aware State Diagnosis and ELDF Surgery are delivering encouraging results in well over 80% of patients when reviewed 2-4 years later, and 70% at 10 years later. 

Case Studies

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