Axial Stenosis

 

What is Axial Stenosis?

In medical terms, Stenosis is a ‘narrowing’ of any tubular vessel or structural passageway within the body. Axial Spinal Stenosis is a condition where the narrowing reduces the available space within the spinal canal. This may be caused by arthritic overgrowth of the Facet Joints, degeneration of the disc with loss of disc height, consequent slackening of surrounding ligaments which bulge in to the spinal canal, and bulging of the disc. This resultant loss of space can cause squeezing or pinching of the nerve roots as they pass up and down within the spinal canal.

What are the symptoms?

In many cases, the sufferer experiences increasing back pain, generally over a period of several years. This is often provoked by exercise and there is an increasing tendency for the back to prefer to be flexed. This means that standing upright or extending the back will increase pain and gradually aggravate the symptoms. As the problem develops, so the thighs or hamstrings or calves are commonly reported to become heavy or leaden during walking. As the condition worsens, the walking distance can be reduced in a process known as ‘Claudication’ caused by starvation of blood supply to the nerves. When the sufferer stops the activity, or crouches or leans forward, the blood supply recovers and the symptoms subside. After some time there may be a rapid decline in function where upon the sufferer “comes off their feet”. Best outcomes are achieved by intervention prior to this point.

What is wrong with conventional diagnosis?

The main difficulty in diagnosing this condition is that many features are misleading. Axial Stenosis is generally over-diagnosed, because the pathology seen on MRI and CAT scans can be present for many years in the absence of symptoms. Inert investigations using these techniques highlight the pathology but do not take into account either the patients’ individual and specific tolerances to pain. Some people can simply handle it better than others, or the individual’s nerve’s may have greater resilience than others to compression. At the same time, problems also occur in distinguishing between Axial Stenosis and Lateral Recess Stenosis. In the experience of The Spinal Foundation, Axial Stenosis can be widespread within the spine but be less significant in causing pain than Lateral Recess Stenosis. Axial Stenosis can also work in tandem with Lateral Recess Stenosis but, whilst it may be a prominent feature on the scans, it may less contributory of the presenting symptoms than Lateral Recess Stenosis.

Is a more accurate diagnosis possible?

It is important to remember that Axial Stenosis and Lateral Recess Stenosis are related conditions.

Axial Stenosis commonly occurs in the lumbar spine region of the lower back at vertebral levels L2/3 & L3/4 and in the neck at vertebral levels C4/5 & C5/6. Lateral Recess Stenosis however commonly occurs in the lumbar spine region of the lower back at vertebral levels L4/5 & L5/S1, and in the neck at vertebral levels C5/6 & C6/7. The significant benefit offered by aware state diagnosis (see below) is that it enables the surgeon to accurately target the problem area and to deliver specific treatment focused only upon that problem area. The first requirement for accurately diagnosing Axial Stenosis therefore is to actually rule out Lateral Recess Stenosis as the causal condition or define whether there are indeed both pathologies present and actively causing symptoms at the same level or at different levels.

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.

What is wrong with conventional surgery?

Conventional surgical treatments encompass a wide range of possibilities; all of which have a place but are not necessarily efficacious. Please note however that this is a general guide and that individual cases should be correctly assessed by a competent surgeon in order to decide upon the most appropriate treatment. The following brief guide is included so that the lay person can gain a basic understanding of the options they may be offered.

  • Laminectomy is the removal of substantial areas of bone from the ‘Lamina’ or vertebral arch. It releases space within the spinal column but also removes muscle purchase points and can lead to extensive scarring on local and related tissues within the spine. In many cases, it can also lead to increased spinal instability and the need for spinal fusion at a later date. Laminoplasty is a process whereby the Lamina arch is split apart to increase the volume of available space. The resultant gap or split is maintained by bone grafting or by the insertion of tissue or implants. These techniques fail to provide sufficient access & liberation of the nerves laterally through the foramen.
  • Medial Facetectomy is the removal of the inner part of the joint on either side of the vertebrae to preserve as much of the Lamina arch as possible. Endoscopic Medial Facetectomy is a similar process, but is facilitated by the insertion of a telescope. However it offers only limited access and can only be used to treat a small area. These techniques fail to provide sufficient access & liberation of the nerves laterally through the foramen.
  • Inter-spinous spacers can be inserted using keyhole surgery at the ‘posterior’ or back of the spine between the spinous processes in order to restore some of the original posterior spacing of the vertebrae in cases where disc height has been lost through degeneration. Often, these spacers take the form of a cushion or a metal implant. By spreading the spinous processes this attempts to restore some segmental height, re-tension the spine and enlarge the foramen. The outcome depends in part upon the amount of residual disc that is present and may alter the posture of the lower lumbar spine and can not be applied at the L5/S1 level. The technique will fail to ease symptoms if the nerve is significantly tethered in the foramen.
    All of the above are ‘posterior’ approaches in the sense that surgery is carried out from the back of the spine. The major problem with these techniques (with the exception of the interspinous spacers) is that they cannot adequately clear the ‘Foramen’ or spaces within the spinal column as they only permit removal of material from inner areas and it is within the lateral areas that the greatest need exists. This means that the surgeon may address too many levels in an ‘overkill’ operation and still not adequately solve the problem.

What is aware state diagnosis?

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”.

How is Axial Stenosis treated?

Following aware state diagnosis, the patient is treated using Endoscopic Transforaminal Endoscopic Lumbar Decompression & Foraminoplasty (ELDF) to liberate the exiting nerve leaving the canal at the specific level and release the nerves descending in the spinal canal. ELDF facilitates the accurate clearance of scarring around the nerves in the foramen and in the spinal canal. ELDF liberates the exiting and descending nerves from tethering to the disc, the facet joint margin and specific ligaments (Superior Foraminal Ligament) and from bone spurs arising from the facet joint margin or vertebral body margin. As the surgeon opens up the doorway using core boring tools this opens up the side of the spinal canal so decompressing the descending nerves further. After this, bulging of the disc wall can be removed by Endoscopic Intradiscal Discectomy thus increasing the volume of the spinal canal. The surgeon can also seal leaks and tears in the disc wall which may be contributing to the irritation of the nerve in the foramen and those in the spinal canal.

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 outcome. 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 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.

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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