What exactly is a High Intensity Zone?
If you have a High Intensity Zone (HIZ) then you are suffering with an area in a ‘disc(s)’ of soft tissue which separate the vertebrae in the spinal column, which on the MRI scan has increased intensity. It may be described as an Annular Tear. The HIZ may represent:
- An area of healing (Granulation tissue) within the disc and wall of the disc.
- An accumulation of breakdown products within the disc and disc wall which may or may not be irritant to neighbouring structures.
It may be associated with bulging of the disc wall (Disc Protrusion), leakage of products from within the disc and or a small tear in the wall of the disc.
The origin of these HIZ may be multi-factorial. They may arise as:
- A pull-off injury of some of the disc wall fibres from the verbral body margin during a flexion and rotation injury. This may be due to a single or repetitive injury. Repair commences and permeates in to the disc wall and disc contents as granulation tissue containing fibrous tissue and blood vessels. The granulation may mature and form a cyst and fluid collection.
- A gradual progression of the internal degeneration within the disc, forming little fluid collections in the disc which gradually amalgamate to form fissures which reach to the back wall of the disc. Here they follow serpiginous pathways spreading round between the leaves of the disc wall or accumulating in a collection of fluid. These canals eventually become lined with endothelium (same cells which line the veins).
- The fluid collection may leak gradually through the remaining disc wall slowly or the disc wall may burst and the contents will leak more frankly.
The effects of the HIZs depends on the noxious degree of the contents and the direction of flow of these breakdown products. They appear to range from non-irritant to highly painful.
Where does it hurt?
A High Intensity Zone or bulge can occur anywhere along the length of the spinal column from the neck to the lower back. The condition most commonly arises in the neck (cervical spine) or lower back (lumbar spine).
The pattern of symptoms is often one of an initial burst of pain in the back or neck which may be disabling for a number of days and resolves. It recurs again on an increasingly frequent basis ultimately resulting in residual neck or back symptoms between more serious outbursts of pain. As degeneration proceeds the patient develops various combinations of back, buttock and leg pain, numbness, muscle weakness and often widespread “Dysaesthaesia”. This takes the form of diffuse often intense pain across the back, spreading up to the thoracic spine, down to involve the sacrum and coccyx, deeply in to the pelvis or perineum and extensively down one or both legs. The symptoms may present as pins and needles, cold or scalding water or a sense of ants crawling up and down the body in these territories.
How is a High Intensity Zone diagnosed?
One of the complications in diagnosing a High Intensity Zone is that whilst the apparent pain or problem may manifest itself in one part of the body, the actual cause of the problem can lie in a different part of the spinal region. For this reason, medical professionals pay close attention to the symptoms as a first step in evaluating what the problem may be, before moving on to more focused diagnostic procedures. Unfortunately many physicians will reach for a psychological explanation for these symptoms.
In fact the MRI scan may show the presence of a HIZ, annular tear or dehydrated (“Black”) disc. The source can be confirmed by Spinal Probing and Discography in the aware state with the symptoms being compounded by the presence of scarring induced by a reaction to these leaking products.
Is the pain in your lower back?
Various combinations of pain in the lower back, buttock, groin one or both leg(s) can arise either from irritation within the disc itself. When the HIZ causes noxious breakdown products to be ejected on to the adjacent nerves, the pain spreads below the knee (termed Sciatica) and. pins and needles develops sometimes with a feeling of cold or scalding water or a sense of ants crawling up and down the leg. As the nerve becomes more swollen weakness may develop resulting in “foot drop” (difficulty lifting the toes and foot up) or weakness when pushing off with the foot.
Is the pain in your neck?
HIZs and leaking discs may cause various combinations of neck pain, headaches and pain in the face, shoulders, arm(s) and hand(s) It may also cause numbness or ‘pins & needles’ in the face, shoulder, arm or hand and may also be associated with weakness of shoulder, elbow, wrist or hand movements. Any one of these symptoms, or a combination of them, can indicate a High Intensity Zone and again may be associated with a feeling of cold or scalding water or a sense of ants crawling up and down the arm(s).
How is the High Intensity Zone treated?
In many centres HIZs, Annular tears and leaking “Black” discs are ignored. This has arisen because a UK found that discography was not always painful in patients with HIZs. Unfortunately this study did not probe the contents of the foramen or structure adjacent to the HIZ or take in to account the often cyclical nature of the decompression of the HIZs. Where they have recently discharged their contents then discography may be relative pain free as is the patient during such interim episodes, In addition an American radiological MRI scan study noted that many HIZs had disappeared after a year and concluded that all HIZ resolve in a year. In fact what had happened was that the HIZs were now discharging their fluid contents and no longer displaying the high intensity zone on the scan. Pathology studies show that once established HIZ develop vascular linings to the fissures and will therefore not resolve.
Treatment in the early stages.
The major symptoms arising from the initial attacks generally settle down between episodes and treatment during this period should be focused upon reducing the irritation. This may include: anti-inflammatory drugs (Steroids or Non-Steroidal Anti-Inflammatory; therapy such as Ibuprofen, Diclofenac or Acemethacin); and Muscle Balance Physiotherapy to correct the posture and maintain mobility.
Treatment of the established HIZ.
Once the HIZ becomes more established then the alternative treatment pathways are:
- Conservative therapy consists of Muscle Balance Physiotherapy, injection, Cognitive Behavioural Therapy and coping courses, plus a restricted lifestyle, and the hope that the symptoms will abate over time.
- Conventional Open Surgery, carries greater risk than conservative therapy and cannot guarantee success. The surgical options are tabulated below and details of these treatments may be explored through the list on the left.
- Endoscopic Minimally Invasive Spine Surgery has shown encouraging results in over 80% of 4,300 procedures carried out. This includes a number of patients with HIZs and on occasion concurrent Slipped discs, Failed Back Surgery, Failed Fusion Surgery, Spine Instability, Chronic Lumbar Spondylosis and Back pain, Lateral Recess Stenosis and Axial Stenosis, Spondylolytic Spondylolisthesis and Disc infections. In addition, our current and yet incomplete survey of patients operated upon 10 years ago is proving surprisingly encouraging.
Comparison of available surgical procedures
|Success @ Year 2
|6% (Recurrent Protrusion 3 – 17%)
|Leg pain but not back pain 90%
|8% (Instability and scarring)
|Poor data @ 75%
|11 – 18% (International Controlled Trials)
|Total Disc Replacement
|16 – 45%
|Endoscopic Minimally Invasive Spine Surgery (Transforaminal)