Lumbar disc herniation

Zeljko Kojadinovic, MD- Neurosurgeon and Pain Specialist

Lumbar disc herniation

Zeljko Kojadinovic, MD- Neurosurgeon and Pain Specialist

There are three types of processes on the spine that can be treated surgically. These are: a) pathological changes that put pressure on nerve structures (nerve roots – one or more of them); b) instability of parts of the spine, and c) another, surgically resolved, cause of pain.

The most common pathological changes that put pressure on nerve structures occur as a consequence of degenerative changes within parts of the spinal column (disc herniation, spurs from vertebrae and joints, ligaments hypetrophy). Tumors, infections, congenital anomalies, or injuries are less common. These changes most often, in addition to pain, also cause some neurological damage.

Degenerative changes can affect the discs. Over the years “material fatigue” occurs as a consequence of the load and/or poorer composition of the disk (a disk less resistant to repeated loads can be hereditary). The disc consists of a central part (nucleus pulposus) that serves as a shock absorber, is richer in water and has a peripheral ring that strengthens the disc. In the case of degeneration, the central part loses water, starts to become fragmented, and the peripheral ring breaks. Because of that, the central fragment can protrude backward through the fractured ring and compress nerve roots. (as is the case in the picture below). This process can be diagnosed as disc herniation, disc protrusion, disc extrusion, etc. In clinical terms compression on nerve roots may correspond to diagnoses of radiculopathy, cauda equina, etc. The discs are named after the vertebrae between which they are located: L1-L2, L2-L3, L3-L4, L4-L5 and L5-S1. Disc diseases are very frequent around the world in different countries (USA, Nigeria, Kenya, Tanzania, Germany, Japan, etc.)

The figure shows cross-sections of 2 lumbar discs. On the left is a healthy disc with no changes in the central (yellow) part of the disc. On the right, there is a separation of the central part of the disc and its passage through the crack of the peripheral ring. The part of the disc that “leaked” backward exerts pressure on the nerve roots (pink). This leads to lumbosacral pain and disturbances in the sense of touch and to muscle weakness in part of the leg innervated by that nerve root.

Figure: The nerve root pinched as pictured in the previous figure protrudes beyond the spinal column and forms the sciatic nerve (No. 3). Due to pinched roots, pain and numbness spread along this nerve, i.e., along the back of the leg towards the foot. Weakness and numbness occur in the foot.

This picture shows a profile section of the thoracic spine and the progression of a disc herniation that puts more and more pressure on the spinal cord. The disc is in front, and the spinal cord is behind it.

These images show magnetic resonance imaging of the lumbosacral spine – a sagittal-section on the left and a cross-section on the right. The red arrows indicate the part of the disc that leaked and puts pressure on the nerve roots. Disc herniations are most common at the L4-L5 and L5-S1 levels.

Vertebral degeneration leads to a bony narrowing of the canal called spinal canal stenosis. Stenosis can be of the central part of the spinal canal or of the lateral parts (lateral recess). The narrowing is most often caused by various bone growths (osteophytes) from parts of the vertebrae (Terms related to this are spondylosis, spondylarthrosis, osteophytes). These osteophytes can also put pressure to nerve roots.

This figure shows a cross section of the thoracic vertebra. On the left, the spinal canal of normal width can be seen, and on the right, the canal is narrowed by bony osteophytes marked by arrows.

Stenosis is more common in the cervical spine, and disc herniation in the lumbar spine. The thoracic spine is less often affected by these processes. Stenosis most often begins with pain when walking (neurogenic claudication), while disc herniation causes sciatica from the beginning.

Symptoms

Diseases of the lumbar spine are numerous and mostly begin with various pain syndromes. The pain is mostly in the form of low back pain and/or sciatica. In advanced disease, and sometimes from the very beginning, there may be signs of damage to the roots (radix) of the leg nerves (radiculopathy). Radiculopathies are manifested mostly by pain, numbness and weakness of the legs. If numbness occurs, it is most often localized on the foot (the patient has numbness on the inside or outside of the foot.) The patient may also have difficulty walking on the toes or heels of one or both feet.

Problems with stenosis of the lumbar part of the spinal canal initially appear only during a long walk. They occur in the form of pain, numbness and/or weakness that occur after walking a certain distance and stop when the patient stops or sits down. They are called neurogenic intermittent claudication. They are the result of pressure on the nerve roots, which is especially increased when walking (venous dilatation in the spinal canal, increased spinal canal stenosis, etc.). They must be distinguished from claudication (pain when walking) which occurs due to narrowing of the arteries of the legs.

Painful syndromes in the lumbar spine can be different from disc protrusion.

Neurological deficits can take the form of damage to the nerve roots for the legs due to pressure on them (radiculopathy) or cauda equina syndrome (damage to most nerve roots for the legs and pelvis). Lumbar radiculopathy is most often manifested by pain that spreads from the lower back, through the back of the leg, to the feet; numbness and tingling most often in the foot; weakness of one or more groups of muscles on one or both legs, followed by muscle atrophy (most often the lower leg muscles are affected and the movement of the feet is weakened). Cauda equina syndrome is most often manifested by weakness of the lower part of the legs, retention or involuntary leakage of urine and stool (incontinence). This is a difficult and very urgent condition.

Diagnosis

If any of these symptoms occur, the patient will be referred to a specialist (neurosurgeon, neurologist or physiatrist) who will examine him neurologically and then determine what additional tests may be needed. The most common additional examinations are X-ray of the spine in various projections; electromyography (EMG, EMNG), which tests the condition of nerves and muscles; somatosensory evoked potentials (SSEP), which tests the condition of the spinal cord and nerves; or imaging of the spine by computed tomography (CT of the spine), or more often by magnetic resonance imaging (MRI). Other diagnostic methods may also be considered.

The number of conditions that can be diagnosed is large. The process which leads to a different level of diagnosis in the same patient can be next: degeneration and stress of the disc lead to “leakage” of the disc (disc protrusion), which presses on the nerve root and damages it (radiculopathy), and this is manifested as leg pain (sciatica). So, this patient will receive a diagnosis of LBP and sciatica from a doctor, a diagnosis of radiculopathy from a neurologist, and after a magnetic resonance imaging of the spine, a diagnosis of disc herniation will be arrived at. Only all three of these diagnoses combined reflect the true condition of the patient. This clinical picture is specific to disc herniation.

Treatment of degenerative diseases of the lumbar spine can be symptomatic, physical or surgical. The goal of treatment is to “move away” the part that puts pressure on the nerve structure. If the patient has a diagnosis of disc herniation, the main question is whether or not to perform surgery.

In practice, the following scenario usually occurs: Low back pain and/or leg pain (lumbago or sciatica) is treated with analgesics and muscle relaxants. If this does not help, the patient undergoes physical treatment. If there are no results, a magnetic resonance imaging of the spine is done. In the case of a disc herniation, since the pain has been going on for a long time and does not pass, surgery is indicated.

However, at this stage of the disease, if there is no neurological deficit (muscle weakness), more accurate pain treatment should be performed. After gathering detailed information about all the characteristics of the patient’s pain, an individual combination of medications should be prescribed. This approach is very effective (pain is resolved in over 80% of such cases). These medications reduce inflammation around the nerve roots, achieve painlessness and enable relief and recovery of the nerves. In this way, surgery can be avoided in most disc herniations, but this is not always possible.

Also, pain intervention procedures may be indicated. These are specific interventions that are performed with the help of X-ray or ultrasound imaging, usually in the form of injections, and do not require hospitalization. Therefore, disc herniation surgery should not be performed before applying these methods. Only 10% of disc herniation require surgery.

Figure: Injection of medication in the source of pain navigated by ultrasound.

If you have been given a neurosurgical diagnosis and suggested operative or non-operative treatment, you can consult us if you have any doubts. This will make it easier for you to accept the proposed treatment from your doctor and, since you have no doubts, the treatment will have a better result or you will opt for a different type of treatment. We will explain whether we think surgery is indicated, which operative methods exist, where in your country such surgeries are performed, what their risks are and how to reduce them. We will also answer all your questions.

Surgical treatment of disc herniation– In the case of lumbar disc herniation, surgery is indicated in only 10% of cases. It is performed if a disc herniation is detected on the image, and there is greater neurological damage or the pain is long-lasting and does not improve through conservative treatment (indication appears after 6 weeks of pain treatment, especially if the disc is large and there is no more space in the spinal canal to move the disc from the nerve root). The most urgent cases involve numbness, pain and weakness in both legs, with urination and stool problems. This is called cauda equina syndrome and requires urgent surgery within 48 hours.

Disc herniation surgery involves removing the part of the disc that has protruded out and also the parts of the disc that can protrude (the central degenerated part of the disc). There are different possible surgery techniques. The operation is performed through a skin incision in the middle of the back about 3 cm long. The surgery does not involve cutting through muscle, nor the removal of much of the vertebral bone. The operation is performed by a microscopic technique or with the help of an endoscope. In addition to removing the pressure on the nerve root, it must be done in such a way as to prevent the formation of a large scar around the nerve root, as well as preventing instability of the vertebrae. This can be accomplished with a minimally invasive surgical technique.

The patient is advised to get up the day after the operation, with the help of a physiotherapist. The physiotherapist then explains techniques for getting up, bending, lying down, exercising, etc. In the immediate period after the surgery, the pain in the leg usually disappears or significantly decreases, but pain in the area of the wound often appears. It can increase up to the 4th day after the surgery and is the result of tissue swelling at the site of surgery. Short-term leg pain may also occur. These pains are not the result of nerve pressure and are successfully treated with analgesics. The patient usually stays in the hospital for a few days. On the ninth day, the sutures are removed and physical treatment begins in the department of physical medicine.

Figure: Penetration of the grasping instrument, with or without removal of part of the posterior wall of the spinal canal, to enter the canal and remove the part of the disc that exerts pressure on the nerve root.

Endoscopic disc removal is indicated in most disc herniations. It enables the removal of pressure on the nerve root without a classic incision on the skin and, most importantly, without damaging the muscles that maintain the stability of the spine, as well as without damaging the bone elements of the vertebrae. The benefits are clear from the low incidence of postoperative problems, and the patient is pain-free and able to get up on the same day as the operation. Complete treatment lasts 2-3 days.

In case there is a disc herniation that meets special conditions, minimal disc intervention can be performed (PLDD, PDD, percutaneous disc decompression). It allows the pressure on the nerve caused by the disc herniation to be removed through a skin puncture, without an incision or surgery. Different devices are used: laser, plasma or mechanical decompressor. All of them remove the degenerate material of the central part of the disc between the vertebrae and thus allow the “leaked” part of the disc to return to its socket and stop pressing on the nerve root. All these devices are equally effective.

Indications for this intervention are:

The cause of back and leg pain is a disc herniation that leads to pressure on the nerve root
Conservative methods of treatment have not yielded results (Any intervention can have side effects and complications that should be taken into consideration. Complications are very rare in both this intervention and classic surgery.)
There is no significant acute impairment of nerve root function with muscle weakness or sphincter disorder, and
A disc herniation has particular anatomical features (as seen on a magnetic resonance imaging of the spine) that ensure that this intervention will be successful.

Only a minority of disc herniations fulfills these criteria.

If there are real indications for this intervention, it has the following features:

It is performed under local anesthesia
It does not require an incision
It is not painful
It lasts about half an hour
Success is achieved in 90% of cases
A hospital stay is usually unnecessary afterwards
In a large percentage of cases success is seen on the same day.

Image: Cannula inserted in a disc with disc protrusion and intact posterior ligaments. Part of the disc inside are shrunk by laser, allowing the intact posterior ligament to push the protruded part backwards away from nerve root.

Replacement of a disc with an artificial one (lumbar disc prosthesis) is much rarer than in the cervical spine. The indications for these interventions are controversial, and long-term results are not yet known.

In the case of stenosis, most of the posterior wall of the spinal canal must be removed by an operation called laminectomy or laminoplasty.

Spinal instability is most often the result of injury or degenerative changes. It involves any change in the relationship between the vertebrae that leads to postural disorders, pain and/or neurological damage. If any of these problems are present, the type of instability must be diagnosed by X-ray, CT and MR images. After that, we can decide whether to treat the instability surgically and, if so, by which method.

This picture shows the instability that is manifested by the sliding of the last lumbar vertebra forward (spondylolisthesis). If it causes problems, stabilization is indicated, as in the following figure.

Figure: Stabilization of the lumbar vertebrae with screws that are screwed into the vertebrae and connected with metal rods. This prevents further movement of the vertebrae, relative to each other, and they can return to their normal position.

Prognosis

In well-chosen cases, the pain is successfully resolved surgically (disappears or is significantly reduced) in 90% of cases. If the operation is performed on time, the damage to the nerves (weakness, numbness, clumsiness) is significantly reduced.

Surgical treatment removes pressure on nerve structures and sometimes stabilizes the spine. This reduces pain and prohibits further deterioration of nerve structures. The damaged nerves recover to a small extent immediately after the pressure on them is removed. Recovery of residual neurological deficits (muscle weakness, numbness, clumsiness) requires time and additional therapy. Usually, 75% of recovery occurs in the first 6 months. If the neurological damage was greater and lasted longer, especially in the elderly, a more permanent deficit may remain.

With pain treatment and surgery, physical treatment and changing the patient’s habits are important. Support for nerve tissue regeneration involves the use of various medications. These drugs are often expensive and their therapeutic effect is not crucial, and often not even proven (various B vitamin preparations, OHB-12 injections, etc.).

There are numerous methods of physical treatment, and we emphasize the importance of kinesitherapy, while educating patients about risk factors. In addition to it, there is electrotherapy, magnetotherapy, laser, heating, massage and more alternative methods – acupressure, chiropractic, acupuncture, etc. These alternative methods of treatment are more common in some countries than others. It is important to know that the therapist must be educated and professional for these methods as well, and that these alternative methods should not be forced when there are more successful methods of treatment available. It is often not clear to patients that these methods can also have contraindications and harmful effects.

Recurrence of disc herniation and recurrent pain after disc surgery

Recurrence of disc herniation can occur at the same or adjacent level from the previously operated one. Back pain after surgery is called Failed back syndrome and its cause needs to be established. As with the first painful phase, the cause of the pain may require surgical or conservative treatment. During the first disc herniation operation, the surgeon removes everything that has leaked from the disc space and that can potentially leak, leaving what looks like a healthy disc. No one can prevent further disc failure, and new disc herniations occur in 10-15% of cases. It does not mean that every recurrent sciatica is a relapse (most of them are not). If the neurosurgeon suspects a new compression of the nerve root, he will indicate an MRI scan of the spine, but, this time, before and after giving intravenous contrast. If imaging is done without contrast, we are often unable to assess whether there is a disk fragment within the scar from an earlier operation. Since there is now a scar around the nerve root from the previous operation, it is enough for even smaller pieces of the disc to protrude in the reduced space of the spinal canal to cause problems. Re-operations at the previously operated level are very technical and should be indicated and performed by a neurosurgeon for whom this is an area of expertise.

Some pain remains after the operation, and in about 25% of cases the pain can not be solved with surgery. In those cases pain treatment is indicated by an expert who is good in pain anatomy and who can determine the real cause of the remaining postsurgical pain.

Problems can remain due to the damage already caused to the nervous structure, but also due to the associated causes of the pain (not related to disc herniation). They involve pain that is not caused by pressure on the nerve root or instability, as mentioned in the introduction. These are, for example, myofascial pain, chronic pain from previous nerve root damage that lasted for a long time, and other types of pain. In addition to this, previous risk factors remain after the operation: extra weight, weakness of the muscles that stabilize the spine, improper movements and lifting of loads, improper posture, etc.

A precise pain diagnosis in the first place requires determining which anatomical structure (specific joint, muscle, tendon, nerve, etc.) is the source of postoperative pain. After that, in order to treat it, the question is which pathological process takes place in it. This can be achieved only by gathering all relevant information about the patients’ pain and all other symptoms. Only experts know what information is relevant and how to interpret it. Over 50% of the sources of pain are not detectable by any recordings. Therefore, the most common mistake is to persistently look for the cause of pain on repeated MRI scans, X-rays, CT scans, etc. It either cannot be found on them, or some changes can be interpreted incorrectly as the source of the pain. After determining the real cause of the postoperative pain, an individual combination and dosages of medication can be prescribed. This combination of medication is always individual and should be adjusted in regular contact with the patient over the first 6 weeks. At the beginning of this period the pain should be significantly reduced or completely solved. It should remain so to the end of the 6 weeks in order to achieve long-lasting results. To provide this during this period, the doctor must be available to the patient at any time so that he can easily contact him if the pain increases.

In conclusion before any surgery if, postsurgical pain is the only symptom, more accurate pain treatment should be performed first. After gathering detailed information about all the characteristics of the patient’s pain, an individual combination of medications should be prescribed. This approach is very effective (pain is resolved in over 80% of cases this way).