1. Introduction

These are tumours (growths) that can originate in the vertebrae, the membrane enveloping the spinal cord, the nerve roots or the spinal cord itself.

They can be classified into the following four categories:

  • Tumours originating from or growing in the vertebrae. They can be metastases of malignant growths elsewhere in the body, and they can lead to pinching or cutting off of the spinal cord by growing around it like a cuff (see Illustration) or even by growing into the spinal cord itself.
  • Tumours originating from the membrane enveloping the spinal cord, called the dura mater.
  • Tumours originating from the nerve roots.
  • Tumours originating from the spinal cord tissue itself (called intrinsic spinal cord tumours, with the growth positioned in the spinal cord itself). The tumours originating in the spinal cord membrane and in the nerve roots are called extrinsic spinal cord tumours, with the growth positioned outside the spinal cord. Extrinsic spinal cord tumours are approximately eight times as frequent as intrinsic tumours.
Anatomy of the vertebrae and the spinal cord

Illustration above:
Anatomy of the vertebrae and the spinal cord. The dural sac (actually a pocket) is cut open so that the hind, or posterior, portion of the spinal cord is visible with the exiting roots and the lateral ligaments that connect the spinal cord to their side. At every vertebra, an anterior and a posterior nerve root come out to the left and to the right of the spinal cord and join a little later to form the entire nerve root. The anterior nerve root arises obliquely out of the front of the spinal cord and contains motor nerve tissue, the posterior nerve root arises obliquely out of the back and contains sensory nerve tissue. In the drawing, the left posterior nerve root is sectioned to show the anterior nerve root more clearly. In normal circumstances, the space between the spinal cord and the dural sac is filled with liquor. In the middle of the transversal section of the spinal cord we can see the central canal, which could be compared to the ventricles in the brain. On the left there are some big enlargements of areas of the spinal cord.

Figure M is an enlargement of the central area, which contains primarily nerve cells as well as glia cells; it shows a glia cell, in this case a star cell (astrocyte) which surrounds a capillary blood vessel with its processes or dendrites. Figure R is an enlargement of a marginal area containing primarily the nerve tissue of the long nerve fibres, next to a single glia cell, in this case an oligodendrocyte. Figure C is an enlargement of the wall of the central canal, lined with ependymal cells characterised by their vermicelli-like flagella.

Schematic representation of spinal cord tumours

Illustration above:
Schematic representation of spinal cord tumours. For a better overview, only one vertebra is shown with the dura mater together with the spinal cord and the tumour in the vertebral canal. The dura mater has been opened longitudinally in order better to show the tumours inside it. Left: extradural (that is, located outside the dura mater) tumour cuff, which is almost always a spreading vertebral metastasis, which in turn is a spreading into the vertebrae of a tumour elsewhere in the body (such as for example in the prostate, breast, stomach or lung). Centre: Intradural but extramedullary tumour, i.e. a tumour located within the dura mater but outside of the spinal cord, usually a meningioma or neurinoma (also called extrinsic spinal cord tumour). Right: An (intradural) intramedullary tumour, a tumour located within the spinal cord (and therefore inside the dura mater) (also called intrinsic spinal cord tumour). This causes the spinal cord to swell; the tumour is usually of the glioma type (astrocytoma or ependymoma).

2. The tumours of the spine and of the spinal cord

As stated earlier, there are various different types of spinal cord tumours. Determination of the type of tumour in each specific case is only possible by means of taking a sample of tumour tissue and examining it under the microscope. This can only be accomplished by surgically removing tumour tissue samples. In many cases, however, an MRI can give a good indication of the type of tumour that may be involved. Whenever metastases are involved, the primary tumour may already be known. The most important tumours are:

3. Tumours of the vertebrae themselves

Metastases. Whenever there is a tumour in a vertebra, it is usually a metastasis of malignant cells originating from a tumour somewhere else in the body. Usually the "primary tumour" (that is the malignant tumour generating the metastases) is in the lung (lung cancer) or in the breast (breast cancer). Other malignant tumours that tend to metastasise towards the spine are prostate cancer and certain forms of blood cancer (Kahler's and Hodgkin's disease). All these tumours can, by attacking the bone in the spine, weaken the vertebrae, causing a collapse of the vertebral body, which in turn can lead to strangulation of the nerve roots and/or the spinal cord itself.

Bone tumours. These tumours are quite rare, and mostly benign. Often they just cause pain symptoms, but over time they can also cause a displacement of the nerve tissue (nerve roots or spinal cord), which will in turn cause neurological symptoms.

MRI overlangse doorsnede borstwervelkolom

Left: The MRI image shows a longitudinal section of the thoracic spine. The arrow points towards an affected vertebra. Behind the vertebrae is the spinal cord (the grey band), surrounded by the cerebrospinal fluid (liquor, white). At the affected vertebra it can be seen how pressure is being exercised on the spinal cord due to the fact that the vertebra has partially collapsed.

Schematic representation of the development of a metastasis.

Right:
Schematic representation of the development of a metastasis.

4. Extrinsic tumours of the spinal cord

  • Meningioma
    Meningiomas are benign tumours originating from the membrane enveloping the spinal cord, called the dura mater. They usually grow on the interior of the membrane and their gradual growth displaces and ultimately compresses the spinal cord. Meningiomas also occur in the skull.
  • Neurinomas
    Neurinomas or schwannomas are also benign. They originate from Schwann cells. These are the "insulation cells" that sheathe the dendrites of the nerve cells. For this reason, these tumours are usually located at the nerve roots arising out of the spinal cord. Thus these tumours are almost always located outside of the spinal cord, but in most cases within the spinal cord membranes. These tumours can as a rule easily be radically removed, although for the most part the nerve section from which the tumour originated must also be removed. Neurinomas can also occur elsewhere on nerves. Within the skull, the best known form is the cerebellopontine angle tumour.
MRI neurimoon

Illustration above:
MRI section in three planes of a very large neurinoma growing out of the left nerve root arising between the first and second cervical vertebra. The tumour grows on the anterior surface along the spinal cord (sc), displacing it to the left and to the back.

5. Intrinsic tumours of the spinal cord

Intrinsieke ruggenmergtumoren 1 Intrinsieke ruggenmergtumoren 2
  • Astrocytoma
    This is a tumour originating from the spinal cord support cells (astrocytes). There are both benign and malignant astrocytomas. The benign kind occurs three times more frequently that the malignant type. In both cases it is often not easily possible to distinguish the tumour tissue from the spinal cord tissue, frequently rendering radical (complete) removal impossible.
  • Ependymoma
    These tumours originate from the cells lining the central canal of the spinal cord (ependymal cells). As opposed to astrocytomas, ependymomas are often well differentiated from the surrounding spinal cord, so that radical surgical removal is more frequently possible. In addition they regularly occur in the lowest portion of the vertebral canal, where there are only the nerve roots.
  • Lipoma
    This type of tumour consists of fat cells, and is mostly seen in connection with spina bifida. Radical removal is not usually possible.

6. Signs and symptoms

Complaints and symptoms will depend on the location of the tumour. They can be caused by direct or indirect pressure exercised by the tumour on the nerve fibres of the spinal cord, or by pressure on the blood vessels of the spinal cord, which may cause an accumulation of blood (swelling of the spinal cord) or a pinching of the blood vessels (spinal cord infarction). Over the long term, pressure on the nerve fibres will damage the nerve tissue. The patient may notice this if he or she feels weak, has difficulty coordinating the movements of arms and/or legs, or if he or she experiences sensitivity disorders (for example a dead or tingling sensation in an arm or leg, or a feeling as if the limb had "gone to sleep"). There can also be problems with control over the bladder and the anal sphincter (urinary and/or bowel incontinence) and impotence problems. Because these are often slow growing tumours (that sometimes develop over several years), the signs and symptoms can develop very slowly and gradually, so that neither the patient nor his or her family may notice them at first. However, it is often the case that the patient (sometimes years before the final diagnosis) will complain of pain in an arm or a leg or in another part of the body (back, trunk). A typical symptom is "night pain" that occurs in a lying down position (during sleep) and disappears when resuming an erect position.

Because spinal cord tumours can occur anywhere along the spinal cord, the signs and symptoms can differ widely. There is no typical combination of complaints, signs and symptoms, so that a diagnosis of "spinal cord tumour" is sometimes not easy to make. For example, compression of the spinal cord up in the cervical spine can lead to paralysis of the arms and legs, while a tumour located lower down in the vertebral canal (for example low down in the thoracic spine) can indeed cause paralysis of the legs, but not of the arms. If nothing is done about the tumour, in most cases over the long term this will lead to total paralysis of the muscles below the segment of the spinal cord affected by the tumour, and to total insensitivity of the same body parts (this is called a spinal cord injury). Vertebral tumours (both malignant metastases and benign tumours of the vertebrae) are frequently associated with (severe) (back) pain, often at the location of the vertebra in which the tumour tissue is growing. However, most of the time back pain, which is a very frequent complaint, is not the result of a tumour.

7. The diagnosis

Nowadays, the examination of choice whenever a patient is suspected of having a tumour of the spinal cord is the MRI. Sometimes, at an earlier stage of the complaint, only a standard X-ray is taken, or a CT scan of the vertebrae. These examinations are mostly not conclusive. A contrast examination by means of an injection of contrast medium into the spine was a common step in the past, sometimes supplemented with a CT scan (after contrast). Currently it is no longer necessary to do a lumbar puncture, as in the meantime most hospitals are equipped with an MRI scanner.

By means of an MRI scan it can often be determined whether the problem is a vertebral tumour, an intrinsic tumour (i.e. a tumour growing in the spinal cord itself) or an extrinsic tumour (originating outside of the spinal cord, but nonetheless leading to displacement/compression of the spinal cord). The exact type of tumour can only be determined by means of removal of a sample of tumour tissue. The sample is then examined by a pathologist under the microscope, whereupon in most cases a true diagnosis can be arrived at. However, to get that far surgery is always necessary.

8. Surgery

Whenever it is believed that a patient may have a tumour of the vertebrae, even if there are no indications of a malignant tumour elsewhere in the body, in most cases surgery will still be necessary in order to be able to make a diagnosis. In such cases, the doctor may select to perform a puncture, mostly guided by a CT scan. Using this technique, the radiologist can introduce a needle into the patient under local anaesthesia precisely at the location of the vertebral tumour and then aspirate a small piece of the growth. This sample then makes it possible to make the tissue diagnosis.

In other cases, more significant surgery (under general anaesthesia) will be necessary if the tumour itself has led to a compression of the nerve tissue. In such cases it is necessary to remove tumour tissue in order to restore sufficient space for the nerve structures. In doing so, it is sometimes necessary to perform whole reconstructions of part of the spine. In certain cases, vertebrae may have to be "radically" (that is entirely, including all tumour cells) removed. The defect thus resulting in the spine must then be replaced with other material (for example donor bone tissue, bone cement, a piece of bone taken from elsewhere in the same patient's body, a metallic vertebral prosthesis, etc.). This is heavy surgery carried out only in special cases, often involving several different specialists at the same time (neurosurgeon, thoracic surgeon, general surgeon). However, most tumours of the vertebrae involve metastases of malignancies already known to both the patient and the doctor. The treatment of such tumours mostly consists only of radiation, and this part of the treatment is carried out by a radiotherapist.

  • Extrinsic spinal cord tumour surgery is always performed under general anaesthesia. The spinal cord does not need to be opened, as the tumour is located outside of it. However, sometimes some manipulation of the spinal cord is nonetheless necessary, for example if the tumour has fastened onto it, or part of the tumour is located on the anterior surface of the spinal cord. Extrinsic spinal cord tumours are usually removed with the aid of a surgery microscope. Tumours originating from a nerve root must often be removed together with the tumour. Most of the time this has no consequences for the patient, because owing to the growth of the tumour the function of that part of the nerve root has already been gradually lost over the period of time during which the tumour was growing. Whenever there is a tumour originating in the dural sac membrane it may be necessary to remove that portion of the membrane together with the tumour itself. The defect thus resulting must then be repaired during the same operation with a piece of man-made material or specially prepared human or animal donor tissue.
  • Intrinsic spinal cord tumour surgery is always performed under general anaesthesia, and the patient is usually lying face down. In certain cases the surgery can also be carried out with the patient in a sitting position (for example if the tumour is located in the cervical spinal canal). The choice of position depends on the personal preferences of the neurosurgeon and the anaesthetist. During surgery, first the spine must be exposed over the area where the tumour is located by bilaterally drawing aside the back muscles. Then the spinous processes and the vertebral arches or laminae must be removed, thus exposing the dural sac. Only once the membrane constituting the dural sac has been longitudinally opened will the spinal cord be visible. Thereafter, in the case of an intrinsic spinal cord tumour the spinal cord itself will also have to be opened. This part of the operation is done under optical magnification using a surgery microscope and special surgical instruments (micro-instrumentation). Opening up the spinal cord often results in mild (but frequently also permanent) sensitivity disorders for the patient. However, this also depends on the place (e.g. in the cervical spine or the thoracic spine) where the longitudinal opening in the spinal cord needs to be made. To remove an intrinsic spinal cord tumour it may be necessary to use special laser instruments and special suction devices, in order, respectively, to disintegrate the tumour or to dislodge it and suction it off with an ultrasound vibrator/suction tube. Of course a sufficient quantity of tumour tissue should previously have been removed to enable the pathologist to make a tissue diagnosis. Intrinsic spinal cord tumours cannot always be entirely removed. This is because the tumour cells grow diffusely throughout the nerve tissue. Removing all the tumour tissue would then irrevocably lead to permanent paralysis and/or sensitivity disorders. Even with extreme care the surgery may be followed by strength and/or sensitivity deficiencies, although in many cases they are of a temporary nature.

9. Complications

Leakage of spinal fluid may occur following an operation in which the spinal cord membrane is opened. Sometimes this fluid may cause a cyst (a blister containing fluid) to develop in the tissue under the skin, which may require removal of the cyst and repair of the leak in the spinal cord membrane. General complications such as infection and bleeding (which could cause compression of the spinal cord) occur occasionally. It is possible that after the surgery the patient may experience greater neurological deficiency than before. This is usually reversible, but not always.

10. After the operation

After an operation in which the spinal cord membrane has been opened, most patients will have to observe bed rest for a few days to prevent any leakage of the spinal fluid between the sutures applied to the spinal cord membrane. Sometimes a temporary drain is fitted at the end of the operation into the dural sac in the lower back. This drain ensures continuous drainage of the spinal fluid. In this way the pressure in the dural sac is kept artificially low to prevent tension on the internal sutures. This promotes adhesion of the membrane, and lowers the risk of developing fluid leakage and/or cysts. After a few days the drain is removed, and the patient can usually start exercising the next day. This is done under the supervision of a physiotherapist, and potentially with the help of an occupational therapist and a doctor specialising in rehabilitation. To what extent the patient will recover depends strongly on the type of tumour found during the surgery, its location (e.g. within or outside of the spinal cord, in a vertebra), the deficiencies that were already present prior to the operation, and how well the surgery went from a technical point of view. Depending on the tissue diagnosis (see above) in certain cases additional treatment in the form of radiation may be necessary (malignant astrocytomas and ependymomas). Nonetheless tumour growth may recur after a certain period of time, potentially requiring repeat surgery.