Spondylodiscite: What is it? Causes, Symptoms, Diagnosis, Therapy and Prognosis of A.Griguolo

Generality

Spondylodiscitis is the simultaneous infection of one or more intervertebral discs (discite) and one or more vertebrae (spondylitis).

Spondylodiscite causes inflammation and deterioration of the spinal components involved.

Spondylodiscite is mostly due to bacteria (in particular, we note the gram-positive and gram-negative pyogenic, and Mycobacterium tuberculosis ); however, it can also be the consequence of fungal or parasitic contamination.

The most common symptoms of spondylodiscitis are: fever, pain and stiffness in the back, neurological deficits, formation of an epidural abscess and spinal deformity.

Spondylodiscitis is a condition whose diagnosis requires numerous investigations, including a disc-vertebral biopsy.

Currently, those who develop spondylodiscitis can rely on both conservative treatment (first line therapy) and surgical treatment (a therapy adopted in the event of failure of the conservative approach).

Short of what the Vertebrae and the Intervertebral Disks are

The vertebrae are the 33-34 irregular bones that, stacked one on top of the other, make up the vertebral column (or rachis ), that is the load-bearing axis of the human body and the seat of the spinal cord (which, with the brain, composes the central nervous system ).
The vertebrae have a different appearance, depending on the section of the vertebral column considered; in general, however, in each of them it is always possible to identify 3 common portions: the vertebral body, the vertebral arch and the vertebral hole;
The intervertebral discs are the circular structures of fibrocartilage, which separate the individual vertebrae between them; an intervertebral disk, therefore, is the element of separation between two adjacent vertebrae.
Thanks to the gelatinous substance contained within them - the so-called pulpy nucleus - the intervertebral discs act as a sort of shock absorber bearings ; their task, in fact, is to absorb the shocks and loads that weigh on the spine.

What is Spondylodiscite?

Spondylodiscitis is the infection of one or more intervertebral discs ( discitis ), combined with the infection of one or more vertebrae of the vertebral column ( spondylitis ).

Spondylodiscitis is an inflammatory condition (inflammation is the result of infection), which produces deterioration of the vertebrae and the intervertebral discs involved.

Spondylodiscitis is a condition that can affect any segment of the spine; however, statistics have shown that, in 60-70% of cases, it affects the lumbar spine (ie lumbar vertebrae and lumbar intervertebral discs).

Causes

Spondylodiscite recognizes its main cause in bacteria and its less common causes in fungi and parasites .

Before going into details of the causes of spondylodiscite, it is necessary to point out that the infectious agents responsible for the condition in question vary according to factors, such as:

The mode of contamination;
The geographical area;
The patient's age;
Risk factors (see dedicated section).

Bacteria that cause spondylodiscite

In the Western world, the bacteria most associated with spondylodiscite are the gram-positive and gram-negative pyogenic bacteria; more specifically, in industrialized countries, the bacteria responsible for most spondylodiscite cases are:

Staphylococcus aureus (or Staphylococcus aureus );
Streptococcus (or Streptococcus );
Coagulase-negative Staphylococcus (or coagulase-negative staphylococcus );
Escherichia coli ;
Pseudomonas ;
Enterococcus (or Enterococcus ).

In developing countries, however, bacterial spondylodiscite is mostly due to Mycobacterium tuberculosis - the bacterium responsible for tuberculosis - and to the bacterium Brucella - the causative agent of brucellosis .

Did you know that ...

Involved in at least 50% of clinical cases, Staphylococcus aureus represents the main bacterial cause of spondylodiscite in the industrialized world.

Mushrooms that cause spondylodiscite

Among the fungi potentially capable of causing spondylodiscite, Candida albicans and Aspergillus deserve a mention.

Parasites that cause spondylodiscite

Spondylodiscite due to parasites is a very rare occurrence.

Among parasites capable of causing spondylodiscitis, Echinococcus granulosus (the etiological agent of hydatidosis or Echinococcus disease ) and Toxoplasma gondii (the infectious agent responsible for toxoplasmosis ) deserve mention.

Spondylodiscite Risk Factors

Spondylodiscite is more likely to arise in the presence of: immunodepression, diabetes mellitus, obesity, cardiovascular disease, hypertension, drug use, cortisone-based drug abuse, advanced age, kidney failure, liver failure, recent history of an operation at spine, urinary tract infections, endocarditis, cancer and rheumatic diseases.

Mode of Contamination of Spondylodiscite

Spondylodiscite can be the result of blood contamination (60-80% of clinical cases), contamination by direct inoculation (about 15% of clinical cases) and contamination by contiguity (about 13% of clinical cases).

Epidemiology

Statistical research shows that:

In the Western world, spondylodiscite has an incidence of 2.4 individuals per 100, 000 people, so it is quite rare ;
Spondylodiscite most strikes individuals over the age of 50 and, although not as frequently as these, individuals between 10 and 20 years;
Spondylodiscitis is 3 times more prevalent in men than women.

Symptoms and Complications

most common symptoms of spondylodiscitis are:

Fever The feverish state is less common in patients with spondylodiscitis due to Mycobacterium tuberculosis ;
Back pain . The precise area varies in relation to the site of infection along the spine;
Sense of stiffness in the spine . This sensation is due to a contraction of the paravertebral muscles of the back;

Motor and / or sensory neurological deficits resulting from a compression of the spinal cord or spinal nerve roots (radiculopathy). Some examples of possible neurological deficits related to spondylodiscitis are: sense of weakness in the legs, paraplegia or tetraplegia of the limbs and loss of control of the anal or bladder sphincter;
Spinal deformity (eg: increase in kyphosis);
Epidural abscess formation. The epidural abscess is responsible, in turn, for symptoms, which vary depending on the place of training; for example, an epidural abscess at the cervical level causes torticollis, cervical rigidity and dysphagia, while an epidural abscess at the lumbar level involves the onset of the so-called cauda equina syndrome.

It is important to note that the severity of a spondylodiscite does not always correspond to the severity of the symptom picture present; in practical terms, this means that you may come across mild spondylodites characterized by severe symptomatology and severe spondyloditis characterized by a few ailments.

Other symptoms

Sometimes, to the symptoms listed above, spondylodiscitis can add further disorders, such as: weight loss, asthenia, hip pain, abdominal pain and alteration of normal lumbar lordosis.

Complications of Spondylodiscite

If severe or not treated properly and promptly, spondylodiscite can, at first, cause extensive deterioration of the vertebrae and intervertebral discs involved, and subsequently lead to vertebral osteomyelitis .

Vertebral osteomyelitis is the infection of the bone tissue of the vertebrae and the medullary cavity, ie the space in which the bone marrow is contained; this possible complication of spondylodiscitis is a very serious medical condition, which, in the absence of treatment, can lead to permanent neurological deficits and, in some cases, even cause death .

Diagnosis

Since spondylodiscite causes somewhat unspecific symptoms (that is, common to many other diseases of the spine), its diagnosis is difficult and always requires the use of a wide range of examinations and instrumental tests.

Going into more detail, the classic process of investigations useful for the diagnosis of spondylodiscitis includes:

Physical examination and medical history . They are used by the doctor to clearly establish the symptomatic picture, to clarify the patient's general health status and to outline a variety of possible causes;
Blood tests, in particular the PCR dosage (PCR = Protein C Reactive). PCR is a protein normally present in the blood, whose concentration increases when an inflammation is underway; therefore, high PCR concentrations are indicative of an inflammatory state.
The PCR assay is a valid test, but not sufficient to diagnose a condition such as spondylodiscitis;
Magnetic resonance and / or CT scan of the spine. They allow the doctor to identify the double inflammation of vertebrae and intervertebral discs, and any abscesses and / or structural deterioration; they are also useful for differential diagnosis (ie the exclusion of those diseases of the spine that cause symptoms similar to spondylodiscitis);
PET and / or bone scintigraphy . They are the best tests to recognize inflammation and other alterations produced by spondylodiscitis, vertebral and discal; it is necessary, however, to point out that these are two tests characterized by a certain invasiveness, as they involve the injection of radiopharmaceuticals which could trigger a serious allergic reaction;
Biopsy of bone and vertebral disc affected by inflammation . It is, obviously, an examination that the doctors carry out after that, with the magnetic resonance, the PET etc., they have evidenced an inflammatory state against the vertebrae and the intervertebral disks.
Also known as a disc-vertebral biopsy, this type of biopsy is fundamental to confirm the diagnosis of spondylodiscitis and to establish with precision, through a microbiological examination, the pathogen at the origin of the condition.

In order to hopefully cure spondylodiscitis and avoid complications, it is essential that the diagnosis of the condition be timely, early.

Therapy

Except for children, currently, those who develop spondylodiscitis can count on either a conservative (or non-surgical ) therapy - which is, in fact, the first-line treatment - both on a surgical therapy - which represents, instead, the extreme treatment, adopted in the face of complete ineffectiveness of non-surgical care.

Spondylodiscite Conservative Therapy: what does it consist of?

Conservative therapy of spondylodiscite is based on the administration of drugs capable of eliminating the pathogen responsible for the condition and on the temporary immobilization of the spinal column affected by inflammation:

The most used drugs in the presence of spondylodiscite are antibiotics, since in most cases the cause of the condition is a bacterium; however, if the causal factor is another, antimycotics (spondylodiscite from fungi) or antiparasitics (spondylodiscite from Echinococcus) may also be used;
Temporary immobilization of the segment of the spinal column subject to inflammation is a useful practice to reduce the stress on the aforementioned segment. It is nevertheless necessary to specify that it has always been a much debated solution, as in some patients it has proved to be a source of unpleasant side effects (eg: it produced abnormal curvatures of the spine).

Numerous medical studies have shown that conservative treatment of spondylodiscitis is all the more effective, the more it is timely (ie implemented when the condition is in its infancy or in any case not at an advanced stage).

To appreciate the effects of conservative treatment, the person suffering from spondylodiscitis must undergo periodic disc-vertebral biopsies .

To benefit from the effects of conservative therapy, the patient with spondylodiscitis may have to wait 4 to 6 weeks ; if after this period of time, there have been no improvements in symptoms, the attending physician is required to resort to surgical therapy.

What is the mode of drug administration?

Generally, administration of drugs against spondylodiscitis occurs intravenously .

Spondylodiscitis Surgical Therapy: what does it consist of?

As a rule, spondylodiscite surgical therapy involves three steps:

The so-called debridement, ie the removal of bone and disc tissue affected by inflammation and therefore deteriorated;
The decompression of the nervous structures possibly involved by the inflammatory state;
Spinal fusion, that is the operation of joining two or more vertebrae together (clearly, the vertebrae subject to spinal fusion are those affected by spondylodiscite).

Currently, to perform the 3 aforementioned operations, the surgical techniques are more than one; the choice of a technique to the detriment of the others is not accidental, but depends on the site of the spondylodiscite and on the possible presence of other problems (eg: epidural abscess, spinal deformity, etc.).

In some circumstances, doctors may find it useful to associate surgery with a drug therapy, based on the administration of medicines capable of eliminating the infecting pathogen.

Spondylodiscitis in Children: which is the most suitable therapy?

In children with spondylodiscitis, the only therapeutic approach that can be adopted is the conservative one (therefore, drugs and immobilization of the spinal column affected by the infection)