*7.3.1.3 Spondylodiscitis*

An infection and inflammation of the endplates of the vertebrae, as well as the joining intervertebral disc. It commonly occurs in sepsis, post-tonsillectomy, urinary tract, gastrointestinal and respiratory tract infections. The most common organisms are staphylococci (40–60%) and tuberculosis (20%). **Figure 8** demonstrates a case of active and healed spondylodiscitis in one patient.

#### **Figure 8.**

*Active spondylodiscitis at the level of LIII-IV and healed spondylodiscitis at the level of L II-III can be seen on both T1 and T2 sagittal images. Destruction of the disc and ossification of the two adjacent vertebral bodies are noted at the level of LII.*

#### *7.3.1.4 Spinal epidural abscess*

Epidural abscesses are often complications of invasive spinal interventions, but spontaneous cases can also occur due to hematogenous spread or adjacent infected sites. The risk factors are diabetes mellitus, HIV, osteomyelitis, urinary tract infection, sepsis, soft tissue infections and spinal abnormality. *S. aureus* is the most common causative agent. The infection can come from contiguous areas, through hematogenous spread and from unknown distant locations as well [15, 17, 18].

Pain and muscle spasm are the most common symptoms of spine infection and the patient can be bedridden. In half of the cases, fever is the systemic manifestation of infection and early diagnosis is hindered by the fact that 30–70% of patients with spondylitis/spondylodiscitis do not show any signs of prior infection. Radicular pain and neurologic deficit are rare finding at the beginning but as a complication or progression of the situation serious neurological symptoms can occur [17].

Prevalence of spinal epidural abscess based on localization is 35% in thoracic region and 48% at lumbar region. Laboratory findings include elevated erythrocyte sedimentation rate and C-reactive protein, in about 40% of cases there are total or PMN leukocytosis [19]. X-ray shots are not very informative for diagnosing epidural abscesses, after 3–4 weeks the inflammation starts spreading around and degenerating the adjacent bony vertebra, and it is only then when destruction of bony parts can be visualized on X-ray shots; X-ray does not rule out the presence of a space occupying lesion in the spinal canal and therefore, post Gadolinium MRI scans are necessary to have a precise diagnosis. In cases where MRI scans are unavailable then CT scans or myelography can be done to gain more information. MRI scans remain the gold standard for confirming diagnosis when spinal epidural abscess formation is suspected. Epidural abscesses appear hypointense on T1 sequences and hyperintense on T2 and STIR sequences. Rim enhancement in post Gd scans can also be visualized. In **Figure 9** an epidural spinal abscess can be seen at the level of L IV – SI; Surgical excision and drainage of the abscess was done along with intensive iv. antibiotic treatment.

#### *7.3.2 Granulomatous infection*

Infectious diseases of spine which is caused by bacteria, fungi and parasites and it is accompanied by formation of granulomas. Granulomas are mixture of transformed macrophages, matrix and other inflammatory cells. Most cases are due to hematogenic spread of microorganisms to the spinal structures but spread from adjacent infected tissues are also a common pathway of infection [20].

#### *7.3.2.1 Tuberculous infections*

The spine is the most common site of skeletal tuberculosis and *Mycobacterium tuberculosis* is the most common causative agent. The lower thoracic spine is the segment frequently involved in tuberculous infections. The infections is a result of past hematogenous foci, contiguous disease or lymphatic spread from pleural disease, it gradually enlarges and spreads to involve two or more adjacent vertebrae by extension beneath the anterior longitudinal ligament or directly across the intervertebral disc.

X-ray shots reveal anterior wedging of two adjacent vertebral bodies with destruction of the intervening disc. On MRI scans post Gd sequences show subligamentous, Dural or discal contrast enhancement whereas T1 sequence shows a hypointense and T2 sequence a hyperintense marrow. Contrast enhanced MRI is the preferred modality of choice and if unavailable then contrast enhanced CT scans are the modality of choice.

*Infections in Neurosurgery and Their Management DOI: http://dx.doi.org/10.5772/intechopen.99115*

#### **Figure 9.**

*A case of spontaneous epidural abscess formation, the patient was referred to the neurosurgical word due to progressive paraparesis; lab test results revealed leucocytosis and elevated CRP and PCT values. MRI scans show diffusion restriction (upper left image – STIR sequence) in the epidural region at the level of LIV-SI as well as LIV disc and LIV LV vertebral bodies, the post Gd T1 image (upper right) shows contrast enhancement of the lesion in the periphery. Control MRI scans after 6 weeks (lower images): On STIR (lower left image) sequence significant reduction of diffusion restriction is seen, T1 Contrast scan (lower right image) show no sign of contrast enhancement. The presence of hemangiomas at the level of LI and LIII vertebral bodies are noted.*

#### *7.3.2.2 Fungal infections*

Fungal infections of the spine are rare and occur mainly as opportunistic infections in immunocompromised patients. They form noncaseating lesions. The common fungal agents causing fungal infections are Candida species, *Cryptococcus neoformans* and Aspergillus species. In fungal vertebral osteomyelitis epidemic fungi, such as Coccidiodes immitis and Blastomyces dermatitidis are the typical causative agents.

#### *7.3.2.3 Parasitic infection*

The parasites that have been reported to cause infections of the spine are Echinococcus granuosus (hydatid disease), Toxoplasma gondii (toxoplasmosis) and rarely Taenia solium (cysticercosis). The parasitic spine infection is extremely rare, and few cases have been reported in the literature.

### *7.3.2.4 Postoperative wound infection*

Postoperative wound infections after spine surgeries are common complications and their occurrence rate vary depending on the type and site of surgery. Simpler surgeries such as lumbar microdiscectomy or sequestrectomy have lower rates of postoperative infection (~0.6–3%) whereas more complicated surgeries such as instrumented fusions have a higher occurrence rate (~6–18%). If left untreated or not diagnosed properly and in time, long term complications such as pseudoarthrosis, spinal deformities, chronic pain and even in severe cases sepsis and death can occur. Deep wound cultures accompanied by CBC and evaluation of CRP, PCT and ESR helps diagnosing postoperative SSIs. Picture modalities such as contrast enhanced MRI and CT scans are important in adding vital information for proper diagnosis, but they can also be very misleading [21].

Treatment of postoperative SSIs in spine surgery is no exception than other SSIs, early proper diagnosis, targeted antibiotic therapy and in severe cases surgical debridement and/or revision of surgery is needed to avoid long term complications. Sepsis and septic shock can be catastrophic outcomes of SSIs, therefore prompt response after diagnosing SSIs is a vital part of a good prognosis. Screening patients for multi resistant skin flora and proper bathing before surgery alongside with proper disinfection of the surgical site at the time of surgery and keeping an aseptic environment are modifiable factors which play an extensive role in SSIs. Factors such as prolonged steroid treatment, or use of immunosuppressant drugs, DM, chronic autoimmune diseases, alcoholism, malnutrition and acquired autoimmune defects are contributing to a higher rate of SSIs.

#### *7.3.2.5 Spinal infection in the immunocompromised*

As mentioned in Section 3, immunocompromised patients are at a greater risk for developing postoperative infections and spontaneous infections in general. The factors and strategies mentioned in Section 3 management and treating immunocompromised patients are all applicable for spine surgery as well. Patients with immune deficiencies should be considered for rare parasitic, fungal, and bacterial spine infections such as Cryptococcus, Mycobacterium and Echinococcus infections.

**Figure 10** shows a case of spontaneous spondylodiscitis in a patient who was on chronic use of methylprednisolone tablets for treating rheumatoid arthritis.

#### *7.3.2.6 Diagnosis of infection*

ESR and CRP are both good indicators for determining inflammation in the body. ESR is more specific for tuberculosis infection, whereas CRP is an indicator for any inflammatory condition, including bacterial infections. Procalcitonin (PCT), a promising marker to distinguish between bacterial and nonbacterial infection, shows lower sensitivity than CRP in patients with spinal infection. Identification of the causative organism is essential, and if MRI or CT scans are suggestive of spinal infection then direct CT-guided biopsy or blood cultures should be obtained to identify the causative agent and clarify the diagnosis.

#### *7.3.2.7 Imaging*

The characteristics of spinal infection foci on picture modalities are as follow:

• X-ray: endplate irregularities and erosion in the vertebral endplates. Disadvantages: It is only after 2 to 4 weeks that the radiographs appreciate *Infections in Neurosurgery and Their Management DOI: http://dx.doi.org/10.5772/intechopen.99115*

#### **Figure 10.**

*A 40 years old male patient was brought to the emergency department due to sudden loss of lower extremities tone and severe paraparesis. Lab results were in favor of inflammatory process and the MRI scans have confirmed the diagnosis of spondylodiscitis. The STIR sequence (upper left image) shows diffusion restriction in the Th VIII-IX vertebral bodies as well as in the sub ligamental region which is causing spinal cord compression. Post Gd T1 sequence (upper right image) shows contrast enhancement of the lesion). The patient was admitted for acute surgery and first intraoperative CT scan (lower left image) shows the extent of posterior bony decompression (laminectomy) and the on the lower right image the final postoperative control scan is seen after percutaneous transpedicular fixation was done to achieve stability. It is important to mention that multiple lesions in the vertebral bodies were seen which typically assemble hemangiomas, but due to the complexity of this case and the fact that the patient was on prolonged steroid use, septic emboli and Pott's disease had to be ruled out. This was done by taking samples from the lesions and performing PCR, culturing, and sending samples for histopathological examination. All results were in favor of hemangiomas and an ongoing spondylodiscitis.*

any changes. A positive radiograph may help in diagnosis, but a negative radiograph does not rule out the diagnosis of spinal infection.


vertebral marrow water content and micro destruction of trabecular bone. Typical findings in patients with spondylodiscitis are hypointense discs and vertebral bodies in T1-weighted images and hyperintense signals of the same structures in T2-weighted images. Although MRI is the gold standard in diagnosis of spinal infection, there is no pathognomonic finding on MRI that dependably discriminates between spinal infection and possible neoplasm [22].

Being a noninvasive and safe procedure follow-up MRI is good for assessing therapeutic-response and to guide clinical decisions. New MRI methods like diffusion-weighted imaging are useful in spinal cord abscess analysis. Contrast obtained pictures are a must in order to visualize the extent of epidural and meningeal inflammation. Diffusion tensor and fiber-tracking imaging methods are in use for assessing spinal cord integrity in long standing cord compression cases [19].

### *7.3.2.8 Management of spinal infections*

Clinical picture and presentation of spinal infections vary widely, but usually the onset is insidious and axial back pain and spasm are the main symptoms. Fever, chills, weight loss, anorexia and malaise are not always present and neurological deficit presents usually late but may present acutely with epidural abscess formation causing paralysis or cauda equina syndrome. WBC, ESR and CRP are nonspecific, but may be helpful in monitoring the response to treatment.

X-ray and CT scan can show us the bony destruction, it takes a few weeks, but MRI is more sensitive and may show changes, early in the course of the disease. It can include bone marrow edema, endplate irregularity, fluid in the disc space, destruction of bone and adjacent disc, and epidural and/or paraspinal soft-tissue infection and abscess formation.

Nonsurgical Treatment consists of appropriate antibiotic treatment which can result in termination of the infection, but precise bacteriological diagnosis and culturing is required from blood culture or aspirated samples in order to have a target antibiotic therapy which is more efficient. It is important to start antibiotic therapy before significant bone destruction occurs, to avoid any long-standing unfavorable biomechanical consequences and spinal instabilities.

The following steps are required for diagnosing spinal infections correctly early in order to have the best maximized therapy:


3.pain medication

4.Thoraco-lumbar spinal orthosis (TLSO) brace – to reduce pain.

Nonoperative treatment is more likely to yield good results if patients are younger than 60 years, having normal immunologic status and the treatment is started early in the course of the disease.

*Infections in Neurosurgery and Their Management DOI: http://dx.doi.org/10.5772/intechopen.99115*

Monitoring response to treatment is crucial and factors like improvement in pain reduction, muscle spasm, general sense of wellbeing, as well as progressive drop in the inflammatory markers like ESR and CRP are good indicators of sufficient treatment. Repetition of MRI scans can be helpful, but in early phases of treatment (within 4 weeks), after starting antibiotic therapy, it can be misleading, due to the fact that the effect of the antibiotic therapy can only be detected on the tissues adjacent to the spine in this period of time. It is recommended to perform post Gd MRI scans after four weeks of continuous iv. antibiotic treatment [24].

When non invasive treatments fail to achieve proper results, surgical treatment needs to be considered in order to control the disease progression. The fundamental goals are drainage of the pus and debridement of granulation and bony stabilization if necessary. Most cases can be managed non-surgically with antibiotics and immobilization, especially if the patient lacks neurological symptoms and if the spine retains its stability. Accordingly, we have to treat the patient surgically when

1.there is progression of disease despite antibiotic therapy


Decompression of neural elements, removal of inflammatory tissue and infected bone (to decrease bioburden) with instrumented fusion can give the best result.
