Infections in the spine most often occur in the vertebral bodies and discs thus impacting the spinal column. This is often referred to as spondylodiscitis or discitis. Other sites commonly affected include the epidural space, meninges, and the spinal cord. This may ultimately result in epidural abscess, arachnoiditis and intramedullary abscess.1
Most infections of the spine are bacterial in origin with staphylococcus aureus being the most common causative organism. Other common organisms include Streptococcus species, Enterococcus coli, pseudomonas aeruginosa, pneumococcus, Enterococcus, klebsiella and Salmonella. Frequently, the organism may not be identified.1-4
Most common causes of spine and spinal cord infections are bacterial in origin. Causative organisms include the following.
- Staphylococcus species.
- Streptococcus species.
- Salmonella in patients with sickle cell anemia
- E. coli, Proteus mirabilis, and Enterococcus in patients who are immunocompromised.
- Pseudomonas aeruginosa and Brucella in intravenous (IV) drug abusers
- Mycobacterium tuberculosis in patients with spinal tuberculosis (Pott disease)
- Treponema pallidum, which causes neurosyphilis
Immunocompromised patients are at high risk of developing viral infections that can affect the spinal cord. Causative agents include the following:
- Human immunodeficiency virus
- Herpes simplex virus I and II
- Varicella zoster virus
- Human T-cell lymphotropic virus
Fungal infections are extremely rare. However, these may also occur in immunosuppressed individuals. The most common organisms in fungal infection of the spine are Aspergillus and Candida. Common fungal species include the following:
Epidemiology including risk factors and primary prevention
The incidence of spine infections has been increasing, and it is estimated that there are about 6.5 cases per 100,000 each year.3,5 Infections of the spine account for 5% of all bone infections. The mortality rate is estimated at 3%. There is a male predominance, and there is a bimodal age distribution with peaks below age 20 and between ages 50-70 years.6,7
Common risk factors include previous spine surgery, diabetes mellitus, advanced age, intravenous drug use, HIV infection, immunosuppression, history of cancer, renal failure, distant infectious source, and liver cirrhosis.3,7
Spine fungal infections and viral infections of the spinal cord are extremely rare. Most occur in immunosuppressed patients.
There are three common modes of spread that are thought to contribute to the development of spondylodiscitis: hematogenous, spread from contagious tissue, and direct external inoculation. Hematogenous spread is thought to be the most common mode of entry. In adult patients, septic emboli may cause extensive vascular bone infarcts and spread infection to adjacent structures. This results in the classic findings on radiologic imaging of erosion of vertebral endplates, osteolytic lesions and spinal cord compression. If the infection progresses to beyond the bony structures and involves surrounding issues, this may result in paravertebral and psoas abscess. If it spreads into the spinal canal, epidural abscesses, subdural abscesses, and meningitis may occur. Hematogenous infection may spread from the skin due to open wounds, genitourinary tract, respiratory tract, GI tract, or oral cavity.1,3,7
Specific secondary or associated conditions and complications
Neurologic deficits that suggest spinal cord involvement include the following:
- Sensory changes
- Severe Intractable regional and/or radicular pain
- Urinary retention or incontinence
- Bowel impairments
- Saddle Anesthesia
Systemic signs and symptoms of infection often include fever and chills.
Essentials of Assessment
It is estimated that there is an average delay of 2-4 months in making a definitive diagnosis of spondylodiscitis. For this reason, it is of the utmost importance to obtain a detailed history of the patient in order to formulate the differential diagnosis and subsequent treatment plan.6
It is imperative to obtain a full history in order to formulate a differential diagnosis and treatment plan. Patients with spinal infection most often present with a history of severe back pain that Is exacerbated by physical activity.3
- Review of systems should include presence of fevers, chills, night sweats, back pain, radicular pain, weakness, sensory changes, and bladder or bowel changes. Other symptoms of infection should also include persistent pain despite rest and anti-inflammatory medications.
- Significant medical and surgical history includes recent and previous infectious illnesses, recent and previous spinal surgeries, procedures, diabetes, chronic steroid use, cancers, IV drug use, long-term intravenous access, such as peripheral or central lines, and /or indwelling bladder catheters.
- Additional historical elements that can direct diagnostic work up include vaccinations, transfusions, recent travel, drug abuse, and psychosocial history.
Clinical presentation of spinal epidural abscess includes fever, localized back pain, radicular pain, muscle weakness, paresthesia, sphincter dysfunction, and motor paralysis.3
Neurosyphilis involves the posterior columns of the spinal cord, and therefore patients with Tabes dorsalis develop impairment of vibration and position sense and progressive ataxia.
Spinal epidural abscess often presents clinically with fever, focal back pain, radicular pain, paralysis of affected limbs, muscle weakness, impaired sensation and impaired bowel and bladder function.3
Initial physical examination should include assessment of vital signs, inspection and palpation of the spine, manual muscle testing of the bilateral upper and lower extremities, assessment of major reflexes, gait assessment, and sensory examination. An International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) examination should be performed if there is suspicion or clinical findings suggestive of spinal cord involvement.8
Tenderness to percussion of the spine is often present on physical examination.
Patients with spondylodiscitis can present with various functional impairments. The Functional Independence Measure (FIM) and the Spinal Cord Independence Measure (SCIM) can be used to formally assess functional ability in these patients.18
There are several laboratory studies that can be obtained to assist with diagnosis.
CBC is used to assess the white blood cell count which may be elevated. This is a nonspecific marker of infection.
ESR is a sensitive but nonspecific marker of inflammation that may be used to assess for clinical response to treatment. It can be used to assess for active infection and response to antibiotic therapy.
CRP is often elevated in infections of the spine. It can be used in conjunction with the ESR to monitor treatment response and active infection.
Cultures of the blood should be obtained in patients with history of fever and back pain prior to initiation of antibiotic therapy. Cultures have been found to be positive in approximately 60% of cases of bacterial spondylodiscitis.6,17
Biopsy of the infected tissue should be obtained in order to establish a microbiological diagnosis.1,4,7
Initial imaging should include plain radiography of the spine to assess for fractures and other causes of bone pain. Although generally considered to have low specificity in discitis, it may reveal end plate irregularity in severe cases of infection.
CT scan is the best imaging modality to assess for bony changes and may show early changes in the vertebral endplate, bony necrosis, and evidence of pathological calcifications.
CT guided needle biopsy can be used to obtain an aspirate of the disc space or paravertebral soft tissue collections to diagnose spinal lesions in patients who are not candidates for surgical intervention or open biopsy. The highest yield from the biopsy occurs if empiric antibiotics have not been initiated.
Contrast enhanced MRI is the gold standard for radiographic diagnosis of spondylodiscitis. It has high sensitivity and specificity, and MRI can provide additional information to assess for infections of the spine and spinal cord as well as surrounding soft tissue. Gadolinium increases specificity of the imaging because it allows for end plate enhancement which may be the earliest sign of acute spondylodiscitis. T2 weighted imaging allows for improved visualization of infected bone which presents as increased signal intensity.9
Supplemental assessment tools
Nerve conduction studies, electromyography, and somatosensory evoked potentials may be used to assess for peripheral nerve injuries, or myopathies, if the laboratory studies and imaging do not identify the source of neurologic presentation.7
Early predictions of outcomes
Improved outcomes after spinal infection are associated with duration and severity of neurologic impairment, time to initiation of treatment, patient’s age, and medical comorbidities. Neurological deficits at time of initial presentation are one of the most important predictors of outcome.
A 5-year case-controlled study comparing neurological outcomes after spinal epidural abscess and traumatic spinal cord injury was performed by Koo et al.10 The patients in the spinal epidural abscess group were noted to have a higher average change in motor scores and a higher conversion rate to incomplete spinal cord injury when compared to patients with traumatic spinal cord injury.
A 10-year retrospective analysis of infection related functional outcomes in patients with spinal cord injury was performed by McKinley et al.11 They found that patients with infection related spinal cord injury were more likely to have incomplete injuries, had lower changes in their FIM scores, and were older in age at time of presentation when compared to patients with traumatic spinal cord injury.
Environmental modifications depend on the level and severity of damage. To allow for greater independence, assistive devices and environmental modifications at home, work, and/or school (e.g. ramps and elevators, wide doorways, grab bars, environmental control units) may be needed.
Social role and social support system
Information regarding the patient’s support system may be needed to assist with management of the patient’s medical and rehabilitation needs. The family may need to assist with home IV antibiotic administration acutely.
Rehabilitation Management and Treatments
Available or current treatment guidelines
Important factors to consider in the treatment of spinal infections include antimicrobial therapy to treat the underlying infection and preservation of spine stability. Consultation with infectious disease specialists and spine surgeons should be considered. Antimicrobial therapy should be initiated once the microbiological causative agent is identified, and the diagnosis is confirmed. Six weeks of systemic antibiotics is thought to be adequate in most cases of spondylodiscitis. If there is extensive spread into the paraspinal soft tissues, the antibiotic course may be extended to up to 8 weeks. Oral antibiotics may be used once the CRP has decreased by 50%, pain is resolved, and there is no evidence of neurological deficits or spinal instability.12,13 Repeat imaging of the spine is not routinely performed unless the back pain recurs and/or the CRP remains persistently elevated.9
If there is evidence of neurological deficits, surgical intervention should be considered. Indications for operative management include, but are not limited to, symptomatic cord compression with neurologic deficits, spinal instability due to extensive bone destruction, intracanal spinal lesion with mass effect, intractable pain, and failure of conservative treatment. Goals for surgical management include early decompression of the spinal canal, stabilization of the involved vertebral segment, aggressive tissue debridement, and tissue harvesting for culture analyses.14
Coordination of care
Coordination of care with all disciplines in the inpatient setting ensures a safe and effective rehabilitation course aimed toward symptom minimization and/or resolution, functional improvement, and prevention of secondary complications.
Specific needs that should be addressed include the following:
- Equipment: manual versus power wheelchair, commode, shower chairs, Hoyer lift, sliding board, hospital bed, adaptive equipment.
- Home modifications: ramps, railings, grab bars, widening doorway entries.
- Patient and family training, bowel and bladder management, spasticity, transfers, pressure ulcer prevention and treatment, mobility tasks, medication administration Coordination
Patient & family education
It is important to provide education to patients, families, and caregivers regarding diagnosis, management, and possible complications. This will help them identify worsening signs and symptoms of infection and when to seek medical attention. IN addition, better understanding of disease progression and prevention of secondary complications will support good physical and mental health. Some of the most common areas of training include the following:
- Bladder management: determination of the most appropriate method of emptying (indwelling catheters or intermittent catheterization), frequency of device changes, medications to prevent urinary incontinence or leaking through device, signs and symptoms that require clinical reassessment, and urological consultation and assessment, if needed.
- Bowel management: the goal is to implement a bowel program that provides adequate bowel emptying, in a reasonable time (preferably 1h or less) without stool incontinence episodes. This may be achieved by a combination of oral and/or rectal stool softeners, stool stimulants, and prokinetic medications. The patient may also require digital stimulation for upper motor bowel injury or manual disimpaction for lower motor bowel injury.
Cutting Edge/ Emerging and Unique Concepts and Practice
Gaps in the Evidence- Based Knowledge
There are inconsistencies in the literature regarding recommendations for the treatment and management of infections of the spine.
- Pharmacologic treatment duration.
- Timing for surgical intervention.
- Surgical approach/technique for debridement and spinal stabilization.
- Role of tissue sampling in the pharmacologic management
- Sharfman ZT, Gelfand Y, Shah Pryiam, et al. Spinal Epidural Abscess: A review of Presentation, Manaement and Medicolegal Implications. Asian Spine J 2020; 14(5): 742-759.
- Cheung WY, Luk KD. Pyogenic spondylitis. Int Orthop. 2012; 36:397-404.
- Rabih O, Darouiche MD. Spinal Epidural Abscess. N Engl J Med. 2006L 355:2012-2020.
- Amadoru S, Lim K, Tacey M, et al. Spinal Infections in older people: an analysis of demographics, presenting features, microbiology and outcomes. Intern Med J 2017; 47: 182-8.
- Hilal MK, Macaulay EJ, Ransom JE, et al. Trends in the Epidemiology of Osteomyelitis: A population-based study, 1969-2009. J Bone Joint Surg Am, 2015; 97 (10):837-845.
- Babic M, Simpfendorfer CS. Infections of the Spine. Infect Dis Clin N Am 31(2017): 279-297.
- Duarte RM, Vaccaro AR. Spinal infection: state of the art and management algorithm. Eur Spine J (2013)22: 2787-2799.
- American Spinal Injury Association. International Standards of Neurologic Classification of spinal Cord Injury. Atlanta, GA: American Spinal Injury Association; 2019.
- Kowalski TJ, Berbari EF, Huddleston PM et al. Do follow up imaging examinations provide useful prognostic information in patients with spine infection? Clin Infect Dis 2006; 43(2): 172-179.
- Koo DW, Townson AF, Dvorak MF, et al. Spinal Epidural abscess: a 5 year case-controlled review of neurologic outcomes after rehabilitation. Arch Phys Med Rehabil. 2009; 90: 512-516.
- McKinley W, MErrel C, Meade M, et al. Rehabilitation outcomes after infection related spinal cord disease: a retrospective analysis. Am J Phys Med Rehabil. 2008;(87): 275-280.
- Park KH, Cho OH, Lee JH, et al. Optimal duration of antibiotic therapy inpatients with hematogenous vertebral osteomyelitis at low risk and high risk of recurrence. Clin Infect Dis 2016; 62(10): 1262-1269.
- Bernard L, Ding H, Ghout I, et al. Antibiotic treatment for 6 weeks versus 12 weeks in patients with pyogenic vertebral osteomyelitis: an open-label, non-inferiority, randomized controlled trial. Lancet 2015; 385(9971): 871-872.
- Strisek G, Iorio J, Mosley Y, et al. Etiology and Surgical management of Cervical Spinal epidural Abscess: A systematic review. Global Spine 2018 vol 8(4S): 59S-67S.
- Kemal N, Yazmalar L, Volkan S, et al. Rehabilitation of spinal cord injury. World J Orthop. 2015; 6(1): 8-16.
- Kemal N, Mehmet K, Abdulkadir A, et al. Rehabilitation in spinal infection diseases. World J Orthop. 2015; 6(1):1-7.
- Mylona E, Samarkos M, Kakalou E, et al. Pyogenic vertebral osteomyelitis: a systematic review of clinical characteristics. Semin Arthritis Rheum 2009: 39(1): 10-7.
- Itzkovich M, Gelernter I, Biering-Sorensen F, et al. The spinal Cord Independence Measure (SCIM) version III: reliability and validity in a multi-center international study. Disabl Rehabil. 20730; 29(24): 1926-33.
Cadotte DW, stroman PW, Mikulis D, et al. A systemicatic review of spinal functional MRI research: outlining the elements of experimental design. J neurosurg Spine. 2012; 17(1 suppl): 102-118.
Vertisky T, Krasnokutsky MV, Augustine M, Bammer R. Cutting edge imaging of the spine. Neuroimaging clin N Am. 2007; 17: 117-136.
Baleriaux DL. Neugroschol C. Spinal c and spinal cord infection. Eur RAdiol. 2004; 14 Suppl 3 E72-83.
Guerado E, Cervan AM. Surgical treatment of spondylodiscitis. An update. Int Orthop. 2012; 36:413-420.
Kupershtein I, Vives M. Spinal and spinal cord infections. IN: Kirshblum S, Campagnolo DI, eds. Spinal Cord Medicine. Philadelphia, PA: Lippincott Williams &Wilkins: 2011: 588-599.
Original Version of topic
Saloni Sharma, MD. Infectious disorders of the spinal cord. 2013/07/17
LaTanya Lofton, MD
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