Epidural abscess natural history, complications and prognosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]; Anthony Gallo, B.S. [3]
Overview
An epidural abscess is a rare suppurative infection of the central nervous system, a collection of pus localised in the epidural space, lying outside the dura mater, which accounts for less than 2% of focal CNS infections. [1] It may occur in two different places: intracranially or in the spinal canal. Due to the fact that the initial symptoms and clinical characteristics are not always identical and are similar in other diseases, along with the fact that they are both rare conditions, the final diagnosis might be delayed in time. This late diagnosis comes at great cost to the patient, since it is usually accompanied by a bad prognosis and severe complications with a potential fatal outcome. According to the location of the collection, the two types of abscesses may have different origins, different organisms involved, symptoms, evolutions, complications and therapeutical techniques. [2] In either type of abscess, the treatment fundamentals are somehow similar, they both involve broad-spectrum antibiotics, until a specific organism is identified, at which time, antibiotics should be re-rirected to that agent, along with surgical drainage.
Natural History
Intracranial Epidural Abscess
If left untreated, intracranial epidural abscess may cause headache, fever, and seizures. If left untreated the condition will aggravate and severe complications will arise, possibly leading to a fatal outcome. Proper diagnosis and treatment are therefore mandatory. Treatment usually involves aggressive antibiotic therapy and surgical drainage.
Spinal Epidural Abscess
In this particular type of epidural abscess, its progression of symptoms and clinical findings, within hours to days or months in more chronicle settings, may be described according to 4 stages: [3][4]
- Back and focal vertebral pain, with tenderness on physical exam.
- Nerve root pain, described as being "electric-shock" like, radiating from affected areas, sometimes accompanied by paresthesia.
- Dysfunction of the spinal cord, presenting by motor and sensory deficits and sphincter incompetence.
- Paralysis, which may quickly become irreversible. [5][6]
The typical triad of symptoms is: fever, back pain and neurologic deficits. However, these may not be present at all times on admission which, along with the vast differential diagnosis, may delay the final diagnosis. The progression of the disease from stage to stage and the duration of symptoms before admission (between 1 day to 2 months) are also highly variable. Along with these symptoms, others may be present, such as: weakness, urinary retention, and tenderness. Attending to the fact that the abscesses tend to form in larger epidural spaces, they will be more frequent in posterior and thoracolumbar areas, where more fat is located, susceptible of being infected. [4][3][7]
According to a meta-analysis published in 2000, "the mortality rates of spinal epidural abscess have not changed significantly over the last 25 years". [8][9]
Complications
The possible complications from this disease will depend on the severity and location of the abscess. The rate of complications rises with the increase of time to reach the proper diagnosis and begin therapy. Complications to epidural abscess include:
It is important to remember that surgery is a vital part of the therapy of epidural abscess, along with the risks that are inherent to it, such as damage to the spinal cord, which may then be added to the list of complications. Following spinal cord injury, other complications may arise:
Other complications include:
- With the progression of the inflammation, the spinal cord may be damaged in several ways:
- Thrombosis and thrombophlebitis of adjacent veins
- Direct compression from the inflammatory mass
- Ischemia
- Bacterial toxins
- Inflammatory response and its mediators
- Bacteria gain access to the epidural space by:
- Hematogenous dissemination Important to notice that, just as the spinal epidural space might be infected by bacteria from elsewhere, so does bacteria infecting the spinal epidural space, may travel through the blood stream to infect other tissues.
- Direct inoculation
- This access is facilitated by several predisposing factors, such as:
- underlying disease (HIV infection, alcoholism or diabetes)
- immunosuppressive therapy [10]
- spinal condition (degenerative joint disease)
- neurosurgical procedure
- local or systemic source of infection (osteomyelitis, UTI, soft-tissue infections, IV drug use, sepsis, infected pressure sore).
Prognosis
The most important factor to predict the final outcome is the patient's neurological status before the surgery: [4]
- Patients undergoing surgery during stages 1 or 2 are expected to become neurologically intact with possible decrease in risk of remaining radicular pain.
- Patients undergoing surgery in stage 3, may experience some improvement of the weakness felt before the surgery.
- Patients undergoing surgery in stage 4 may experience some neurological function improvement.
In recent studies full recovery has been common among survivors and the mortality rate has been low (<5%). In the event of death, it is usually due to sepsis, secondary to prolonged immobility or evolution of meningitis.[1] Studies from Khanna and colleagues[11] revealed three factors associated with poor outcomes:
- age
- degree of thecal sac compression
- duration of symptoms
Other important factors include:
- absence of paralysis or its presence with less than 36 hours, is associated with better chances of returning to normal function and better chances of surviving;
- presence of purulent material, instead of granulation tissue, indicating a more acute scenario.
Considering that following treatment, neurological function improvements are noticed during one year, with the help of rehabilitation, the final neurological outcome and functional capacity of these patients should only be fully assessed after a one year period. [4]
References
- ↑ 1.0 1.1 Longo, Dan L. (Dan Louis) (2012). Harrison's principles of internal medici. New York: McGraw-Hill. ISBN 978-0-07-174889-6.
- ↑ Danner, R. L.; Hartman, B. J. (1987). "Update of Spinal Epidural Abscess: 35 Cases and Review of the Literature". Clinical Infectious Diseases. 9 (2): 265–274. doi:10.1093/clinids/9.2.265. ISSN 1058-4838.
- ↑ 3.0 3.1 Mandell, Gerald L.; Bennett, John E. (John Eugene); Dolin, Raphael. (2010). Mandell, Douglas, and Bennett's principles and practice of infectious disease. Philadelphia, PA: Churchill Livingstone/Elsevier. ISBN 0-443-06839-9.
- ↑ 4.0 4.1 4.2 4.3 Darouiche, Rabih O. (2006). "Spinal Epidural Abscess". New England Journal of Medicine. 355 (19): 2012–2020. doi:10.1056/NEJMra055111. ISSN 0028-4793.
- ↑ Mooney RP, Hockberger RS (1987). "Spinal epidural abscess: a rapidly progressive disease". Ann Emerg Med. 16 (10): 1168–70. PMID 3662166.
- ↑ Liem LK, Rigamonti D, Wolf AL, Robinson WL, Edwards CC, DiPatri A (1994). "Thoracic epidural abscess". J Spinal Disord. 7 (5): 449–54. PMID 7819646.
- ↑ Darouiche RO, Hamill RJ, Greenberg SB, Weathers SW, Musher DM (1992). "Bacterial spinal epidural abscess. Review of 43 cases and literature survey". Medicine (Baltimore). 71 (6): 369–85. PMID 1359381.
- ↑ Strauss I, Carmi-Oren N, Hassner A, Shapiro M, Giladi M, Lidar Z (2013). "Spinal epidural abscess: in search of reasons for an increased incidence". Isr Med Assoc J. 15 (9): 493–6. PMID 24340840.
- ↑ Reihsaus E, Waldbaur H, Seeling W (2000). "Spinal epidural abscess: a meta-analysis of 915 patients". Neurosurg Rev. 23 (4): 175–204, discussion 205. PMID 11153548.
- ↑ Grewal, S. (2006). "Epidural abscesses". British Journal of Anaesthesia. 96 (3): 292–302. doi:10.1093/bja/ael006. ISSN 0007-0912.
- ↑ Khanna RK, Malik GM, Rock JP, Rosenblum ML (1996). "Spinal epidural abscess: evaluation of factors influencing outcome". Neurosurgery. 39 (5): 958–64. PMID 8905751.