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==Overview==
==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. <ref>{{Cite book  | last1 = Longo | first1 = Dan L. (Dan Louis) | title = Harrison's principles of internal medici | date = 2012 | publisher = McGraw-Hill | location = New York | isbn = 978-0-07-174889-6 | pages =  }}</ref> It may occur in two different places: [[intracranial space|intracranially]] or in the [[spinal canal]]. Due to the fact that the initial symptoms and clinical characteristics are not always identical and are similar to 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 [[abscess]] may have different origins, different organisms involved, symptoms, evolutions, complications and therapeutical techniques. <ref name="DannerHartman1987">{{cite journal|last1=Danner|first1=R. L.|last2=Hartman|first2=B. J.|title=Update of Spinal Epidural Abscess: 35 Cases and Review of the Literature|journal=Clinical Infectious Diseases|volume=9|issue=2|year=1987|pages=265–274|issn=1058-4838|doi=10.1093/clinids/9.2.265}}</ref> With the advent of antibiotics, along with accurate imaging studies and surgical techniques, prognosis and outcome of epidural abscess has greatly improved.
An epidural abscess is an infection that forms in the [[epidural space]]. Specifically, intracranial epidural abscess is limited on the inner side by the cranial [[dura mater]] and on the outer side by the cranial bone.<ref name="pmid15043336">{{cite journal| author=Fountas KN, Duwayri Y, Kapsalaki E, Dimopoulos VG, Johnston KW, Peppard SB et al.| title=Epidural intracranial abscess as a complication of frontal sinusitis: case report and review of the literature. | journal=South Med J | year= 2004 | volume= 97 | issue= 3 | pages= 279-82; quiz 283 | pmid=15043336 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15043336  }} </ref> Spinal epidural abscess is limited on the inner side by the spinal [[dura mater]] and on the outer side, by the [[spinal canal]].<ref name="pmid24340840">{{cite journal| author=Strauss I, Carmi-Oren N, Hassner A, Shapiro M, Giladi M, Lidar Z| title=Spinal epidural abscess: in search of reasons for an increased incidence. | journal=Isr Med Assoc J | year= 2013 | volume= 15 | issue= 9 | pages= 493-6 | pmid=24340840 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24340840  }} </ref> Spinal epidural abscess is the more common type of [[epidural abscess]]. ''[[Staphylococcus aureus]]'' is responsible for approximately 2/3 of the reported cases.<ref name="Darouiche2006">{{cite journal|last1=Darouiche|first1=Rabih O.|title=Spinal Epidural Abscess|journal=New England Journal of Medicine|volume=355|issue=19|year=2006|pages=2012–2020|issn=0028-4793|doi=10.1056/NEJMra055111}}</ref><ref name="pmid10447289">{{cite journal| author=Rigamonti D, Liem L, Sampath P, Knoller N, Namaguchi Y, Schreibman DL et al.| title=Spinal epidural abscess: contemporary trends in etiology, evaluation, and management. | journal=Surg Neurol | year= 1999 | volume= 52 | issue= 2 | pages= 189-96; discussion 197 | pmid=10447289 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10447289  }} </ref> Prevalence is greatest between the fifth and seventh decades of life, with a male predominance.<ref name="pmid3589332">{{cite journal |vauthors=Danner RL, Hartman BJ |title=Update on spinal epidural abscess: 35 cases and review of the literature |journal=Rev. Infect. Dis. |volume=9 |issue=2 |pages=265–74 |year=1987 |pmid=3589332 |doi= |url= |accessdate=2015-11-09}}</ref><ref name="pmid1359381">{{cite journal| author=Darouiche RO, Hamill RJ, Greenberg SB, Weathers SW, Musher DM| title=Bacterial spinal epidural abscess. Review of 43 cases and literature survey. | journal=Medicine (Baltimore) | year= 1992 | volume= 71 | issue= 6 | pages= 369-85 | pmid=1359381 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1359381 }} </ref> If left untreated, intracranial epidural abscess may cause [[headache]], [[fever]], and [[seizures]]. If left untreated, spinal epidural abscess may cause [[back pain]], [[nerve root]] pain, and [[paralysis]]. Complications of epidural abscess include neurological deficits, [[meningitis]], and [[sepsis]]. Generally, epidural abscess is a medical emergency and requires prompt treatment. If treated timely, the prognosis for epidural abscess is generally good. Physical examination of patients with epidural abscess is usually remarkable for [[fever]], [[back pain]], and generally well appearance, often contributing to misdiagnosis. [[MRI]] is the primary imaging study of epidural abscess, with CT scan as a secondary alternative. A combination of surgical drainage and prolonged systemic [[antibiotics]] (6-12 weeks, IV followed by PO) is the mainstay of therapy for either intracranial or spinal epidural abscess.<ref name="pmid16431882">{{cite journal |vauthors=Grewal S, Hocking G, Wildsmith JA |title=Epidural abscesses |journal=Br J Anaesth |volume=96 |issue=3 |pages=292–302 |year=2006 |pmid=16431882 |doi=10.1093/bja/ael006 |url= |accessdate=2015-11-09}}</ref> Due to the importance of preoperative neurologic status, along with the unpredictable progression of neurologic impairment, for the neurological outcome of the patient, surgical therapy varies depending on the location of the abscess.
 
==Historical Perspective==
In general, abscesses were first described by Hippocrates between 400-370 B.C. Despite scientific advances, both epidural abscesses remain a serious health condition, with significant risks for patients. However, diagnosis, management and outcome have been considerably improved due to more accurate imaging studies, better antibiotics, and improved surgical techniques.<ref name="pmid3589332">{{cite journal |vauthors=Danner RL, Hartman BJ |title=Update on spinal epidural abscess: 35 cases and review of the literature |journal=Rev. Infect. Dis. |volume=9 |issue=2 |pages=265–74 |year=1987 |pmid=3589332 |doi= |url= |accessdate=2015-11-09}}</ref>
 
==Classification==
Epidural abscess may be classified according to the location of the infection into 2 groups: intracranial and spinal.<ref name="pmid3589332">{{cite journal |vauthors=Danner RL, Hartman BJ |title=Update on spinal epidural abscess: 35 cases and review of the literature |journal=Rev. Infect. Dis. |volume=9 |issue=2 |pages=265–74 |year=1987 |pmid=3589332 |doi= |url= |accessdate=2015-11-09}}</ref> Additionally, spinal epidural abscess can be further classified based on the duration of symptoms into either acute or chronic.


==Pathophysiology==
==Pathophysiology==
According to the location of the epidural abscess, its pathophysiology will differ, particularly in the origin of the [[infection]] but also in [[symptoms]],  commonly causing organism, progression of the condition and therefore the treatment required.
Epidural abscess pathophysiology differs based on the location of the [[infection]] and responsible organism. The majority of intracranial epidural abscess cases occur as a complication of cranial surgical procedures and [[sinusitis]].<ref name="pmid15043336">{{cite journal| author=Fountas KN, Duwayri Y, Kapsalaki E, Dimopoulos VG, Johnston KW, Peppard SB et al.| title=Epidural intracranial abscess as a complication of frontal sinusitis: case report and review of the literature. | journal=South Med J | year= 2004 | volume= 97 | issue= 3 | pages= 279-82; quiz 283 | pmid=15043336 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15043336  }} </ref> The majority of spinal epidural abscess cases occur as a result of spinal instrumentation, vascular access, and [[IV drug use]].<ref name="pmid24340840">{{cite journal| author=Strauss I, Carmi-Oren N, Hassner A, Shapiro M, Giladi M, Lidar Z| title=Spinal epidural abscess: in search of reasons for an increased incidence. | journal=Isr Med Assoc J | year= 2013 | volume= 15 | issue= 9 | pages= 493-6 | pmid=24340840 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24340840  }} </ref>
In the case of intracranial epidural abscess, it surges most frequently as a complication of cranial surgical procedures or [[sinusitis]], particularly paranasal [[sinusitis]], as the [[infection]] progresses intracranially. <ref name="pmid15043336">{{cite journal| author=Fountas KN, Duwayri Y, Kapsalaki E, Dimopoulos VG, Johnston KW, Peppard SB et al.| title=Epidural intracranial abscess as a complication of frontal sinusitis: case report and review of the literature. | journal=South Med J | year= 2004 | volume= 97 | issue= 3 | pages= 279-82; quiz 283 | pmid=15043336 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15043336  }} </ref>
 
On the other hand, spinal epidual abscess happens most frequently due to spinal instrumentation, vascular access and injection drug use. <ref name="pmid24340840">{{cite journal| author=Strauss I, Carmi-Oren N, Hassner A, Shapiro M, Giladi M, Lidar Z| title=Spinal epidural abscess: in search of reasons for an increased incidence. | journal=Isr Med Assoc J | year= 2013 | volume= 15 | issue= 9 | pages= 493-6 | pmid=24340840 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24340840  }} </ref>
==Causes==
Common causes of intracranial epidural abscess include paranasal [[sinusitis]], [[osteomyelitis]] of the skull, and extension of infection from concurrent [[otitis]] or [[mastoiditis]]. Common causes of spinal epidural abscess include spinal instrumentation, [[vascular]] access, and [[IV drug use]]. Irrespective of cause, [[epidural abscess]] is a life-threatening, but treatable, condition.
 
==Differentiating Epidural Abscess from Other Diseases==
Intracranial epidural abscess must be differentiated from [[epidural hematoma]], [[subdural empyema]], [[brain abscess]], [[tuberculous meningitis]], and other intracranial mass lesions. Spinal epidural abscess must be differentiated from other conditions that cause [[back pain]], [[weakness]], and spinal [[tenderness]], such as [[arthritis]], [[osteoarthritis]], [[intervertebral disc]] disease, [[vertebral osteomyelitis]], [[primary tumor|primary]] or [[metastatic tumor]]s, and [[musculoskeletal pain]].


==Epidemiology and Demographics==
==Epidemiology and Demographics==
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]]. <ref>{{Cite book  | last1 = Longo | first1 = Dan L. (Dan Louis) | title = Harrison's principles of internal medici | date = 2012 | publisher = McGraw-Hill | location = New York | isbn = 978-0-07-174889-6 | pages = }}</ref>.  It may occur in two different places: [[intracranial space|intracranially]] or in the [[spinal canal]]. According to the location of the infection, the epidemiology of each of the two types of abscess will differ. This is due to the nature of the location of the disease, but also due to other factors. In either case, in order to prevent severe [[morbidity]] and fatal outcomes, accurate [[diagnosis]] and prompt [[therapy]] should be applied as early as possible.
In general, epidural abscess is rare. Intracranial epidural abscess is the more rare type of epidural abscess and the 3rd most common focal intracranial infection. Spinal epidural abscess is more common than intracranial epidural abscess, however it is still rare in the general population, accounting for 2.5 to 3 cases per 10,000 hospital admissions per year.<ref name="pmid10229519">{{cite journal |vauthors=Sampath P, Rigamonti D |title=Spinal epidural abscess: a review of epidemiology, diagnosis, and treatment |journal=J Spinal Disord |volume=12 |issue=2 |pages=89–93 |year=1999 |pmid=10229519 |doi= |url= |accessdate=2015-11-09}}</ref> Estimates of the incidence following central nerve block vary from 1 per 1,000 hospital admissions to 1 per 100,000 hospital admissions.<ref name="pmid16431882">{{cite journal |vauthors=Grewal S, Hocking G, Wildsmith JA |title=Epidural abscesses |journal=Br J Anaesth |volume=96 |issue=3 |pages=292–302 |year=2006 |pmid=16431882 |doi=10.1093/bja/ael006 |url= |accessdate=2015-11-09}}</ref> Prevalence of epidural abscess is greatest between the fifth and seventh decades of life.<ref name="pmid3589332">{{cite journal |vauthors=Danner RL, Hartman BJ |title=Update on spinal epidural abscess: 35 cases and review of the literature |journal=Rev. Infect. Dis. |volume=9 |issue=2 |pages=265–74 |year=1987 |pmid=3589332 |doi= |url= |accessdate=2015-11-09}}</ref>


==Causes==
==Risk Factors==
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]]. <ref>{{Cite book  | last1 = Longo | first1 = Dan L. (Dan Louis) | title = Harrison's principles of internal medici | date = 2012 | publisher = McGraw-Hill | location = New York | isbn = 978-0-07-174889-6 | pages =  }}</ref> It may occur in two different places: [[intracranial space|intracranially]] or in the [[spinal canal]]. According to the region of [[infection]], some causing organisms will be shared by both types of abscess, however, others will be different, mainly because of the risk factors involved in that particular area and the mechanisms of [[infection]]. In the case of ''intracranial epidural abscess'', the most common risk factors are [[sinusitis]] and [[neurosurgery|neurosurgical procedures]], while in the case of ''spinal epidural abscess'', the most common risk factors are [[infections]] of the surrounding tissues and spinal procedures.
Common risk factors in the development of intracranial epidural abscess include [[trauma]], [[neurosurgery|neurosurgical]] procedures, and infections such as [[sinusitis]], [[otitis]], and [[mastoiditis]]. Common risk factors for the development of spinal epidural abscess include [[diabetes mellitus]], [[trauma]], and [[bacteremia]].<ref name="pmid15043336">{{cite journal| author=Fountas KN, Duwayri Y, Kapsalaki E, Dimopoulos VG, Johnston KW, Peppard SB et al.| title=Epidural intracranial abscess as a complication of frontal sinusitis: case report and review of the literature. | journal=South Med J | year= 2004 | volume= 97 | issue= 3 | pages= 279-82; quiz 283 | pmid=15043336 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15043336 }} </ref>
 
==Natural History, Complications, and Prognosis==
If left untreated, intracranial epidural abscess may cause [[headache]], [[fever]], and [[seizures]]. If left untreated, spinal epidural abscess may cause [[back pain]], [[nerve root]] pain, and [[paralysis]]. Complications of epidural abscess include neurological deficits, [[meningitis]], and [[sepsis]]. If treated timely, the prognosis for epidural abscess is generally good.


==Diagnosis==
==Diagnosis==
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. <ref>{{Cite book  | last1 = Longo | first1 = Dan L. (Dan Louis) | title = Harrison's principles of internal medici | date = 2012 | publisher = McGraw-Hill | location = New York | isbn = 978-0-07-174889-6 | pages =  }}</ref> It may occur in two different places: [[intracranial space|intracranially]] or in the [[spinal canal]].  Due to the fact that the initial [[symptoms]] and clinical characteristics are not always identical and are similar to the ones 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. The [[diagnosis]] of epidural abscess should be first suspected from the clinical presentation of the patient and posteriorly supported by laboratory tests and imaging studies, however it can only be confirmed after surgical drainage and proper study of the collected material. According to the location of the collection, the [[abscess]] may have different origins, different organisms involved, [[symptoms]], evolutions, [[complications]] and therapeutical techniques. <ref name="DannerHartman1987">{{cite journal|last1=Danner|first1=R. L.|last2=Hartman|first2=B. J.|title=Update of Spinal Epidural Abscess: 35 Cases and Review of the Literature|journal=Clinical Infectious Diseases|volume=9|issue=2|year=1987|pages=265–274|issn=1058-4838|doi=10.1093/clinids/9.2.265}}</ref>
===History and Symptoms===
===Symptoms===
A detailed and thorough history from the patient is necessary. Specific areas of focus when obtaining a history from the patient include [[immunodeficiency]], [[intravenous drug use]], [[neurosurgery|spinal procedure]], and [[trauma]]. Common symptoms of intracranial epidural abscess include [[headache]], [[fever]], and [[vomiting]]. Common symptoms of spinal epidural abscess include [[back pain]], [[weakness]], and [[Paresthesia|persistent pins and needles]].
 
===Physical Examination===
Physical examination of patients with epidural abscess is usually remarkable for [[fever]], [[back pain]], and generally well appearance, often contributing to misdiagnosis.  
 
===Laboratory Findings===
===Laboratory Findings===
Laboratory findings consistent with the diagnosis of epidural abscess include elevated inflammatory markers, abnormal [[platelet count]], and presence of ''[[Staphylococcus aureus]]''. Laboratory results, while helpful, are not diagnostic of epidural abscess. Laboratory findings should supplement clinical and imaging findings to aid in the diagnosis.<ref name="Darouiche2006">{{cite journal|last1=Darouiche|first1=Rabih O.|title=Spinal Epidural Abscess|journal=New England Journal of Medicine|volume=355|issue=19|year=2006|pages=2012–2020|issn=0028-4793|doi=10.1056/NEJMra055111}}</ref>
===CT===
Computed tomography may be helpful as a secondary method of imaging in the diagnosis of epidural abscess. If [[MRI]] is not available, [[CT scan]] may serve as the primary imaging technique. Findings on CT scan suggestive of intracranial epidural abscess include the appearance of a crescent-shaped, hypodense, extraaxial lesion or a lens.<ref name=Harris>{{Cite book  | last1 = Longo | first1 = Dan L. (Dan Louis) | title = Harrison's principles of internal medici | date = 2012 | publisher = McGraw-Hill | location = New York | isbn = 978-0-07-174889-6 | pages =  }}</ref>
===MRI===
[[MRI]] may be helpful in the diagnosis of epidural abscess, as it is the preferred imaging study. Epidural abscess appearance varies depending on the location of the disease. On MRI, intracranial epidural abscess appears as a lentiform or crescent-shaped fluid collection. On T2-weighted images, epidural abscesses appear hyperintense compared to the [[cerebrospinal fluid]]. On T1-weighted images, epidural abscesses appear isointense or hypointense when compared to the [[brain]]. Following administration of [[gadolinium]] contrast, the [[dura mater]] is enhanced on T1-weighted images.<ref name=Harris>{{Cite book  | last1 = Longo | first1 = Dan L. (Dan Louis) | title = Harrison's principles of internal medici | date = 2012 | publisher = McGraw-Hill | location = New York | isbn = 978-0-07-174889-6 | pages =  }}</ref> On [[MRI]], spinal epidural abscess is characterized by low or intermediate intensity on T1-weighted MR sequences and high or intermediate intensity on T2-weighted images.
===Other Imaging Findings===
[[X ray]] is likely not helpful in the diagnosis of epidural abscess. [[Myelography]] may be helpful in the diagnosis of epidural abscess, however it is now considered obsolete.
===Other Diagnostic Studies===
[[Lumbar puncture]] is likely not helpful in the diagnosis of epidural abscess. [[Cerebrospinal fluid]] study is not routinely performed because it offers little information, and has high associated risks. It should be analyzed only when [[myelography]] is performed.


==Treatment==
==Treatment==
===Medical Therapy===
===Medical Therapy===
Epidural abscess is generally a medical emergency and requires prompt treatment. The treatment of epidural abscess generally involves a combined medical and surgical approach. Antimicrobial therapy for intracranial epidural abscess includes [[metronidazole]], a third generation [[cephalosporin]], and either [[penicillin]] or [[vancomycin]]. Antimicrobial therapy for spinal epidural abscess includes [[vancomycin]], [[cefepime]], [[ceftazidime]], and [[meropenem]].


===Surgery===
A combination of surgical drainage and prolonged systemic [[antibiotics]] (6-12 weeks, IV followed by PO) is the mainstay of therapy for both intracranial and spinal epidural abscess.<ref name="pmid16431882">{{cite journal |vauthors=Grewal S, Hocking G, Wildsmith JA |title=Epidural abscesses |journal=Br J Anaesth |volume=96 |issue=3 |pages=292–302 |year=2006 |pmid=16431882 |doi=10.1093/bja/ael006 |url= |accessdate=2015-11-09}}</ref> Due to the importance of preoperative neurologic status, along with the unpredictable progression of neurologic impairment, for the neurological outcome of the patient, surgical therapy varies depending on the location of the abscess. In intracranial epidural abscess cases, [[burr hole]] placement or [[craniotomy]] should occur as early as possible. In spinal epidural abscess cases, decompressive [[laminectomy]] and [[debridement]] of [[infected]] tissues should occur as early as possible.<ref name="Darouiche2006">{{cite journal|last1=Darouiche|first1=Rabih O.|title=Spinal Epidural Abscess|journal=New England Journal of Medicine|volume=355|issue=19|year=2006|pages=2012–2020|issn=0028-4793|doi=10.1056/NEJMra055111}}</ref><ref name="pmid1359381">{{cite journal| author=Darouiche RO, Hamill RJ, Greenberg SB, Weathers SW, Musher DM| title=Bacterial spinal epidural abscess. Review of 43 cases and literature survey. | journal=Medicine (Baltimore) | year= 1992 | volume= 71 | issue= 6 | pages= 369-85 | pmid=1359381 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=1359381  }} </ref>


===Primary Prevention===
Effective measures for the primary prevention of epidural abscess include rapid treatment of inflammatory diseases of the head, prevention of [[trauma]], and decreased [[IV drug use]].


 
===Secondary Prevention===
Secondary prevention strategies following epidural abscess include treatment and management of existing infection.


==References==
==References==
{{Reflist|2}}
{{Reflist|2}}


[[Category:Wikinfect]]
[[Category:Infectious disease]]
[[Category:Disease]]
[[Category:Disease]]
[[Category:Neurology]]
[[Category:Neurology]]
[[Category:Primary care]]

Latest revision as of 21:36, 29 July 2020

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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 an infection that forms in the epidural space. Specifically, intracranial epidural abscess is limited on the inner side by the cranial dura mater and on the outer side by the cranial bone.[1] Spinal epidural abscess is limited on the inner side by the spinal dura mater and on the outer side, by the spinal canal.[2] Spinal epidural abscess is the more common type of epidural abscess. Staphylococcus aureus is responsible for approximately 2/3 of the reported cases.[3][4] Prevalence is greatest between the fifth and seventh decades of life, with a male predominance.[5][6] If left untreated, intracranial epidural abscess may cause headache, fever, and seizures. If left untreated, spinal epidural abscess may cause back pain, nerve root pain, and paralysis. Complications of epidural abscess include neurological deficits, meningitis, and sepsis. Generally, epidural abscess is a medical emergency and requires prompt treatment. If treated timely, the prognosis for epidural abscess is generally good. Physical examination of patients with epidural abscess is usually remarkable for fever, back pain, and generally well appearance, often contributing to misdiagnosis. MRI is the primary imaging study of epidural abscess, with CT scan as a secondary alternative. A combination of surgical drainage and prolonged systemic antibiotics (6-12 weeks, IV followed by PO) is the mainstay of therapy for either intracranial or spinal epidural abscess.[7] Due to the importance of preoperative neurologic status, along with the unpredictable progression of neurologic impairment, for the neurological outcome of the patient, surgical therapy varies depending on the location of the abscess.

Historical Perspective

In general, abscesses were first described by Hippocrates between 400-370 B.C. Despite scientific advances, both epidural abscesses remain a serious health condition, with significant risks for patients. However, diagnosis, management and outcome have been considerably improved due to more accurate imaging studies, better antibiotics, and improved surgical techniques.[5]

Classification

Epidural abscess may be classified according to the location of the infection into 2 groups: intracranial and spinal.[5] Additionally, spinal epidural abscess can be further classified based on the duration of symptoms into either acute or chronic.

Pathophysiology

Epidural abscess pathophysiology differs based on the location of the infection and responsible organism. The majority of intracranial epidural abscess cases occur as a complication of cranial surgical procedures and sinusitis.[1] The majority of spinal epidural abscess cases occur as a result of spinal instrumentation, vascular access, and IV drug use.[2]

Causes

Common causes of intracranial epidural abscess include paranasal sinusitis, osteomyelitis of the skull, and extension of infection from concurrent otitis or mastoiditis. Common causes of spinal epidural abscess include spinal instrumentation, vascular access, and IV drug use. Irrespective of cause, epidural abscess is a life-threatening, but treatable, condition.

Differentiating Epidural Abscess from Other Diseases

Intracranial epidural abscess must be differentiated from epidural hematoma, subdural empyema, brain abscess, tuberculous meningitis, and other intracranial mass lesions. Spinal epidural abscess must be differentiated from other conditions that cause back pain, weakness, and spinal tenderness, such as arthritis, osteoarthritis, intervertebral disc disease, vertebral osteomyelitis, primary or metastatic tumors, and musculoskeletal pain.

Epidemiology and Demographics

In general, epidural abscess is rare. Intracranial epidural abscess is the more rare type of epidural abscess and the 3rd most common focal intracranial infection. Spinal epidural abscess is more common than intracranial epidural abscess, however it is still rare in the general population, accounting for 2.5 to 3 cases per 10,000 hospital admissions per year.[8] Estimates of the incidence following central nerve block vary from 1 per 1,000 hospital admissions to 1 per 100,000 hospital admissions.[7] Prevalence of epidural abscess is greatest between the fifth and seventh decades of life.[5]

Risk Factors

Common risk factors in the development of intracranial epidural abscess include trauma, neurosurgical procedures, and infections such as sinusitis, otitis, and mastoiditis. Common risk factors for the development of spinal epidural abscess include diabetes mellitus, trauma, and bacteremia.[1]

Natural History, Complications, and Prognosis

If left untreated, intracranial epidural abscess may cause headache, fever, and seizures. If left untreated, spinal epidural abscess may cause back pain, nerve root pain, and paralysis. Complications of epidural abscess include neurological deficits, meningitis, and sepsis. If treated timely, the prognosis for epidural abscess is generally good.

Diagnosis

History and Symptoms

A detailed and thorough history from the patient is necessary. Specific areas of focus when obtaining a history from the patient include immunodeficiency, intravenous drug use, spinal procedure, and trauma. Common symptoms of intracranial epidural abscess include headache, fever, and vomiting. Common symptoms of spinal epidural abscess include back pain, weakness, and persistent pins and needles.

Physical Examination

Physical examination of patients with epidural abscess is usually remarkable for fever, back pain, and generally well appearance, often contributing to misdiagnosis.

Laboratory Findings

Laboratory findings consistent with the diagnosis of epidural abscess include elevated inflammatory markers, abnormal platelet count, and presence of Staphylococcus aureus. Laboratory results, while helpful, are not diagnostic of epidural abscess. Laboratory findings should supplement clinical and imaging findings to aid in the diagnosis.[3]

CT

Computed tomography may be helpful as a secondary method of imaging in the diagnosis of epidural abscess. If MRI is not available, CT scan may serve as the primary imaging technique. Findings on CT scan suggestive of intracranial epidural abscess include the appearance of a crescent-shaped, hypodense, extraaxial lesion or a lens.[9]

MRI

MRI may be helpful in the diagnosis of epidural abscess, as it is the preferred imaging study. Epidural abscess appearance varies depending on the location of the disease. On MRI, intracranial epidural abscess appears as a lentiform or crescent-shaped fluid collection. On T2-weighted images, epidural abscesses appear hyperintense compared to the cerebrospinal fluid. On T1-weighted images, epidural abscesses appear isointense or hypointense when compared to the brain. Following administration of gadolinium contrast, the dura mater is enhanced on T1-weighted images.[9] On MRI, spinal epidural abscess is characterized by low or intermediate intensity on T1-weighted MR sequences and high or intermediate intensity on T2-weighted images.

Other Imaging Findings

X ray is likely not helpful in the diagnosis of epidural abscess. Myelography may be helpful in the diagnosis of epidural abscess, however it is now considered obsolete.

Other Diagnostic Studies

Lumbar puncture is likely not helpful in the diagnosis of epidural abscess. Cerebrospinal fluid study is not routinely performed because it offers little information, and has high associated risks. It should be analyzed only when myelography is performed.

Treatment

Medical Therapy

Epidural abscess is generally a medical emergency and requires prompt treatment. The treatment of epidural abscess generally involves a combined medical and surgical approach. Antimicrobial therapy for intracranial epidural abscess includes metronidazole, a third generation cephalosporin, and either penicillin or vancomycin. Antimicrobial therapy for spinal epidural abscess includes vancomycin, cefepime, ceftazidime, and meropenem.

Surgery

A combination of surgical drainage and prolonged systemic antibiotics (6-12 weeks, IV followed by PO) is the mainstay of therapy for both intracranial and spinal epidural abscess.[7] Due to the importance of preoperative neurologic status, along with the unpredictable progression of neurologic impairment, for the neurological outcome of the patient, surgical therapy varies depending on the location of the abscess. In intracranial epidural abscess cases, burr hole placement or craniotomy should occur as early as possible. In spinal epidural abscess cases, decompressive laminectomy and debridement of infected tissues should occur as early as possible.[3][6]

Primary Prevention

Effective measures for the primary prevention of epidural abscess include rapid treatment of inflammatory diseases of the head, prevention of trauma, and decreased IV drug use.

Secondary Prevention

Secondary prevention strategies following epidural abscess include treatment and management of existing infection.

References

  1. 1.0 1.1 1.2 Fountas KN, Duwayri Y, Kapsalaki E, Dimopoulos VG, Johnston KW, Peppard SB; et al. (2004). "Epidural intracranial abscess as a complication of frontal sinusitis: case report and review of the literature". South Med J. 97 (3): 279–82, quiz 283. PMID 15043336.
  2. 2.0 2.1 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.
  3. 3.0 3.1 3.2 Darouiche, Rabih O. (2006). "Spinal Epidural Abscess". New England Journal of Medicine. 355 (19): 2012–2020. doi:10.1056/NEJMra055111. ISSN 0028-4793.
  4. Rigamonti D, Liem L, Sampath P, Knoller N, Namaguchi Y, Schreibman DL; et al. (1999). "Spinal epidural abscess: contemporary trends in etiology, evaluation, and management". Surg Neurol. 52 (2): 189–96, discussion 197. PMID 10447289.
  5. 5.0 5.1 5.2 5.3 Danner RL, Hartman BJ (1987). "Update on spinal epidural abscess: 35 cases and review of the literature". Rev. Infect. Dis. 9 (2): 265–74. PMID 3589332. |access-date= requires |url= (help)
  6. 6.0 6.1 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.
  7. 7.0 7.1 7.2 Grewal S, Hocking G, Wildsmith JA (2006). "Epidural abscesses". Br J Anaesth. 96 (3): 292–302. doi:10.1093/bja/ael006. PMID 16431882. |access-date= requires |url= (help)
  8. Sampath P, Rigamonti D (1999). "Spinal epidural abscess: a review of epidemiology, diagnosis, and treatment". J Spinal Disord. 12 (2): 89–93. PMID 10229519. |access-date= requires |url= (help)
  9. 9.0 9.1 Longo, Dan L. (Dan Louis) (2012). Harrison's principles of internal medici. New York: McGraw-Hill. ISBN 978-0-07-174889-6.