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 name=McGraw>{{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 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 [[abscess|abscesses]] 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> 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 [[neurosurgery|surgical drainage]].
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.
==Natural History==
==Natural History==
Depending on the location of the [[epidural abscess]], its natural history and related [[symptoms]] will invariably change. Therefore, it is important to distinguish the two:
===Intracranial Epidural Abscess===
===Intracranial Epidural Abscess===
The less common of the three main focal [[suppurative]] [[central nervous system]] [[infections]] ''([[brain abscess]] and [[subdural empyema]])''. It may have several origins, however the more common are: complication of [[sinusitis]] or following [[neurosurgery|neurosurgical procedures]] or [[head trauma]]. Since the [[dura mater]] is tightly adherent to the [[bone]] surface of the [[skull]], making the [[epidural space]] a ''virtual space'', the [[abscess]] tends to have an indolent evolution, usually creating small, round collections of [[purulent]] material. Since this [[infected]] material is able to cross the [[dura mater]], through the [[emissary veins]], the [[epidural abscess]] is usually accompanied by a [[subdural empyema]]. This explains the fact that these two entities share common [[etiologies]]. In the case of the [[abscess]] originating from [[sinusitis]], the responsible organisms are usually similar to the ones causing [[subdural empyema]], such as [[streptococci]] and [[anaerobes]], while if the [[abscess]] originates on a [[trauma]] or a [[neurosurgery|neurosurgical procedure]], the responsible organisms are usually [[staphylococci]] or [[Gram-negative bacteria|gram-negatives]]. At the time of presentation, patients usually complain of [[headache]], [[fever]] and [[seizures]] and present with [[nuchal rigidity]] and focal neurologic deficits. Since the [[abscess]] develops slowly, the [[signs]] and [[symptoms]] may develop insidiously. A particular situation may arise, when the [[abscess]] is located near the [[Petrous portion of the temporal bone|petrous bone]], compressing the nearby structures, being responsible for the so called ''Gradenigo’s syndrome'', in which, compression of the [[cranial nerves]] V and VI, results in unilateral [[facial pain]] and [[lateral rectus muscle]] [[weakness]]. <ref>{{Cite book | last1 = Mandell | first1 = Gerald L. | last2 = Bennett | first2 = John E. (John Eugene) | last3 = Dolin | first3 = Raphael. | title = Mandell, Douglas, and Bennett's principles and practice of infectious disease | date = 2010 | publisher = Churchill Livingstone/Elsevier | location = Philadelphia, PA | isbn = 0-443-06839-9 | pages = }}</ref><ref name=McGraw>{{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> 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 [[neurosurgery|surgical drainage]].
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 necessary. Treatment usually involves aggressive [[antibiotic]] therapy and [[neurosurgery|surgical drainage]].
===Spinal Epidural Abscess===
===Spinal Epidural Abscess===
This type of [[abscess]] usually develops following hematogenous dissemination of an [[infection]], located elsewhere in the [[body]] or following [[neurosurgery|neurosurgical procedure]] or [[trauma]], particularly in patients with predisposing conditions, such as [[spinal cord|spinal]] deformities or [[bacteremia]].<ref>{{Cite book | last1 = Mandell | first1 = Gerald L. | last2 = Bennett | first2 = John E. (John Eugene) | last3 = Dolin | first3 = Raphael. | title = Mandell, Douglas, and Bennett's principles and practice of infectious disease | date = 2010 | publisher = Churchill Livingstone/Elsevier | location = Philadelphia, PA | isbn = 0-443-06839-9 | pages = }}</ref> 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'': <ref>{{Cite book | last1 = Mandell | first1 = Gerald L. | last2 = Bennett | first2 = John E. (John Eugene) | last3 = Dolin | first3 = Raphael. | title = Mandell, Douglas, and Bennett's principles and practice of infectious disease | date = 2010 | publisher = Churchill Livingstone/Elsevier | location = Philadelphia, PA | isbn = 0-443-06839-9 | pages = }}</ref><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>
If left untreated, spinal epidural abscess may cause the following sequelae, which is classified into 4 stages:<ref name=Mandell>{{Cite book | last1 = Mandell | first1 = Gerald L. | last2 = Bennett | first2 = John E. (John Eugene) | last3 = Dolin | first3 = Raphael. | title = Mandell, Douglas, and Bennett's principles and practice of infectious disease | date = 2010 | publisher = Churchill Livingstone/Elsevier | location = Philadelphia, PA | isbn = 0-443-06839-9 | pages = }}</ref><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="pmid3662166">{{cite journal| author=Mooney RP, Hockberger RS| title=Spinal epidural abscess: a rapidly progressive disease. | journal=Ann Emerg Med | year= 1987 | volume= 16 | issue= 10 | pages= 1168-70 | pmid=3662166 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=3662166 }} </ref><ref name="pmid7819646">{{cite journal| author=Liem LK, Rigamonti D, Wolf AL, Robinson WL, Edwards CC, DiPatri A| title=Thoracic epidural abscess. | journal=J Spinal Disord | year= 1994 | volume= 7 | issue= 5 | pages= 449-54 | pmid=7819646 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=7819646 }} </ref>
#[[Back pain|Back]] and focal [[vertebral]] pain, with [[tenderness]] on [[physical exam]].
#[[Back pain|Back]] and focal [[vertebral]] pain, with [[tenderness]]; [[fever]]; neurologic deficits
#[[Nerve root]] [[pain]], described as being "electric-shock" like, radiating from affected areas, sometimes accompanied by [[paresthesia]].
#[[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.
#Dysfunction of the [[spinal cord]], presenting by motor and sensory deficits and [[sphincter]] incompetence
#[[Paralysis]], which may quickly become irreversible
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 space]]s, they will be more frequent in posterior and thoracolumbar areas, where more [[fat]] is located, susceptible of being [[infected]]. <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>{{Cite book | last1 = Mandell | first1 = Gerald L. | last2 = Bennett | first2 = John E. (John Eugene) | last3 = Dolin | first3 = Raphael. | title = Mandell, Douglas, and Bennett's principles and practice of infectious disease | date = 2010 | publisher = Churchill Livingstone/Elsevier | location = Philadelphia, PA | isbn = 0-443-06839-9 | pages = }}</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>
According to a meta-analysis published in 2000, "the mortality rates of [[spinal cord|spinal]] [[epidural abscess]] have not changed significantly over the last 25 years". <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><ref name="pmid11153548">{{cite journal| author=Reihsaus E, Waldbaur H, Seeling W| title=Spinal epidural abscess: a meta-analysis of 915 patients. | journal=Neurosurg Rev | year= 2000 | volume= 23 | issue= 4 | pages= 175-204; discussion 205 | pmid=11153548 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=11153548 }} </ref>
==Complications==
==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 [[diagnosis]]. The later the [[diagnosis]] is reached and proper [[therapy]] is initiated, worst the [[complications]] will be. These include:
Complications from epidural abscess include:
*Neurological deficits
*Neurological deficits
*[[Meningitis]]
*[[Sepsis]]
*Irreversible [[paralysis]]
*Irreversible [[paralysis]]
*[[Sepsis]]
*[[Sepsis]]
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:
*[[Spinal cord]] injury
*[[Pressure sores]]
*[[Pressure sores]]
*[[UTI]]
*[[Urinary tract infection]]
*[[Thrombophlebitis]]
*[[Thrombophlebitis]]
*[[Pneumonia]]
*[[Pneumonia]]
*[[Thrombosis]]
*[[Thrombophlebitis]] of adjacent [[veins]]
*[[Ischemia]]
*Bacterial [[toxin]]s
*[[Inflammatory]] response and its mediators
Other complications include:
The rate of [[complications]] rises with the increase of time to reach the proper [[diagnosis]] and begin therapy.
*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 effect|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 cord|spinal]] [[epidural space]] might be infected by [[bacteria]] from elsewhere, so does [[bacteria]] infecting the [[spinal cord|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]] <ref name="Grewal2006">{{cite journal|last1=Grewal|first1=S.|title=Epidural abscesses|journal=British Journal of Anaesthesia|volume=96|issue=3|year=2006|pages=292–302|issn=0007-0912|doi=10.1093/bja/ael006}}</ref>
:*local or systemic source of [[infection]] ([[osteomyelitis]], [[UTI]], soft-tissue [[infections]], [[IV drug use]], [[sepsis]], infected [[pressure sore]]).
==Prognosis==
==Prognosis==
The most important factor to predict the final outcome is the ''patient's neurological status'' before the [[neurosurgery|surgery]]: <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>
If treated timely, the prognosis of epidural abscess is generally good. Full recovery is common among survivors and the [[mortality rate]] is low (<5%). Mortality is usually due to [[sepsis]], prolonged [[immobility]], or the development of [[meningitis]].<ref name=McGraw>{{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> Positive outcomes are generally associated with:
*Patients undergoing [[neurosurgery|surgery]] during '''stages 1 or 2''' are expected to become neurologically intact with possible decrease in risk of remaining [[radicular pain]].
*Presence of [[purulent]] material, instead of [[granulation tissue]], indicating a more acute case
*Patients undergoing [[neurosurgery|surgery]] in '''stage 3''', may experience some improvement of the [[weakness]] felt before the [[neurosurgery|surgery]].
*Absence of [[paralysis]] or its presence for < 36 hours, indicating increased chances of returning to normal function
*Patients undergoing [[neurosurgery|surgery]] in '''stage 4''' may experience some neurological function improvement.
The most important factor to predict the final outcome is the patient's neurological status prior to [[neurosurgery]]. The stages are:<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>
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]]. <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> Studies from Khanna and colleagues<ref name="pmid8905751">{{cite journal| author=Khanna RK, Malik GM, Rock JP, Rosenblum ML| title=Spinal epidural abscess: evaluation of factors influencing outcome. | journal=Neurosurgery | year= 1996 | volume= 39 | issue= 5 | pages= 958-64 | pmid=8905751 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8905751 }} </ref> revealed three factors associated with poor outcomes:
! style="background: #4479BA; width: 120px;" | {{fontcolor|#FFF|Staging prior to neurosurgery}}
*''duration of [[symptoms]]''
! style="background: #4479BA; width: 550px;" | {{fontcolor|#FFF|Patient expectation}}
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;
| style="padding: 5px 5px; background: #F5F5F5;" | May observe some neurological function improvement and improvement of the [[weakness]] felt prior to [[neurosurgery|surgery]]
| style="padding: 5px 5px; background: #F5F5F5;" | May experience some neurological function improvement
|-
|}
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. <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>
Poor outcomes are generally associated with three factors:<ref name="pmid8905751">{{cite journal| author=Khanna RK, Malik GM, Rock JP, Rosenblum ML| title=Spinal epidural abscess: evaluation of factors influencing outcome. | journal=Neurosurgery | year= 1996 | volume= 39 | issue= 5 | pages= 958-64 | pmid=8905751 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8905751 }} </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. If treated timely, the prognosis for epidural abscess is generally good.
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 necessary. Treatment usually involves aggressive antibiotic therapy and surgical drainage.
Spinal Epidural Abscess
If left untreated, spinal epidural abscess may cause the following sequelae, which is classified into 4 stages:[1][2][3][4]
The rate of complications rises with the increase of time to reach the proper diagnosis and begin therapy.
Prognosis
If treated timely, the prognosis of epidural abscess is generally good. Full recovery is common among survivors and the mortality rate is low (<5%). Mortality is usually due to sepsis, prolonged immobility, or the development of meningitis.[5] Positive outcomes are generally associated with:
↑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. ISBN0-443-06839-9.