Subdural empyema, also referred to as [[subdural abscess]], [[pachymeningitis interna]] and [[circumscript meningitis]], is a life-threatening [[infection]].<ref name="AgrawalTimothy2007">{{cite journal|last1=Agrawal|first1=Amit|last2=Timothy|first2=Jake|last3=Pandit|first3=Lekha|last4=Shetty|first4=Lathika|last5=Shetty|first5=J.P.|title=A Review of Subdural Empyema and Its Management|journal=Infectious Diseases in Clinical Practice|volume=15|issue=3|year=2007|pages=149–153|issn=1056-9103|doi=10.1097/01.idc.0000269905.67284.c7}}</ref> It consists of a localised collection of [[pus|purulent]] material, usually unilateral, between the [[dura mater]] and the [[arachnoid mater]] and accounts for about 15-22% of the reported focal intracranial [[infections]] The [[empyema]] may develop intracranially (about 95%) or in the [[spinal canal]] (about 5%), and in both cases, it constitutes a [[medical emergency|medical]] and [[surgical emergency|neurosurgical emergency]].<ref name="pmid12521560">{{cite journal| author=Greenlee JE| title=Subdural Empyema. | journal=Curr Treat Options Neurol | year= 2003 | volume= 5 | issue= 1 | pages= 13-22 | pmid=12521560 | doi= | pmc=|url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12521560 }} </ref>
Common causes of subdural empyema include: [[anaerobes]], [[aerobic]] [[streptococci]], [[staphylococci]], ''[[Haemophilus influenzae]]'', ''[[Streptococcus pneumoniae]]'' and other [[gram-negative]] [[bacilli]] <ref name="AgrawalTimothy2007">{{cite journal|last1=Agrawal|first1=Amit|last2=Timothy|first2=Jake|last3=Pandit|first3=Lekha|last4=Shetty|first4=Lathika|last5=Shetty|first5=J.P.|title=A Review of Subdural Empyema and Its Management|journal=Infectious Diseases in Clinical Practice|volume=15|issue=3|year=2007|pages=149–153|issn=1056-9103|doi=10.1097/01.idc.0000269905.67284.c7}}</ref>. In children, the majority of cases of subdural empyema occur due to [[meningitis]] while in adults the most common causes are [[sinusitis]], [[otitis media]], [[mastoiditis]], [[trauma]] or as a complication of neurological procedures.<ref name="AgrawalTimothy2007">{{cite journal|last1=Agrawal|first1=Amit|last2=Timothy|first2=Jake|last3=Pandit|first3=Lekha|last4=Shetty|first4=Lathika|last5=Shetty|first5=J.P.|title=A Review of Subdural Empyema and Its Management|journal=Infectious Diseases in Clinical Practice|volume=15|issue=3|year=2007|pages=149–153|issn=1056-9103|doi=10.1097/01.idc.0000269905.67284.c7}}</ref><ref name="pmid16777239">{{Cite journal|author=Quraishi H, Zevallos JP |title=Subdural empyema as a complication of sinusitis in the pediatric population |journal=Int. J. Pediatr. Otorhinolaryngol. |volume=70 |issue=9 |pages=1581–6 |year=2006 |month=September |pmid=16777239 |doi=10.1016/j.ijporl.2006.04.007 |url=http://linkinghub.elsevier.com/retrieve/pii/S0165-5876(06)00135-2}}</ref>.
Depending on the site of origin of the [[infection]], as well as location of the [[empyema]] in the [[subdural space]], there will be different causative agents. The rate of success of growth of bacterial cultures, from the surgically removed [[pus]] is 54-81%. Common agents of subdural empyema include: [[anaerobes]], [[aerobic]] [[streptococci]], [[staphylococci]], ''[[Haemophilus influenzae]]'', ''[[Streptococcus pneumoniae]]'' and other [[gram-negative]] [[bacilli]]. <ref name="AgrawalTimothy2007">{{cite journal|last1=Agrawal|first1=Amit|last2=Timothy|first2=Jake|last3=Pandit|first3=Lekha|last4=Shetty|first4=Lathika|last5=Shetty|first5=J.P.|title=A Review of Subdural Empyema and Its Management|journal=Infectious Diseases in Clinical Practice|volume=15|issue=3|year=2007|pages=149–153|issn=1056-9103|doi=10.1097/01.idc.0000269905.67284.c7}}</ref>
In children, subdural empyema most often happens as a complication of [[meningitis]] while in adults it usually occurs as a complication of [[sinusitis]], [[otitis media]], [[mastoiditis]], [[trauma]] or as a complication of neurological procedures.<ref name="AgrawalTimothy2007">{{cite journal|last1=Agrawal|first1=Amit|last2=Timothy|first2=Jake|last3=Pandit|first3=Lekha|last4=Shetty|first4=Lathika|last5=Shetty|first5=J.P.|title=A Review of Subdural Empyema and Its Management|journal=Infectious Diseases in Clinical Practice|volume=15|issue=3|year=2007|pages=149–153|issn=1056-9103|doi=10.1097/01.idc.0000269905.67284.c7}}</ref><ref name="pmid16777239">{{Cite journal|author=Quraishi H, Zevallos JP |title=Subdural empyema as a complication of sinusitis in the pediatric population |journal=Int. J. Pediatr. Otorhinolaryngol. |volume=70 |issue=9 |pages=1581–6 |year=2006 |month=September |pmid=16777239 |doi=10.1016/j.ijporl.2006.04.007 |url=http://linkinghub.elsevier.com/retrieve/pii/S0165-5876(06)00135-2}}</ref>
Subdural empyema is a life-threatening condition and must be treated as such irrespective of the causes. Life-threatening conditions may result in death or permanent disability within 24 hours if left untreated.
The most common cause of subdural empyema in adults is the complication of an infection of the air sinuses: frontal, ethmoid, sphenoid and maxillary. The causative organisms of the empyema will be similar to those causing the infection of the sinuses, as well as in other possible causes, such as epidural abscess and brain abscess. Generally multiple organisms are present in the empyema, where anaerobes are almost always an important agent. [3][4]
The most common cause of subdural empyema in children is the complication of meningitis. The agents isolated from the pus, are usually similar to the ones causing the meningitis. [3][5]
Common causative agents:
Haemophilus influenzae
Streptococcus pneumoniae
Nontyphoidal Salmonella
Adults and Children
Common causative agents in trauma:
Coagulase negative strains of Staphylococcus
Anaerobes
Gram negative organisms (Campylobacter fetus)
Common causative agents in neurosurgical procedures:
↑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.