=====Supratentorial subdural empyema=====
//J.Sales-Llopis//

//Neurosurgery Department, University General Hospital of Alicante, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Alicante, Spain//

The supratentorial [[subdural empyema]] is a [[intracranial subdural empyema]]

====Etiology====
It is a rare complication of [[bacterial meningitis]],
((Dakkak M, Cullinane WR Jr, Ramoutar VR. Subdural Empyema Complicating Bacterial Meningitis: A Challenging Diagnosis in a Patient with Polysubstance Abuse. Case Rep Med. 2015;2015:931819. doi: 10.1155/2015/931819. Epub 2015 Oct 12. PubMed PMID: 26543484; PubMed Central PMCID: PMC4620381.))
more common caused by Str. pneumoniae 
((Jim KK, Brouwer MC, van der Ende A, van de Beek D. Subdural empyema in
bacterial meningitis. Neurology. 2012 Nov 20;79(21):2133-9. doi:
10.1212/WNL.0b013e3182752d0e. Epub 2012 Nov 7. PubMed PMID: 23136260.
)).

Bacterial or occasionally [[fungal infection]] of the skull bones or air sinuses can spread to the subdural space, producing a subdural empyema. 

The [[infection]] of a [[subdural hematoma]] is an unusual cause of [[subdural empyema]] with fewer than 50 cases reported till 2015 
((Dabdoub CB, Adorno JO, Urbano J, Silveira EN, Orlandi BM. Review of the
Management of Infected Subdural Hematoma. World Neurosurg. 2015 Nov 13. pii:
S1878-8750(15)01532-6. doi: 10.1016/j.wneu.2015.11.015. [Epub ahead of print]
PubMed PMID: 26585725.)). 

===Following the evacuation of a chronic subdural hematoma===
see [[Supratentorial subdural empyema following the evacuation of a chronic subdural hematoma]].

====Pathophysiology=====
The underlying [[arachnoid]] and [[subarachnoid space]]s are usually unaffected, but a large subdural empyema may produce a mass effect. Further, a [[thrombophlebitis]] may develop in the [[bridging vein]]s that cross the subdural space, resulting in venous occlusion and infarction of the brain.
====Symptoms====
Include those referable to the source of the infection. In addition, most patients are febrile, with headache and neck stiffness, and, if untreated, may develop focal neurologic signs, lethargy, and coma. The CSF profile is similar to that seen in brain abscesses, because both are parameningeal infectious processes. 

====Diagnosis====
Diagnosis of SDE is based on a strong clinical suspicion and the clinical features include fever, altered mental state, focal neurological deficits, and seizures with a fulminant and rapid downhill course.

CT typically demonstrates a crescent-shaped extra-axial fluid collection that can be either iso- or hyper-attenuating compared with the [[cerebrospinal fluid]]. Classically, there is also enhancement of the inner membrane with contrast administration
((Greenlee JE. Subdural empyema. Curr Treat Options Neurol 2003;5:13-22.)).

MRI has become the imaging modality of choice. Increased signal intensity is usually seen on T1-weighted and fluid-attenuated inversion recovery (FLAIR) MRI sequences because of the increased protein concentration of an empyema relative to cerebrospinal fluid. A fluid collection surrounded by a contrast-enhancing rim is often the feature
((Zimmerman R, Girard N. Imaging of intracranial infections. In: Scheld WM, Whitley RJ, Durack DT, editors. Infections of the Central Nervous System. 2 nd ed. Philadelphia: Lippincott-Raven; 1997. p. 923-44.)).

====Differential Diagnosis====
The main difficulties, in term of diagnosis, result from differential diagnosis between hematoma, hygroma, and empyema
((Guénot M. [Chronic subdural hematoma: diagnostic imaging studies].
Neurochirurgie. 2001 Nov;47(5):473-8. French. PubMed PMID: 11915760.)).
====Treatment====
Subdural empyema represents a neurosurgical emergency and if left untreated is invariably fatal. Rapid diagnosis, surgical intervention and intensive antibiotic therapy improve both morbidity and mortality
((Aryasinghe L, Sabbar S, Kazim Y, Awan LM, Khan HK. Streptococcus
pluranimalium: A novel human pathogen? Int J Surg Case Rep. 2014 Nov
14;5(12):1242-1246. doi: 10.1016/j.ijscr.2014.11.029. [Epub ahead of print]
PubMed PMID: 25437686.
)).

Treatment consists of surgery to establish bacteriologic identification and subsequently guide [[antibiotic]] [[therapy]]. 

With treatment, including surgical drainage, resolution of the empyema occurs from the dural side, and, if it is complete, a thickened dura may be the only residual finding. 

Drainage by craniotomy is associated with better outcome and lower mortality as it ensures maximal drainage of the loculated pus and also allows inspection of adjacent structures, and removal of the bone flap if necessary. However, some reports advocate drainage via burr-holes
((Tsai YD, Chang WN, Shen CC, Lin YC, Lu CH, Liliang PC, et al. Intracranial suppuration: A clinical comparison of subdural empyemas and epidural abscesses. Surg Neurol 2003;59:191-6.))
((Tummala, RP, Chu, RM, Hall WA. Subdural empyema in children. Neurosurg Q 2004;14:257-65.)).

====Outcome====
They result in significant morbidity and mortality despite improvements in neuroimaging, surgical techniques and antibiotic therapy.


====Case series====
===2009===
Mat Nayan et al. studied the efficacy of two surgical methods used for the treatment of intracranial subdural empyema (ISDE). A cross-sectional study (1999-2005) of 90 patients with non-traumatic supratentorial ISDE revealed that the two surgical methods used for empyema removal were burr hole/s and drainage (50 patients, 55.6%) and a cranial bone opening procedure (CBOP) (40 patients, 44.4%). Patients in the CBOP group had a better result in terms of clinical improvement (chi-squared analysis, p=0.006) and clearance of empyema on brain CT scan (chi-squared analysis, p<0.001). Reoperation was more frequent among patients who had undergone burr hole surgery (multiple logistic regression, p<0.001). The outcome and morbidity of ISDE survivors were not related to the surgical method used (p>0.05). The only factor that significantly affected the morbidity of ISDE was level of consciousness at the time of surgery (multiple logistic regression, p<0.001). We conclude that CBOP and evacuation of the empyema is a better surgical method for ISDE than burr hole/s and drainage. Wide cranial opening and empyema evacuation improves neurological status, gives better clearance of the empyema and reduces the need for reoperation. Level of consciousness at the time of presentation is a predictor of the morbidity of ISDE. Thus, aggressive surgical treatment should occur as early as possible, before the patient deteriorates
((Mat Nayan SA, Mohd Haspani MS, Abd Latiff AZ, Abdullah JM, Abdullah S. Two
surgical methods used in 90 patients with intracranial subdural empyema. J Clin
Neurosci. 2009 Dec;16(12):1567-71. doi: 10.1016/j.jocn.2009.01.036. Epub 2009 Sep
29. PubMed PMID: 19793660.
)).
----
65 pediatric patients (age <or=18 years) with supratentorial SDEs were treated between January 1988 and May 2006.

There was a slight male preponderance (55%), with mean age being 9.54 +/- 6.43 years (range 3 months to 18 years). Otogenic source was the most common identifiable etiology, followed by postmeningitic and rhinogenic sources. The initial surgical intervention, burr holes (44 patients; 67.7%) and craniotomy (21 patients; 32.3%), varied with individual cases and surgeon preference. Initial craniotomy was associated with lesser repeat procedures, and slightly better clinical outcome. The majority (83.3%) of patients with significant residual requiring repeat surgery were found to have undergone burr hole evacuation initially. The mortality rate in the present series was 10.8%. Follow-up was available for 41 patients (70.7%) with an average follow-up of 10.4 months. 88% of patients showed good outcomes (Glasgow Outcome Scores of 4 or 5) at the latest follow-up.

Pediatric supratentorial SDEs, although rapidly fatal if not identified promptly, can be effectively managed with early surgical drainage (preferably craniotomy), eradication of the source, and sensitive broad-spectrum antibiotics (i.v.) with good outcomes
((Banerjee AD, Pandey P, Devi BI, Sampath S, Chandramouli BA. Pediatric
supratentorial subdural empyemas: a retrospective analysis of 65 cases. Pediatr
Neurosurg. 2009;45(1):11-8. doi: 10.1159/000202619. Epub 2009 Feb 17. PubMed
PMID: 19221458.
)).

===2007===
Between 1997 and 2006, Mikami et al. treated eight patients with recalcitrant postcraniotomy subdural empyema and epidural abscess with combinations of myocutaneous free flap transfer. The free flap transfer was intended for patients who could not be cured with conventional surgical debridement and bone flap removal. Patient ages ranged from 15 to 67 years (mean, 41.5 yr). There were six men and two women. Treatment was required for cranial base tumors (n = 3), the result of trauma (n = 2), malignant tumors (n = 2), and cerebral hematoma (n = 1). In six patients (75%), an expanded polytetrafluoroethylene sheet was used as a dural substitute at the original surgery. They used three rectus abdominis myocutaneous flaps and five latissimus dorsi myocutaneous flaps. In six patients (75%), surgery was performed in the chronic stage of infection, and the other two patients were in the acute stage of infection.

Among all the patients, two failures occurred because of flap ischemia, but these were resolved after an additional procedure. However, one of these two patients, in whom surgery was performed at the acute stage of infection, died 4 weeks after the surgery. The postoperative course of the other six patients was uneventful. Isolated microorganisms were methicillin-resistant Staphylococcus aureus (four patients), Pseudomonas aeruginosa (three patients), and methicillin-sensitive Staphylococcus aureus (one patient).

Myocutaneous free flap transfer allows sufficient blood circulation and dead space control and is resistant to infection. Therefore, free flap transfer is useful for eliminating intractable empyema and abscess; however, it is important that the procedure be considered in the chronic stage of infection
((Mikami T, Minamida Y, Sugino T, Koyanagi I, Yotsuyanagi T, Houkin K. Free flap
transfer for the treatment of intractable postcraniotomy subdural empyemas and
epidural abscesses. Neurosurgery. 2007 Feb;60(2 Suppl 1):ONS83-7; discussion
ONS87-8. PubMed PMID: 17297370.
)).

===2004===
In 45 patients, there were 35 males and 10 females in the series. The majority of the patients were either infants (22.2%) or in their second and third decade of life (37.8%). For supratentorial SDE, craniotomy was done in 5 cases (11.1%). In six cases (13.3%) two burr-holes and in the rest of the cases multiple burrholes were done to evacuate the empyema. Craniectomy was done in three cases (6.7%), of which two had posterior fossa SDE. All patients received appropriate preoperative and postoperative broad-spectrum antibiotics.

There was good recovery in 35 (77.8%) patients, six patients (13.3%) had moderate disability, two patients (4.4%) had severe disability, and two (4.4%) died. Three patients who developed recollection at operation site required evacuation of residual SDE. Median follow-up was 3(1/2) years (range 4 months to 3(1/2) years).

Emergent evacuation of SDE using multiple burr-holes and irrigation of the subdural cavity with saline for 24 hours results in a satisfactory outcome in cases with SDE
((Tewari MK, Sharma RR, Shiv VK, Lad SD. Spectrum of intracranial subdural
empyemas in a series of 45 patients: current surgical options and outcome. Neurol
India. 2004 Sep;52(3):346-9. PubMed PMID: 15472424.
)).
====Case reports====
===2015===
A 55-year-old man was admitted complaining of headache, seizure, and urinary incontinence. He had a history of alcoholism and several hospitalizations for mild head trauma. Neuroimaging studies revealed a chronic hematic collection in the left frontal-parietal region. Laboratory tests showed increased C-reactive protein levels. In addition, surgical results revealed an infected subdural hematoma. A bacterial culture of the purulent specimen identified Escherichia coli. In view of the urinary complaint and leukocyturia, the etiology of the infected subdural hematoma was postulated as a urinary tract infection.

Infected subdural hematoma is an unusual disorder. We must keep in mind the possibility of this complication when seeing a patient who present with any of the three most common symptoms in this review. In these patients, craniotomy should be the method of surgical drainage, especially in adults. It ensures maximal drainage of the loculated pus and allows the total removal of the infected hematoma capsule
((Dabdoub CB, Adorno JO, Urbano J, Silveira EN, Orlandi BM. Review of the
Management of Infected Subdural Hematoma. World Neurosurg. 2015 Nov 13. pii:
S1878-8750(15)01532-6. doi: 10.1016/j.wneu.2015.11.015. [Epub ahead of print]
PubMed PMID: 26585725.
)).
----

A case of delayed [[Escherichia coli]] subdural empyema following a head injury in an elderly patient without significant risk factors. Computed tomography imaging was equivocal for subdural empyema. The patient underwent surgery and was treated with intravenous antibiotic therapy. Although initial improvement in the patient's clinical condition was observed, he eventually succumbed to nosocomial pneumonia. In this article, the authors discuss the presentation, diagnostic tools, and treatment options for subdural empyema with an emphasis on the challenges
((Munusamy T, Dinesh SK. Delayed Occurrence of Escherichia coli Subdural Empyema
Following Head Injury in an Elderly Patient: A Case Report and Literature Review.
J Neurol Surg Rep. 2015 Jul;76(1):e79-82. doi: 10.1055/s-0035-1547366. Epub 2015 
Mar 23. PubMed PMID: 26251817; PubMed Central PMCID: PMC4521004.
)).
----
A 69-year-old man developed motor aphasia and right hemiparesis with severe headache, during the treatment of cellulitis and sepsis due to cat bites. Brain CT showed a low density, crescent-shaped lesion in the left subdural space, which was hypointense on brain diffusion-weighted imaging (DWI). One week later, when his neurological symptoms had worsened, the signal of the subdural lesion had changed to hyperintense on DWI. The lesion was capsule-shaped when enhanced by Gadolinium. The signal changes on DWI of the lesion indicated the existing hematoma had changed to an empyema, or so-called infected subdural hematoma, due to a hematogenous bacterial infection. Pasteurella multocida, a resident microbe in the oral cavity of cats, could be the responsible pathogen in this case. The patient recovered completely after treatment with intravenous high dose antibiotics. This is an important case report describing the transformation from a chronic subdural hematoma into a subdural empyema by DWI
((Konno T, Yamada K, Kasahara S, Umeda Y, Oyake M, Fujita N. [Transformation
from chronic subdural hematoma into subdural empyema following cat bites: a case 
report]. Rinsho Shinkeigaku. 2015;55(9):657-60. doi:
10.5692/clinicalneurol.cn-000725. Epub 2015 Jul 11. Japanese. PubMed PMID:
26165810.
)).
----
A case of M. hominis subdural empyema in a woman occurring shortly after delivery. The patient presented with symptoms suggestive of bacterial meningitis. Spinal imaging revealed a subdural empyema that required neurosurgical intervention. Cultures from intraoperatively obtained biopsies identified M. hominis as the causative pathogen. The patient was treated with oral moxifloxacin for 4 weeks resulting in the resolution of the spinal lesion. The subdural empyema was presumably caused by a contaminated epidural blood patch performed with the patient's own blood during an episode of transient M. hominis bacteremia after delivery. The blood patch was indicated for the treatment of cerebrospinal fluid leakage, which had occurred after epidural anesthesia. Our findings highlight the significance of transient M. hominis bacteremia after delivery and implicate that M. hominis should be considered as a causative agent of extra-genitourinary tract infections particularly during the postpartum period or after genitourinary manipulation
((Hos NJ, Bauer C, Liebig T, Plum G, Seifert H, Hampl J. Autoinfection as a
cause of postpartum subdural empyema due to Mycoplasma hominis. Infection. 2015
Apr;43(2):241-4. doi: 10.1007/s15010-014-0713-2. Epub 2014 Dec 10. PubMed PMID:
25491170.
)).

===2013===
A 54-year-old male presented with 20 hour duration of headache, fever, and progressive deterioration of consciousness. He had undergone two burr-holes craniostomy and closed system drainages two times in a month for right fronto-parietal chronic subdural hematoma (CSDH). He presented to emergency department 10 days after the last surgery. There was history of closed head trauma 4 months ago and no skull fracture. Neurological examination revealed a Glasgow Coma Scale score of 10 (E3, V2, M5) and left side hemiparesis (3/5). Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated subdural collection in the same localization of the prior SDH.

With a possible diagnosis of SDE, he underwent emergent surgery under local anesthesia using the same burr holes to evacuate the subdural collection. At operation, a very thick capsule was seen around the lesion. A yellowish purulent material was drained with puncturing of the capsule. The empyema cavity was irrigated with sterile saline solution until the returning fluid was clear, and drains were placed in the subdural space for 2 days. Postoperatively he was alert and the hemiparesis resolved rapidly on postoperative day-1. Culture of the subdural fluid identified methicillin-resistant [[Staphylococcus epidermidis]]. He was treated with intravenous vancomycin and meropenem for 6 weeks. He was on prophylactic antiepileptic treatment since the first subdural hematoma drainage. He recovered fully and repeat MRI at 6 weeks follow-up did not show any recurrence of pus collection. He has been followed up in the outpatient clinic for 2 years
((Ovalioglu AO, Aydin OA. A case of subdural empyema following chronic subdural 
hematoma drainage. Neurol India. 2013 Mar-Apr;61(2):207-9. doi:
10.4103/0028-3886.111165. PubMed PMID: 23644343.
)).
===2010===
A 42- year-old male presented with headache and purulent discharge from right parietal burr hole wound site. Patient gave a history of head injury two years ago. He underwent burr hole evacuation of chronic subdural haematoma, excision of outer membrane and right parietal craniectomy. The cultures grew S. paratyphi A. Recovery was uneventful following surgical intervention and antibiotic therapy
((Bhooshan P, Shivaprakasha S, Dinesh KR, Kiran M, Karim P. Chronic subdural
empyema and cranial vault osteomyelitis due to Salmonella paratyphi A. Indian J
Med Microbiol. 2010 Jan-Mar;28(1):60-2. doi: 10.4103/0255-0857.58733. PubMed
PMID: 20061768.
)).

===2009===
A case of a bilateral chronic subdural hematoma which was contaminated with Klebsiella pneumoniae and resulted in a life-threatening central nervous system infection. After repeated of bilateral burr-hole drainage, the patient became hyperpyrexic and drowsy. Suppuration within the subdural space was suspected and then the patient underwent bilateral fronto-temporo-parietal craniotomies, and pus was evacuated. Its cultures revealed Klebsiella pneumoniae. Intravenous meropenem was given for 6 weeks. He recovered completely. Microorganisms like Klebsiella pneumoniae may directly infect the subdural space with iatrogenic contamination
((Bakar B, Sungur C, Tekkok IH. Bilateral chronic subdural hematoma contaminated
with Klebsiella pneumoniae : an unusual case. J Korean Neurosurg Soc. 2009
Jun;45(6):397-400. doi: 10.3340/jkns.2009.45.6.397. Epub 2009 Jun 30. PubMed
PMID: 19609428; PubMed Central PMCID: PMC2711242.
)).
----
A 80-year-old man who had undergone total gastrectomy and splenectomy for gastric cancer 13 years ago presented with headache, drowsiness, and high fever 1 month after a traffic accident. Brain CT scans revealed bilateral subdural fluid collections. Diffusion-weighted imaging (DWI) showed mixed high and low signal intensities in the left subdural fluid, and contrast-enhanced MR imaging revealed capsule enhancement of the left subdural fluid collection. The patient was diagnosed with left subdural empyema, and 2 burr-holes were drilled for drainage and irrigation. Operative findings revealed a neomembrane underneath the dura mater. Old hematoma and yellowish-white purulent fluid were present within the neomembrane. This confirmed the diagnosis of infected subdural hematoma (ISH). Abscess culture results were positive for Escherichia coli. The patient's symptoms resolved postoperatively with subsequent antibiotic therapy. However, 4 months after the operation, he suddenly died of severe sepsis and disseminated intravascular coagulation following cholecystitis, which was possibly associated with splenectomy. The clinical presentation, diagnosis, and treatment of an unusual case of ISH have been discussed. We emphasize that DWI and enhanced MR imaging may be useful for diagnosing ISH, and serial DWI evaluations may help in monitoring the therapeutic response in ISH
((Narita E, Maruya J, Nishimaki K, Heianna J, Miyauchi T, Nakahata J, Kitahara
H, Minakawa T. [Case of infected subdural hematoma diagnosed by
diffusion-weighted imaging]. Brain Nerve. 2009 Mar;61(3):319-23. Review.
Japanese. PubMed PMID: 19301604.
)).
----
A 23-year-old male was admitted due to headache and fever. One month ago, he had mild head injury by his coworkers. Physical examination showed a macrocephaly and laboratory findings suggested purulent meningitis. Neuroimaging studies revealed a huge size of epidural space-occupying lesion. Under the impression of epidural abscess, operation was performed. Eventually, the lesion was located at subdural space and was proven to be subdural empyema. Later, histological examination of the specimen obtained by surgery demonstrated finings consistent with the capsule of the chronic subdural hematoma. Two weeks after operation, Propionibacterium acnes was isolated. The intravenous antibiotics were used for total of eight weeks under monitoring of the serum level of the C-reactive protein. Follow-up brain computed tomography (CT) scan showed the presence of significant amount of remaining subdural lesion. However, he has complained of minimal discomfort. It is suggested that the subdural empyema occurred with preexisting chronic subdural hematoma after head injury about one month prior to admission and it took a long time to treat Propionibacterium acnes subdural empyema with systemic antibiotics, at least over eight weeks
((Kim JH, Lee CH, Hwang SH, Kang DH. Superimposed propionibacterium acnes
subdural empyema in a patient with chronic subdural hematoma. J Korean Neurosurg 
Soc. 2009 Jan;45(1):53-6. doi: 10.3340/jkns.2009.45.1.53. Epub 2009 Jan 31.
PubMed PMID: 19242574; PubMed Central PMCID: PMC2640823.)).

===2008===
A 51-year-old man was found lying unconscious on a street and was brought to the hospital in an ambulance. He had no past history of any underlying disease but he had suffered head trauma approximately 1 month prior to this episode. On admission, he had high fever and developed a convulsion fit. Because the cerebrospinal fluid (CSF) findings showed mononuclear dominant pleocytosis and Gram staining revealed spiral-shaped gram negative bacilli, meningitis caused by C. fetus was suspected. Brain CT preformed on admission did not reveal any obvious abnormality. He was immediately treated with antibiotics effective against C. fetus. His disease was complicated by bilateral subdural empyema; therefore, bilateral burr hole drainage was performed. Durling the operation, a hematoma with an outer membrane and containing yellowish pus was revealed. Infection of a chronic subdural hematoma and consequent formation of subdural empyema was deduced. Eventually, C. fetus was isolated from the CSF arterial blood and subdural empyema. The patient was discharged with no complication after the completion of the treatment
((Kanayama S, Ohnishi K, Yamaura T, Katayama M, Makino J, Takemura N, Hamabe Y. 
[Case of bilateral subdural empyema complicating Campylobacter fetus subspecies
fetus meningitis]. Brain Nerve. 2008 Jun;60(6):659-62. Japanese. PubMed PMID:
18567362.
)).

===2007===
A 87-year old male was admitted due to generalized convulsion with loss of consiousness. He was afebrile and his blood sampling was not infectious. Computed tomography scan suspected left chronic subdural hematoma. Burr hole drainage was performed to remove the hematoma, but the abscess was aspirated in the subdural space
((Otsuka T, Kato N, Kajiwara I, Tanaka T, Sawauchi S, Numoto RT, Murakami S, Abe
T. [A case of infected subdural hematoma]. No Shinkei Geka. 2007 Jan;35(1):59-63.
Japanese. PubMed PMID: 17228769.
)).
===1998===
A 63-year-old male with a preexisting chronic subdural hematoma presented with progressive confusion and left hemiparesis as well as high fever. Subdural empyema was strongly suspected. At surgery, the empyema was encapsulated by definite inner and outer membranes. Cultures isolated from the subdural fluid and from an abscess of his left thigh yielded methicillin-resistant Staphylococcus aureus. A pulsed-field gel electrophoresis showed these two strains were genetically identical. Hematogenous infection of a preexisting subdural hematoma is an extremely rare cause of subdural empyema
((Kawamoto S, Nagata K, Mochizuki Y, Hara T, Abe T, Sashida J. Subdural empyema 
caused by hematogenous dissemination from an abscess in thigh to a preexisting
chronic subdural hematoma--case report. Neurol Med Chir (Tokyo). 1998
Nov;38(11):743-5. PubMed PMID: 9919908.
)).
----
A 64-year-old man had been in a nearby hospital due to myelodysplastic syndrome with cerebral infarction for two months. His condition there had been almost uneventful. But spike fever occurred and the patient became drowsy two days before his transfer to our medical center. His consciousness level deteriorated progressively and CT scan showed a right chronic subdural hematoma. He had had no history of head trauma in the previous two months. On admission to our center, his consciousness level was semicoma with anisocoria. An emergency operation was performed via a single burr hole initially. From the burr hole, old bloody fluid accompanied by yellowish pus was obtained. Thus so-called ISH was diagnosed and the craniotomy was carried out. Gram stain of the specimen revealed gram negative rods. Although an epileptic state developed after the operation, it was controlled by barbiturate coma therapy for 3 days, followed by phenytoin administration. Fever subsided gradually with antibiotics sensitive to the bacteria and his anisocoria disappeared on the 4th postoperative day. In this case, Salmonella enteritidis was detected from bacterial culture both of the specimen and of the arterial blood. Salmonella enteritidis might have been implanted on the capsule of the chronic subdural hematoma by bacteremia derived from immunological dysfunction due to myelodysplastic syndrome. In conclusion, the possibility of ISH should be considered in chronic subdural hematoma patients with immunological dysfunction
((Kan M, Kim T, Miyaichi T, Rinka H, Matsuo Y, Shigemoto T, Yoshimura T, Kaji A,
Tsukioka K, Ukai T, Nishikawa M, Yamanaka K. [A case of Salmonella subdural
empyema developed in chronic subdural hematoma]. No Shinkei Geka. 1998
Oct;26(10):903-7. Japanese. PubMed PMID: 9789295.)).
===1997===
A 70-year-old male presented with rapid neurological deterioration and fever 3 months after suffering a closed head trauma. He underwent craniotomy for possible subdural empyema based on computed tomography and clinical findings. Dural incision revealed an outer membrane typical of chronic subdural hematoma which covered a clear, yellowish fluid containing Campylobacter fetus. Histological examination confirmed the capsule of the hematoma, with a necrotic focus infiltrated by neutrophils. Administration of intravenous imipenem and topical tobramycin and cefalothin achieved total resolution of his neurological deficits. Development of the infected subdural effusion was probably secondary to bacterial infection in the pre-existing chronic subdural hematoma in the resolving stage. The presence of the hematoma capsule always carries the risk of development of an infectious focus
((Aoki N, Sakai T, Oikawa A, Takizawa T, Shishido T. Infected subdural effusion 
associated with resolving subdural hematoma--case report. Neurol Med Chir
(Tokyo). 1997 Aug;37(8):637-9. PubMed PMID: 9301203.)).
===1996===
Two patients with postoperative subdural empyema following burr hole evacuation of chronic subdural haematoma are reported, both caused by [[Propionibacterium acnes]]. The need to consider this diagnosis in patients developing recurrent symptoms after surgical drainage of chronic subdural haematoma is emphasized
((Critchley G, Strachan R. Postoperative subdural empyema caused by
Propionibacterium acnes--a report of two cases. Br J Neurosurg. 1996
Jun;10(3):321-3. PubMed PMID: 8799549.
)).

----

A 71-year-old man developed a large multi-loculated subdural empyema following the evacuation of a chronic subdural haematoma. The pockets of pus were successfully evacuated endoscopically via the burr holes resulting in good recovery and no re-accumulation
((Kirollos RW, Tyagi AK, Boles DM. Endoscopy-assisted burr hole evacuation of
subdural empyema. Br J Neurosurg. 1996 Aug;10(4):395-7. PubMed PMID: 8864506.
)).

===1995===
Takamura et al. report the MR imaging of two patients with multiple subdural empyemas, including one in the interhemispheric fissure. MRI demonstrated convexity and interhemispheric collections which were mild hyperintense relative to CSF, hypointense relative to gray and white matter on T1W1, and marked hyperintense relative to CSF, and brain on T2W1. On the basis of signal intensity differences, MRI can distinguish subdural empyemas from most sterile effusions and chronic subdural hematomas with similar CT appearances. MRI was found to be clearly more sensitive to subdural empyemas than CT, though such lesions missed on CT were considered to be relevant. MR was superior to CT in demonstrating the nature, presence, and extent of these lesions. In both cases, the capsule of the lesions demonstrated enhancement, and connection between each lesion was obvious on contrast-enhanced MRI. It seems that contrast-enhanced MR image may detect encapsulation of an abscess which can not be detected from contrast-enhanced CT. We emphasized that the most significant factor in the successful surgical management of multiple subdural empyema, particularly including interhemispheric collections is the accurate location of pus. This can be reliably achieved with MR imaging
((Takamura Y, Uede T, Igarashi K, Tatewaki K. [Magnetic resonance imaging of
supratentorial and parafalcial empyema]. No Shinkei Geka. 1995 Jan;23(1):61-4.
Japanese. PubMed PMID: 7845522.)).
===1981===
A case is presented in which computerized tomography (CT) demonstrated a supratentorial and parafalcial purulent collection. However, neither carotid angiography nor CT revealed the small scattered pockets of pus that were found over the convexity at operation. The entire subdural space was exposed by a wide craniectomy, permitting adequate subdural drainage and decompression of the brain. It is thought that thorough drainage of the entire subdural space is crucial for the attainment of a successful result in a single-state operation
((Borovich B, Braun J, Honigman S, Joachims HZ, Peyser E. Supratentorial and
parafalcial subdural empyema diagnosed by computerized tomography. Case report. J
Neurosurg. 1981 Jan;54(1):105-7. PubMed PMID: 7463108.
)).