Review of 140 patients with brain abscess

Brain abscess following kidney transplantation: A single centre observational study from North India

Background

Amongst the infections in kidney transplant recipients, brain abscess represents an uncommon life-threatening complication. Mortality continues to be high despite improvements in diagnostics and therapeutics.

Method

We conducted an observational study, describing the incidence, presentation, implicating pathogen, management and outcome of brain abscess following kidney transplantation at our centre.

Result

Amongst the 1492 patients who underwent kidney transplantation at our centre between June 1991 and January 2023 (cumulative follow-up: 4936 patient-years), five females and four males, developed brain abscesses. The incidence proportion (risk) is 0.6% with an incidence rate of 6.03 cases per 1000 patient years. The median duration from transplant to development of brain abscess was 5 weeks (range: 4 weeks to 9 years). The commonest presentation was a headache. A definitive microbiological diagnosis was established in eight out of nine patients. The commonest implicated organism was a dematiaceous fungus, Cladophialophora bantiana (3 patients, 33.3%). Despite the reduction in immunosuppression, surgical evacuation and optimal medical therapy, five (55.55%) patients succumbed to their illness.

Conclusions

Brain abscesses following kidney transplantation is an uncommon, life-threatening condition. It usually occurs in the early post-transplant period and the presentation is often subtle. Unlike immunocompetent individuals, a fungus is the most common causative organism in those with solid organ transplants. The management includes a reduction in immunosuppression, early antimicrobial therapy, and surgical decompression.

Retrospective Review of the Clinical Outcomes of Surgically Managed Patients with Intracranial Abscesses: A Single-Center Review

OBJECTIVE

This study analyzed patient, radiologic, and clinical factors associated with operative brain abscesses and patients' functional outcomes.

METHODS

A retrospective analysis was conducted of neurosurgical cases of brain abscesses from 2009 to 2019 at a Canadian center. Functional outcome was recorded as Modified Rankin Scale score and Extended Glasgow Outcome Scale score. Multivariate analysis was conducted to identify relevant prognostic factors.

RESULTS

We identified 139 patients managed surgically for brain abscesses. Resection alone was performed in 64% of patients, whereas 26.6% underwent aspiration alone. Most were adults (93.2%) and male (68.3%). Immunocompromise risk factors included diabetes (24.5%), cancer (23.7%), and immunosuppressive therapy (11.5%). Likely sources were postoperative (17.3%), systemic spread (16.5%), and poor dentition (12.9%). Microorganisms cultured from abscess samples were mixed growth (28%), Streptococcus anginosus (24.5%), and Staphylococcus aureus (7.9%). Disposition was home (42.4%) or repatriation to a home hospital (50.4%). By Extended Glasgow Outcome Scale, 25.2% had an unfavorable outcome including a mortality of 11.5%. Factors on multivariate analysis associated with poor outcome included diabetes (odds ratio, 2.8; 95% confidence interval [CI], 1.2-5.0) and ventricular rupture (odds ratio, 5.0; 95% CI, 1.7-13.5; hazard ratio, 12; 95% CI, 3.9-37.0). Supratentorial superficial eloquently located abscess was also associated with poor outcome (hazard ratio, 5.5; 95% CI, 1.8-16.7). Outcomes were similar with surgical excision and aspiration.

CONCLUSIONS

Ventricular rupture and diabetes are significant risk factors for poor outcomes in intraparenchymal brain abscesses. No clear difference in outcomes was found between surgical excision or aspiration in our retrospective cohort.

Secondary Bacterial Infection of a Solitary Cysticercus Granuloma

The most common presenting form of neurocysticercosis in the Indian subcontinent is a solitary cysticercus granuloma (SCG). Patients with typical SCGs almost never require any form of surgical intervention. Herein, we report an extremely rare case of bacterial superinfection of a left frontal SCG in a 23-year-old female, resulting in severe perilesional edema and mass effect. The patient had to undergo an emergency left decompressive hemicraniectomy and excision of the infected granuloma. Serum enzyme-linked immunoelectrotransfer blot (EITB) for cysticercal antibodies was positive and histopathological examination of the lesion revealed a cysticercus. The culture of the pus from within the lesion grew vancomycin-resistant Enterococcus spp. for which she was treated with linezolid for 6 weeks. At 6 months follow-up, she had residual motor dysphasia, right homonymous hemianopia, and right hemiparesis but was steadily improving. Secondary bacterial infection of an SCG is very uncommon and can be devastating. A high index of suspicion is therefore required when there is disproportionate perilesional edema and mass effect.

HIV, Tuberculosis, and Otogenic Intracranial Sepsis: A Devastating Disease With a Subtle Presentation

OBJECTIVES

To undertake a large-scale review of otogenic intracranial sepsis in an area of highly prevalent HIV and tuberculosis (TB) to re-examine and inform early diagnosis and treatment efforts.

METHODS

Seventy-seven consecutive cases of otogenic intracranial sepsis in KwaZulu-Natal, South Africa were reviewed for demographics, presentation, imaging, HIV status, culture results, and outcomes.

RESULTS

The most common intracranial complications were intracranial abscess (46.8%), hydrocephalus (31.2%), subdural empyema (28.6%), and epidural empyema (26.0%). Ear discharge (87.0%), postauricular abscess (29.9%), and hearing loss (29.9%) were notable presenting symptoms. Overall mortality was 15.6%. Of the 45.5% of patients with HIV testing, 54.2% were HIV+, Mortality among HIV+ patients was 15.8% but only 6.3% in HIV- patients (p = 0.61, OR = 2.8). Eight patients (10.4%) had culture or histological evidence of TB infection.

CONCLUSIONS

Otogenic intracranial complications continue to present late and are associated with significant mortality and morbidity, despite advances in diagnostic and treatment modalities. This study represents one of the largest case-series in the literature, and the first to specifically evaluate the effects of HIV and TB infection.Patient presentation and severity of illness varied; however, a majority of patients presented with ear discharge and no focal neurological signs. An effect size for higher mortality among HIV+ patients compared with HIV- patients was noted but was not significant. Tuberculosis infection was prevalent compared with previous studies.This study reinforces the need for enhanced screening and early treatment of ear disease to minimize associated mortality and morbidity, particularly in immunocompromised patients.

Thalamic Abscess in a Newly Diagnosed Diabetic Patient

Brain abscesses are commonly located in the cerebral cortex and cerebellum; however, solitary thalamic lesions are rare. Recent cases report dental pathology as a common source, potentially compounded by immunocompromise. Here, we report a newly diagnosed diabetic male with poor dentition presenting with evidence of meningitis wherein thalamic abscess was discovered.

Successful management of intraventricular rupture of pyogenic brain abscess (IVROBA): Systematic review and illustrative case

OBJECTIVES

Intraventricular rupture of brain abscess (IVROBA) is one of the most dreaded complications of pyogenic brain abscess due to its high mortality rate. Because of its relative infrequency and poor outcome, the optimal management of this condition remains to be determined.

PATIENTS AND METHODS

We report the case of a 5-year old female with a presumptive diagnosis of IVROBA who was discharged with good neurologic outcome after completing intravenous antibiotic treatment and undergoing insertion of an external ventricular drain (EVD) and later, a ventriculoperitoneal (VP) shunt. We also performed a systematic review of the SCOPUS and PubMed databases for case reports and series documenting patients who survived after undergoing treatment for IVROBA.

RESULTS

A total of 24 cases of IVROBA survivors were reported in the literature, including the present case. The median age was 48.5 years (range: 5-71), with a male predilection (3:1). The most common location of the brain abscesses was temporal while the most common route of spread was hematogenous. Surgery was performed in 92% of cases, with EVD being the most common surgical procedure. Twenty nine percent of cases required a VP shunt. The duration of systemic antibiotic treatment ranged from 31 to 180 days (median: 56 days) while intraventricular antibiotics were given for 8-42 days (median: 14 days).

CONCLUSION

The management of IVROBA in this series varied widely, with surgery playing an important role. Although IVROBA is still a devastating complication of intracranial abscess, a good neurologic outcome may still be possible with treatment.

Brain and Spinal Epidural Abscess

PURPOSE OF REVIEW

Brain abscesses and spinal epidural abscesses are serious, potentially life-threatening infections of the central nervous system. This article outlines the clinical presentation, evaluation, and management of brain abscesses and spinal epidural abscesses, with a specific focus on bacterial infections.

RECENT FINDINGS

The overall incidence of brain abscesses has declined, in part because of fewer brain abscesses associated with otogenic infections. However, emerging patient populations at high risk for brain abscess include those with a history of penetrating head trauma, neurosurgery, or immunodeficiency. Improved mortality rates for brain abscess are attributable to modern diagnostic imaging, stereotactic-guided aspiration, and newer antimicrobials that readily penetrate into the central nervous system and abscesses. Brain MRI is more sensitive than CT for brain abscess, particularly in the early stages, but CT remains more widely available and can adequately identify potential abscesses and confirm response to treatment. With the advent of minimally invasive neurosurgical techniques, surgical excision is often employed only for posterior fossa, multiloculated, or superficial well-circumscribed abscesses. In select clinical scenarios, conservative medical management may be a safe alternative to a combined surgical and medical approach. Unlike brain abscess, the incidence of spinal epidural abscess is on the rise and has been attributed to higher prevalence of predisposing factors, including spinal procedures and instrumentation.

SUMMARY

Successful diagnosis and management of brain abscess and spinal epidural abscess requires a collaborative approach among neurologists, neurosurgeons, radiologists, and infectious disease physicians. The foundation of management of brain abscess includes surgical intervention for diagnostic purposes if a pathogen has not been identified or for decompression of larger abscesses or those with mass effect and significant surrounding edema; appropriate dosing and adequate duration of an antimicrobial regimen tailored to the presumptive source of infection and available culture data, and eradication of the primary source of infection. For spinal epidural abscesses, neurologic status at the time of presentation is directly related to outcomes, underscoring the importance of prompt recognition and intervention.

MRI detection of bacterial brain abscesses and monitoring of antibiotic treatment using bacCEST

PURPOSE

To develop a new MRI method to detect and characterize brain abscesses using the CEST contrast inherently carried by bacterial cells, namely bacCEST.

METHODS

Bacteria S. aureus (ATCC #49775) and F98 and 9L glioma cells were injected stereotactically in the brains of F344 rats to form abscesses and tumors. The CEST signals of brain abscesses (n = 4) and tumors (n = 7) were acquired using 2 B1 values (i.e., 1 and 3 µT) and compared. The bacCEST signal of the brain abscesses in the rats (n = 3) receiving ampicillin (intraperitoneal injection 40 mg/kg twice daily) was acquired before, 4 and 10 days after the treatment.

RESULTS

The bacCEST signal of S. aureus was characterized in vitro as a strong and broad signal in the range of 1 to 4 ppm, with the maximum contrast occurring at 2.6 ppm. The CEST signal in S. aureus-induced brain abscesses was significantly higher than that of contralateral parenchyma (p = .003). Moreover, thanks to their different B1 independence, brain abscesses and tumors could be effectively differentiated (p = .005) using ΔCEST(2.6 ppm, 3 µT-1 µT), defined by the difference between the CEST signal (offset = 2.6 ppm) acquired using B1  = 3 µT and that of 1 µT. In treated rats, bacCEST MRI could detect the response of bacteria as early as 4 days after the antibiotic treatment (p = .035).

CONCLUSION

BacCEST MRI provides a new imaging method to detect, discriminate, and monitor bacterial infection in deep-seated organs. Because no contrast agent is needed, such an approach has a great translational potential for detecting and monitoring bacterial infection in deep-seated organs.

Brain Abscess Following Intracerebral Hemorrhage in a Patient With Pneumonia

Brain abscess is a rare but potentially lethal infection of brain parenchyma, requiring prompt surgical intervention and high-dose antibiotic therapy. Brain abscess is a known complication of surgically treated intracerebral hemorrhage (ICH), but it is exceptionally rare that it occurs at the same site of a nonoperated ICH. Such cases may result from hematogenous spread from distant foci (pneumonia, infectious endocarditis) or contiguous sites. Herein, the authors report a case of 75-year-old woman presenting with a brain abscess 6 weeks after a nonoperated ICH. As the patient suffered from pneumonia during the course of ICH, the authors suspected that the brain abscess might originate from the pneumonia via hematogenous spread. The awareness of brain abscess formation at the site of ICH is of great importance for early diagnosis and prompt treatment.

Good Outcomes with the Intraventricular Vancomycin Therapy in a Patient with Ruptured Brain Abscesses

Brain abscesses are associated with high morbidity and mortality rates. In particular, patients with intraventricular rupture of brain abscess (IVROBA) exhibit mortality rates up to 85%. Treatment options are lacking for IVROBA, once patients become refractory to intravenous antibiotics and surgical drainage. Limited data exist regarding the risks and benefits of intraventricular therapy in such a scenario. We report a patient with IVROBA, who deteriorated while on systemic antibiotics; once intraventricular vancomycin was employed, the patient demonstrated remarkable improvement without perceivable side effects. This case suggests that intraventricular vancomycin may be a safe, effective, and viable option for the treatment of IVROBA, especially for patients becoming refractory to systemic antibiotics.

Neuroimaging in Central Nervous System Infections

Radiologic imaging is often employed to supplement clinical evaluation in cases of suspected central nervous system (CNS) infection. While computed tomography (CT) is superior for evaluating osseous integrity, demineralization, and erosive changes and may be more readily available at many institutions, magnetic resonance imaging (MRI) has significantly greater sensitivity for evaluating the cerebral parenchyma, cord, and marrow for early changes that have not yet reached the threshold for CT detection. For these reasons, MRI is generally superior to CT for characterizing bacterial, viral, fungal, and parasitic infections of the CNS. The typical imaging features of common and uncommon CNS infectious processes are reviewed.

Evaluation of Continuous Irrigation and Drainage with a Double-Cavity Sleeve Tube to Treat Brain Abscess

BACKGROUND

Brain abscesses carries a high morbidity and mortality, and despite medical advances, it continues to pose diagnostic and therapeutic challenges worldwide. The traditional surgical approaches to treating brain abscess (burr hole aspiration and craniotomy) have both advantages and disadvantages and remain controversial. Here we report a single institution's experience with a new surgical approach for brain abscess.

METHODS

We retrospectively analyzed 46 patients with intracranial abscess who underwent continuous irrigation and drainage through a double-cavity sleeve tube placed surgically in conjunction with a 4-week course of intravenous cefotaxime and metronidazole at Renmin Hospital of Wuhan University between January 2008 and December 2016. The patients' medical records were analyzed for demographic data, clinical presentation, predisposing factors, imaging findings, microbiological test results, treatments, surgical techniques, and outcomes.

RESULTS

The 46 patients included 29 males and 17 females, ranging in age from 22 to 74 years. A single abscess was detected in 34 patients, whereas 12 patients had multiple abscesses. The average duration of hospitalization was 12.6 days. After treatment, 38 of the 46 patients resumed a normal life despite minor deficits (Glasgow Outcome Score [GOS] 5), 6 patients exhibited slight neurologic deficits (GOS 4), and 2 patients died of severe systemic infection and multiorgan failure. In particular, a patient with a brain abscess broken into the ventricle recovered well (GOS 5). No patient required repeat aspiration or surgical excision.

CONCLUSIONS

Continuous brain abscess cavity irrigation and drainage with a double-cavity sleeve tube is an effective treatment for brain abscess and produces excellent results, especially for an abscess broken into the ventricle. It combines the advantages of burr hole aspiration and open craniotomy excision. It is easy to perform and reduces costs and damage to the patient, and also shortens hospitalization time and antibiotic treatment time, greatly reducing the likelihood of reoperation. This approach may be the optimal choice to treat brain abscess.

Relationship between demography, etiology, level of consciousness, and outcome of surgical intracranial suppurations of bacterial origin in a tropical tertiary center

Introduction:

Intracranial suppurations (ICS) of bacterial origin are associated with significant mortality and morbidity. This study aimed to review demography, etiology, level of consciousness, and outcome of surgical ICS in a tropical tertiary hospital.

Materials and Methods:

All patients admitted to the neurosurgical unit within the study period of 7 years that had a surgical intervention for their ICS were prospectively included in the study. In accordance with the unit protocol, all patients in whom there was clinical suspicion of ICS had a preoperative computed tomography scan and/or magnetic resonance imaging done. The following data among others were documented and recorded electronically: demography, clinical and radiological diagnosis, etiology of ICS, admission Glasgow Coma Scale (GCS) score, type of neurosurgical intervention, mode of anesthesia, and outcome.

Results:

Forty-nine patients were included in the study. There were 33 males with a male-to-female ratio of 2.1:1. All patients presented at least a week after the use of antibiotics. The most common type of ICS was cerebral abscess (33 patients, 67.3%). There was no statistical significant association between outcome and age group (P = 0.630), gender (P = 0.999), diagnosis (P = 0.464), etiology of ICS (P = 0.169), solitary or multiplicity of ICS (P = 0.485), or type of offending organism (P = 0.278).

Conclusions:

ICS usually follows otorhinological infections in our center. The surgical outcome is dependent on the admission GCS score.

Surgical Treatment of a Chronic Brain Abscess and Growing Skull Fracture in a Dog

A 2-year-old female spayed Miniature Dachshund was presented for seizures and right prosencephalic signs. A multiloculated, ring-enhancing mass in the right cerebrum associated with dilation of the right lateral ventricle and brain herniation was seen on magnetic resonance imaging. An irregular calvarial defect with smoothly scalloped edges was seen overlying the mass on computed tomography. The mass was removed via craniectomy and was diagnosed as a chronic brain abscess caused byPeptostreptococcus anaerobius. The patient was maintained on antibiotics for 12 weeks. Follow-up MRI performed 14 weeks after surgery confirmed complete removal of the abscess as well as a contrast-enhancing collection of extra-axial material consistent with a chronic subdural hematoma. The neurologic abnormalities, including seizures, have improved in the 44 months since surgery. Brain abscesses in dogs can have an insidious clinical course prior to causing serious neurologic deterioration. Ventricular entrapment by an intracranial mass can contribute to acute neurologic decline. If surgically accessible, outcome following removal of a brain abscess can be excellent; aerobic and anaerobic bacterial culture should be performed in these cases. Subdural hematoma can occur following removal of a large intracranial mass. Growing skull fractures can occur in dogs but may not require specific surgical considerations.

Brain infection with Staphylococcus aureus leads to high extracellular levels of glutamate, aspartate, γ-aminobutyric acid, and zinc

Staphylococcal brain infections may cause mental deterioration and epileptic seizures, suggesting interference with normal neurotransmission in the brain. We injected Staphylococcus aureus into rat striatum and found an initial 76% reduction in the extracellular level of glutamate as detected by microdialysis at 2 hr after staphylococcal infection. At 8 hr after staphylococcal infection, however, the extracellular level of glutamate had increased 12-fold, and at 20 hr it had increased >30-fold. The extracellular level of aspartate and γ-aminobutyric acid (GABA) also increased greatly. Extracellular Zn(2+) , which was estimated at ∼2.6 µmol/liter in the control situation, was increased by 330% 1-2.5 hr after staphylococcal infection and by 100% at 8 and 20 hr. The increase in extracellular glutamate, aspartate, and GABA appeared to reflect the degree of tissue damage. The area of tissue damage greatly exceeded the area of staphylococcal infiltration, pointing to soluble factors being responsible for cell death. However, the N-methyl-D-aspartate receptor antagonist MK-801 ameliorated neither tissue damage nor the increase in extracellular neuroactive amino acids, suggesting the presence of neurotoxic factors other than glutamate and aspartate. In vitro staphylococci incubated with glutamine and glucose formed glutamate, so bacteria could be an additional source of infection-related glutamate. We conclude that the dramatic increase in the extracellular concentration of neuroactive amino acids and zinc could interfere with neurotransmission in the surrounding brain tissue, contributing to mental deterioration and a predisposition to epileptic seizures, which are often seen in brain abscess patients.

Utilization of multidisciplinary surgical techniques to successfully manage 20 brain abscesses in a child

PURPOSE

This study describes a case of multiple brain abscesses in a four-year-old boy who presented with a history of fever and disorientation.

METHODS

Medical investigations revealed severe leukocytosis and the presence of 20 hypodense lesions in the boy's cerebrum. Initial medical treatment included intravenous antibiotics, antiepileptics, and dexamethasone. The boy underwent five surgical interventions within a period of 5 weeks that included frameless stereotactic craniotomies for aspiration and resection of the abscesses.

RESULTS

At the 3-month follow-up, the boy displayed no neurological deficits and no lesions were detected in his brain.

CONCLUSIONS

This study reveals the importance of instituting a standardized protocol to determine the urgency of surgical intervention in cases of brain abscess so that surgical treatment can be applied in the appropriate time period. This case also shows that rewarding results can be obtained in treating brain abscesses in children when the proper treatment method is initiated in the appropriate amount of time.

[A case of intracranial abscess caused by peri-odontogenic infection]

The authors report a case in which a 42-year-old woman developed an intracranial abscess in the temporal lobe as a result of a peri-odontogenic infection. A subdural abscess also developed in the middle cranial fossa, expanding directly from the base of the skull through the foramen ovale and the foramen spinosum. An operation involving a left-front temporal incision extending to the tragus was performed. Debridement and brain aspiration with drainage were carried out after the craniotomy via the same skin incision without operative complications. The patient left hospital 36 days after the operation without sequelae.

Open craniotomy for brain abscess: A forgotten experience?

Background:

Brain abscess carries a high morbidity and mortality despite medical advances. In this paper, we present a single institution's experience with the surgical treatment of brain abscess.

Methods:

We retrospectively analyzed 33 cases of intracranial abscess who underwent surgical treatment between January 2001 and December 2009. Patients were treated with aspiration through a single burr hole, open aspiration with ultrasound guidance, or complete abscess resection. The medical records were analyzed for demographics, clinical presentation, predisposing factors, imaging, microbiological investigations, treatment, and outcomes.

Results:

There were 26 male and 7 female patients, aged between 12 and 78 years. The most common predisposing factor was head trauma. Surgical excision of the abscess was performed in 22 patients, open aspiration in 9 patients, and burr-hole aspiration in 2 patients. Repeat surgical procedure was required in six patients. Mortality in this series was 21%. A favorable outcome (Glasgow outcome scale 4 and 5) was achieved in 54%. There was no significant correlation between outcome and age, predisposing factor, treatment modality, or culture results.

Conclusions:

In this series, most patients were treated with an open technique, either by surgical excision or open aspiration of brain abscess. An open technique may reduce the need for additional imaging, surgical treatment, and length of antibiotic therapy. In resource-limited settings, excision of brain abscess may play a more important role in patient management while maintaining favorable outcomes.

Fever and limp: thinking outside the box

Fever and limp is a common presentation in the pediatric emergency department. We describe a case of a 21-month-old female patient with prolonged fever and difficulty bearing weight, ultimately diagnosed with a large intracranial abscess. Intracranial abscesses are a rare cause of limp and an uncommon diagnosis in pediatric patients without underlying congenital heart disease. This case highlights the importance of differentiating the features of limp secondary to pain from limp secondary to weakness, which is particularly difficult in the preschool-aged group. It is imperative for practitioners to consider disease of the central nervous system when evaluating acutely nonambulatory children with fevers.

Hyperbaric oxygen is effective in early stage of healing of experimental brain abscess in rats

OBJECTIVES

Current therapy of brain abscess (BA) includes a combined approach that involves antibiotics and minimal invasive surgery, but also hyperbaric oxygen treatment (HBOT) as a supportive measure. Optimum treatment is still a matter of significant controversy.

METHODS

The experiment, previously approved by a relevant ethical committee, involved 80 female Wistar rats. BA was experimentally induced by inoculation of Staphylococcus aureus. The animals were randomized into groups and treated either with antibiotics, HBOT, or with a combination of both.

RESULTS

Beneficial effect of HBOT was evident in groups treated with HBOT or with a combination of antibiotic+HBOT. It was mainly manifested on days three and five of the experiment and was evident as statistically significant increase of a number of newly formed blood vessels, increase in mean vascular density, and smaller abscess necrotic core.

DISCUSSION

Although the results of the present study should be interpreted cautiously, they suggest that HBOT has an important but limited role in the treatment of BA.

Epidemiology of central nervous system infection

In cases of central nervous system infection, it is crucial for the neuroradiologist to provide an accurate differential diagnosis of the possible pathogens involved so that treating physicians can be aided in the choice of empiric therapy. This approach requires the radiologist to be aware of local epidemiology and have knowledge of infectious agents that are endemic to their area of practice. This article reviews and discusses the changing epidemiology of pathogens most often observed in meningitis, brain abscess, epidural abscess, postoperative infections, and human immunodeficiency virus infection.

Metagenomic analysis of brain abscesses identifies specific bacterial associations

BACKGROUND

The bacterial flora involved in brain abscess is often complex. In a previous study, using a metagenomic approach based on 16S ribosomal DNA (rDNA) amplification, we demonstrated that the diversity of the microbial flora involved in these infections was underestimated.

METHODS

We performed a 16S rDNA-based metagenomic analysis of cerebral abscesses from patients diagnosed from 2006 through 2010. All bacteria present in brain abscess specimens were identified, in view of the clinical and epidemiological characteristics of the patients.

RESULTS

Fifty-one patients were included in our study. By detecting polymicrobial infections in 19 patients, our strategy was significantly more discriminatory and enabled the identification of a greater number of bacterial taxa than did culture and conventional 16S rDNA polymerase chain reaction (PCR) and sequencing, respectively (P < 10(-2)). Data mining discriminated 2 distinct bacterial populations in brain abscess from dental and sinusal origin. In addition, of the 80 detected bacterial species, we identified 44 bacteria that had never been found in brain abscess specimens, including 22 uncultured bacteria. These uncultured agents mostly originated from the buccal or sinusal floras (P < 10(-2)) and were found in polymicrobial specimens (P < 10(-2)).

CONCLUSIONS

Cloning and sequencing of PCR-amplified 16S rDNA is a highly valuable method to identify bacterial agents of brain abscesses.

Brevibacterium casei as a cause of brain abscess in an immunocompetent patient

Coryneform bacteria belonging to the genus Brevibacterium have emerged as opportunistic pathogens. Of the nine known species of Brevibacterium isolated from human clinical samples, Brevibacterium casei is the most frequently reported species from clinical specimens. We report the first case of B. casei brain abscess in an immunocompetent patient successfully treated by surgery and antimicrobial therapy.

Taming an old enemy: a profile of intracranial suppuration

Intracranial suppurative disorders (ICSDs; brain abscess, empyema, and purulent ventriculitis), have been a scourge through the ages and attempts at curative surgery, as for cranial trauma, are considered to be one of the first true neurosurgical interventions performed. ICSDs, seen initially as a consequence of poor socioeconomic conditions and neglected otorhinogenic infections, predominantly manifest today as postsurgical complications, and/or in immunocompromised patients where they continue to result in significant neurologic morbidity and death. The reduction in the incidence of "old world" classic ICSDs can be attributed to the modernization of society, driven inter alia by a shift from an agricultural to an industrial economic society. It can also be coupled with pivotal achievements in public health and the dramatic developments in medicine in the 20th century. This trend was first noted in developed countries but now, with improved socioeconomic circumstances and globalization of medical technology, it is occurring in the developing regions of the world as well. Although ICSDs have undergone a metamorphosis in their clinical profile and despite their rarity in contemporary "developed world" neurosurgical practice, they still have undoubted potential for fatal consequences and continue to pose a significant challenge to the 21st-century neurosurgeon.

T2*-weighted MR angiography substantially increases the detection of hemorrhage in the wall of brain abscess: implications in clinical interpretation

INTRODUCTION

The purpose of the present study was to identify the true prevalence of hemorrhage in the abscess using T2*-weighted angiography (SWAN) imaging and to study its influence on diffusion tensor imaging (DTI) metrics.

METHODS

Fifteen patients of brain abscess underwent conventional, SWAN, and DT imaging on a 3-T MRI followed by its confirmation with histology. DTI metrics were quantified by region-of-interest analysis on hemorrhagic and non-hemorrhagic regions of the abscess wall. Prussian blue staining was performed on excised abscess walls to confirm hemorrhage on histology.

RESULTS

Eleven of 15 patients showed evidence of hemorrhage on both Prussian blue staining as well as SWAN imaging. Fractional anisotropy (FA) and linear anisotropy (CL) values were significantly higher, while spherical anisotropy was significantly lower in hemorrhagic compared to non-hemorrhagic regions of the abscess wall.

CONCLUSION

Hemorrhage in the abscess wall is a common feature and may not always indicate neoplasm. The presence of intracellular iron in addition to concentrically laid collagen fibers may have synergistic effect on FA and CL values in the abscess wall. Inclusion of SWAN to MRI protocol will define the true prevalence of hemorrhage in brain abscess.

Brain abscess: management and outcome analysis of a computed tomography era experience with 973 patients

OBJECTIVE

Brain abscess (BA) is a neurosurgical emergency and despite significant medical advances, it remains a surgical challenge. A single institution's two decade computed tomography era management experience with BA is reported.

METHODS

A retrospective analysis of patients with BA, admitted to the Department of Neurosurgery, Wentworth Hospital, Durban, KwaZulu-Natal, South Africa, was performed. The medical records were analyzed for demographic, clinical, neuroimaging, neurosurgical and otolaryngology management, microbiological characteristics, and their relationship to outcome.

RESULTS

During a 20-year period (1983-2002), 973 patients were treated. The mean age was 24.36 ± 15.1 years (range: 0.17-72 years) and 74.2% (n = 722) were men. The mean admission Glasgow Coma Score was 12.5 ± 2.83. The majority of BAs were supratentorial (n = 872, 89.6%). The causes were otorhinogenic (38.6%), traumatic (32.8%), pulmonary (7%), cryptogenic (4.6%), postsurgical (3.2%), meningitis (2.8%), cardiac (2.7%), and "other" (8.6%). Surgical drainage was performed in 97.1%, whereas 19 patients had nonoperative management. The incidence of BA decreased during the study period. Patient outcomes were good in 81.3% (n = 791), poor in 5.3% (n = 52), and death (13.4%, n = 130) at discharge. The management morbidity, which included postoperative seizures, was 24.9%. Predictors of mortality were cerebral infarction (odds ratio [OR] 31.1), ventriculitis (OR 12.9), coma (OR 6.8), hydrocephalus (OR 5.1), dilated pupils (OR 4.8), bilateral abscesses (OR 3.8), multiple abscesses (OR 3.4), HIV co-infection (OR 3.2), papilledema (OR 2.6), neurological deterioration (OR 2.4), and fever (OR 1.7).

CONCLUSIONS

Optimal management of BA involves surgical drainage for medium-to-large abscesses (≥2.5 cm) with simultaneous eradication of the primary source, treatment of associated hydrocephalus, and administration of high doses of intravenous antibiotics. The incidence of BA is directly related to poor socioeconomic conditions and therefore, still poses a public health challenge in developing countries.

Brain abscess: an overview

Intracranial abscess is a formidable entity. Despite the advent of newer antibiotics and surgical strategies, the overall outcome and quality of life issues in brain abscess patients still remain a continuous challenge for the neurosurgical community. It is a direct interplay between the virulence of the offending microorganism and the immune response of the host. An analysis of our experience in the 289 cases of surgically treated pyogenic brain abscess is presented along with an overview of intra-cranial abscess of varied etiology and in different locations. The etiology, pathogenesis, radiological advances and treatment modalities of brain abscess are discussed in light of current literature.

Brain abscess in Korean children: A 15-year single center study

Purpose

A brain abscess is a serious disease of the central nerve system. We conducted this study to summarize the clinical manifestations and outcomes of brain abscesses.

Methods

A retrospective chart review of pediatric patients diagnosed with brain abscesses from November 1994 to June 2009 was performed at Samsung Medical Center, Seoul, Korea.

Results

Twenty-five patients were included in this study. On average, 1.67 cases per year were identified and the median age was 4.3 years. The common presenting clinical manifestations were fever (18/25, 72%), seizure (12/25, 48%), altered mental status (11/25, 44%), and signs of increased intracranial pressure (9/25, 36%). A total of 14 (56%) patients had underlying illnesses, with congenital heart disease (8/25, 32%) as the most common cause. Predisposing factors were identified in 15 patients (60%). The common predisposing factors were otogenic infection (3/25, 12%) and penetrating head trauma (3/25, 12%). Causative organisms were identified in 64% of patients (16/25). The causative agents were S. intermedius (n=3), S. aureus (n=3), S. pneumoniae (n=1), Group B streptococcus (n=2), E. coli (n=1), P. aeruginosa (n=1), and suspected fungal infection (n=5). Seven patients received medical treatment only while the other 18 patients also required surgical intervention. The overall fatality rate was 16% and 20% of patients had neurologic sequelae. There was no statistical association between outcomes and the factors studied.

Conclusion

Although uncommon, a brain abscess is a serious disease. A high level of suspicion is very important for early diagnosis and to prevent serious consequences.

[Risk factors and disposition in development of the nervous system infections]

INTRODUCTION

Although well protected, brain is not resistant to infection agents. Acute infections of our nervous system appear more often in children and in persons who have medical history data about previous disorders, especially disorders of the nervous system. It is difficult to list possible risk factors which can be responsible for the appearance of infections of CNS and the resulting conditions. It is often difficult or impossible to determine what previous neural damage was (trauma, anoxic damages etc.) from those appearing during infections of CNS. All-inclusive anamnestic research reduces the possibility of approximate judgements.

MATERIAL AND METHODS

The research was based on the retrospective analysis of medical documentation of 275 patients. All patients were divided into three groups according to the final diagnosis. The first group consisted of 125 patients who were treated for acute virus encephalitis, the second group consisted of 125 patients who were treated for acute bacterial meningoencephalitis and the third group consisted of 25 patients who were treated for cerebritis.

DISCUSSION

In our studies sample, the youngest patient was 3 years old and the oldest was 87 years old. The highest number of patients with virus infection of the CNS was in the group under 25 years of age (45.6%). The highest number of patients with bacterial infections of the CNS and cerebritis was in the group of patients over 45 years of age (64%, 37%).

CONCLUSION

Risk factors were more present in bacterial infections of the nervous system and cerebrit than in virus infection of CNS. In virus infections of the CNS, 28% of patients had some risk factor, most often-chronic ethylism, diabetes mellitus and acquired heart diseases. In bacterial infections of the CNS, 64% of patients had some predisposed factor. The most frequent factor of risk in these patients were chronic otitis (21.6%) and cranio-trauma (14.4%). In cerebritis, risk factors were present in 76% of patients and they were: sepsis (20%), chronic otitis (12%) and systemic lupus erythematosus (8%).

Multiple brain abscesses - a rare complication of bronchiectasis

BACKGROUND

Brain abscess can arise as a complication of a variety of infections, trauma or surgery. Bacteria can invade the brain by direct spread or through haematogenous seeding. Brain abscesses are described as a rare complication of bronchiectasis.

CASE DESCRIPTION

A 44 -year -old woman with pulmonary tuberculosis in childhood and with the diagnosis of bilateral extensive bronchiectasis who presented behaviour alterations and later, paresis of the sixth cranial nerve, was diagnosed multiple brain abscesses. The microbiological exams were negative. The study of the primary focus of infection could only identify infected bronchiectasis. Empiric antibiotics and anti- -oedematous treatment were prescribed with progressive clinical improvement. Because of inadequate response she was submitted to surgery. She was discharged with diplopia, without any other neurological alterations.

CONCLUSION

In the present clinical case, the infected bronchiectasis were the only focal infection detected, so in patients with this disease and with new neurological manifestations, infected lesions in the central nervous system should be excluded.

Gas-forming brain abscess caused by Klebsiella pneumoniae

Gas forming brain abscess is a rare disease caused by Klebsiella pneumoniae occurring in patients with impaired host defense mechanism such as diabetes mellitus or liver cirrhosis. A 59-year-old man with 2-year history of diabetes mellitus and 20-year history of liver cirrhosis presented to the hospital with headache. On the day after admission, severe headache was developed and he deteriorated rapidly. Brain CT showed a non-enhanced mass including multiple air density as well as surrounding edema seen in the right occipital lobe, and isodensity air-fluid level seen in the right lateral ventricle. Despite emergent ventricular drainage and intraventricular and intravenous administration of antibiotics, his condition progressively worsened to sepsis and to death after 5 days. Bacterial culture of blood and ventricular fluids disclosed a Gram (-) rod, Klebsiella pneumoniae. In this report we review the pathogenic mechanism and its management.

Pyogenic brain abscess

✓ Brain abscesses have been one of the most challenging lesions, both for surgeons and internists. From the beginning of the computed tomography (CT) era, the diagnosis and treatment of these entities have become easier and less invasive. The outcomes have become better with the improvement of diagnostic techniques, neurosurgery, and broad-spectrum antibiotics. Atypical bacterial abscesses are more often due to chemotherapy usage in oncology, long life expectancy in patients with human immunodeficiency virus (HIV) infection, and immunosuppression in conjunction with organ transplantation. Surgical treatment options showed no significant difference with respect to mortality levels, but lower morbidity rates were achieved with stereotactically guided aspiration. Decompression with stereotactically guided aspiration, antibiotic therapy based on results of pus culture, and repeated aspirations if indicated from results of periodic CT follow-up scans seem to be the most appropriate treatment modality for brain abscesses. Immunosuppression and comorbidities, initial neurological status, and intraventricular rupture were significant factors influencing the outcomes of patients. The pitfalls and evolution in the diagnosis and treatment of brain abscesses are discussed in this study.

Does supplementation of contrast MR imaging with thallium-201 brain SPECT improve differentiation between benign and malignant ring-like contrast-enhanced cerebral lesions?

OBJECTIVE

To determine whether thallium-201 ((201)Tl) brain single photon emission computed tomography (SPECT) could supplement magnetic resonance (MR) imaging diagnostic information by visual comparison of two separate data sets from patients with ring-like contrast-enhanced cerebral lesions.

METHODS

A combination of MR imaging and (201)Tl brain SPECT sets obtained from 13 patients (10 men, 3 women) ranging in age from 26 years to 86 years (mean 61.0 years) were retrospectively reviewed. A total of 12 patients had a solitary lesion, and the others had multiple lesions. All but two intracranial foci were pathologically confirmed. The final diagnoses were six glioblastomas, two cerebral metastases from lung cancer, and one each of abscess, resolving hematoma, primary central nervous system lymphoma, toxoplasmosis, and radiation necrosis. The two separate image formats (MR images and SPECT) were shown to ten readers with practical experience. All of the MR images for each patient were shown to each reader first. After interpreting them, the readers were shown the SPECT images. Images were scored in terms of how benign or malignant the foci were on a 5-point scale from "definitely benign" to "definitely malignant."

RESULTS

The improvement in the performance of all ten readers was from 67.7% to 93.8% in mean accuracy (P = 0.0028) and from 0.730 to 0.971 in mean Az value (P = 0.0069) after they were shown the (201)Tl brain SPECT images.

CONCLUSIONS

(201)Tl brain SPECT should substantially increase confidence in the diagnosis of intracranial lesions with ring-like contrast enhancement when MR imaging does not permit differentiation between benign and malignant disease.

Clinical features and predictive factors of intraventricular rupture in patients who have bacterial brain abscesses

BACKGROUND

Intraventricular rupture of brain abscesses (IVRBA) remains a catastrophic and fatal complication of bacterial brain abscess (BBA). However, no information has been reported about the risk factors that are predictive of intraventricular rupture.

METHODS

This study was undertaken to determine the potential risk factors that are predictive of intraventricular ruptures in patients with BBA but without intraventricular rupture when arriving at the hospital. A comparison is also made between patients who already have IVRBA at the time of admission (initial IVRBA) and those who have the episode during hospitalisation (subsequent IVRBA).

RESULTS

62 patients, including 45 who had initial IVRBA and 17 who had subsequent IVRBA, were examined. Stepwise logistic regression analysis showed that the adjusted risk of intraventricular rupture during hospitalisation for patients with multiloculated brain abscesses had an odds ratio (OR) of 4.2 (95% confidence interval (CI) 1.24 to 14.3; p = 0.02) compared with those without multiloculated brain abscesses (referent); a reduction of 1 mm in the distance between the ventricle and brain abscesses would increase the rupture rate by 10% (p = 0.006, OR 0.9, 95% CI 0.83 to 0.97).

CONCLUSION

This study shows that if the abscess is deep seated, multiloculated and close to the ventricle wall, a reduction of 1 mm in the distance between the ventricle and brain abscesses will increase the rupture rate by 10%. Despite aggressive medical and surgical management shown in this series, many patients continue to progress poorly.

Brain abscess following intracerebral haemorrhage

We report two cases of brain abscess, which developed at the site of an intracerebral haemorrhage (ICH) in a 75-year-old man and a 32-year-old-man. The patients recovered after surgical treatment and systemic antibiotic therapy. The route of infection could not be detected in either case. The literature contains only 13 reported cases of brain abscess as a complication of ICH. Although the interval from initial ICH to abscess formation ranged from 4 to 20 weeks, almost all patients had episodes of high fever, indicating the presence of systemic infection and bacterial seeding, 0-14 days after the onset of their ICH. Therefore, abscess formation appears to be caused by haematogenous seeding of infection in patients with ICH. Abscess formation should be considered when a patient deteriorates clinically with a febrile episode after an ICH.

Multiple brain abscesses following surgical treatment of a perianal abscess

We report a case of multiple brain abscesses (BAs) in a 67-year-old man with symptoms of progredient disorientation and amnestic aphasia. Onset of symptoms occurred one week after surgical treatment of a perianal abscess. No other source of infection was identified and the abscesses were limited to the brain. The immune status was normal but a patent foramen ovale (pFO) was found. The patient was treated with high-dose antibiotics, leading to a complete radiological disappearance of the BAs. Hematogenous spread of infectious emboli from a perianal focus exclusively to the brain is very rare. In our patient, the mechanisms of infectious spread into the brain might have occurred via a cardiac right-to-left shunt or alternatively via the non-valvular vertebral venous system. In this manuscript, both pathways are critically reviewed.

Analysis of microbial etiology and mortality in patients with brain abscess

OBJECTIVES

Despite the technological advancements in diagnostic and neurosurgical procedures, brain abscess continues to remain a potentially fatal central nervous system infection. In a prospective study we determined the predisposing factors and the microbiological profile of brain abscess. We also analyzed the mortality in patients with the type of infections identified.

METHODS

Over a period of 8 years (1997-2004), aspirated pus from 118 patients with brain abscess was directly inoculated into BACTEC PLUS+ aerobic and BACTEC PLUS+ anaerobic media immediately after collection and subcultured on solid media as appropriate. Predisposing factors, if any, were recorded in all patients. Mortality of patients during hospital stay was correlated with the type of infections identified.

RESULTS

Predisposing factors were identified in 94 (79.7%) patients, otogenic infection being the most common (37/118; 31.4%). Microorganisms were demonstrated in 96 (81.4%) patients, by culture in 89 (75.4%) patients and by Gram stain in 7 (5.9%) additional cases. A total of 105 organisms were isolated - 67 (63.8%) aerobes, 32 (30.5%) anaerobes, 5 (4.8%) mycobacteria and 1 (0.9%) fungus. Viridans streptococci (23.8%), Staphylococcus aureus (14.3%), Bacteroides fragilis group/species and Peptostreptococcus species (10.5% each) were the common isolates. Overall mortality was 14.4%; patients with Gram-negative infections had higher mortality than Gram-positive infections (6/20; 30% vs. 6/63; 9.5%; P=0.02).

CONCLUSIONS

Culture of pus immediately after aspiration in an automated system yields good results. Gram stain coupled with culture can guide the neurosurgeons better to treat their patients more rationally. Patients with Gram-negative infections need special attention in terms of management because of high mortality rate.

Hyperbaric oxygen therapy for the treatment of brain abscess in children

INTRODUCTION

The treatment of brain abscess remains a challenging topic usually involving a multimodal concept.

METHODS

We report our experience with hyperbaric oxygen (HBO) therapy in five children presenting with brain abscesses between 1995 and 2002 at the Department of Neurosurgery, Graz. Mean age was 14.8 (range 11-17 years). All abscesses were located supratentorially. One child had a single abscess and one had multilocated abscesses. Two other patients presented with both subdural empyema and brain abscess, one of them showing an epidural empyema as well. In another child, the brain abscess was associated with meningoencephalitis and subdural empyema. In all of them the underlying condition was spread of infection from the paranasal sinuses, except for one, who was immunocompromised due to cytotoxic chemotherapy for acute lymphocytic leukaemia.

RESULTS

One single brain abscess and one of the multiple abscesses were drained. All subdural/epidural empyemas were treated surgically. Antibiotics were administered intravenously for 13 to 22 days (mean 22 days). All patients underwent HBO therapy; the number of treatments ranged from 26 to 45 "dives" (mean 30). Treatments were given once daily at 2.2 atmosphere absolutes for 60 min at 12 m. During the hospital stay all improved their clinical condition, with continued regression of abnormalities on magnetic resonance imaging (MRI). In the following weeks, other interventions were performed to treat the origin of the infections. At 6 months follow-up they were all in good clinical condition, either symptom free or with minor residual symptoms. MRI at this time showed no evidence of disease in three, a residual dural enhancement in one and a residual shrunken collection in the child with multilocated abscesses. No recurrence was observed during a mean follow-up of 21 months (range from 7 to 72 months).

CONCLUSION

HBO therapy in children with brain abscesses seems to be safe and effective, even when they are associated with subdural or epidural empyemas. It provides a helpful adjuvant tool in the usual multimodal treatment of cerebral infections and may reduce the intravenous course of antibiotics and, consequently, the duration of hospitalization. Multidisciplinary management is recommended to optimize care for these critically ill children.