Brain abscess case series

A retrospective analysis was performed using data from 87 patients admitted to a single UK neurosurgical unit with brain abscesses over a 16-year period. Using microbiological data obtained from abscess sampling and peripheral cultures, species of bacteria were categorised in patients where no primary source of infection was identified (NSI) for their brain abscess (n=52), or where an infective source (ISI) was identified. The microbiological data was then screened to identify common oral bacteria in each group.

Brain abscesses from the ISI group (n=35) demonstrated a significantly lower preponderance of oral bacteria (n=8), than the NSI group (n=29) (p<0.05). Brain abscesses from the NSI group also had significantly higher counts of Streptococcus Anginosus compared to ISI (p<0.05), with brain abscesses being most common in the frontal and parietal lobes for both ISI and NSI.

These findings suggest that the oral cavity could be considered as a source of occult infection in cases of brain abscess where no clear cause has been identified. Future studies should include oral screening and microbiome analysis to better understand the mechanisms involved and develop approaches for prevention ¹⁾.

435 patients were diagnosed with brain abscesses and 3909 individuals in the comparison cohort - 61% were male and the median age was 54 years. Patients diagnosed with brain abscesses were more likely to suffer from comorbidity. The risk of a hospital diagnosis of psychiatric disorders was increased during the first 5 years of observation. In the subpopulation, who had never been in contact with psychiatric hospitals or received psychiatric medication prior to study inclusion, the risk of developing psychiatric disorders was close to that of the background population, especially when we excluded dementia from this outcome. There was a substantial increase in the receipt of anxiolytics and antidepressants. The difference in the proportion of individuals who received anxiolytics and antidepressants increased from 4% (95% CI: 0%-7%) and 2% (95% CI: -1%-5%) 2 years before study inclusion to 17% (95% CI: 12%-21%) and 11% (95% CI: 7%-16%) in the year after study inclusion.

Patients with brain abscesses without prior psychiatric disorders or receipt of psychiatric medications are not at increased risk of psychiatric disorders diagnosed in psychiatric hospitals, but they have an increased receipt of psychiatric medication ²⁾.

Lange et al. retrospectively identified 47 patients (24 male, 23 female) who had received surgery or undergone the frameless stereotactic drainage of brain abscesses in our center from March 2009 to May 2017. We analyzed the clinical characteristics of the patients, as well as comorbidities and outcomes.

The mean age was 58 (range 7 to 86). Focus identification was successful in 28 patients (60%), with the most frequent causes of brain abscesses including the following: sinusitis (25%), dental infections (25%), and mastoiditis (21%). The mean Charlson Comorbidity Index was 1.57. Among the patients, 34% showed immunosuppressive conditions. We performed 1.5 surgeries per patient (53% via craniotomy, 28% biopsies or stereotactic drainage, 19% both procedures), followed by antibiotic treatment for 6.5 weeks (mean). In 30% of patients, no bacteria could be isolated. During the follow-up period (a median of 12 months), 23.4% of the patients died. The mortality rate during the initial hospital stay was 4.3%. CONCLUSION:

One third of the patients with brain abscesses showed immunosuppressive conditions, whereas brain abscesses also often occur in patients with good medical conditions. The isolation of the focus of infection is often possible. Surgical procedures showed very good outcomes. Patients over 60 years showed significantly worse clinical outcomes ³⁾.

44 patients (23 male, 21 female) receiving surgery or frameless stereotactic drainage at our center from March 2009 to January 2018. We conducted 12,101 cranial surgeries during that time.

The mean age was 55 (range 21 to 82). The median duration between brain surgery and the following brain abscess was 1.5 months (range 1 to 23). Previous brain surgeries were emergency procedures in 27 % of the cases. Surgery type frequency occured as follows: tumor resection (61%), craniotomy for traumatic brain injury (16%), aneurysm surgery (7%), biopsies (5%), hemicraniectomy after malignant cerebral infarction (5%) and other. We performed 1.3 surgeries per patient followed by antibiotic treatment for 4 weeks (=median) according to the respective germ spectrum. Germ entity was successfully identified in 39 patients (89%). In 18 cases (41%) we identified staphylococcus aureus. 20.5% of the patients died during the follow-up period. The mortality rate for patients with isolated bacteria was 18% compared to 40% for patients without isolation of specific microorganisms.

Secondary BA is a rare complication and occurs mainly in tumor patients and patients receiving emergency surgery. 41% of the patients suffered from a Staphylococcus aureus infection. Isolation of the responsible microorganisms is often possible and leads to improved outcomes ⁴⁾.

113 patients were included with a median age of 53 years and a male preponderance. At presentation symptoms were variable, 28% had a focal neurological deficit, and 39% had a reduced Glasgow coma scale (GCS). Brain abscesses most frequently affected the frontal, temporal, and parietal lobes while 36% had a subdural empyema. An underlying cause was identified in 76%; a contiguous ear or sinus infection (43%), recent surgery or trauma (18%) and haematogenous spread (15%). A microbiological diagnosis was confirmed in 86%, with streptococci, staphylococci, and anaerobes most frequently isolated. Treatment involved complex, prolonged antibiotic therapy (> 6 weeks in 84%) combined with neurosurgical drainage (91%) and source control surgery (34%). Mortality was 5% with 31% suffering long-term disability and 64% achieving a good clinical outcome. A reduced GCS, focal neurological deficit, and seizures at presentation were independently associated with an unfavorable clinical outcome (death or disability).

CONCLUSIONS: Complex surgical and antimicrobial treatment achieves a good outcome in the majority of patients with bacterial brain abscess and subdural empyema. Factors present at diagnosis can help to predict those likely to suffer adverse outcomes. Research to determine optimal surgical and antibiotic management would be valuable ⁵⁾.

Although brain abscess is a fatal neurological infection, the studies in Thailand are quite limited and outdate. This study aims to identify predictors of mortality among patients with brain abscess in Thailand. Patients with a diagnosis of brain abscess admitted to Songklanagarind Hospital, a referral tertiary care hospital in southern Thailand, between 2002 and 2017 were enrolled into this retrospective case control study. Demographic data, neurological status, clinical presentations, predisposing factors, microbiological profiles, neuroimaging findings, treatments, and outcomes were collected from electronic medical records. Predictors of death outcome were analyzed by univariate and multivariate logistic regression analysis. Among eighty-one patients enrolled into the study, forty-seven patients (58.0%) were male and 34 patients (42.0%) were female. The overall mean age (±SD) was 47.68 (±16.92) years old. The major predisposing factors of brain abscess were an immunocompromised state (42.0%) and the extension of a paracranial infections (24.7%). The common clinical presentations included headache (61.7%), fever (50.6%), and hemiplegia (34.6%). Eleven patients (13.6%) were dead at hospital discharge. The independent factor associated with death outcome identified by multivariate analysis was confusion (odds ratio 7.67, 95% CI 1.95-30.14; p = 0.003). In summary, the current study shows that an immunocompromised state is a significant predisposing factor of brain abscess. The independent factor associated with death outcome was confusion which was correlated with septic encephalopathy ⁶⁾.

Total number of patients were 50 with 31 (62%) male and 19 (38%) female children. Patients' age ranged from 5-10 years with mean age of 7.44 ±1.11 years. Single abscess in supra tentorial was commonly found in 44 (88%) patients. Multiple abscesses were present in 4 (8%) patients. Cerebellum was involved in 2 (4%) patients. Abscess was completely aspirated in single attempt in 37 (74%) patients, two attempts in 9 (18%) patients, and three attempts in 4 (8%) patients. No bacterial growth on culture was reported in 32 (64%) patients. Culture was positive in 18 (36%) patients. Postoperative hematoma developed in 2 (4%) patients. No mortality was reported in early postoperative period.

Aspiration of brain abscess in children with cyanotic heart disease through a burr hole is safe and successful ⁷⁾.

Raffaldi et al. retrospectively collected patients aged 0-18 years, with a diagnosis of 'brain abscess'. Seventy-nine children were included; the median age was 8·75 years. As predisposing factor, 44 children had preceding infections. The Gram positive cocci were mostly isolated (27 cases). Sixty (76%) children underwent a surgical intervention. Intravenous antibiotic therapy was administered in all patients, then switched to oral treatment. Clinical sequelae were recorded in 31 (39·2%) children. Twenty-one of them had a single sequela, of which, the most represented, was epilepsy in nine of them. This study focus the attention on the need to have standardized national guidelines or adequate recommendations on type and duration of antibiotic treatment ⁸⁾.

162 patients with proved brain abscess who underwent surgical treatment were included in this study. The prospectively recorded data of surgical management of brain abscess and the ultimate outcome (by Glasgow outcome scale) were studied retrospectively.

Results: Total number of cases was 162, of which 113 were acute pyogenic abscess while 49 were chronic abscess. Among the chronic abscess, 29 were chronic pyogenic abscess, 14 were tubercular, 3 aspergillus, and 3 abscesses were in malignant brain metastases. In acute cases, common clinical features were headache, fever, vomiting, focal deficit and seizure. In chronic abscesses, common clinical features were mild to moderate headache and progressive focal deficit. Seventy-three (45.06%) patients had adjacent localized sinus, middle ear or cranial infection. The common predisposing factors included postneurosurgery, postpenetrating injury to brain, chronic suppurative otitis media, and congenital heart disease, infective endocarditis, sinusitis and sub optimum immuno-status. Frontal lobe involved in 30.2% cases, temporal lobe is next to involved. Single time burr hole aspiration in 111 (68.5%) cases, two or more times burr hole aspiration were done in 34 (21%) cases. Pus culture was negative in 129 (79.62%) cases. Total number of death was 22 (13.58%) cases. Complete resolution of abscess with complete recovery of preoperative neuro-deficit was seen in 80.86% cases and recovery with major neuro-deficit was observed in 5.55% cases. There is a significant association between Glasgow coma scale (GCS) on admission and mortality in brain abscess.

Conclusion: In most of the cases, pus culture did not yield growth of any causative organism. Mortality was not directly related to surgical intervention, but GCS on admission has a significant association with mortality. Early diagnosis, optimum follow-up and timely surgical interventions are the keys in the proper management of brain abscess ⁹⁾.

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 ¹⁰⁾.

A retrospective study at Sher-i-Kashmir Institute of Medical Sciences included 47 patients with pyogenic brain abscess from a total of 114 patients evaluated in the Department of Neurosurgery over a period of 10 years from October 2001 to October 2011. Comparisons were made between aspiration and excision in terms of duration of antibiotic use, length of hospital stay, and overall treatment cost. Aspiration was performed in 29 patients (61.7%), of whom 7 patients needed second aspiration, and 18 patients underwent excision (38.3%) of the abscess capsule. The mean duration of antibiotic use in the excision group was significantly shorter at 2.7 weeks (standard deviation [SD]±1.1) compared to the aspiration group at 3.8 weeks (SD±1.3) (p=0.006). Similarly, mean length of hospital stay was significantly shorter in the excision group at 18.1 days (SD±7.7) compared to the aspiration group at 24.9 days (SD±6.6) (p=0.002). In addition, significantly earlier improvement in neurological function (p=0.025) and significantly lower rate of re-surgery (p=0.0238) were found in the excision group compared to the aspiration group. Excision is better than aspiration as far as duration of antibiotic use, length of hospital stay, and overall cost of treatment is concerned, with no significant difference in morbidity and mortality ¹¹⁾.

Forty-five patients with brain abscesses were treated with CT-guided stereotatic implantation of Ommaya reservoir and followed up between September 1998 and February 2008. The Glasgow Outcome Scale (GOS) was use to evaluate the effectiveness of the Ommaya Reservoir treatment. The GOS score at 3-months post-operation was 5 for 41 patients (91.1%), 4 for 2 patients (4.4%) and 3 for 2 patients (4.4%), respectively. The results suggest that the CT-guided stereotatic implantation of Ommaya reservoir is a potential technique that can be safely used to treat the brain abscess ¹²⁾.

Fifty-one cases were included in this study: 64.7% of patients were male and 35.5% were female. Most of the patients were Malay (70.6%); 28 patients (54.9%) had undergone craniotomy and excision of abscess, and the rest had undergone burr hole aspiration as their first surgical treatment.

This study reveals that patients who had undergone craniotomy and excision of abscess showed a significantly earlier improvement in neurological function, better radiological clearance and lower rate of re-surgery as compared to the burr hole aspiration group (P<0.05). However, with respect to neurological improvement at 3 months, morbidity and mortality, there is no significant difference between the two surgical methods.

The significance of these findings can only be confirmed by a prospective randomised series. Further study will be required to assess the cost effectiveness, intensive care needs, and possibility of shorter antibiotic usage as compared to burr hole aspiration ¹³⁾.

Twenty patients who had large, solitary, capsulated, and superficially located lobar abscesses were analyzed retrospectively to compare the efficiency of two different surgical approaches and their impact on postoperative antibiotic use and the length of hospital stay.

Nine patients underwent the capsule excision and 11 patients had the aspiration of their abscesses. There were no differences in terms of age, sex, location of abscesses, and radiographic features. There were 3 residual/recurrence in the aspiration group, who needed a second aspiration whereas; no residual/recurrence was observed in the excision group. Postoperative utilization of antibiotics was significantly less in the excision group (Mean: 26.7 days in the excision group vs. 46.6 days in aspiration group). Length of hospital stay for the purpose of iv antibiotic administration was significantly shorter in the excision group in close correlation with iv antibiotic use.

The study demonstrated that excision of abscess capsule was superior to aspiration in terms of efficiency of surgical intervention and postoperative cost of the treatment in a highly selected group of brain abscesses ¹⁴⁾,

The medical records of all inpatients with a diagnosis of brain abscess or subdural empyema from 1998 to 2007 were reviewed. The diagnosis was confirmed by imaging study or operative findings.

RESULTS: 151 episodes of brain abscess were diagnosed in 150 patients, and 10 patients had subdural empyema. The incidence of brain abscess fluctuated over time, while that of subdural empyema remained stable. The mean +/- standard deviation age of patients with brain abscess was significantly greater than that of patients with subdural empyema (48.5 +/- 19 years vs 25.4 +/- 24 years; p = 0.004). The number of patients with hematogenous brain abscess increased from 7 in 1998 to 2002 to 19 in 2003 to 2007, while that of those with infection related to operation decreased from 10 to 5. Most subdural empyema was related to bacterial meningitis (4 of 10). Etiological agents were identified in 53% of brain abscesses, including Enterobacteriaceae spp. (21.3%), Streptococcus spp. (20%), and mixed pathogens (17.5%). Klebsiella pneumoniae was the most common enteric bacteria isolated (15.3%), especially in patients with diabetes mellitus, but was not observed in children younger than 18 years.

CONCLUSIONS: In contrast to western countries, K. pneumoniae plays an important role in intracranial pyogenic infections in Taiwan. The pathogens and routes of infection are different between children and adults ¹⁵⁾.

Cases involving 22 patients (including 9 children) with deep-seated and/or eloquent-region intracranial abscesses who underwent CT- or MR imaging-guided stereotactic aspiration between January 1995 and July 2001 were analyzed.

RESULTS: A definite source of infection could be identified only in 9 of the cases. In 18 patients, the abscess was deep seated, whereas in the rest it was located in the eloquent cortex. Five patients had abscesses located in multiple sites. In 17 patients only 1 aspiration was required; in 5 others subsequent procedures were required. In the initial postaspiration CT, minor hemorrhage was noted in 3 patients not requiring further intervention. Antibiotics were administered for a period varying from 4 to 8 weeks following aspiration. An early recurrence (within 2 weeks of initial aspiration) was evident in 5 patients. All recurrent abscesses were reaspirated. In 2 patients new abscesses developed while the patients were still receiving antibiotic therapy. There were no late recurrences. In 1 patient ventriculitis developed, with subsequent hydrocephalus requiring a shunt insertion. Follow-up CT scans showed complete resolution of the abscess in all patients. There were no deaths.

CONCLUSIONS: Stereotactic aspiration is a useful management option for abscesses located in eloquent or inaccessible regions. Repeated aspiration should be considered in patients in whom the initial aspiration proves ineffective or partially effective. Complete resolution may require repeated stereotactic aspirations and continued antibiotic therapy ¹⁶⁾.

The case records of 49 patients discharged from St George's Hospital, London, between December 2000 and March 2004 with the diagnosis of brain abscess were reviewed in order to document the epidemiology, causes, treatment, and prognostic factors associated with brain abscess. Brain abscess occurred at all ages, more frequently in men than in women. Headache and altered mental status were common presenting symptoms. The frontal lobe was the most common site. Streptococcal infection was seen most commonly, but staphylococcal infection predominated in cases following neurosurgery. Computed tomography provided sufficient diagnostic information in most cases. All but five patients had early surgical drainage. Cefotaxime and metronidazole were used most often for empirical therapy. Thirty-nine patients recovered fully or had minimal incapacity. Five patients died. Patients with underlying cranial neoplasms or medical conditions had a worse outcome than those with a contiguous focus of infection or post-traumatic abscess. Changes in disease pattern were determined by comparison to a literature review. A PubMed search of the literature using the keywords “brain abscess” was undertaken, and identified papers and relevant citations were reviewed. Compared to earlier series, there was a marked decrease in the number of cases of brain abscess secondary to otitis media and congenital heart disease. There was an increase in the number of cases of brain abscess secondary to neurosurgery and trauma. Changes in the epidemiology of predisposing conditions for brain abscess are associated with changes in the patient population and causative organisms. Though still a potentially fatal infection, there have been recent improvements in diagnosis, treatment, and outcome ¹⁷⁾.

The purpose of this study was to identify prognostic factors by reviewing data on 142 patients with brain abscess.

METHODS: Clinical data, including age, sex, medical history, duration of symptoms, initial neurological status, associated predisposing factors, laboratory data, treatment, and abscess characteristics, were considered as potential prognostic factors. A comparison was made between patients with favorable (GOS: moderate disability or good recovery) and those with unfavorable (GOS: death, persistent vegetative status, or severe disability) outcomes at discharge. Univariate (chi(2) analysis or Fisher's exact test) and multivariate logistic regression analyses were used to identify prognostic factors. Data were considered significant when the 2-tailed P value was lower than .05.

There were 98 male and 44 female patients (male/female ratio, 2.2). Their average age at diagnosis was 41.5 years (range, 2-84 years). There were 105 patients with a favorable outcome and 37 with an unfavorable outcome. Both univariate and multivariate analyses indicated that patients who were male, had an initial GCS score >12, had no other septic complication, or had Gram-positive cocci grown in abscess cultures had better outcomes. No association was found between outcome and other factors, including age, focal neurological deficits, seizures, laboratory findings, characteristics of the abscesses, associated factors, and treatment modalities.

With the advancement of imaging studies and broad-spectrum antibiotic therapies, the outcome of brain abscess depends on prompt awareness of the diagnosis and effective infection control ¹⁸⁾.

From 1991 to 1997 we have used computed tomography-guided stereotactic aspiration to diagnose and treat 21 patients with a total of 58 bacterial brain abscesses. The ages of the patients ranged from 4 to 72 years (median 25 years); 11 of these 21 patients had multiple abscesses. The number of abscesses per patient with multiple abscesses ranged from 2 to 9, all located deep in subcortical white matter.

RESULTS: All patients underwent stereotactic surgical drainage and an 8-week intravenous antibiotic medical treatment. Of the 58 abscesses, 23 were aspirated. Of these 23 abscesses, 19 were radiologically stage III or IV and four were stage I or II. Pathological examination confirmed radiological staging in 19 patients (83%). Except for the three patients who have mild residual hemiparesis and one patient recovering from ataxia, all patients had complete neurological recovery.

CONCLUSIONS: Computed tomography-guided stereotaxy achieved all the objectives of management; namely, ascertaining the diagnosis, draining the content of the mass, and obtaining pus for accurate bacteriological diagnosis without morbidity. Stereotactic aspiration combined with an 8-week intravenous antibiotic regimen has yielded an effective therapeutic result in all of our abscesses, small or large, solitary or multiple, superficial or deep-seated. A high radiological-pathological correlation was also deduced from this study ¹⁹⁾.