Long-term insights into brain abscess management: An 8-year study from a single center in India

Abstract

Background:

Both industrialized and developing nations continue to face difficulties in diagnosing and treating brain abscesses. Their etiology and management are still complicated and uncertain, which make treatment and result challenging.

Methods:

To ascertain management, demographics, and factors influencing the outcome of subjects with brain abscesses, we performed a retrospective analysis of data from 48 individuals who underwent surgical treatment for brain abscesses at Mahatma Gandhi Hospital in Jaipur between January 2015 and December 2023 using image-guided aspiration, craniotomy, and excision. Independent analyses were conducted on variables such as age, gender, clinical presentation, location, number of lesions, predisposing factors, etiological agent, infection mechanism, therapy, and Glasgow Coma Scale (GCS) score during admission.

Results:

The risk of developing a brain abscess was higher for male patients over 40. The outcome was influenced by the admission GCS score. Only 16 instances (33.3%) had positive cultures, despite the low incidence of successful infectious agent culture. The most frequent isolates in these cases were Streptococcus sp. and tubercular abscess. While the death rate was 10.4%, 89.5% of the participants had favorable outcomes. Five patients had poor outcomes because of immunosuppression in two of them, a 1.8-year-old child had ventriculitis, and the other two had low GCS scores.

Conclusion:

An efficient treatment for brain abscesses that have generally positive results is medical care combined with image-guided suction. excision and craniotomy are rarely necessary. Neither surgical technique nor surgery was directly associated with brain abscess mortality.

INTRODUCTION

Of all intracranial masses, the incidence of brain abscesses ranges from 2% in wealthy nations to 8% in impoverished nations.[4]

At the moment, image-guided aspiration and craniotomy and excision are the two main methods utilized to treat brain abscesses. Since image-guided aspiration is less invasive than craniotomy and excision, it is the preferred treatment since it lowers the risk of neurological aftereffects. Brain abscesses continue to be a public health concern, particularly in developing nations, even with the development of contemporary neurosurgical techniques such as stereotactic aspiration, improved culturing methods to identify infectious agents, new antibiotics, and contemporary noninvasive neuroimaging procedures. The microbiological range has evolved, and more people with weakened immune systems are getting these kinds of abscesses.[2,32]

Our experience treating 60 surgically treated brain abscesses in 48 individuals over an 8-year period at a single institution served as the basis for this research. To find patterns in the incidence, risk factors that predispose people, infectious agents, and prognosis of brain abscesses, we examined the prognostic factors and therapeutic approaches.

MATERIALS AND METHODS

Patient cohort

From January 2015 to December 2023, 48 patients with 60 brain abscesses at Mahatma Gandhi Hospital’s Neurosurgery department underwent surgery. The following information was gathered from the hospital data: diagnostic information, neurological status at admission, clinical presentation, predisposing variables, anatomical location, number of lesions, surgical methods, organisms cultured, and neurological outcome [Table 1].

Table 1:

Predictors of unfavourable outcomes in intracranial abscess

Radiology

Preoperative computed tomography (CT) and magnetic resonance imaging (MRI) scans were obtained for all patients. CT facilitates early detection, exact localization, accurate characterization, and determination of number, size, and staging of the abscess. It also detects hydrocephalus, raised intra cranial pressure, edema, and associated infections such as subdural empyema and ventriculitis and thus helps in treatment planning. It is invaluable in the assessment of adequacy of treatment and sequential follow-up. However, MRI (Brain) (Plain + Contrast) is the investigation of choice [Figure 1].

Figure 1:

Flowchart showing our methodology. CAE: Craniotomy and excision, IGA: Image guided aspiration

Patient evaluation

Any circumstance or incident that was directly linked to the development of a brain abscess was considered a predisposing factor. The routes of transmission were divided into five categories: contiguous spread, neurosurgical procedures, open head injuries, hematogenous spread, and unknown reasons. The Glasgow Coma Scale (GCS) was used to assess the neurological condition at admission. Standard laboratory tests, such as a complete blood count, serum chemistry, blood cultures, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), were performed in each patient. The analysis of microbiology laboratory data for every intracranial sample served as the foundation for the case findings. Following the laboratory’s regular procedure, all intracranial pus samples were swiftly transported to the Mahatma Gandhi Hospital microbiology laboratory for susceptibility testing, aerobic, anaerobic, fungal culture, and microscopy. At 6 months following surgery, the patient’s results were evaluated at the outpatient clinic using the Glasgow Outcome Scale (GOS), which was scored with a five-point rating. A score of 4–5 points denoted a favorable conclusion, whereas a score of 0–3 points was seen as an unfavorable one.

Medical management

1. Antibiotics – Ceftriaxone and metronidazole were chosen as the first empirical antimicrobial treatments based on the abscess’s anatomical location and portal of entry. Based on the findings of culture and sensitivity, the treatment either stayed the same or altered 3–5 days later. According to the results of the neuroimaging and the therapeutic response, the intravenous (IV) antibiotic treatment lasted for 6 weeks. This treatment was routinely overseen by infectious disease specialists

2. Steroids – In patients with a significantly significant mass effect, perilesional edema was treated with a low-dose corticosteroid (IV dexamethasone, administered at a dosage of 4 mg/8 hourly). As soon as the patient was stable, the medication was stopped

3. In every patient, antiepileptic medication or seizure prophylaxis was administered and sustained for a minimum of 2 years.

Surgical management

Image-guided aspiration was performed in abscesses larger than 2.5 cm, in cases showing signs of brain herniation due to mass effect, proximity to ventricles, involvement of eloquent areas, deep-seated locations (such as the brainstem or basal ganglia), progressive enlargement during medical therapy, or neurological deterioration. This approach was avoided in cases of cerebritis lacking imaging evidence of necrosis or capsule formation. If postaspiration imaging showed no reduction or an increase in abscess size, the procedure was repeated. During surgery, the abscess was fully drained and irrigated with gentamicin-infused saline until clear.

Craniotomy and excision were indicated in patients who showed poor response to repeated aspirations (>3 attempts) and medical therapy. Specific indications included:

• Abscesses secondary to open head injuries (to remove bone chips, foreign bodies, and devitalized tissue)

• Multiloculated abscesses with high recurrence risk

• Fungal abscesses

• Postoperative abscesses where burr hole aspiration might compromise bone flap reintegration

• Cerebellar abscesses associated with chronic otitis media, where radical mastoidectomy was also performed.

Statistics

The range (median) and percentage (number of patients) are used to express the data. The categorical variables in the two groups were compared using Fisher’s exact test. P-value <0.05 was considered statistically significant. The Statistical Package for the Social Sciences software was used for the statistical analysis.

RESULTS

60 abscesses in 48 patients were identified and treated surgically. In 81.2% of the cases, there was a single brain abscess, while in 18.8%, there were several. The patient’s age ranged from 1.8 to 76 years, with a mean of 47.33 ± 2.18 years. The ratio of men to women was 2.69:1. As a result, the current study indicated that males were more affected than females.

The most common clinical manifestations were localized neurological abnormalities, fever, and headache. The most frequent occurrence was a headache, which affected 72.91% (35) of the participants. 21 patients (43.7%) exhibited focal neurological dysfunction, while 9 patients (18.7%) experienced nausea. Fifty-two percent (25) of the cases had seizures. Three individuals reported vision disturbances linked to occipital lesions. Three patients were found to have aphasia. The clinical result in this trial was unaffected by the fact that 43 out of 48 patients (89.6%) had good GCS scores at admission. The GOS results at 6 months did not correspond with the symptoms that the patients had when they were admitted.

This cohort’s participants had a wide range of comorbidities and risk factors. Eight patients (16.7%) had a posttraumatic abscess, which was the most prevalent risk factor. Congenital heart disease (in 3 patients, 6.2%), postoperative (in 5 patients, 10.4%), and chronic suppurative otitis media (CSOM) (in 5 patients, 10.4%) were additional predisposing variables; nevertheless, 24 patients (50%) lacked any discernible predisposing risk factors. Upon arrival, three patients had immunosuppression [Table 2].

Table 2:

The site of the abscess in relation to underlying cause

15 patients (31.2%) had the frontal lobe, followed by the temporal (11 patients, 22.9%) and cerebellar (seven patients, 14.6%) areas [Table 1].

In 18.75% (n = 9) of the cases, contiguous infection was the mode of transmission. This characteristic has a direct impact on the affected brain region [Table 2]. For instance, temporal (3/5) or cerebellar abscesses (2/5) were linked to otogenic infections. Nevertheless, the predisposing factors for 41.18% of the frontal lesions were unknown.

Image-guided aspiration was the preferred treatment in 56.25% (27) of the instances, whereas craniotomy and excision were necessary in 37.5% (18) of the cases. Three patients (6.2%) underwent radical mastoidectomy in addition to excision treatment and craniotomy. Due to kidney transplantation, three patients experienced immunosuppression [Table 1].

The clinical outcome of this research was unaffected by the fact that 89.58% of the patients had a satisfactory GCS score at admission.

There was limited diagnostic or prognostic significance in laboratory data [Table 3]. Peripheral white blood cell counts were high in 12 patients (25%) with a predominance of leukocytosis. Twelve patients had a 25% increase in the ESR. Nonetheless, 50% of the patients had normal CRP values.[24]

Table 3:

Major clinical and laboratory findings of patients

89.58% of the 48 patients who were a part of this trial had positive results. One patient’s result was unfavorable due to the formation of an abscess following the evacuation of a hematoma in the right basal ganglia. Two additional patients had poor outcomes because their initial GCS scores were low (E- eye, M- motor [E1VtM1]). Our study’s death rate was 10.4% (5 instances). Five patients passed away in the first few days following surgery. Two of these died of multisystem organ failure and were immunosuppressed at diagnosis. One child, who was 1.8 years old, had ventriculitis and was in the E1VtM1 stage. In addition, two patients with occipital and temporal lobe abscesses had low GCS scores (E1VtM1).

Seizures were the most common postoperative complication and were managed with antiepileptic therapy. After hospital discharge, patients were monitored in the outpatient clinic. Six individuals could not be traced for long-term assessment, while the rest maintained stable neurological scores, with no clinical or radiological evidence of recurrence among the survivors.

Culture results from a study of 48 individuals with brain abscesses showed that 32 patients had no growth and 16 patients had positive isolates [Table 4].

Table 4:

Culture positive isolates from patients with brain abscess locations

DISCUSSION

The frontal lobe was the most damaged area (31.2%) in a group of 48 individuals with brain abscesses, followed by the temporal (22.9%) and cerebellar areas (14.6%). Seizures occurred in 52.2% of cases, while headache (72.9%), fever, and focal neurological impairments were common symptoms. The majority of patients received surgical intervention, with 37.5% undergoing craniotomy and 56.2% undergoing aspiration. Overall, results were satisfactory, with 89.6% of patients recovering well; however, 10.4% of patients passed away, mostly those who were immunocompromised or had low initial GCS scores. In sixteen cases, cultures were positive. According to laboratory results, 50% of patients had normal CRP levels and 25% had high white blood cell counts.

Our study’s male-to-female ratio was 2.69:1, meaning that regardless of age group, men were shown to be more impacted than women. Around the world, similar observations have been observed.[5,16,30] Nonetheless, according to Landrieu et al., women made up 59.3% of the patients with cerebral abscesses.[13] The research showed that the female gender was linked to an adverse result, even though it was more common in males in this cohort. These results need to be confirmed in a bigger sample size and multicenter trial in the area due to the short sample size.

The most vulnerable patients to brain abscesses were those over 40. In total, 32 (66.6%) of the individuals were above 40. These findings are consistent with a prior study that found that patients over 40 are more vulnerable to brain abscesses.[13] Conversely, according to some authors, brain abscesses are more common in younger people, typically occurring in the first three decades of life.[13,18,20,29] The bulk of patients in Manzar et al. study were under 40 years old, and 34 (64.2%) of the individuals were older than 15.[16] Similarly, 74.89% of the patients in a research by Sinha et al. were under 40 years old.[30] Overall, it is evident from the statistics that the age range most impacted by brain abscesses is still unclear. Predisposition to brain abscess at any age may be influenced by other, underlying causes.

Similar to what Landrieu et al. reported that 81.2% of the individuals had a single brain abscess, and 18.8% had several ones.[13] Of the subjects, 72.91% experienced a headache. Several other investigations have reported similar findings. Epilepsy and fever were also prevalent, affecting 52.08% of the patients, respectively. The “classic” triad – headache, fever, and focal neurological deficits – was observed in just 20% of cases, despite being the most prevalent.[6,11,13,14,19,23,31,33] 52.02% of the cases had seizures, which is similar to the incidence rates reported in other extensive research.[7,22]

The most common location of abscesses in patients was the frontal lobe, followed by the temporal and cerebellar regions; however, in a study conducted by Cavuşoglu et al.,[7] the most frequently affected location was the temporoparietal region. Abscesses of unknown cause accounted for 50.0% of the subjects, which is a percent higher than the values reported for other series.

Similar to this finding, middle ear infections have been identified to be the most frequent cause of intracranial suppuration in the majority of big series of brain abscesses from developing nations. However, because of greater awareness, early diagnosis, and treatment, the number of CSOM cases in wealthy nations has decreased.[10,24]

Only 16 of the cases had positive cultures, with Streptococcus species being the most frequently isolated organism, due to the fact that many patients were on antibiotic medication before surgery [Table 4]. A single organism was found in 6 out of 16 cases, indicating a monomicrobial etiology. This pattern has been observed in other research conducted worldwide.[8,9,12,16] The percentage of negative cultures was 66.66%, significantly greater than the rates noted by other authors.[6,7,13,22,28] The hypothesized causal agent must be treated empirically, even in cases where culturing results are negative. The high cultural negative rate may be caused by a number of factors. First, India has comparatively lax antibiotic management regulations, and the use of antibiotics for prevention is widespread. Second, it is possible that the intracranial pus samples were not sent to the microbiological laboratory in time for a satisfactory analysis. Finally, some organisms, such anaerobic bacteria, might have been overlooked by the hospital’s routine culturing procedures.

Saito et al. used direct nucleotide sequence analysis of the 16 s ribosomal RNA gene to diagnose Streptococcus intermedius in culture-negative brain abscesses.[27] Cloning and sequencing polymerase chain reaction (PCR)-amplified 16S recombinant deoxyribonucleic acid (rDNA) is a very useful technique to identify the bacterial species present in brain abscesses, according to Al Masalma et al. 16S rDNA-based metagenomic investigation of cerebral abscesses.[1] Bajpai et al.[3] examined the molecular technique (16S ribosomal ribonucleic acid PCR and sequencing), and conventional culture for the identification of aerobic and anaerobic bacteria in brain abscesses. As a noninvasive technique, they discovered that in vivo PMRS is helpful for quickly classifying bacteria with a respectable level of sensitivity and specificity. Even in sterile samples, it is capable of classifying bacteria into anaerobes or aerobes as well as those that are generally slow-growing or challenging to identify using traditional techniques.

There were no appreciable variations in the outcomes or related complications between the two surgical approaches. The efficacy of craniotomy and excision as well as image-guided aspiration varies throughout publications, though. According to Xiao et al., the two operations were equally successful; however, excision and craniotomy had far lower fatality rates.[33] When compared to image-guided aspiration, Mampalam and Rosenblum found that brain abscess recurrence was less common after craniotomy and excision.[15] When computer tomographic scanning became accessible, they discovered that the high aspiration mortality rates from the pre-CT era sharply declined. According to their research, the average aspiration death rate for publications involving more than five patients after 1990 was 6.6%. In the same time frame, the mean mortality rate for surgical excision through craniotomy was 12.7%. They concluded that in patients with supratentorial parenchymal brain abscesses, aspiration might be the initial surgical option.[26]

The clinical outcome in this research was unaffected by the fact that 89.58% of the patients had a satisfactory GCS score at admission. The fact that some individuals with high GCS scores had immunocompromised conditions or concomitant primary fatal diseases could be one explanation for why the score was unrelated to the outcome. In a similar vein, 79.6% of patients in research by Landrieu et al. had a satisfactory GCS score when they were admitted.[13]

Although there is sufficient evidence that neurological impairment is one of the most significant elements influencing prognosis, no judgments can be made about its impact on the outcome in light of these findings.[22,31,33] According to earlier research, up to two-thirds of patients exhibit an altered state of awareness.[15,21,26] 69.8% of the patients in Manzar et al. study arrived at the hospital in a state of altered awareness.[16] Other authors have demonstrated the high predictive value of the state of awareness upon presentation.[7,17]

The death rate displayed here is comparable to the rates between 8% and 53% that other writers have noted.[19] The neurologic state of the patient at the time of admission was the most significant factor impacting death, according to Manzar et al.[16] According to Landrieu et al., poor results were linked to immunosuppression, age, and hemogenous spread.[13] On the other hand, our research showed that the sole significant factor affecting the result was gender. In terms of therapeutic efficacy, Park et al.[25] showed that MRI + fluorodeoxyglucose positron emission tomography helped optimize therapy and increased the precision of evaluating therapeutic responses to antibiotic treatment of brain abscess.

CONCLUSION

Individuals over 40 are most vulnerable to brain abscesses. It has been discovered that men are more likely than women to develop brain abscesses. The most frequently impacted region is the frontal lobe. The most common isolated pathogen is Streptococcus species. IV antibiotics should be administered to all patients. If an abscess is ≥2.5 cm in diameter, has neurological impairments, is difficult to diagnose, or does not improve with medical treatment, image guided aspiration (IGA) is advised. Craniotomy and excision (CAE) should be taken into consideration if the abscess is unusual, thick-walled, numerous, or multiloculated, or if there is no remission after 6 weeks. The surgical method or technique employed has no direct bearing on the mortality rate linked to brain abscesses. Improving prognosis requires early diagnosis and suitable treatment.

Ethical approval:

Institutional review board approval is not required. Being retrospective study ,ethical approval was not required as per author’s institutional guidelines, they are following guidelines set by their institute.

Declaration of patient consent:

Patient’s consent is not required as there are no patients in this study.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

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