Supratentorial Subdural Pyogenic Abscess: A Case Series of Meningoencephalitis

Vidhya S et al | DOI: 10.65188/nurexus.1072

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Journal of MedVerse Research & Practice

ISSN: 3107-4278

Supratentorial Subdural Pyogenic Abscess: A Case Series of

Meningoencephalitis

Dr. S Vidhya

1

, Dr. M Venkatesh

2

Postgraduate, Professor

Department of Radiology, Madras Medical College, Dr.MGR University, Chennai.

Email: Vidhya1997@gmail.com

Submission Date: 11.02.2026

Accepted Date:23.03.2026

Published Date: 31.03.2026

DOI: 10.65188/nurexus.1072

article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted

use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Abstract

Meningoencephalitis complicated by supratentorial subdural pyogenic abscess is a rare but fatal intracranial

infection and associated with much morbidity and mortality to the patient who needs early diagnosis and

intervention. In this case series, we describe four patients in the age group of 12–50 years, each with a different

combination of clinical features including fever, headaches, vomiting, seizures, altered sensorium and focal

neurological deficits. Several of these cases had predisposing conditions, such as chronic sinusitis, otitis media and

diabetes mellitus. In all patients, magnetic resonance imaging with contrast was essential in establishing the

diagnosis. All patients were treated with an urgent neurosurgical intervention consisting of burr hole evacuation,

craniotomy or decompressive craniectomy followed by a prolonged course of intravenous antibiotics based on

microbiological results. Isolated organisms were Streptococcus milleri, Staphylococcus aureus, Escherichia coli

and mixed anaerobic flora. Patients had different clinical outcomes, with two cases recovering completely and one

case resulting in neurological sequelae or mortality. This series emphasizes the need for high index suspicion, timely

neuroimaging, aggressive surgical approaches and direction of antimicrobial therapy towards common pathogens

can improve outcomes which are hindered by delayed presentation and underlying comorbidities.

Keywords: Meningoencephalitis; Subdural empyema; Supratentorial abscess; Pyogenic abscess; Intracranial

infection; Neurosurgical emergency; Magnetic resonance imaging (MRI); Diffusion-weighted imaging (DWI)

Introduction

Meningoencephalitis is an inflammatory process affecting both the meninges and brain parenchyma,

typically due to infectious etiologies such as bacteria, viruses, fungi or parasites. Of these pathologies, the

bacterial infections are the most serious as they can develop rapidly and cause intracranial complications

(1,2). One of these serious complications is the formation of a subdural pyogenic abscess, especially in the

supratentorial compartment that can lead to considerable morbidity and mortality if not rapidly diagnosed

and treated (3). Subdural empyema is an accumulation of pus between the dura mater and arachnoidal

membrane, usually resulting from contiguous infections like sinusitis or otitis media or sequelae to

meningitis (4,5). More often the supratentorial region is involved owing to its proximity to paranasal

sinuses, particularly to the frontal sinus (6). The presence of subdural empyema together with

meningoencephalitis represents a severe form of intracranial infection, featuring widespread inflammation,

cerebral edema and mass effect (7).

Clinically, patients are frequently asymptomatic at onset but can present with fever, change in sensorium,

Vidhya S et al | DOI: 10.65188/nurexus.1072

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focal neurological deficit(s), seizures and symptoms of raised intracranial pressure (8). Early neuroimaging,

especially contrast-enhanced MRI, remains an essential diagnostic tool demonstrating typical crescent-

shaped collections with restrictive diffusion (9). Management usually consists of urgent neurosurgical

drainage and prolonged intravenous antibiotic therapy (10).

Outcomes are highly variable, even with advances in imaging and antimicrobial therapy (11), particularly

within resource-limited settings where delayed presentation is the norm. This case series aims to describe

the clinical presentation, diagnostic challenge, management approaches and outcome in four patients with

meningoencephalitis complicated by supratentorial subdural pyogenic abscess.

Case presentation

Case 1

A 19-year-old healthy non-atopic male presented with a seven-day history of high-grade intermittent fever

associated with progressively severe diffuse headache and multiple episodes of non-bilious vomiting. He

had altered sensorium noted as confusion, decreased responsiveness, and decreased verbal output 2 days

before admission. There was no history of seizures, trauma, or prior neurologic illness. The patient was

drowsy on examination (GCS 11/15: E3V3M5). He had neck stiffness and positive Kernig’s sign suggestive

of meningeal irritation. Neurological examination showed right-sided hemiparesis with upper and lower

limb motor power of 3/5 bilaterally, brisk deep tendon reflexes and extensor plantar response.

Laboratory investigations demonstrated leukocytosis (total leukocyte count: 17,500/mm³) with significant

neutrophilic predominance and increased inflammatory parameters. Blood cultures were initially negative.

Magnetic resonance imaging (MRI) of the brain with contrast showed a crescentic left frontoparietal

subdural collection that showed diffusion restriction on diffusion-weighted imaging, consistent with

subdural empyema. Cortical edema and meningeal enhancement also were present, consistent with

concurrent meningoencephalitis.

Figure 1: Magnetic resonance imaging (MRI) brain study with contrast revealing left fronto-

parieto-temporal extra axial pachymeningeal

Vidhya S et al | DOI: 10.65188/nurexus.1072

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A neurosurgical emergency was performed, burr hole evacuation of the subdural collection. Thick purulent

material, ~40 mL was drained. Pus cultured positive for Streptococcus milleri, sensitive to beta-lactam

antibiotics. He was given intravenous ceftriaxone and metronidazole for 6 weeks in total. The patient

demonstrated gradual improvement in both sensorium and motor function postoperatively. At the time of

discharge he was awake and oriented, with residual slight right side weakness (power 4/5), and

recommendations for neurorehabilitation and follow-up imaging.

Case 2

A 35-year-old female with a known history of chronic sinusitis presented with high-grade fever, severe

frontal headache and two episodes of generalized tonic-clonic seizures in last 24 hours prior to the

admission. The headache was characterized as pulsatile, frontally localized, and accompanied by

photophobia and/or nausea. On presentation, she was confused, oriented to neither time nor place, and had

a GCS of 13/15. There was neither history of epilepsy nor any neurological diseases.

Examination by fundoscopy revealed bilateral papilledema, which suggested raised intracranial pressure.

Neurological examination showed mild left hemiparesis (motor power 4/5) but no cranial nerve deficits.

Laboratory results indicated leukocytosis and increased C-reactive protein. Brain MRI demonstrated a right

frontal subdural empyema with severe diffusion restriction and surrounding cerebritis. Opacification of the

frontal sinus was also noted, indicating a possible source of infection.

Considering the double pathology, a surgical intervention was performed combining functional endoscopic

sinus surgery (FESS) to drain the infected sinus and right frontal craniotomy for evacuation of subdural

empyema. Intraoperative findings: thick purulent material under pressure. Staphylococcus aureus was

cultured from drained pus, vancomycin sensitive.

Intravenous vancomycin, ceftriaxone, and anticonvulsants (levetiracetam) were initiated. Postoperative

course was uneventful with quick neurological status improvement. Repeat imaging demonstrated

resolution of the empyema. She completed a 4-week course of antibiotics and was discharged with full

neurological recovery and no residual deficits.

Case 3

A 12-year-old boy was admitted with a 5-day history of fever, irritability, and gradual deterioration in the

level of consciousness. He had a two-week history of untreated right-sided otitis media with ear pain and

purulent discharge. He had no history of seizures, but hiscondition quickly worsened with marked lethargy

and decreased responsiveness. On examination, the child was febrile (39°C) and obtunded with GCS of

[E2V2M5] 9/15. He had signs of meningeal irritation, including neck stiffness and positive Brudzinski’s

sign. Neurologic exam was notable for early generalized hypotonia and no overt focal motor deficits.

Laboratory investigations revealed leukocytosis and increased inflammatory markers.

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Figure 2: Coronal CT brain showing bilateral subdural hygroma more on left side

MRI brain showed left temporal subdural empyema with significant surrounding edema and encephalitis

features. Marital conflict is common and can be damaging to the integrity of a family. A left temporal

craniotomy and empyema evacuation was performed as an emergency in the patient. Pus collected during

the operation cultured Escherichia coli, a rare but known pathogen in such an infection.

The management of the patient included ventilatory support and intravenous broad spectrum antibiotics as

per culture sensitivity in the intensive care setting. His hospital course was complicated by focal seizures,

which were controlled with antiepileptic drugs. While he gradually improved his state of consciousness, he

was left with significant residual cognitive deficits such as poor memory and attention and recurrent focal

seizures. He was discharged on chronic antiepileptic therapy and arranged for neurocognitive rehabilitation.

Case 4

A 50-year-old man with poorly controlled type 2 diabetes mellitus had a 5-day history of fever, persistent

headache, and progressively worsening confusion. The headache was diffuse and accompanied by nausea

and occasional vomiting. She did not have a history of trauma, sinusitis or ear infection. Family members

noted a rapid change in his mental status over the past 48 hours.

Upon examination, the patient had disorientation with GCS of 10/15 (E3V2M5). He had pronounced neck

stiffness and signs of meningeal irritation. Neurological examination showed left-sided hemiplegia, with

motor power of 1/5 and an extensor plantar response. Fundoscopic examination showed early papilledema.

Laboratory tests showed prominent leukocytosis, increased blood glucose, and high inflammation markers.

MRI brain showed a large right hemispheric subdural empyema with significant mass effect, an 8 mm

midline shift and diffuse meningoencephalitis. Because of the gravity of the findings, the patient had been

taken for an emergency decompressive craniectomy along with empyema evacuation. Intraoperatively, a

large amount of foul-smelling purulent material was evacuated. Culture demonstrated mixed anaerobic

species, suggestive of polymicrobial infection.

Despite aggressive management, including broad-spectrum intravenous antibiotics, glycemic control and

intensive care support, the patient’s clinical condition continued to worsen. He had refractory intracranial

hypertension and septic complications. His condition worsened and despite maximal medical and surgical

intervention, he died.

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Discussion

Subdural pyogenic abscess (subdural empyema) is an acute and progressing intracranial infection,

representing a real neurosurgical emergency due to the risk of rapid neurological deterioration and high

lethality if not treated in time (12). When it presents with meningoencephalitis, as described in this case

series, the disease represents an aggressive and widespread infectious process of both the meninges and

cerebral parenchyma. A dual pathology that severely worsens prognosis through synergistic inflammation,

cerebral edema, and mass effect. The four cases described herein comprise a broad clinical spectrum, from

relatively good recovery (Cases 1 and 2), to persistent neurological sequelae (Case 3), to mortality (Case

4), illustrating wide variability in outcomes.

The most common etiology in the pathogenesis of subdural empyema is direct extension of contiguous

infection from adjacent structures: usually the paranasal sinuses and middle ear. In adults, frontal sinusitis

is the most common predisposing factor; in pediatric populations, otitis media and mastoiditis are more

prevalent (13). Cases 2 and 3 are well illustrative of the above, as chronic sinusitis resulted in frontal

empyema, and otitis media progressed to temporal subdural empyema without treatment. Infection may

spread through thrombophlebitis of emissary veins or direct erosion of bone. Besides contiguous spread,

hematogenous dissemination is another recognized possible mechanism, especially in

immunocompromised hosts such as diabetics (equal to Case 4) (14). This finding further supports a

systemic or mixed source of infection in this case with polymicrobial anaerobic infection of the patient.

Its underlying pathophysiology entails a rapid accumulation of purulent material within the subdural space

that is anatomicallly liberated from barrier formation limiting its spread. This leads to diffuse cortical

irritation, inflammatory cytokine release and vasogenic edema (15). As the volume of empyema increases,

raised intracranial pressure and mass effect ensue that may present clinically as headache, vomiting, altered

sensorium, focal neurological deficits, and seizures. Seizures were prominent in Cases 2 and 3, likely

reflecting cortical irritation, whereas focal deficits including hemiparesis reported in Cases 1 and 4 reflect

localized mass effect and neuronal injury.

An accurate and early diagnosis is crucial for better outcomes. Based on the type of imaging data,

neuroimaging is at the heart of diagnosis, where contrast-enhanced MRI and diffusion-weighted imaging

(DWI) have historically served as gold standard for assessment of subdural empyema (9). DWI is especially

helpful in distinguishing empyema from sterile subdural effusions, because pus shows restricted diffusion.

MRI further depicts associated complications like cerebritis, encephalitis, and venous sinus thrombosis

better than CT. In all cases, MRI allowed for early identification and localization of the empyema, which

guided timely surgical intervention.

Patients diagnosed with a subdural empyema require multidisciplinary input, so the management of this

uncommon but serious disease involves neurosurgeons, neurologists and infectious disease specialists.

Surgical evacuation is the cornerstone of treatment, since antibiotic therapy alone is rarely adequate given

poor drug penetration into a purulent collection and the risk for rapid expansion (10). The surgical

techniques (burr hole drainage or craniotomy) will largely depend upon the size, location, and extent of the

empyema. Case 1 demonstrated that burr hole evacuation is enough for localized collections, while cases

of extensive or multiloculated empyemas (cases 3 and 4) commonly necessitate craniotomy or

decompressive craniectomy.

Empiric antimicrobial therapy should be started and later adjusted based on culture and sensitivity results.

Empirical regimens usually consist of all–third-generation cephalosporin, metronidazole, and vancomycin

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to cover the most common aerobic and anaerobic organisms (16). Pathogens described in this series

included Streptococcus milleri, Staphylococcus aureus, Escherichia coli and mixed anaerobes with a

spectrum of organisms consistent with the microbiology. Neither Koening et al. nor Whitney et al. discuss

the length of therapy, which is longer than most antibiotics at 4-6 weeks duration and based on clinical

improvement and radiological resolution.

The outcome of subdural empyema is determined by multiple factors such as age, immune status, source

of infection, neurological status at the time of presentation and timing to intervention (11). Early diagnosis

and timely surgical drainage are linked with markedly better outcomes, as illustrated in Cases 1 and 2.

Conversely, poor outcomes are associated with delayed presentation and significant neurological disability

on admission, as in Case 4; comorbid conditions, such as diabetes mellitus. Pediatric patients like Case 3

can survive but more frequently experience long-term neurological sequelae including cognitive

impairment and epilepsy.

This case series highlights the importance of a high index of suspicion for subdural empyema in patients

presenting with meningoencephalitis and focal neurological deficits, particularly when there is a history of

antecedent sinus or ear infections. Early imaging, aggressive surgical management, and appropriate

antimicrobial therapy are critical to decreasing morbidity and mortality.

Summary

We report four cases of meningoencephalitis complicated by supratentorial subdural pyogenic abscess to

exhibit their clinical spectrum and vary outcomes of this severe intracranial infection. Presentation varied

from classical signs of fever, headache and vomiting to more severe manifestations such as seizures, focal

neurological deficits and altered levels of consciousness. Several cases featured predisposing factors:

chronic sinusitis, otitis media and systemic comorbidities must be considered when identifying possible

sources of infection.

Neuroimaging, especially contrast-enhanced magnetic resonance imaging with diffusion-weighted

imaging, was essential for early diagnosis and accurate localization of the empyema. Timely neurosurgical

management, with burr hole drainage, craniotomy/resection of abscess or decompressive craniectomy and

a course of prolonged targeted intravenous antibiotics provided the key in having a good outcome in

selected patients. However, later presentation at the hospital, severe neurological impairment on admission

and comorbidities such as diabetes mellitus were associated with worse outcomes in terms of residual

deficits and mortality.

Conclusion

Supratentorial subdural pyogenic abscess associated meingoencephalitis is an important neurological

emergency with substantial morbidity and mortality. Clinicians need to have a high index of suspicion,

especially in individuals who present with fever, neurologic deficits, and a history of sinus or ear infections.

Early and adequate neuroimaging is critical for diagnosis, while rapid surgical evacuation together with

broad-spectrum culture-directed antimicrobial therapy forms the pillar of treatment. The results are highly

time-dependent as well as based on the presenting neurological condition. Delays in diagnosis or

management have devastating complications which can result in lingering neurological deficits or death.

Consequently, a multidisciplinary and collaborative approach linking together neurosurgery, neurology,

radiology and infectious disease specialists is essential to tailor patient management according to individual

characteristics ensuring higher survival rates.

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