Current Clinical Strategies Publishing Home | Table of Contents
January 1999--Volume 166, Number 21, pp 1491-1582
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Maria A. Guglielmo, MD
Department of Neurosurgery |
Renee Ridzon, MD
Division of Infectious Disease |
A case report of the rapid development of a fatal brain abscess secondary to frontal sinusitis is presented. The patient presented with a herniation syndrome from a large bacterial brain abscess. The clinical and imaging studies in this case are presented and typical symptoms, laboratory findings, and the diagnostic evaluation of brain abscesses are discussed.
Brain abscesses remain an important consideration in the differential diagnosis of mass lesions of the brain. Brain abscess is an unusual but life-threatening complication of sinusitis. Prompt diagnosis and aggressive treatment are required to avoid mortality and serious neurologic morbidity. A case of patient who died from a large brain abscess secondary to frontal sinusitis is presented, and the diagnostic and therapeutic approache to the management of this disease is reviewed.
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A 32 year old, previously healthy, male presented to the emergency department with a chief complain of headaches. The patient reported fevers at home, but he was afebrile at the time of examination. A non-contrast CT (Figure A) was performed which revealed a normal left frontal lobe. Retrospective review of the CT scan revealed a small amount of fluid in the frontal sinus (arrow), not appreciated upon initial review of the film. The patient underwent a lumbar puncture, and the white cell count was 24 cells/cm3, with 92% neutrophils, and the red cell count was 8,010 cells/cm3. The glucose and protein values were within normal limits.
The patient returned 10 days later with a fever of 103 degrees F and was comatose. Repeat CT with contrast (Figure B) demonstrated a large frontal abscess with intraventricular rupture and pneumocephalus, seen as areas of hypodense signal (arrow). Approximately 35 cc of foul, thick, purulent material was emergently aspirated from through a frontal burr hole. The Gram stain of the aspirate (Figure C) demonstrated numerous gram positive cocci in pairs and chains as well as Gram negative rods and Gram positive rods. The culture was positive for group C beta-hemolytic streptococcus, Bacteroides melaninogenicus, and beta-lactamase positive propionibacterium. Despite aggressive treatment, the patient rapidly expired. Postmortem coronal section (Figure D) of the frontal lobe revealed the abscess cavity with a necrotic center and a poorly formed capsule (large arrow), and the coronal section revealed a left-to-right shift (small arrows). |
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| Figure A. Initial non-contrast CT showing a normal left frontal lobe. A small amount of fluid in the frontal sinus can be seen (arrow). | |
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| Figure B. Repeat CT with contrast one week later (with patient comatose) demonstrates frontal abscess, intraventricular rupture and pneumocephalus (arrow). | Figure C. Gram stain of the abscess fluid demonstrates typical mixed flora. |
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| Figure D. Post-mortem coronal section demonstrates the abscess cavity (large arrow) and midline shift (small arrows). |
Discussion
Mortality due to brain abscess, even with aggressive treatment, is as high as 16%.5 Intraventricular rupture, as in this case, is usually a fatal event. Although brain abscess as a complication of sinusitis has decreased in frequency since the introduction of antibiotic therapy, it remains a source of mortality and severe neurologic morbidity.7
Clinical Presentation
Clinically, brain abscesses present with symptoms that are similar to other space occupying lesions. Headache, which is frequently progressive and unresponsive to therapy, is the most common symptom, occurring in more than 70% of all patients.5 Up to half of affected patients will have nausea and vomiting.5 Fever is present in only about half of all patients, and is usually low-grade, unless there is also meningitis. Seizures, decreased mental status, and focal neurologic findings are common. Adults with normal immune systems typically have rapid progression of symptoms, as occurred in this case. In contrast, immunocompromised hosts may have a more insidious course because of the lower virulence of organisms typically found in these patients.5
Brain abscesses in immunocompetent hosts can result from contiguous spread of infection or hematogenous dissemination. Direct extension from paranasal sinuses often causes frontal lobe lesions, while middle ear infections and mastoiditis typically cause temporal lobe abscesses. Multiple metastatic abscesses can result from remote sites of infection, such as dental abscess and subacute bacterial endocarditis. Cyanotic heart disease, in particular tetralogy of Fallot, is a major risk factor for the development of these types of abscesses. Other risk factors include previous craniotomy and penetrating craniocerebral trauma.5
Microbiology
Prior to the antibiotic era, Staphylococcus aureus was a common pathogen in brain abscesses, along with aerobic streptococci. With aggressive antibiotic treatment of serious staphylococcal infections, anaerobic bacteria are now the most common cause of most brain abscesses. In immunocompetent adults mixed anaerobes and aerobes predominate, and Peptostreptococcus, Bacteroides species, and Hemophilus influenzae are common organisms.1,7 Immunocompromised patients are at risk for fungal abscesses caused by Candida albicans and Aspergillus species.5 Infants can develop abscesses after meningitis which are caused by Proteus and Citrobacter species. Citrobacter meningitis is associated with abscess formation in over two-thirds of cases.4
Diagnostic Evaluation
Laboratory studies are often of little help in the diagnosis. The peripheral white count is often normal or mildly elevated. The erythrocyte sedimentation rate, although nonspecific, is frequently elevated. Lumbar puncture diagnosis of brain abscess is now infrequent because of the hazards associated with lumbar puncture in the presence of a mass lesion. Findings in brain abscess, subdural empyema, and extradural sepsis (collectively referred to as parameningeal infection) include a mild pleocytosis with polymorphonuclear predominance, mild protein elevation, normal glucose, and a negative gram stain and culture.3 These finding were present in this case.
Imaging studies in the diagnosis of sinusitis associated infectious complications include skull radiographs, CT with or without contrast, and magnetic resonance imaging. In early infection, non-contrast CT may be unrevealing, as in this case. Cranial CT, with and without contrast, was found to be inadequate for visualization of intracranial infection in 4 of 14 children later shown to have intracranial sepsis secondary to sinusitis.6 Bone window imaging is a useful adjunct to detect sinus disease and osteomyelitis, as it was retrospectively in this case. In cases of sinusitis, infected frontal sinus fluid can cause a local osteomyelitis which may progress to a frank abscess. MRI findings in brain abscess include a thin discrete rim of enhancement surrounding the necrotic center.6
Therapeutic Options
Although conservative management with high dose antibiotics has been successfully used with small lesions, the mainstay of abscess management is surgical treatment for both decompression of mass lesions and the identification of the pathogen in order to optimize antibiotic coverage. Both open surgical excision and aspiration are frequently used. In cases of retained foreign material, such as in penetrating trauma, excision is preferred. Multiple deep lesions are often amenable to CT or MRI guided stereotactic drainage, which can be repeated serially and performed under local anesthesia in critically ill patients.2 Empiric antibiotics, initiated before culture results are available, should include broad spectrum agents such as metronidazole, with either ceftriaxone or penicillin. Corticosteroids may inhibit host defenses and alter contrast enhancement characteristics.5
Summary
A high index of suspicion is required to diagnose brain abscesses. Intracranial septic complications of sinusitis, although uncommon, have a high morbidity and mortality unless diagnosed early. CT imaging, although useful, may be unremarkable early in the course of the disease. Bone window imaging may prove useful in the detection of sinus or bone infection. The CSF findings of a mild polymorphonuclear pleocytosis is highly suspicious for parameningeal infection. If diagnosed early, aggressive antibiotic and neurosurgical treatment can lead to excellent long-term outcomes.
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