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Complicated acute pediatric bacterial sinusitis: imaging updated approach
Complicated Acute Pediatric Bacterial Sinusitis: Imaging Updated Approach Elida Va ´ zquez, MD,a Santiago Creixell, MD,a Juan Carlos Carren ˜o, MD,a Amparo Castellote, MD,a Concepcio ´ n Figueras, MD,b Fe ´lix Pumarola, MD,c Jose Marı´a Poch, MD,d and Javier Lucaya, MDa
Acute bacterial sinusitis is usually a clinical diagnosis. Orbital complications require emergent evaluation with computed tomography. Using the orbital septum as an anatomic landmark, such infections can be classified as pre- or postseptal and treated with the most adequate therapy, ie, oral or intravenous antibiotics or surgical endonasal drainage. Intracranial complications can be seen in 3.7% to 11% of these patients, often with subtle clinical symptoms and signs. Radiologists play a decisive role in the final management of these patients and should be familiar with the most relevant complications. In this article, we present a retrospective review of all pediatric patients referred to our department for paranasal sinuses and orbital computed tomography because of acute complicated bacterial sinusitis. They were studied with an emergent enhanced facial and cranial computed tomography within 24 hours of admission, followed by magnetic resonance imaging when intracranial complications were suspected. Particular emphasis is placed on the imaging algorithm and the most relevant complications; we correlate imaging findings with clinical and bacteriological data.
Acute bacterial sinusitis is usually a clinical diagnosis in children. Acute sinusitis is defined as a prolonged “cold,” with cough and nasal discharge extending beyond 10 days, or a more severe “cold” with fever greater than 39°C and purulent nasal discharge. Causal organisms are usually Streptococcus pneumoniae, Moraxella catarrhalis, and Hemophilus influenza.1,2 Predisposing factors in children are the smaller size of their sinuses and a From the Departments of aPediatric Radiology, bPediatric Infectious Diseases, cPediatric ENT, and dPediatric Neurosurgery, Hospital MaternoInfantil Vall d’Hebron & Institut de Diagnostic per la Imatge, Hospitals Vall d’Hebron, UAB, Barcelona, Spain. Reprint requests: Elida Va´zquez, MD, Departamento de Radiologı´a Pedia´trica & IDI, Hospital Vall d’Hebron–HMI, Psg. Vall d’Hebron, 112-119 Barcelona, Spain. E-mail: [email protected]. Curr Probl Diagn Radiol 2004;33:127-45. © 2004 Elsevier Inc. All rights reserved. 0363-0188/2004/$30.00 ⫹ 0 doi:10.1067/j.cpradiol.2004.01.003
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tendency toward upper respiratory infections. Because sinus disease in children is usually bilateral, anatomic variants probably play a minor role in pediatric sinusitis.3 Conventional radiography is of limited value in the evaluation of paranasal sinus inflammatory disease because of poor anatomic detail and poor correlation with clinical symptoms, although some physicians still require it for confirmation of acute sinusitis.4 A single Waters’ view has been recommended as sufficient in this setting,5 but recent authors have reported very poor contribution of this view and a better outcome with low-dose computed tomography (CT).6 CT is therefore the gold standard for sinus imaging because it can better depict anatomy and provides information needed for surgical planning. Nevertheless, following the recommendations of the American Academy of Pediatrics, CT should be reserved for children who present with complications of acute bacterial sinusitis or who have very persistent or recurrent infections and are not responsive to medical management.1 Most studies can be performed in children without sedation by using the spiral CT technique with reconstructed slices at 3-mm increments. Serious limitations of CT in children are its nonspecificity—with incidental soft-tissue changes found in up to 50% of patients without sinus disease—and persistence of mucosal changes despite the resolution of clinical symptoms after a bacterial sinusitis (8 weeks or more).7 Bacterial sinusitis cannot be distinguished from viral infections on CT scans, because criteria such as air-fluid levels, complete sinus opacification, mucosal enhancement, or asymmetric mucous thickening can be seen in either viral or bacterial disease.3 Because of this lack of specificity, CT findings must be correlated with the patient’s clinical course, physical examination, and nasal endoscopy. The clinical manifestations of orbital complications of sinusitis are the main factor in determining the provisional diagnosis, but CT improves the accuracy
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TABLE 1. Imaging findings Total number of patients: Orbitary complications: Preseptal: Postseptal: Bony complications: Intracranial complications: Subdural empyema: Epidural abscess: Cerebral abscess: Cavernous sinus thrombosis:
FIG 1. Orbital anatomy is shown in a sagittal plane with the orbital septum (arrow) as the anatomic landmark that divides the orbit into preseptal and postseptal compartments. (Color version of figure is available online.)
of the diagnosis and facilitates therapeutic planning. Although CT scanning may not be necessary in purely preseptal infections, it is usually required in clinical practice to prevent possible false negatives and subsequent inappropriate initial therapy.8,9 With the orbital septum as anatomic landmark, the infection can be classified easily as pre- or postseptal and treated with the most adequate therapy, ie, oral or intravenous antibiotics or surgical endonasal drainage (Fig 1). Intracranial complications can be seen in 3.7% to 11% of patients, often with subtle clinical symptoms and no previous sinus disease. A multidisciplinary approach by the radiologist, pediatrician, otorhinolaryngologist, and neurosurgeon is essential for early detection and lower morbidity.10 Magnetic resonance imaging (MRI) is useful in complicated or complex sinus disease and for diagnosing intracranial complications. MRI is superior to CT at the identification of marrow-space abnormalities such as edema or osteomyelitis, the evaluation of meninges and small extra-axial empyemas, and early detection of areas of cerebritis.3 Therefore, although CT remains the standard initial modality for diagnosing sinusitis and orbital complications, MRI should be mandatory in the evaluation of intracranial complications.9
105 98 70 28 1 6 2 2 1 1
patients
patient patients patients patients patient patient
orbital CT because of acute complicated bacterial sinusitis since 1990. They were studied with an emergent enhanced facial and cranial CT within 24 hours of admission. MRI was performed when intracranial complications were suspected. Particular emphasis is made on the most relevant complications (Table 1). CT is usually obtained in the emergency department and is performed with high-resolution contrast spiral technique, with reconstructed slices at 3-mm increments and the lowest mA possible (100-150), and covering the paranasal sinuses and orbits. To rule out intracranial complications, cranial enhanced CT is then obtained in cases of visible postseptal orbitary disease. Sedation of the patient is usually unnecessary with fast, modern, helical CT equipment. With the orbital septum as the anatomic landmark, the infection is classified as pre- or postseptal, and adequate antibiotic therapy can be started very shortly after admission. Repeat CT scans are obtained after 48 hours of medical therapy if the patient’s condition does not improve or worsens. Direct or reformatted coronal images are very useful in assessing subperiosteal collections beneath the orbitary floor, which are sometimes overlooked on axial slices because of beamhardening artifacts. Contrast enhanced MRI is only performed when intracranial complications are suspected. MR images are usually acquired with a head coil, T1, and fast spin-echo T2 sequences in both axial and coronal planes, with postcontrast fat-saturation T1 sequences of the orbits and postcontrast T1-weighted images of the entire brain. Sedation is usually required in those patients younger than 5 to 6 years of age.
Materials and Methods
Orbital Complications
We present a retrospective review of 105 children referred to our department for paranasal sinuses and
Orbital cellulitis is a relatively common and potentially serious disease in children. It’s more frequent in
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children than in adults, with a mean age of 7 years; it predominates in males and is more common in winter. The offending organisms include S. pneumoniae, S. pyogenes, S. influenzae, S. aureus, S. epidermidis, Gram-negative organisms, and anaerobes.
Pathologic Features Orbital infection can arise from infection of periorbital structures such as face, globe, or lachrymal sac, but most commonly originates in the paranasal sinuses (up to 85%). Spread may occur after osseous erosion or by thrombophlebitis.11,12 The ethmoid sinus is the most common source because the medial orbital wall, or lamina papyracea, is thin and perforated by numerous blood vessels, nerves, or congenital defects, which allows communication between the ethmoidal air cells and the subperiosteal space in the medial aspect of the orbit. The maxillary sinus is the second most common source of orbital cellulitis. Orbital cellulitis complicating sphenoid or frontal sinusitis appears in older children, because pneumatization of these sinuses happens around 6 years of age.13 Sphenoid sinusitis, although less frequent, is hazardous because its presentation can be atypical, with headache only, and it carries a risk of potential neuro-ophthalmic complications.14
Symptoms and Signs Symptoms of orbital disease include the following: erythema or edema of the eyelids (common to all orbital infections), proptosis and ophthalmoplegia (main predictors of postseptal disease), and decreased visual acuity (associated with advanced infection). Preseptal complications of sinusitis often can be suspected clinically, but physical examination can be difficult in younger uncooperative children or when there is massive edema of the eyelids.15,16 Furthermore, postseptal disease that presents with swelling and erythema of the eyelid as the only signs has been reported.17 Orbital sonography has recently been reported as useful in diagnosing and monitoring the treatment of acute orbital inflammation in pediatric patients.16 Sonography is portable, widely available, and does not use ionizing radiation, but this method is limited in the exact assessment of associated paranasal sinus disease, bony resorption, and serious intracranial complications. It is also of little value in differentiating between phlegmon and abscess, with subsequent therapeutic consequences. In our opinion, sonography can be useful for assessing clinically suspected pre-
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TABLE 2. Classification of orbital infections Stage 1: Preseptal cellulitis (inflammation of the eyelids without edema of orbital contents) 1 (a) Cellulitis 1 (b) Abscess Stage 2: Postseptal subperiosteal (located between the bony wall of the orbit and the fibrous periorbita) 2 (a) Subperiosteal phlegmon 2 (b) Subperiosteal abscess Stage 3: True orbital cellulitis (spread of inflammation to the intraconal space) 3 (a) Localized 3 (b) Diffuse Stage 4: Orbital abscess (with abscess formation involving the intraconal or extraconal spaces) Stage 5: Cavernous sinus thrombosis (infectious thrombosis of the ophthalmic vein and/or cavernous sinus; now better considered as an intracranial complication)
septal disease, but CT continues to be mandatory for the correct diagnosis of postseptal disease.9,10,14
Classification Orbital inflammation is best classified in relation to the anatomic landmark of the orbital septum, a thin fibrous sheet that separates the tissues of the eyelid from those of the orbit.18 This septum acts as a barrier to the spread of infection, extending vertically from the periosteum of the orbital rim to the levator muscle aponeurosis in the upper eyelid (the superior septum) and to the inferior border of the tarsal plate in the lower eyelid (inferior septum), dividing the orbit into preseptal and postseptal compartments. Following a modified classification from several authors,19-21 orbital infections secondary to sinusitis can be staged by CT in 5 overlapping categories (Table 2). Preseptal infection is much more common (76%) than postseptal infection (28%). In preseptal disease, CT reveals a diffuse increase in density and thickening of the lid and conjunctiva (Fig 2). Visualization of the orbital septum can be very difficult in patients with cellulitis, so determination of intraorbital extension depends on one’s knowledge of anatomic location. Abscesses with a low-density area and peripheral enhancement can also be seen.11,12 Postseptal inflammation is characterized by a softtissue density or low-attenuation area adjacent to the lamina payracea, in the medial subperiosteal-extraconal space of the orbit (Fig 3). Bone demineralization or frank destruction may also be present. The medial rectus
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FIG 3. Postseptal cellulitis with bony erosion and medial subperiosteal phlegmon. Axial CT image demonstrates discrete phlegmonous subperiosteal tissue adjacent to the lamina papyracea on the left orbit (black arrow). Left ethmoidal sinusitis is also seen, with normal aeration of the right ethmoidal cells. There is accompanying bony erosion of the left lamina papyracea (white arrow).
muscle may be displaced, enhanced, or thickened by inflammatory edema (extraocular myositis; Fig 4). Abscesses appear as hypodense areas with rim enhancement and mass effect (Fig 5). Subperiosteal abscesses can also be seen at the superior location, adjacent to the orbital roof and are usually secondary to frontal sinusitis (Figs 6 and 7). Extension into the intraconal space appears on CT as an ill-defined infiltration of the orbital fat, with obliteration of the optic nerve and extraocular muscles (Fig 8). Diffuse extraconal and intraconal infection is the least common complication, presenting with severe proptosis. It can spread from the subperiosteal space, although it may also be hematogenous, involving the whole orbit, with increased fat density and obliteration of the muscles and optic nerve.14 Cavernous sinus thrombosis is now considered among the intracranial complications; it is better demonstrated by MRI.
Therapy
FIG 2. (A-C) Preseptal cellulitis. Clinical picture (A) shows the eyelid swelling and erythema. Axial CT slices (B and C) show minimal ethmoidal sinusitis with discrete preseptal orbital cellulitis (arrow) on the right side. Notice the normal fat plane between the lamina papyracea and medial rectus muscle (*). (Color version of figure is available online.)
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Preseptal cellulitis can be treated by oral antibiotics. Management of patients with postseptal infection primarily includes hospitalization, with prompt administration of intravenous antibiotics and local decompression, and surgery reserved for selected cases. Frank abscesses should be drained urgently. Small subperiosteal abscesses with normal vision, mild proptosis, and normal extraocular muscle function may be treated conservatively. All patients with orbital complications managed medically should be closely observed, and those who experience a decrease in visual
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FIG 4. (A-C) Subperiosteal phlegmon with associated extra-ocular myositis. Axial enhanced CT images show maxillary and ethmoidal sinus disease on the right side, with associated postseptal cellulitis (subperiosteal phlegmon). There is no evidence of osseous resorption. The medial rectus muscle is displaced by the inflammatory tissue, with thickening and strong enhancement.
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FIG 5. (A-C) Subperiosteal abscess. Clinical presentation (A) with severe swelling and proptosis on the right. Enhanced axial (B) and coronal (C) CT images demonstrate pansinusitis on the right, with a hypodense collection suggesting incipient subperiosteal abscess (arrows). (Color version of figure is available online.)
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FIG 6. (A and B) Subperiosteal phlegmon beneath the orbital roof. Axial (A) and coronal (B) CT images after contrast administration show fronto-ethmoidal sinusitis more extensive on the left side, with subperiosteal phlegmon below the left orbital roof (arrows). There is no evidence of bony lesion. Notice the caudal displacement of the left ocular globe.
acuity, worsening extraocular muscle function, or failure to improve in 48 to 72 hours should undergo surgical sinus drainage.13-15
Bony Complications The association of frontal osteomyelitis and subperiosteal abscess has been termed Pott’s Puffy Tumor. Signs and symptoms include a soft and fluctuant forehead mass, headache, photophobia, low-grade fever, and leukocytosis. Osteomyelitis is usually related to acute frontal sinusitis. Staphylococcus sp. are implicated in the majority of cases. The spread of infection from the sinus is either by retrograde thrombophlebitis or directly via erosion or through existing fractures or dehiscences.13,22,23 CT can delineate a ring-enhancing subgaleal collection anterior to an opacified frontal sinus and the permeative lytic changes in the anterior frontal table
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(Fig 9). MRI is better at evaluating the central nervous system complications that can consist of epidural abscess, subdural empyema, or brain abscess.24 As in other types of complicated sinusitis, longterm intravenous antibiotics and sinus drainage are required. Patients may require debridement of infected bone if they fail to respond to antibiotics. In cases of intracranial infection, craniotomy and neurosurgical evacuation may be required.
Intracranial Complications Intracranial complications (meningitis, subdural empyema, epidural abscess, and cerebral abscess) may complicate acute sinusitis and range from 0.5% to 24% of patients admitted for acute sinusitis.13,25 Insufficient antibiotic treatment, excessive virulence of a microorganism, and congenital bony defects are all predisposing factors.26 Infection is spread via
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FIG 7. (A-C) Subperiosteal abscess beneath orbital roof. Coronal (A and C) and axial (B) CT slices demonstrate acute frontal sinusitis (air-fluid level), with secondary subperiosteal abscess (air bubble) attached to the right orbital roof (arrows).
thrombophlebitis or less commonly via direct extension. Streptococcal sp. are the microorganisms most commonly responsible for central nervous system complications. Exceptions include cerebral abscess
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and epidural abscess near a focus of osteomyelitis when Staphylococcus is more common. Despite antibiotics and aggressive treatment, high rates of morbidity (up to 33%) and mortality (5-10%) still
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FIG 8. (A-C) True orbital cellulitis. Axial (A) and coronal (B and C) enhanced CT images show exophthalmos on the right side and associated ethmoidal and maxillary sinus disease with subperiosteal phlegmonous tissue. Coronal views (B and C) better demonstrate the subtle increased fat attenuation involving the extra- and intraconal compartments (stage 3a, following the classification shown in Table 2). No defined abscess was depicted and the patient’s condition improved after endonasal sinus drainage and intravenous antibiotics.
exist; therefore, early diagnosis and treatment are very important to minimize both. Thin axial slices (3-5 mm) through the fronto-ethmoidal area and anterior cranial fossa or MRI should be obtained in cases of suspected intracranial complications, because small collections can be missed in a routine CT scan.9 Also in suspected intracranial infection, frontal, ethmoidal, or sphenoid disease must be assumed to be clinically significant rather than an incidental finding.27
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Symptoms and Signs Common symptoms of increased intracranial pressure (headache, altered mental status, fever, vomiting, and stiff neck), seizures, unilateral weakness, hemiparesis, and systemic toxicity usually occur. In a recent review, hemiparesis was the most common localizing neurological sign (35.5%), and orbital inflammation was present in 41.5% of affected patients; therefore, the presence of an extracranial collection of pus does not mean there will
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FIG 9. (A-D) Frontal osteomyelitis and abscess (Pott’s Puffy tumor). Axial unenhanced (A and B) and enhanced (C and D) CT slices show evidence of frontal sinus disease, with preseptal edema and small abscess (black arrow) on the left side. There is also bony destruction in the anterior frontal table, suggesting osteomyelitis with sequestration (white arrow).
be no intracranial involvement.10 “Silent” intracranial involvement can also occur, and it may be found incidentally on CT or MRI.26,28
Types of Intracranial Complications In order of decreasing frequency, the intracranial complications are subdural empyema, intracerebral ab-
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scess, epidural abscess, meningitis, and, more rarely, cavernous and other dural venous sinuses thrombosis. Subdural empyema is referred to in several articles as the most prevalent complication.28-30 The infection leads to a progressive thrombophlebitis through mucosal veins to emissary veins and subdural space. The falx and tentorium tend to limit spread to an area over
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FIG 10. (A-H) Subdural empyema. A 10-year-old girl was admitted with suspected postseptal orbital cellulitis. Axial CT slices without (A) and with contrast (B) and coronal images (C and D) demonstrate frontoethmoidal sinus disease on the left side, with associated preseptal and subperiosteal abscess (arrows). Despite surgical drainage, the patient’s condition got worse and she developed right hemiparesis. Subtle interhemispheric fissure widening was noted on enhanced cranial CT (black arrow in D, white arrows in E and F).
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FIG 10. Continued. (E and F). Neurosurgical drainage was undertaken, and follow-up MR post-Gd T1WI (G and H) showed complete resolution of the disease. The patient’s condition improved, and she was discharged without any sequela.
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FIG 11. (A-F) Subdural empyema with cerebritis. A 13-year-old girl suffered acute bacterial sinusitis with preseptal cellulitis and minimal postseptal compromise (A). Because of persistent fever and headache, thin section CT scan was repeated along the anterior cranial fossa. Small subdural collections could be seen on enhanced CT (B). Neurosurgeons decided against craniotomy; endonasal sinus drainage was performed and antibiotics were modified. MRI was performed 2 days later because of a partial seizure episode. Hyperintense areas in both frontal lobes were demonstrated on FLAIR sequences, suggesting cerebritis (C) together with abnormal meningeal enhancement on contrast T1WI (D). Diffusionweighted images showed a small extra-axial abscess in the right frontal lobe.
one hemisphere (Fig 10). On an unenhanced CT scan, a subdural empyema appears as a hypodense or isodense crescentic area adjacent to the inner table of the skull, parafalcial, or over the tentorium. A curvilinear ring of enhancement may be seen underneath an
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empyema, representing membranes or inflamed subjacent cortex. Occasionally, enhancement of the subjacent cerebral cortex may be seen in a gyriform pattern, indicating the presence of a concomitant cerebritis (Fig 11) or infarction. Recently, MRI has become the
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FIG 11. Continued. (E and F), with normal increased values of the cerebral parenchyma. Adequate prolonged antibiotherapy eventually resolved the infection, and the patient was discharged with normal neurological condition.
diagnostic modality of choice because of its ability to detect collections earlier than CT. MRI demonstrates subdural collections with a low signal on T1-weighted sequences and a high signal on T2-weighted sequences with peripheral enhancement after gadolinium administration. Subdural empyema is a neurosurgical emergency that will invariably become fatal if left untreated. It should be at the top of the differential diagnosis in any patient presenting with a history of sinusitis and a change in mental status or neurological focal sign.28,30 Intracerebral abscess is mainly related to frontal sinusitis, and the frontal lobe is the most common location. As a neurologically silent area of the brain, there may be only subtle changes in mood or personality, which can be misinterpreted in adolescents. The late pneumatization and development of frontal sinuses, combined with a highly vascular valveless diploic system, are considered responsible for the higher incidence in adolescents and young adults.26,31 Acute cerebritis is seen as an ill-defined low-density area on CT scan in the frontal lobe, progressing to a coalescent lesion with a collage-
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nous capsule that appears as a thin-walled rim typically thickest toward gray matter and with ring enhancement. MRI demonstrates the distinct hypointense capsule on T2-weighted images with typical decreased diffusion coefficient content. The high viscosity and inflammatory cellular composition may explain restricted water diffusion in the purulent fluid, causing increased signal intensity on diffusion-weighted imaging and markedly decreased signal intensity on apparent diffusion coefficient map images (Fig 12). Although reported as nonspecific, markedly increased signal intensity of a rim-enhancing brain mass on diffusion-weighted imaging and a low apparent diffusion coefficient indicating restricted water diffusion are features highly suggestive of pyogenic brain abscess.32 Epidural abscess is rarely referred, although it has a high prevalence in some series.24 It appears as a low-attenuation extra-axial mass, iso- or hyperdense relative to cerebrospinal fluid due to the proteinaceous content. It usually requires surgical drainage. Meningitis is a rare complication, typically occurring with ethmoidal or frontal sinusitis.33 It is generally
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FIG 12. (A-H) Cerebral abscess. A 12-year-old boy was being treated for acute sinusitis for 2 weeks before admission. He developed increased headache, and cranial CT (A) was performed showing a cystic lesion with a hyperdense peripheral rim in the left frontal lobe and surrounding edema. Sinus disease was also discovered, mainly frontosphenoidal (B and C). MRI disclosed a typical cystic lesion with hypointense strongly enhanced capsule and decreased diffusion coefficient (D-G). Surgical abscess drainage confirmed the purulent content of the lesion with posterior growth of S. pneumoniae. Follow-up CT examination was normal except for the small postsurgical porencephaly (H).
managed clinically. Excluding endocranial hypertension before the lumbar puncture should be emphasized because of the risk of herniation. Venous sinus and cavernous sinus thrombosis are rare; nevertheless, they are very severe intracranial
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complications. Engorgement of the ophthalmic vein is a frequent finding, with enlargement of the cavernous sinus and bowing of the lateral dural margin.34 Direct reported signs include changes in density or signal intensity caused by filling defects and expansion of the
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FIG 12. Continued.
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FIG 13. (A-G) Cavernous sinus thrombosis. A 14-year-old girl was being treated for sphenoid sinusitis. She presented with left ocular proptosis and meningeal signs during therapy. Axial enhanced CT images showed some residual sphenoidal sinus disease, left proptosis, and quite normal-appearing cavernous sinuses (A and B). MRI was later performed because of a lack of clinical improvement; cavernous sinuses appeared heterogeneous on coronal T2WI (C and D), with convex lateral walls and enlarged ophthalmic vein on the left side (arrow).
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FIG 13. Continued. Both cavernous sinuses appeared abnormal on coronal T1WI (E), with isointense signal relative to cerebral gray matter and slightly decreased size of the internal carotid artery flow void, particularly on the left side. Post-Gd coronal T1WI (F and G) also shows slightly increased cavernous sinuses, with convex lateral walls and enlarged left ophthalmic vein. The patient was treated with prolonged intravenous antibiotics and anticoagulant therapy, and follow-up MRI was normal.
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cavernous sinus with lateral convexity better shown on coronal planes. Indirect signs consist of dilation of the superior ophthalmic vein and other tributary veins such as superior/inferior petrosal and sigmoid sinuses, exophthalmos, and increased dural enhancement along the lateral border.35 Focal defects of enhancement after gadolinium administration can also be seen on MRI as clots within the sinus, and the ipsilateral cavernous carotid artery flow void can be diminished or absent (Fig 13).
Therapy Surgical drainage of the affected paranasal sinuses and any intracranial abscess is emergently required. Antibiotics should be chosen to cover the most common organisms, and prolonged therapy is usually necessary. Neurosurgical consultation is strongly recommended, even in cases that are not immediately surgical. Despite modern diagnostic and surgical capabilities, the mortality rate associated with subdural empyema and brain abscesses remains over 25%.
Conclusion Complications of acute bacterial sinusitis in children are less frequent since the advent of antibiotics, and their prognosis is improved with better management and earlier detection. CT and MRI have become indispensable diagnostic tools and should be obtained as early as possible in every child with postseptal orbital or intracranial infection. Although CT remains the standard initial modality, MRI is mandatory when intracranial extension is suspected. Acknowledgments: Thanks to Drs. F. Moraga, M. Boronat, M. Pellicer, and P. Nogue´ s, from the departments of Pediatric Infectious Disease and Pediatric Neurosurgery, who always provide invaluable help with the difficult clinical and surgical aspects of the presented pediatric patients. We also thank A. Casadesu´ s for nursing assistance, C. Batista for secretarial help, and C.L. Cavallo for English language advice.
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23. Pender ES. Pott’s puffy tumor: a complication of frontal sinusitis. Pediatr Emerg Care 1990;6:280-4. 24. Bambakidis NC, Cohen AR. Intracranial complications of frontal sinusitis in children: Pott’s puffy tumor revisited. Pediatr Neurosurg 2001;35:82-9. 25. Clayman GL, Adams GL, Paugh DR, et al. Intracranial complications of paranasal sinusitis: a combined institutional review. Laryngoscope 1991;101:234-9. 26. Jones NS, et al. The intracranial complications of rhinosinusitis: can they be prevented? Laryngoscope 2002;112: 59-63. 27. Saxton VJ, Boldt DW, Shield LK. Sinusitis and intracranial sepsis: the CT imaging and clinical presentation. Pediatr Radiol 1995;25:S212-7. 28. Giannoni C, Sulek M, Friedman EM. Intracranial complications of sinusitis: a pediatric series. Am J Rhino 1998;12:173-8. 29. Oliveira Monteiro JP, Duarte Teles AL, Silva Gonzalves ML, Carmo Fonseca MJ. Subdural empyema secondary to sinusitis: four pediatric cases. Rev Neurol 2002;16:35:331-6.
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30. Dill SR, Cobbs CG, McDonald CK. Subdural empyema: analysis of 32 cases and review. Clin Infect Dis 1995;20:372-86. 31. Maniglia AJ, Goodwin WJ, Arnold JE, Ganz E. Intracranial abscesses secondary to nasal, sinus, and orbital infections in adults and children. Arch Otolaryngol Head Neck Surg 1989; 115:1424-9. 32. Tung GA, Evangelista P, Rogg JM, Duncan JA III. Diffusionweighted MR imaging of rim enhancing brain masses: is markedly decreased water diffusion specific for brain abscess? AJR 2001;177:709-12. 33. Younis RT, Anand VK, Childerss C. Sinusitis complicated by meningitis: current management. Laryngoscope 2001;111: 1338-42. 34. Odabasi AO, Akgul A. Cavernous sinus thrombosis: a rare complication of sinusitis. Int J Pediatr Otorhinolaryyngol 1997;39:77-83. 35. Schuknecht B, Simmen D, Yu¨ ksel C, Valavanis A. Tributary venosinus occlusion and septic cavernous sinus thrombosis: CT and MR findings. AJNR 1998;19:617-26.
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Acute bacterial sinusitis is usually a clinical diagnosis. Orbital complications require emergent evaluation with computed tomography. Using the orbital septum as an anatomic landmark, such infections can be classified as pre- or postseptal and treated with the most adequate therapy, ie, oral or intravenous antibiotics or surgical endonasal drainage. Intracranial complications can be seen in 3.7% to 11% of these patients, often with subtle clinical symptoms and signs. Radiologists play a decisive role in the final management of these patients and should be familiar with the most relevant complications. In this article, we present a retrospective review of all pediatric patients referred to our department for paranasal sinuses and orbital computed tomography because of acute complicated bacterial sinusitis. They were studied with an emergent enhanced facial and cranial computed tomography within 24 hours of admission, followed by magnetic resonance imaging when intracranial complications were suspected. Particular emphasis is placed on the imaging algorithm and the most relevant complications; we correlate imaging findings with clinical and bacteriological data.
Acute bacterial sinusitis is usually a clinical diagnosis in children. Acute sinusitis is defined as a prolonged “cold,” with cough and nasal discharge extending beyond 10 days, or a more severe “cold” with fever greater than 39°C and purulent nasal discharge. Causal organisms are usually Streptococcus pneumoniae, Moraxella catarrhalis, and Hemophilus influenza.1,2 Predisposing factors in children are the smaller size of their sinuses and a From the Departments of aPediatric Radiology, bPediatric Infectious Diseases, cPediatric ENT, and dPediatric Neurosurgery, Hospital MaternoInfantil Vall d’Hebron & Institut de Diagnostic per la Imatge, Hospitals Vall d’Hebron, UAB, Barcelona, Spain. Reprint requests: Elida Va´zquez, MD, Departamento de Radiologı´a Pedia´trica & IDI, Hospital Vall d’Hebron–HMI, Psg. Vall d’Hebron, 112-119 Barcelona, Spain. E-mail: [email protected]. Curr Probl Diagn Radiol 2004;33:127-45. © 2004 Elsevier Inc. All rights reserved. 0363-0188/2004/$30.00 ⫹ 0 doi:10.1067/j.cpradiol.2004.01.003
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tendency toward upper respiratory infections. Because sinus disease in children is usually bilateral, anatomic variants probably play a minor role in pediatric sinusitis.3 Conventional radiography is of limited value in the evaluation of paranasal sinus inflammatory disease because of poor anatomic detail and poor correlation with clinical symptoms, although some physicians still require it for confirmation of acute sinusitis.4 A single Waters’ view has been recommended as sufficient in this setting,5 but recent authors have reported very poor contribution of this view and a better outcome with low-dose computed tomography (CT).6 CT is therefore the gold standard for sinus imaging because it can better depict anatomy and provides information needed for surgical planning. Nevertheless, following the recommendations of the American Academy of Pediatrics, CT should be reserved for children who present with complications of acute bacterial sinusitis or who have very persistent or recurrent infections and are not responsive to medical management.1 Most studies can be performed in children without sedation by using the spiral CT technique with reconstructed slices at 3-mm increments. Serious limitations of CT in children are its nonspecificity—with incidental soft-tissue changes found in up to 50% of patients without sinus disease—and persistence of mucosal changes despite the resolution of clinical symptoms after a bacterial sinusitis (8 weeks or more).7 Bacterial sinusitis cannot be distinguished from viral infections on CT scans, because criteria such as air-fluid levels, complete sinus opacification, mucosal enhancement, or asymmetric mucous thickening can be seen in either viral or bacterial disease.3 Because of this lack of specificity, CT findings must be correlated with the patient’s clinical course, physical examination, and nasal endoscopy. The clinical manifestations of orbital complications of sinusitis are the main factor in determining the provisional diagnosis, but CT improves the accuracy
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TABLE 1. Imaging findings Total number of patients: Orbitary complications: Preseptal: Postseptal: Bony complications: Intracranial complications: Subdural empyema: Epidural abscess: Cerebral abscess: Cavernous sinus thrombosis:
FIG 1. Orbital anatomy is shown in a sagittal plane with the orbital septum (arrow) as the anatomic landmark that divides the orbit into preseptal and postseptal compartments. (Color version of figure is available online.)
of the diagnosis and facilitates therapeutic planning. Although CT scanning may not be necessary in purely preseptal infections, it is usually required in clinical practice to prevent possible false negatives and subsequent inappropriate initial therapy.8,9 With the orbital septum as anatomic landmark, the infection can be classified easily as pre- or postseptal and treated with the most adequate therapy, ie, oral or intravenous antibiotics or surgical endonasal drainage (Fig 1). Intracranial complications can be seen in 3.7% to 11% of patients, often with subtle clinical symptoms and no previous sinus disease. A multidisciplinary approach by the radiologist, pediatrician, otorhinolaryngologist, and neurosurgeon is essential for early detection and lower morbidity.10 Magnetic resonance imaging (MRI) is useful in complicated or complex sinus disease and for diagnosing intracranial complications. MRI is superior to CT at the identification of marrow-space abnormalities such as edema or osteomyelitis, the evaluation of meninges and small extra-axial empyemas, and early detection of areas of cerebritis.3 Therefore, although CT remains the standard initial modality for diagnosing sinusitis and orbital complications, MRI should be mandatory in the evaluation of intracranial complications.9
105 98 70 28 1 6 2 2 1 1
patients
patient patients patients patients patient patient
orbital CT because of acute complicated bacterial sinusitis since 1990. They were studied with an emergent enhanced facial and cranial CT within 24 hours of admission. MRI was performed when intracranial complications were suspected. Particular emphasis is made on the most relevant complications (Table 1). CT is usually obtained in the emergency department and is performed with high-resolution contrast spiral technique, with reconstructed slices at 3-mm increments and the lowest mA possible (100-150), and covering the paranasal sinuses and orbits. To rule out intracranial complications, cranial enhanced CT is then obtained in cases of visible postseptal orbitary disease. Sedation of the patient is usually unnecessary with fast, modern, helical CT equipment. With the orbital septum as the anatomic landmark, the infection is classified as pre- or postseptal, and adequate antibiotic therapy can be started very shortly after admission. Repeat CT scans are obtained after 48 hours of medical therapy if the patient’s condition does not improve or worsens. Direct or reformatted coronal images are very useful in assessing subperiosteal collections beneath the orbitary floor, which are sometimes overlooked on axial slices because of beamhardening artifacts. Contrast enhanced MRI is only performed when intracranial complications are suspected. MR images are usually acquired with a head coil, T1, and fast spin-echo T2 sequences in both axial and coronal planes, with postcontrast fat-saturation T1 sequences of the orbits and postcontrast T1-weighted images of the entire brain. Sedation is usually required in those patients younger than 5 to 6 years of age.
Materials and Methods
Orbital Complications
We present a retrospective review of 105 children referred to our department for paranasal sinuses and
Orbital cellulitis is a relatively common and potentially serious disease in children. It’s more frequent in
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children than in adults, with a mean age of 7 years; it predominates in males and is more common in winter. The offending organisms include S. pneumoniae, S. pyogenes, S. influenzae, S. aureus, S. epidermidis, Gram-negative organisms, and anaerobes.
Pathologic Features Orbital infection can arise from infection of periorbital structures such as face, globe, or lachrymal sac, but most commonly originates in the paranasal sinuses (up to 85%). Spread may occur after osseous erosion or by thrombophlebitis.11,12 The ethmoid sinus is the most common source because the medial orbital wall, or lamina papyracea, is thin and perforated by numerous blood vessels, nerves, or congenital defects, which allows communication between the ethmoidal air cells and the subperiosteal space in the medial aspect of the orbit. The maxillary sinus is the second most common source of orbital cellulitis. Orbital cellulitis complicating sphenoid or frontal sinusitis appears in older children, because pneumatization of these sinuses happens around 6 years of age.13 Sphenoid sinusitis, although less frequent, is hazardous because its presentation can be atypical, with headache only, and it carries a risk of potential neuro-ophthalmic complications.14
Symptoms and Signs Symptoms of orbital disease include the following: erythema or edema of the eyelids (common to all orbital infections), proptosis and ophthalmoplegia (main predictors of postseptal disease), and decreased visual acuity (associated with advanced infection). Preseptal complications of sinusitis often can be suspected clinically, but physical examination can be difficult in younger uncooperative children or when there is massive edema of the eyelids.15,16 Furthermore, postseptal disease that presents with swelling and erythema of the eyelid as the only signs has been reported.17 Orbital sonography has recently been reported as useful in diagnosing and monitoring the treatment of acute orbital inflammation in pediatric patients.16 Sonography is portable, widely available, and does not use ionizing radiation, but this method is limited in the exact assessment of associated paranasal sinus disease, bony resorption, and serious intracranial complications. It is also of little value in differentiating between phlegmon and abscess, with subsequent therapeutic consequences. In our opinion, sonography can be useful for assessing clinically suspected pre-
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TABLE 2. Classification of orbital infections Stage 1: Preseptal cellulitis (inflammation of the eyelids without edema of orbital contents) 1 (a) Cellulitis 1 (b) Abscess Stage 2: Postseptal subperiosteal (located between the bony wall of the orbit and the fibrous periorbita) 2 (a) Subperiosteal phlegmon 2 (b) Subperiosteal abscess Stage 3: True orbital cellulitis (spread of inflammation to the intraconal space) 3 (a) Localized 3 (b) Diffuse Stage 4: Orbital abscess (with abscess formation involving the intraconal or extraconal spaces) Stage 5: Cavernous sinus thrombosis (infectious thrombosis of the ophthalmic vein and/or cavernous sinus; now better considered as an intracranial complication)
septal disease, but CT continues to be mandatory for the correct diagnosis of postseptal disease.9,10,14
Classification Orbital inflammation is best classified in relation to the anatomic landmark of the orbital septum, a thin fibrous sheet that separates the tissues of the eyelid from those of the orbit.18 This septum acts as a barrier to the spread of infection, extending vertically from the periosteum of the orbital rim to the levator muscle aponeurosis in the upper eyelid (the superior septum) and to the inferior border of the tarsal plate in the lower eyelid (inferior septum), dividing the orbit into preseptal and postseptal compartments. Following a modified classification from several authors,19-21 orbital infections secondary to sinusitis can be staged by CT in 5 overlapping categories (Table 2). Preseptal infection is much more common (76%) than postseptal infection (28%). In preseptal disease, CT reveals a diffuse increase in density and thickening of the lid and conjunctiva (Fig 2). Visualization of the orbital septum can be very difficult in patients with cellulitis, so determination of intraorbital extension depends on one’s knowledge of anatomic location. Abscesses with a low-density area and peripheral enhancement can also be seen.11,12 Postseptal inflammation is characterized by a softtissue density or low-attenuation area adjacent to the lamina payracea, in the medial subperiosteal-extraconal space of the orbit (Fig 3). Bone demineralization or frank destruction may also be present. The medial rectus
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FIG 3. Postseptal cellulitis with bony erosion and medial subperiosteal phlegmon. Axial CT image demonstrates discrete phlegmonous subperiosteal tissue adjacent to the lamina papyracea on the left orbit (black arrow). Left ethmoidal sinusitis is also seen, with normal aeration of the right ethmoidal cells. There is accompanying bony erosion of the left lamina papyracea (white arrow).
muscle may be displaced, enhanced, or thickened by inflammatory edema (extraocular myositis; Fig 4). Abscesses appear as hypodense areas with rim enhancement and mass effect (Fig 5). Subperiosteal abscesses can also be seen at the superior location, adjacent to the orbital roof and are usually secondary to frontal sinusitis (Figs 6 and 7). Extension into the intraconal space appears on CT as an ill-defined infiltration of the orbital fat, with obliteration of the optic nerve and extraocular muscles (Fig 8). Diffuse extraconal and intraconal infection is the least common complication, presenting with severe proptosis. It can spread from the subperiosteal space, although it may also be hematogenous, involving the whole orbit, with increased fat density and obliteration of the muscles and optic nerve.14 Cavernous sinus thrombosis is now considered among the intracranial complications; it is better demonstrated by MRI.
Therapy
FIG 2. (A-C) Preseptal cellulitis. Clinical picture (A) shows the eyelid swelling and erythema. Axial CT slices (B and C) show minimal ethmoidal sinusitis with discrete preseptal orbital cellulitis (arrow) on the right side. Notice the normal fat plane between the lamina papyracea and medial rectus muscle (*). (Color version of figure is available online.)
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Preseptal cellulitis can be treated by oral antibiotics. Management of patients with postseptal infection primarily includes hospitalization, with prompt administration of intravenous antibiotics and local decompression, and surgery reserved for selected cases. Frank abscesses should be drained urgently. Small subperiosteal abscesses with normal vision, mild proptosis, and normal extraocular muscle function may be treated conservatively. All patients with orbital complications managed medically should be closely observed, and those who experience a decrease in visual
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FIG 4. (A-C) Subperiosteal phlegmon with associated extra-ocular myositis. Axial enhanced CT images show maxillary and ethmoidal sinus disease on the right side, with associated postseptal cellulitis (subperiosteal phlegmon). There is no evidence of osseous resorption. The medial rectus muscle is displaced by the inflammatory tissue, with thickening and strong enhancement.
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FIG 5. (A-C) Subperiosteal abscess. Clinical presentation (A) with severe swelling and proptosis on the right. Enhanced axial (B) and coronal (C) CT images demonstrate pansinusitis on the right, with a hypodense collection suggesting incipient subperiosteal abscess (arrows). (Color version of figure is available online.)
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FIG 6. (A and B) Subperiosteal phlegmon beneath the orbital roof. Axial (A) and coronal (B) CT images after contrast administration show fronto-ethmoidal sinusitis more extensive on the left side, with subperiosteal phlegmon below the left orbital roof (arrows). There is no evidence of bony lesion. Notice the caudal displacement of the left ocular globe.
acuity, worsening extraocular muscle function, or failure to improve in 48 to 72 hours should undergo surgical sinus drainage.13-15
Bony Complications The association of frontal osteomyelitis and subperiosteal abscess has been termed Pott’s Puffy Tumor. Signs and symptoms include a soft and fluctuant forehead mass, headache, photophobia, low-grade fever, and leukocytosis. Osteomyelitis is usually related to acute frontal sinusitis. Staphylococcus sp. are implicated in the majority of cases. The spread of infection from the sinus is either by retrograde thrombophlebitis or directly via erosion or through existing fractures or dehiscences.13,22,23 CT can delineate a ring-enhancing subgaleal collection anterior to an opacified frontal sinus and the permeative lytic changes in the anterior frontal table
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(Fig 9). MRI is better at evaluating the central nervous system complications that can consist of epidural abscess, subdural empyema, or brain abscess.24 As in other types of complicated sinusitis, longterm intravenous antibiotics and sinus drainage are required. Patients may require debridement of infected bone if they fail to respond to antibiotics. In cases of intracranial infection, craniotomy and neurosurgical evacuation may be required.
Intracranial Complications Intracranial complications (meningitis, subdural empyema, epidural abscess, and cerebral abscess) may complicate acute sinusitis and range from 0.5% to 24% of patients admitted for acute sinusitis.13,25 Insufficient antibiotic treatment, excessive virulence of a microorganism, and congenital bony defects are all predisposing factors.26 Infection is spread via
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FIG 7. (A-C) Subperiosteal abscess beneath orbital roof. Coronal (A and C) and axial (B) CT slices demonstrate acute frontal sinusitis (air-fluid level), with secondary subperiosteal abscess (air bubble) attached to the right orbital roof (arrows).
thrombophlebitis or less commonly via direct extension. Streptococcal sp. are the microorganisms most commonly responsible for central nervous system complications. Exceptions include cerebral abscess
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and epidural abscess near a focus of osteomyelitis when Staphylococcus is more common. Despite antibiotics and aggressive treatment, high rates of morbidity (up to 33%) and mortality (5-10%) still
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FIG 8. (A-C) True orbital cellulitis. Axial (A) and coronal (B and C) enhanced CT images show exophthalmos on the right side and associated ethmoidal and maxillary sinus disease with subperiosteal phlegmonous tissue. Coronal views (B and C) better demonstrate the subtle increased fat attenuation involving the extra- and intraconal compartments (stage 3a, following the classification shown in Table 2). No defined abscess was depicted and the patient’s condition improved after endonasal sinus drainage and intravenous antibiotics.
exist; therefore, early diagnosis and treatment are very important to minimize both. Thin axial slices (3-5 mm) through the fronto-ethmoidal area and anterior cranial fossa or MRI should be obtained in cases of suspected intracranial complications, because small collections can be missed in a routine CT scan.9 Also in suspected intracranial infection, frontal, ethmoidal, or sphenoid disease must be assumed to be clinically significant rather than an incidental finding.27
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Symptoms and Signs Common symptoms of increased intracranial pressure (headache, altered mental status, fever, vomiting, and stiff neck), seizures, unilateral weakness, hemiparesis, and systemic toxicity usually occur. In a recent review, hemiparesis was the most common localizing neurological sign (35.5%), and orbital inflammation was present in 41.5% of affected patients; therefore, the presence of an extracranial collection of pus does not mean there will
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FIG 9. (A-D) Frontal osteomyelitis and abscess (Pott’s Puffy tumor). Axial unenhanced (A and B) and enhanced (C and D) CT slices show evidence of frontal sinus disease, with preseptal edema and small abscess (black arrow) on the left side. There is also bony destruction in the anterior frontal table, suggesting osteomyelitis with sequestration (white arrow).
be no intracranial involvement.10 “Silent” intracranial involvement can also occur, and it may be found incidentally on CT or MRI.26,28
Types of Intracranial Complications In order of decreasing frequency, the intracranial complications are subdural empyema, intracerebral ab-
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scess, epidural abscess, meningitis, and, more rarely, cavernous and other dural venous sinuses thrombosis. Subdural empyema is referred to in several articles as the most prevalent complication.28-30 The infection leads to a progressive thrombophlebitis through mucosal veins to emissary veins and subdural space. The falx and tentorium tend to limit spread to an area over
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FIG 10. (A-H) Subdural empyema. A 10-year-old girl was admitted with suspected postseptal orbital cellulitis. Axial CT slices without (A) and with contrast (B) and coronal images (C and D) demonstrate frontoethmoidal sinus disease on the left side, with associated preseptal and subperiosteal abscess (arrows). Despite surgical drainage, the patient’s condition got worse and she developed right hemiparesis. Subtle interhemispheric fissure widening was noted on enhanced cranial CT (black arrow in D, white arrows in E and F).
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FIG 10. Continued. (E and F). Neurosurgical drainage was undertaken, and follow-up MR post-Gd T1WI (G and H) showed complete resolution of the disease. The patient’s condition improved, and she was discharged without any sequela.
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FIG 11. (A-F) Subdural empyema with cerebritis. A 13-year-old girl suffered acute bacterial sinusitis with preseptal cellulitis and minimal postseptal compromise (A). Because of persistent fever and headache, thin section CT scan was repeated along the anterior cranial fossa. Small subdural collections could be seen on enhanced CT (B). Neurosurgeons decided against craniotomy; endonasal sinus drainage was performed and antibiotics were modified. MRI was performed 2 days later because of a partial seizure episode. Hyperintense areas in both frontal lobes were demonstrated on FLAIR sequences, suggesting cerebritis (C) together with abnormal meningeal enhancement on contrast T1WI (D). Diffusionweighted images showed a small extra-axial abscess in the right frontal lobe.
one hemisphere (Fig 10). On an unenhanced CT scan, a subdural empyema appears as a hypodense or isodense crescentic area adjacent to the inner table of the skull, parafalcial, or over the tentorium. A curvilinear ring of enhancement may be seen underneath an
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empyema, representing membranes or inflamed subjacent cortex. Occasionally, enhancement of the subjacent cerebral cortex may be seen in a gyriform pattern, indicating the presence of a concomitant cerebritis (Fig 11) or infarction. Recently, MRI has become the
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FIG 11. Continued. (E and F), with normal increased values of the cerebral parenchyma. Adequate prolonged antibiotherapy eventually resolved the infection, and the patient was discharged with normal neurological condition.
diagnostic modality of choice because of its ability to detect collections earlier than CT. MRI demonstrates subdural collections with a low signal on T1-weighted sequences and a high signal on T2-weighted sequences with peripheral enhancement after gadolinium administration. Subdural empyema is a neurosurgical emergency that will invariably become fatal if left untreated. It should be at the top of the differential diagnosis in any patient presenting with a history of sinusitis and a change in mental status or neurological focal sign.28,30 Intracerebral abscess is mainly related to frontal sinusitis, and the frontal lobe is the most common location. As a neurologically silent area of the brain, there may be only subtle changes in mood or personality, which can be misinterpreted in adolescents. The late pneumatization and development of frontal sinuses, combined with a highly vascular valveless diploic system, are considered responsible for the higher incidence in adolescents and young adults.26,31 Acute cerebritis is seen as an ill-defined low-density area on CT scan in the frontal lobe, progressing to a coalescent lesion with a collage-
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nous capsule that appears as a thin-walled rim typically thickest toward gray matter and with ring enhancement. MRI demonstrates the distinct hypointense capsule on T2-weighted images with typical decreased diffusion coefficient content. The high viscosity and inflammatory cellular composition may explain restricted water diffusion in the purulent fluid, causing increased signal intensity on diffusion-weighted imaging and markedly decreased signal intensity on apparent diffusion coefficient map images (Fig 12). Although reported as nonspecific, markedly increased signal intensity of a rim-enhancing brain mass on diffusion-weighted imaging and a low apparent diffusion coefficient indicating restricted water diffusion are features highly suggestive of pyogenic brain abscess.32 Epidural abscess is rarely referred, although it has a high prevalence in some series.24 It appears as a low-attenuation extra-axial mass, iso- or hyperdense relative to cerebrospinal fluid due to the proteinaceous content. It usually requires surgical drainage. Meningitis is a rare complication, typically occurring with ethmoidal or frontal sinusitis.33 It is generally
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FIG 12. (A-H) Cerebral abscess. A 12-year-old boy was being treated for acute sinusitis for 2 weeks before admission. He developed increased headache, and cranial CT (A) was performed showing a cystic lesion with a hyperdense peripheral rim in the left frontal lobe and surrounding edema. Sinus disease was also discovered, mainly frontosphenoidal (B and C). MRI disclosed a typical cystic lesion with hypointense strongly enhanced capsule and decreased diffusion coefficient (D-G). Surgical abscess drainage confirmed the purulent content of the lesion with posterior growth of S. pneumoniae. Follow-up CT examination was normal except for the small postsurgical porencephaly (H).
managed clinically. Excluding endocranial hypertension before the lumbar puncture should be emphasized because of the risk of herniation. Venous sinus and cavernous sinus thrombosis are rare; nevertheless, they are very severe intracranial
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complications. Engorgement of the ophthalmic vein is a frequent finding, with enlargement of the cavernous sinus and bowing of the lateral dural margin.34 Direct reported signs include changes in density or signal intensity caused by filling defects and expansion of the
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FIG 12. Continued.
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FIG 13. (A-G) Cavernous sinus thrombosis. A 14-year-old girl was being treated for sphenoid sinusitis. She presented with left ocular proptosis and meningeal signs during therapy. Axial enhanced CT images showed some residual sphenoidal sinus disease, left proptosis, and quite normal-appearing cavernous sinuses (A and B). MRI was later performed because of a lack of clinical improvement; cavernous sinuses appeared heterogeneous on coronal T2WI (C and D), with convex lateral walls and enlarged ophthalmic vein on the left side (arrow).
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FIG 13. Continued. Both cavernous sinuses appeared abnormal on coronal T1WI (E), with isointense signal relative to cerebral gray matter and slightly decreased size of the internal carotid artery flow void, particularly on the left side. Post-Gd coronal T1WI (F and G) also shows slightly increased cavernous sinuses, with convex lateral walls and enlarged left ophthalmic vein. The patient was treated with prolonged intravenous antibiotics and anticoagulant therapy, and follow-up MRI was normal.
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cavernous sinus with lateral convexity better shown on coronal planes. Indirect signs consist of dilation of the superior ophthalmic vein and other tributary veins such as superior/inferior petrosal and sigmoid sinuses, exophthalmos, and increased dural enhancement along the lateral border.35 Focal defects of enhancement after gadolinium administration can also be seen on MRI as clots within the sinus, and the ipsilateral cavernous carotid artery flow void can be diminished or absent (Fig 13).
Therapy Surgical drainage of the affected paranasal sinuses and any intracranial abscess is emergently required. Antibiotics should be chosen to cover the most common organisms, and prolonged therapy is usually necessary. Neurosurgical consultation is strongly recommended, even in cases that are not immediately surgical. Despite modern diagnostic and surgical capabilities, the mortality rate associated with subdural empyema and brain abscesses remains over 25%.
Conclusion Complications of acute bacterial sinusitis in children are less frequent since the advent of antibiotics, and their prognosis is improved with better management and earlier detection. CT and MRI have become indispensable diagnostic tools and should be obtained as early as possible in every child with postseptal orbital or intracranial infection. Although CT remains the standard initial modality, MRI is mandatory when intracranial extension is suspected. Acknowledgments: Thanks to Drs. F. Moraga, M. Boronat, M. Pellicer, and P. Nogue´ s, from the departments of Pediatric Infectious Disease and Pediatric Neurosurgery, who always provide invaluable help with the difficult clinical and surgical aspects of the presented pediatric patients. We also thank A. Casadesu´ s for nursing assistance, C. Batista for secretarial help, and C.L. Cavallo for English language advice.
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