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The MR image showed a large fluid-filled collection overlying the apical aspect of both cerebral hemispheres (Figure 2), consistent with epidural abscess. An MR venogram showed significant compression of the superior sagittal sinus by the abscess (Figure 3), prompting urgent burr hole drainage of the collection in conjunction with frontal sinus surgery. A postoperative MR venogram showed that venous circulation had been successfully restored. Following surgery, a combination of ticarcillin disodium and clavulanate potassium was initiated intravenously. Cultures of pus drained intraoperatively grew Streptococcus intermediussusceptible to penicillin, ampicillin, and cephalexin. The patient made an uneventful recovery and was discharged without neurological sequelae after 2 weeks. A computed tomographic scan after 6 weeks of intravenous antibiotic therapy showed complete resolution of the intracranial and extracranial pathology, as well as improvement of the osteolytic changes.

Bacterial sinusitis is a common infection that generally resolves without sequelae.¹Intracranial complications associated with sinusitis are thought to be rare, although definitive data are lacking. One large multicenter study²reported intracranial complications in 3.7% of patients hospitalized with sinusitis. However, because these represent the severe end of the disease spectrum, the overall incidence is likely to be considerably lower.

The spectrum of suppurative intracranial complications associated with sinusitis includes meningitis, intracerebral (parenchymal) abscess, subdural empyema, and epidural abscess. Epidural abscess is thought to result from retrograde bacterial spread into the epidural space via diploic skull veins.³Coexisting osteomyelitis of the skull, which was also present in the case described herein, is commonly observed.³

The absence of characteristic features associated with epidural abscess often makes the diagnosis difficult. Most patients have nonspecific symptoms, frequently consisting of only fever and headache; in contrast to intracerebral abscess, focal neurological symptoms are rare.^1- 2,4Signs of meningeal irritation, such as nuchal rigidity and Kernig and Brudzinski signs, are rarely present, whereas these are common in patients with subdural empyema.⁵

A broad range of bacteria can cause intracranial complications associated with sinusitis, including streptococci, Staphylococcus aureus, Haemophilus influenzae, enterococci, and anaerobic bacteria such as Peptostreptococcusspecies, Bacteroidesspecies, and Fusobacteriumspecies.¹Bacteria of the Streptococcus millerigroup, which includes S intermedius, Streptococcus constellatus,and Streptococcus anginosus, are generally overrepresented.^{1- 2,4,6- 7}These bacteria are part of the normal commensal respiratory and gastrointestinal flora.⁸However, unlike other viridans streptococci, they have a propensity to cause deep-seated abscesses and are responsible for 56% to 81% of central nervous system abscesses.^8- 9The majority of clinical S millerigroup isolates are susceptible to penicillin and most cephalosporins, although isolates with multiple resistance have been reported.^9- 10

Thrombosis of the cavernous sinus or intracranial dural sinuses are further potential intracranial complications of sinusitis.²The patient described herein was at considerable risk of sagittal sinus thrombosis given the proximity of this structure to an area of inflammation in conjunction with marked compression. The MR venogram provided valuable additional information that helped to guide management decisions toward a surgical rather than a conservative approach.

Most patients with epidural abscess make a full recovery⁷if appropriate management is initiated in a timely fashion. However, cases with poor outcome and long-term neurological sequelae have been described.¹¹

This report highlights that inadequate treatment of sinusitis can result in severe suppurative intracranial complications, which may present with only nonspecific clinical features.

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Correspondence:Marc Tebruegge, MRCPCH, MD, Infectious Diseases Unit, Department of General Medicine, Royal Children's Hospital Melbourne, Parkville, Victoria 3052, Australia (marc.tebruegge@rch.org.au).

Accepted for Publication:November 30, 2009.

Author Contributions:Study concept and design: Tebruegge, Curtis, and Bryant. Acquisition of data: Tebruegge and Bryant. Analysis and interpretation of data: Tebruegge, Wallace, Starr, and Bryant. Drafting of the manuscript: Tebruegge, Curtis, and Bryant. Critical revision of the manuscript for important intellectual content: Tebruegge, Curtis, Wallace, Starr, and Bryant. Study supervision: Tebruegge, Curtis, Wallace, Starr, and Bryant.

Financial Disclosure:None reported.