Epidural intracranial abscess as a complication of frontal sinusitis: case report and review of the literature.

Abstract: Two cases of epidural abscess as a complication of frontal sinusitis are presented. The diagnoses were suspected on the basis of history and were confirmed by magnetic resonance imaging and computed tomography. Both patients were treated successfully by means of surgery and intravenous antibiotics. One patient developed meningitis in the postoperative course and was treated by changing the antibiotic regimen. However, further follow-up in the outpatient clinic by physical examinations and brain computed tomography scans showed no long-term neurologic complications in either case. Intracranial suppuration, including epidural abscesses, can complicate acute and chronic frontal sinusitis. These complications are diagnosed by maintaining a high index of suspicion and using the appropriate neuroimaging studies without delay.

Key Words: abscess, epidural, frontal sinusitis

**********

In the era of antibiotic therapy the incidence of epidural abscesses has been significantly decreased. Paranasal sinusitis can be complicated uncommonly by epidural abscesses as the infection spreads intracranially. We report two patients with this complication who had no significant symptoms until two weeks before they presented to our clinic.

Case Reports

Patient 1

A 29-year-old female presented with continuous headaches of two-weeks' duration. She had no past history of similar headaches or sinusitis. Neither did she complain of retro-orbital pain or fever. She was investigated by computed tomographic (CT) scan as an outpatient. The scan showed a large epidural lesion in the frontal lobes bilaterally that had a thick wall with a small calcification and peripheral enhancement after intravenous contrast administration. The frontal bone and the ethmoid sinus wall were markedly thickened but with no evidence of boney erosions (Fig. 1).

A magnetic resonance imaging (MRI) scan of the brain was consequently done and revealed an epidural lesion of low signal intensity on the T1-weighted images and of high signal intensity on the T2-weighted images in the frontal lobes. Again there was noted thickening of the bones. The sagittal images were very specific in identifying a small area of communication between the lesion and the frontal sinus (Fig. 2).

The patient was treated by a frontal craniotomy for evacuation of the lesion under general anesthesia. The outer wall of the lesion was adherent to the periosteum and it was full of yellowish fluid suggesting it was an abscess. The whole abscess was meticulously evacuated and the specimen was sent for pathologic examination. A communication port of the lesion with the frontal sinus was identified. The intact dura was reexpanded easily and the thickened bone was replaced. (Fig. 3)

The patient was covered with broad-spectrum antibiotics for the prevention of postoperative meningitis. Unfortunately, she deteriorated ten days after surgery. Meningitis was suspected and her cerebrospinal fluid grew Staphylococcus aureus. The antibiotic treatment was readjusted and this complication was treated successfully. The patient was discharged on the 20th post-operative day with no neurologic deficits. She was followed up later with clinical examinations and CT scans, and she developed no long-term sequelae.

Patient 2

A 44-yr-old male presented with a long history of headaches. During the previous week, he had a couple of blackout spells and developed ptosis of the left eye.

Brain CT scan showed a large ring-enhancing epidural collection with erosion of the frontal bones and the frontal sinuses. Brain MRI revealed the presence of a highly proteinaceous mass, intraosseous or epidural, extending upwards from the frontal sinus (Fig. 4, Fig. 5).

A bifrontal craniotomy was performed. Massive intradiploic mucocele and an epidural abscess were identified with pansinusitis and erosions of the orbital roof on the left side. The abscess was drained and cranialization of the frontal and ethmoid sinuses was done (Fig. 6).

This patient was also covered with broad-spectrum antibiotics for the prevention of meningitis and was discharged one week after surgery with no neurologic deficits. He was later followed up as an outpatient with clinical examinations and CT scans and developed no further complications.

Discussion

This report emphasizes the importance of early diagnosis and management of the intracranial complications of frontal sinusitis. We report two cases of epidural abscesses. Various etiologies of this condition are described in the literature. (1,2) These include: paranasal sinusitis, especially of the frontal sinuses (1-14) with the extension of infection from the sphenoid and ethmoid sinuses being relatively uncommon; (2) osteomy-elitis of the skull, which can be associated rarely with Pott's Puffy Tumor; (3,4,5) direct extension from the middle ear, the mastoid, or the orbit; trauma resulting in skull fracture; iatrogenic causes like craniotomy, skull traction for cervical fractures or scalp venous catheters in the pediatric population; (6) and hematological spread from a remote focus of infection. There were even reports of epidural abscesses associated with exposure to expanded polytetrafluethylene. (7) However, in many instances no obvious etiology can be found. In our discussion we will focus mainly on the epidural abscesses resulting from frontal sinusitis.

[FIGURE 1 OMITTED]

The frontal sinus originates from the frontal recess, which is the most anterior part of the anterior ethmoid cells, and grows into the frontal bone. This process starts at about one year of age, and continues until 16 to 18 years of age, at which time the average volume of 6 to 7 mL is found. The spread of the infection from the frontal sinuses intracranially usually occurs by progressive thrombophlebitis through valveless diploic veins. (8) Other possible mechanisms include direct extension through osteomyelitis of the skull, or between the cranium and the frontal sinuses when there is a posttraumatic, surgical, or congenital defect. (9)

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

Frontal sinusitis and its complications occur most commonly in adolescent and young males. (10,11) It is postulated that this is owing to a peak in the vascularity of the diploic system and the development of the frontal sinus between ages of 7 and 20 years. The extensive nature of this diploic venous system affords direct communication from the sinus mucosa to the marrow spaces of the frontal bone, to veins in the dura mater, to the superior sagital sinus, and through the cortical veins to distant parts of the skull and cerebrum. The lack of valves within these diploic veins allows for blood flow in any direction and accounts for the propagation of septic thrombi from the vessels of the mucosa to bone, dura, and brain.

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

The proportions of patients with intracranial suppuration who have sinusitis as a cause were found by Gallagher et al (12) to be 15 of 176 (8.5%). Clayman et al (1) reported a 3.7% incidence of intracranial complications in a study of 649 patients with sinusitis.

[FIGURE 6 OMITTED]

The distribution of those complications in Gallaghar's retrospective analysis was as follows: epidural abscess 23%, subdural empyema 18%, meningitis 18%, cerebral abscess 14%, superior sagittal sinus thrombosis 9%, cavernous sinus thrombosis 9%, and osteomyelitis 9%. (12) Jones et al reported the distribution of complications in their 47 patients to be subdural empyema 38%, intracerebral abscess 30%, extradural abscess 23%, meningitis 2%, and more rarely cavernous and superior sagittal sinus thrombosis. (9)

The most common presenting signs and symptoms (9,10) are headache, fever, vomiting, altered mental state, seizure, hemiparesis, or cranial nerve signs. Forty-five percent of patients present with periorbital cellulites or frontal swelling. (9) Jones et al also found that 55% of patients had visited their primary care physician with an upper respiratory infection and had been treated appropriately, thus suggesting that these complications are usually unpreventable. (9)

The diagnostic accuracy of imaging and clinical findings for patients with intracranial complications was analyzed by Younis et al. and MRI was found to be the most accurate (97%) in determining the diagnosis, while the accuracies of CT and clinical findings were 87% and 82% respectively. (13) Even though CT is the most cost-effective diagnostic modality for the diagnosis of intracranial abscesses, MRI is also valuable. MRI is better in evaluating the intracranial lesions but is much less effective in evaluating boney erosions. In our first case, it was the MRI that clearly showed the site of communication of the abscess with the frontal sinuses. The site of communication was very small and went undetected by CT scan (both in the axial and the coronal images). This is due to the ability of the MRI to obtain high quality sagittal images, which were the most diagnostic.

Treatment (9,10,14) is mostly surgical with a combined neurosurgical and ear, nose, and trachea approach. Craniotomy with evacuation of the intracranial collection should be performed and, in the case of osteomyelitis, necrotic bone needs to be removed. It is important to explore the posterior wall of the sinus; if it is involved, a cranializtion procedure should be performed. If the sinus walls are intact, a drainage procedure should be used. Combined endonasal and percutaneous surgery has been used with some good results. A prolonged course of antibiotics is a vital part of the treatment, usually consisting of 4 to 8 weeks of intravenous therapy.

Our two patients are a 29-year-old female and a 44-year-old male. Although intracranial complications are most commonly found in adolescent and young adult males, they have been reported in all ages. (14)

The first patient does not have a clear history of preceding acute or chronic sinusitis. Her recent headache triggered us to consider neuroimaging. The small area of communication between the lesion and the frontal sinus, which was most probably the cause of this condition, can be congenital or a result of a chronic process in the frontal sinus. She was treated by evacuation of the epidural abscess and correction of the boney defect. However, her postoperative course was complicated by S aureus meningitis despite antibiotic coverage.

The second patient, in contrast, had a history suggestive of chronic sinusitis that was complicated acutely by an intracranial suppuration. Imaging was essential and revealed osteomyelitis of the frontal bones and an epidural abscess. He was treated by removal of the infected bone, cranialization of the frontal and ethmoid sinuses, draining of the abscess and the sinuses, and a prolonged course of antibiotic coverage. His postoperative course was free of complications.

Conclusion

Frontal sinusitis is a very common disease that should be carefully treated because of the severe complications that may develop. The antibiotics and the newer diagnostic modalities such as CT and MRI should be correctly used to prevent such problems.

Accepted November 16, 2003

Copyright [c] 2004 by The Southern Medical Association

0038-4348/04/9703-0279

References

1. Clayman GL, Adams GL, Paugh DR, Koopman CF Jr. Intracranial complications of paranasal sinusitis: a combined institutional review. Laryn-goscope 1991;101:234-239.

2. Moonis G, Granados A, Simon S. Epidural hematoma as a complication of sphenoid sinusitis and epidural abscess, a case report and literature review. J Clin Imaging 2002;26:382-385.

3. Verbon A, Husni RN, Gordon SM, Lavertu P, Keys TF. Pott's puffy tumor due to Haemophilus influenza: Case Report and Review. Clin Infect Dis 1996;23:1305-1307.

4. Chandy B, Todd J, MD, Stucker FJ, Nathan CA. Pott's puffy tumor and epidural abscess arising from dental sepsis: a case report. Laryngoscope 2001;111:1732-1734.

5. Marshall AH, Jones NS. Osteomyelitis of the frontal bone secondary to frontal sinusitis. J of Laryngol Otol 2000;114:944-946.

6. Lefkowitz MA, Chin LS, Couldwell WT. Pediatric intracranial epidural abscess secondary to an infected scalp vein catheter. Pediatr Neurosurg 1998;29:297-299.

7. Uemura T, Suse T, Yokoyama T, Mitsukawa N, Anegawa S. Staged cranial reconstruction after epidural abscess associated with dural substitute exposure. J Craniofac Surg 2002;13:415-417.

8. Remmler D, Boles R. Intracranial complications of frontal sinusitis. Laryngoscope 1980;90(11 Pt 1):1814-1824.

9. Jones NS, Walker JL, Bassi S, Jones T, Punt J. The intracranial complications of rhinosinusitis: Can they be prevented? Laryngoscope 2002;112:59-63.

10. Rosenfeld EA, Rowley AH. Infectious intracranial complications of sinusitis, other than meningitis, in children: 12-year review. Clin Infect Dis 1994;18:750-754.

11. Wenig BL, Goldstein MN, Abramson AL. Frontal sinusitis and its intracranial complications. Int J Pediatr Otorhinolaryngol 1983;5:285-302.

12. Gallagher RM, Gross CW, Phillips CD. Suppurative intracranial complications of sinusitis. Laryngoscope 1998;108(11 Pt 1):1635-1642.

13. Younis RT, Anand V, Davidson B. The role of computed tomography and magnetic resonance imaging in patients with sinusitis with complications. Laryngoscope 2002;112:224-229.

14. Lang EE, Curran AJ, Patil N, Walsh RM, Rawluk D, Walsh MA. Intracranial complications of acute frontal sinusitis. Clin Otolaryngol 2001;26:452-457.

RELATED ARTICLE: Key Points

* Intracranial suppuration, including epidural abscesses, can complicate acute and chronic frontal sinusitis.

* Neuroimaging by magnetic resonance imaging and computed tomography is essential in the diagnosis and management of intracranial abscesses.

* Treatment of epidural abscesses is by surgical evacuation and prolonged course of intravenous antibiotics.

Kostas N. Fountas, MD, PhD, Yazan Duwayri, MD, Eftychia Kapsalaki, MD, Vassilios G. Dimopoulos, MD, Kim W. Johnston, MD, Sean B. Peppard, MD, Joe S. Robinson, MD

From the Departments of Neurological Surgery, Radiology and E.N.T., The Medical Center of Central Georgia, Mercer University School of Medicine, Macon, Georgia

Reprint requests to Kostas N. Fountas MD, PhD, The Georgia Neurosurgical Institute, P.A., 840 Pine Street, Suite 880, Macon, Georgia 31201. Email: [e-mail]