Intraparenchymal brain abscesses are rare but serious brain infections with very high morbidity and mortality. One-half of these abscesses originate from otogenic and rhinogenic sources. The purpose of this paper is to review all relevant studies on cerebral abscesses from otogenic and rhinogenic sources, identify possible patterns in pathogen frequency, and streamline antimicrobial therapy based on this information. Extensive meshterm searches on Medline were performed. Data was compiled and analyzed. Proteus spps. were commonly associated with otogenic abscesses; S. milleri was commonly associated with rhinogenic abscesses. Limitations to the study exist. Future research should include investigation of virulence factors contributing to these common intraparyncymal pathogens as well as obtaining culture results from both the ear or sinus as well as the intraparenchymal abscess for further correlation. Intracerebral abscesses from otologic and rhinologic sources: Is there a difference? Micah Hill, MD; David Yao MD; Arvind Kumar, MD; David Conley, MD Department of Otolaryngology - Northwestern University, Feinberg School of Medicine INSERT YOUR ORGANIZATION’S LOGO HERE 437 otogenic abscesses with 562 pathogens and 75 rhinogenic abscesses with 163 pathogens were identified. Otogenic locations included temporal 45% (197), cerebellar 24% (106), frontal <0.5% (2), unknown 13% (56), and other 5% (21). Rhinogenic locations included frontal 36%, (n=27) and unknown 35%, (n=26). Otogenic culture results in decreasing order of frequency these included sterile 25%, n=134; Proteus spps. 24%, n=128; Bacteriodes spps. 7%, n=36; anaerobic 6%, n=31; E. coli 5%, n=25; and streptococcus (species not noted) 5%, n=24. Distilled into broad subgroups in decreasing order of frequency these yielded enteric gram negative rods 31%, n=169; sterile 25%, n=134; streptococcus 12%, n=65; non-enteric gram negative rods 8%, n=44. Rhinogenic culture results in decreasing order of frequency included S. milleri 33%, n=54; sterile 13%, n=21; Streptococcus spps. 9%, n=15; and Bacteriodes spps. 7%, n=11. Broadly distilled into subgroups, Streptococcus spps. accounted for 48%, n=76 followed by sterile 13%, n=21, enteric gram negative rods 11%, n=18, and Staphylococcus spps. 10%, n=16. The 532 separate otogenic culture results from 437 abscesses and the 163 culture results from 75 total rhinogenic abscesses suggest polymicrobial etiologies for a significant portion of abscesses. The results demonstrate a predominance of otogenic Proteus spps. and rhinogenic S. milleri as pathogens. No difference in pathogens between developed and developing nations was noted; no difference between early and late studies was noted. Few rhinogenic abscess data, however, originated from developing nations. Limitations to this type of review are inherent. The studies were heterogeneous in data presentation. For example, not all case series had culture results for each patient. Patients had variable antibiotic therapy prior to culture likely altering pathogen yields. Heterogeneity also resulted from the age of the studies and the reclassification of bacterial species over the past 50 years. Not all abscess specimens underwent anaerobic and fungal cultures or evaluation for fastidious organisms--possibly underestimating the contribution of these bacteria. With the wide variability of pathogens documented in intracranial abscesses and the absence of other strong relationships, recommendations regarding antibiotic choice cannot be made. Medline searches were performed. The meshterms “otitis media” and “brain abscess” limited to English resulted in 190 hits. A meshterm search for “sinusitis” and “brain abscess” yielded 157 articles. Articles were reviewed. Total case numbers of intracerebral abscesses and culture results were collected. Articles that did not include cultures of intracerebral abscesses were excluded. Articles that grouped all intracranial complications were distilled into intracerebral abscesses. The otogenic abscess search was narrowed to 29 articles were relevant and available for complete review. 18 case series with a total of 421 patients with 437 abscesses were identified. 11 case reports were identified. The 157 rhinogenic abscesses articles were narrowed to 8 case series with 67 patients and 8 case reports were available and relevant for review. Dates ranged from 1962 to 2007 for the otogenic papers while dates ranged from 1983 to 2004 for the rhinogenic abscesses. Locations included the US, the UK, and developing nations. Intraparenchymal brain abscesses are rare but serious infectious infections with a mortality of 25% and an even higher associated morbidity. Studies demonstrate one half of these abscesses are secondary to otogenic and rhinogenic infections. During the past 50 years, numerous case series and case reports have been published contributing data to the limited fund of knowledge available on this subject. Brain abscesses can be evaluated based on location and pathogens. The review papers can be categorized based on date of publication and geographic location of the publishing hospitals. The purpose of this review is to analyze the case series and reports of rhinogenic and otogenic intracranial abscesses with an intention to investigate for possible relationships between particular pathogens, locations, time periods, and intracranial sites. Such information could prove valuable in the selection of antimicrobial therapy. INTRODUCTION METHODS AND MATERIALS Albu S, Tomescu E, Bassam S, Merca Z. Intracranial complications of sinusitis. Acta oto-rhino-larynologica Belg., 2001; 55:265-72 Aldana B Jr. Otogenic Brain Abscess. Philippine Journal of Surgery & Surgical Specialties. 1966; 21(6): 337-42 Arseni, C, Ciurea AV. Rhinogenic cerebral abscesses. Zentralblatt fur Neurochirurgie. 1982; 43(2): 129-42 Blumenfeld RJ, Skolnik EM. Intracranial complications of sinus disease. Transactions- American Academy of Opthomology and Otolaryngology 1966; 70(6); 899-908 Bodur H, Colpan A, Gozukucuk R, Akinci E, Cevik MA, Balaban N. Venous Sinus Thrombosis after Proteus Vulgaris meningitis and concomitant Clostridium abscess formation. Scandinavian Journal of Infectious Diseases 2002; 34(9): 694-6 Bradley PJ, Manning KP, Shaw MDM. Brain abscess secondary to otitis media. The Jounrnal of Laryngology and Otology 1984; 98: 1185-91 Bradley PJ, Manning KP, Shaw MDM. Brain abscess secondary to paranasal sinusitis. The Journal of Laryngology and Otology 1984; 98: 719-25 Buchheit W, Ronis ML, Liebman E. Brain abscesses complicating head and neck infections. Transactions- American Academy of Ophthalmology & Otolarngology 1970; 74(3): 548-54 Charlstrey S, Pfleiderer AG, Moffat DA. Persisting incidence and mortality of sinogenic cerebral abscess: a continuing reflection of late clinical diagnosis. Journal of the Royal Society of Medicine 1991; 84(4): 193-5 Clayman G, Adams GL, Paugh DR, Koopmann CF. Intracranial complications of paranasal sinusitis: a combined institutional review. Laryngoscopye 1991; 101: 234-39 Couloigner V, Sterkers O, Redondo A, Rey A. Brain abscesses of ear, nose, and throat origin: comparison between otogenic and sinogenic etiologies. Skull Base Surgery 1998; 8 (4): 163-8 Debruyne F. Intracranaial complications of otitis media. Acta Oto-Rhino-Laryngologia Belgica. 1984; 38(2): 128-32 Dolan RW, Chowdhury K. Diagnosis and Treatment of Intracranial Complications of Paranasal sinus infections. Journal of Oral Maxillofacial Surgery 1995; 53:1080-87 Dubey SP, Larawin V. Complications of Chronic suppurative otitis media and their management. The Laryngoscope 2007; 117:264-7 El-Hakim H, Mlik A, Aronyk K, Ledi E, Bhargava R. The prevalence of intracranial complications in pediatric frontal sinusitis. International Journal of Pediatric Otorhinolaryngology 2006; 70: 1383-87 Elidan J, Saah D, Gomori M. Imaging case study of the month- Intracranial complications of otitis media. Annals of Otology, Rhinology & Laryngology. 1997; 106: 873-4 Eufinger H, Machtens E. Purulent pansinusitis, orbital cellulites and rhinogenic intracranial complications. Journal of Cranio-Maxillofacial Surgery 2001; 29:111-117 Fenton JE, Smyth DA, Viani LG, Walsh MA. Sinogenic Brain Abscess. American Journal of Rhinology 1999; 13(4): 299-302 Giannoni C, Sulek M, Friedman E. Intracranial Complications of sinusitis: a pediatric series. American Journal of Rhinology 1998; 12:173-78. Go C, Bernstein HM, de Jong AL, Sulek M, Friedman EM. Intracranial complications of acute mastoiditis. International Journal of Pediatric Otorhinolaryngology 2000; 52: 143-8 Hilsinger RL Jr, Caparosa RJ. Otogenic brain abscess. Laryngoscope 1970; 80(5): 697-711 Jones NS, Walker JL, Bassi S, Jones T, Punt J. The intracranial complications of rhinosinusitis: can they be prevented? Laryngoscope 2002; 112: 59-64\ Juselius H, Kaltiokallio K. Complications of acute nad chronic otitis media in the antibiotic era. Acta Otolaryngolitica 1972; 74:445-50 Kangsanarak J, Navacharoen N, Fooanant S, Ruckphaopunt K. Intracranial complications of suppurative otitis media: 13 years’ experience. The American Journal of Otology 1995; 16(1): 104-109 Kornblut AD. Cerebral abscess- a recurrent otologic problem. Laryngoscope 1972; 82(8): 1541-56 Kramer ME, Romanczuk BJ, Liebman EP. Brain abscess of otitic origin- A Legg, NJ. Intracranial abscess. British Journal of Hospital Medicine 1979; 12: 608-14 Leotta N, Chaseling R, Duncan G, Isaacs D. Intracranial suppuration. Journal of Pediatric Child Health 2005; 41: 508-512 Lerner DN, Choi SS, Zalzal GH, Johnson DL. Intracranial complications of sinusitis in childhood. Annals of Otology, Rhinology & Laryngology. 1995; 104:288-93 Leskinen K, Jero J. Acute complications of otitis media in adults. Clinical Otolaryngology 2005; 30:511-16 Maniglia AJ, Goodwin WJ, Arnold JF, Ganz E. Intracranial abscesses secondary to nasal, sinus, and orbital infections in adults and children. Archives of Otolaryngology--9 The remaining references are held due to space limitations. CONCLUSIONS DISCUSSION RESULTS REFERENCES 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Sterile Staphylococcus Streptococcus Gram Negative Rod, Enteric Gram Negative Rod, non-enteric Otogenic Rhinogenic Frontal Temporal Cerebellar Other Otogenic Abscess 2 197 106 77 Rhinogenic Abscess 27 0 0 26 Total 29 197 106 103 Chart 1. Percentage of abscesses caused by pathogen groups. Table 1. Frequency of Brain Abscess Location ABSTRACT Name: Micah Hill, MD Organization: Northwestern University Email: Micah-Hill@md.northwestern.edu Phone: (312) 695-8182 CONTACT Intraparenchymal brain abscesses caused by rhinogenic and otogenic sources are similar in the variability of pathogens without effect from abscess location, geographic location, or time period. Proteus spps. is most common in otogenic abscesses; S. milleri is most common in rhinogenic abscesses. Developing research may ultimately yield insight into how particular pathogens’ virulence factors may facilitate intracranial abscess formation.