Oral Medicine

Brain abscess and dentistry: A review ofthe literatnreNorman J, Schuman '̂ / James E, Turner**

Brain ab.-.cess is a rare, extremely aggressive, life-threatening infection. A mortality rate ofbe-t^veen 36% and 90% has been reported as recently as 1990. It is resistant to antibiotics and isone of the few bacterial infections whose morbidity md mortality statistics remain unaffectedh tf^e development of antimicrobial medications. Successfid treatment appears to be depen-dent on early diagnosis, surgical intervention, and direct antibiotic irrigation ofthe surgicalwound site, as well as intravenous administration of high doses of antibiotics throughout thecrisis. It has been .'iuggested that there is a relationship between dental infection or treatmentand brain abscess. Dental infection and treatment have been found culpable in numerouscases reported in the literature. However, careful review ofthe articles reveals that dental in-fection or treatment has often been named as a causative factor (1) solely because an infectionor treatment occurred within several months of brain abscess: (2) when nondental bacteriawere cultured from the brain abscess: and (3) without culturing both the dental infection andthe brain abscess to ascertainßora match. (Qninlessenct Inl 1994:25:41 I^L^.)

Introduction

The practice of dentistry involves the maintenance andestablishment of good patient oral health by dentalhealth personnel, including the diagnosis and treat-ment of oral infection by the dentist. The overwhel-ming majority of infected teeth are treated conserva-tively by the practitioner, with knowledge that the like-hhood that dental infection will spread to other areas ofthe hody is extremely remote. However, some risk doesexist for the spread of infection even for clinicallyhealthy patients,' Dental procedures as benign as oralprophylaxis have been reported to canse infective en-docarditis, brain abscess, and other life- and health-threatening conditions,'"' Infected teeth have alsocaused the above-mentioned conditions, in addition toLudwig's angina and mediastinitis,^'' Untreated dental

Associate Professor, Departmenl of Biologic and DiagnosticSciences, University of Tennessee, College of Dentistry,875 Union Avenue. Memphis. Tennessee 38t 63,Professor and Chairman. Department of Biologic and Diagnos-tic Sciences, University of Tennessee,

infections are occasionally cited as a cause of serioussystemic illness and even death by state and federalhealth authorities.^ Infection from dental abscess canspread by either anatomic or hematogenous routes.The heart, brain, and respiratory system arc at greatrisk when a dental infection spreads beyond the oralcavity,̂ This paper will foeus on brain abscess and itsrelationship to dental infection.

Review ofthe literature and discussion

Brain abscess is a rare, life-threatening infection. It hasan incidence of 1 per ltJIJ.OOO population and has beenreported to be fatal in 36% to 90% of cases.^"" Reportsof brain abscess associated with dental infection havestated that most infections reach the brain via direct ex-tension or cavernous sinus thrombosis, although bothhematogenous and anatomic routes of infection aresuspected,^'" Kemper and Aseltine'" argued that ana-tomic extension must be rare because of the brain'snatural barriers, the skull and dura. They stated that itis clear, however, that some cases of brain abscessspread directly from the jaws to the brain anatomicallyby dissection through fascial spaces.'" All case reports

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have noted that diagnosis was made through sympto-matic illness. Symptoms of intracranial abscess are in-dicative of central nervous system disorder and includemalaise, hyperirritability, lethargy, confusion, and neu-ropathy (eg, seizures),'-

Brewer et al'-' noted that, of 60 reviewed cases ofbrain absee,ss, four were attributed to '"dental proce-dure or abscess." The greatest number of cases (12) wasattributed to "otic or paranasal sinus infection," Alsoexceeding dental infection as a cause of brain abscesswere "pulmonary infection" (eight), "general surgery"(six), "head injury" (five), and "congenital heart dis-ease" (five). Fifteen of the 60 cases were ot unknownorigin,'"' Haymaker''' attributed 2S fatal central ner-vous system infections to odontogenic origin and drewa relationship between tooth extraction and fatal brainabscess. Tooth extraction appears to be tbe most com-mon dental factor in patients who are diagnosed withbrain abscess,'"* Other dental procedures that havebeen noted include operative dentistry, periodontaltherapy, injection of local anesthetie, and dental pro-phylaxis,'" '̂̂ '"Gold'-^ reported a fatal brain abscess in apatient who exhibited dental infection and was nottreated. He strenuously argued that treatment couldpossibly have saved the life of this patient,'"

Arch location of the dental infection has little bear-ing on occurrence of brain abscess. Haymaker'"* attrib-uted incidence primarily to molars, but maxillary andmandibular teeth contributed equally to fatal cranialinfection in this study. This finding is unremarkable,since both hématologie and anatomic spread have beenreported as possible routes of infection, Andrews andFarnham' citedHollinetal" as linking dental treatmentto one of five intracranial infections studied. Only fivecases were studied by Hollin et al,''

The microbiologie flora found in brain abscesseshave been varied. Most infections attributed to odon-togenic origin have noted Streptococcus viridans as theprimary microbe found on culture.'""•''•^"'̂ However,Brewer et al'' found Streptococcus spp in 32 of 60 cases,and S viridans in 18 of those 60 cases, but attributedonly four cases to odontogenic origin.'^ On the otherextreme, Escherichia coli has been cultured from non-fatal and fatal brain abscesses attributed to dental in-fection.'""

Periodontal infections contain a wide variety of an-aerobes,'^'*' Cultures of brain abscesses attributed toperiodontal origin have Tevealed Peptostreptococcusspecies, Fusobacterium nucleatum, Staphylococcus epi-dermidis, Propionibacterium species, Bacteroides spe-cies. S viridans, S tnitior. S milleri. S sctnguis. and S mu-

tatis. '" '" Marks et al̂ argued that when a brain abscessarises from a contiguous source, such as the ear or nasalsinus, the bacterial flora are likely to be representativeof the upper respiratory tract and arc also likely to hemixed. Respiratory tract flora are also found in the oralcavity,'̂ Other bacteria attributed to the oral flora in-clude Staphylococcus aureus, Micrococcus foetidus,and Ilaemophilusparainfluenzae.^^'-"

Hollin et al'' attributed one of the five intraeranial ab-scess cases they studied to dental origin. They madethis conclusion on the basis of a negative culture (ster-ile brain abscess), solely because the patient had 14teeth extracted between 4 months and 1 month prior tohospital admission. The final extraction was performed1 month prior to the onset of symptoms, Tlie culturewas negative, yet, incredibly, the brain abscess was at-tributed to dental extraction. In a second case attrib-uted to dental treatment, S viridans and Hparainfiuen-zae were cultured bacteria.^ Haemophilus spp are re-spiratory tract microbes, and their alleged associationwith dental treatment (in this case the restoration of apremolar 5 days preadmission) seems less than conclu-sive,''' Lewis et al"" found the microbial flora in the ma-jority of dental infections to be mixed, consisting of75% anaerobes. The most common oral microbes werePeptococcus spp, Bacteroides spp, and S mitleri.-"

Dental procedures alleged to cause brain abscess in-clude simple operative dentistry, oral prophylaxis, andthe routine injection of local anesthetic, Hollin et al'stated that, although the role of local anesthesia is con-troversial, "a variety of bacteria, actually or potentiallypathogenic is always present on the oral mucosathrough which the local anesthetic must be injected. Itis conceivable that, in a susceptible patient, enoughbacteria may be transported into the bloodstream tometastasize to a distant area, such as the brain," Hollinet al'' also cited the work of Round et al,-' who pro-posed general anesthesia for all dental procedures,"since their experiments indicated that the injectionof local anesthetic agents forces bacteria deep intotissues,"

The American Heart Association's"^' guidelines forendocarditis specifically exempt injection of localanesthetic from mandatory antibiotic prophylaxis forat-risk patients. Also to be considered are the millionsof local anesthetic injections administered without sideeffects,

Tliroughout the literature, there is no example orprofile of the patient at risk for brain or intracranial ab-scess. There are no reports of increased incidence ofbrain abscess in patients who have a history of brain

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disease, encephalitis, meningitis, or head trauma (sub-dural hematoma, etc). In fact, there is no pattern of epi-demiologie distribution of reported cases. Brain abs-cess has been demonstrated to occur without regard toage, race, or gender. One article stated that one groupat apparently higher risk is medically compromised pa-tients, such as those with a history of endocarditis,"Presumably, these patients would be given appropriateantibiotic prophylaxis by the dentist because of Iheirat-risk status for endocarditis.

Another troubling aspect of brain abscess is its highmortality rate. The antibiotic era has had a remarkableeffect on endocarditis and Ludwig's angina, loweringthe mortality rate to below 10%.'*- '--•'•' Brain abscess,however, rematns remarkably resistant to antibiotictherapy, maintaining a mortality rate of 36% to 65%,according to Brewer et al.'' who stated that the lack ofimprovement tn mortality rates from 195^ to 1973 was-disconcerting,"" Aldous ct al,"̂ in 1987. stated thatthe mortality rate for brain abscess was 90%. Later ar-ticles have reported similarly high mortality rates.'"

Summary

Brain abscess, a rare infection with an incidence of 1per 100.000 population, is sometimes linked to dentalinfection or dental treatment, A review of the medicaland dental literature demonstrated that a number ofcases that clearly do not appear to be linked to dentalcauses (Escherichia coli abscess, sterile abscess, orHaemophilus spp abscess) have been reported as casesof brain abscess secondary to dental abscess or dentaltreatment. Brain abscess has a high mortality rate,reportedly between 36% and 90%, but it can be treatedsuccessfully with a combination of antibiotics andstirgery.

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fection. Gen Dent 1990;38;224^225,2, Andersen WC, Horton HL, Parietal lobe abscess following pe-

riodontai recall therapy. Report of a case, J Penodontol1990:6:243-247,

3, Gallagher DM. Eriekson K, Hollin SI, Fatal brain ahscess fol-lowing periodontal therapy: A case report. Mt Sinai J Med19fi

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Dierks EJ, Meyerhoff WL, Schultz B, Finn R, Fulminant infec-tions of odontogenic origin. Laryngoscope 19S7;97:271-274.Schuman NJ. Owens BM, Ludwig's angina following dentaltreatment in a five year old male patient: Report of a case, J ClinPediatr Dent 1992:J6:2(i3-2(i5,

Marks PV, P^tel KS, Mee EW, Multiple brain abscesses secon-dary to detital caries and severe periodontal disease, Br J OralMa\illofacSurgl988;26:24-247,Hollin SA. Hayashi H, Gross SW, Intracranial abscesses ofodonlogenlc origin. Oral Surg Oral Med Oral Pathol1967:23:277-293,Kemper JW. Aseltme LF, [ntraeranial lesions resulting fromdental infection. Am J Orthod Oral Surg t944;30;7U 1-770,Baddour H, Dtirst N. Tilson H, Frontal lohe abscess of dentalorigin. Oral Surg Oral Med Oral Fathol 1979:47:303-306,GoTeiner D, Sonis ST. Fasciano R. Cavernous sinus thrombosisand brain abscess initiated and maintained by periodontally in-voived teeth. J Oral Med 1982:37:50-83.Brewer MS. MaeCarty CS. Wellman WE, Brain ahseess: A re-view ofrecenteNperience. Ann Intern Med 1975:82:571-576,HaymakerW. Fatal infections (if tlitfcerlr¡ilner\ouí system andmeninges after tooth extraction. Am J Ortlwd Oral Surg1945:31:117-188,

Gold L, Brain abscess secondary to dental infection: report anddiseussion of a case. Oral Surg Oral Med Oral Pathol1949:2:1107-1117,Aldous JA. Powell GL. Stensaas SS, Brain abscess of odonto-genic origin: Report of a case. J Am Dent Assoc 1987:115:861-863.Lau DW. Klein NC, Cunha BA, Brain abscess mimicking braintumor. Heart Lung 1989:18:634-637,Brook 1, Anaerobic infections in childhood. Am Fani Phys1986:34:130-136,Sabiston CB, Grigsby WB. Seigerstrotn N. Bacterial study ofpyogenic infections of dental origin. Oral Surg Oral Med OralPathol 1976:41:430-435.Lewis MAO, MacFarlane TW, MeGowan DA, Ouantitativebacteriology of acute den to-alveolar abscesses, J Med Miero-biol 1986:21:10122-104,Round H, Kirkpatrick HJR, Hails CG. Further investigationson bacteriological infections ofthe nioulh. Proc Royal Soe Med1936:29:1552,American Heart Association Committee on Rheumatic Fever,Endocarditis, Prevention of bacterial endocarditis: Recom-mendations by the American Heart Association, JAMA1990:264:2919-2922,American Heart Association Committee on Rheumatic Fever.Endocarditis. Prevention of bacterial endocarditis: Recom-mendations by the American Heart Association, J Am DentAssoc ]991;122:87-92, ••

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