Surgical management of intracranial complications of otogenic infection.

Abstract

We conducted a prospective study of 24 patients to evaluate the evolution of intracranial complications resulting from otogenic infection and to correlate the course of the disease with surgical treatment. Almost half of the patients were younger than 18 years, and most were male. The most common intracranial complication was brain abscess, followed by meningitis, lateral sinus thrombosis, and extradural abscess. Cholesteatoma was found in 14 patients. After the complications were confirmed by computed tomography, initial treatment consisted of intravenous systemic antibiotics followed by mastoid surgery. The surgical approach was determined by the type of ear disease, not by the type of neurologic complication. Modified radical mastoidectomy was performed in 16 patients, tympanomastoidectomy in 6, and myringotomy in 2. No significant morbidity, mortality, recurrence, or residual neurologic deficit was observed at the 6-month follow-up. Early surgical intervention is important in achieving positive outcomes in patients with such intracranial complications.

Introduction

During the preantibiotic era, the incidence of intracranial complications in cases of otogenic infection, with or without cholesteatoma, was 2.3%, and mortality rates in such cases were as high as 80%). (1,2) At that time, radical mastoidectomy was considered to be the most appropriate form of treatment. However, the discovery of antimicrobial agents, especially penicillin and metronidazole, and the development of several newer open- and closed-cavity techniques for cholesteatoma surgery have diminished the usefulness of radical mastoidectomy for these patients; the procedure is now considered to be unnecessarily invasive and too aggressive for treating chronic ear infections. (1)

The widespread use of broad-spectrum antibiotics has not only changed the clinical presentation of intracranial complications of middle ear infections, it has even reduced their incidence in developed countries to between 0.04 and 0.15%. (2,3) Otitis media, both chronic and acute, is a potentially severe disease that makes a patient susceptible to serious complications. In the chronic form, progressive and extensive bone erosion frequently causes complications that increase the risk of damage to the facial nerve, labyrinth, and dura. In the acute form, complications occur earlier because anatomic barriers are destroyed. The three main modes of dissemination of the infection are thrombophlebitic, hematogenic, and via direct extension along classic pathways. (4,5) Thrombophlebitis may take place in any of the diploic veins in and around the temporal bone. (4)

Otogenic complications can be classified as either intracranial or extracranial. Intracranial complications include meningitis, extradural abscess, brain abscess, lateral sinus thrombosis, and hydrocephalus. (6) Extracranial complications include subperiosteal abscess, labyrinthitis, mastoiditis, facial paralysis, and perichondritis.

The purpose of this study was to prospectively document the evolution of intracranial complications resulting from otogenic infection. Patients who underwent surgical treatment were evaluated, and the otologic findings were correlated with both the intracranial complications and the mastoid surgery.

Patients and methods

Our study population was made up of 24 patients--18 males and 6 females, aged 2 to 64 years (mean: 22.6)--with intracranial complications of otogenic infection who had been admitted to the University of Sao Paulo School of Medicine from 1998 through 2003. As our hospital is a referral center, all patients had already received initial clinical treatment (antibiotics) at their local hospitals.

To make an accurate diagnosis, computed tomography of the temporal bones and skull was performed on all patients. In cases of meningitis, a cerebrospinal fluid culture, including biochemical analysis, was performed.

We followed a three-step protocol: (1) determination of the type of intracranial complication and its relation to the ear disease, (2) selection of the type of ear surgery, and (3) selection of a neurologic approach to the treatment of the intracranial complication.

Results

Ear disease. Cholesteatoma was found in 14 patients (58.3%), acute otitis media (AOM) in 7 (29.2%), and chronic suppurative otitis media (CSOM) in 3 (12.5%) (table). Of the 14 patients with cholesteatoma, 2 had the congenital form, but they were diagnosed only as adults during the course of treatment for intracranial complications. In patients with cholesteatoma, the most common complication was cerebral abscess.

Intracranial complications. The most common intracranial complication was brain abscess, which occurred in 8 patients (33.3%); meningitis was seen in 7 patients (29.2%), sigmoid sinus thrombosis in 5 (20.8%), and extradural abscess in 4 (16.7%) (table). In the brain abscess category, cerebral abscesses (n=6) and cerebellar abscesses (n = 2) were considered as a single entity.

Ear surgery. All patients underwent surgery. Surgical interventions for the otogenic infection and for the complications were carded out simultaneously. The surgical approach was determined by the type of ear disease, not by the type of neurologic complication. During surgery, the mastoid bone was irrigated with a solution of 1 gram of chloramphenicol per liter of water.

Modified radical mastoidectomy was performed in 16 patients (66.7%), including all 14 who had a cholesteatoma and 2 in whom CSOM required revision of a previous mastoidectomy (table). Another patient with CSOM and 5 patients with AOM underwent canal-wall-up tympanomastoidectomy. Two patients with AOM underwent myringotomy upon admission.

Neurologic approach. The choice of treatment for neurologic complications varied depending on the type and location of the lesion. Treatment fell into two general categories: (1) for lesions located adjacent to the dura or the tegmental area, such as those occurring in cases of extradural abscess and sigmoid sinus thrombosis, a mastoidectomy was performed by an otologist; (2) when lesions were identified in less easily accessible areas, a craniotomy was performed by a neurosurgeon. As an experimental measure, patients with meningitis were treated with 4 g/day of ceftriaxone until the results of their cerebrospinal fluid analysis were known.

In cases of extradural abscess, an otologist performed a mastoidectomy, and aspiration was achieved by insertion of a thick needle through the mastoid tegmen to obtain material for culture. The tegmen bone was removed to expose the totality of the abscess location.

Cerebral abscesses were treated with craniotomy performed by a neurosurgeon when such a procedure would allow access to the lesion, as occurred in 4 cases. In the 2 cases in which the abscess was located adjacent to the temporal bone, aspiration of the secretion was achieved by insertion of a thick needle through the exposed dura by the otologist. The two cerebellar abscesses were treated without surgical drainage.

The cases of sigmoid sinus thrombosis were also treated with mastoidectomy. After the covering bone had been removed and the vein exposed, needle aspiration of the sinus was performed with a thick needle. If pus was seen in the aspirate, the sigmoid sinus was opened for complete drainage. If blood or nothing was seen, the sinus was not opened.

Microbiology. When pus was found, all secretions were sent for Gram's stain, culture, and antibiogram. Bacterial growth was observed in fewer than 50% of cases. The most common bacteria were Staphylococcus aureus, Morganella morganii, Corynebacterium spp, Bacteroides melaninogenicus, Pseudomonas aeruginosa, and Proteus spp.

Recurrence. None of the 24 otologic surgeries performed for control of the intracranial complication required revision. However, 1 patient with cholesteatoma suffered a recurrence of his cerebral abscess 2 weeks after the surgery, and he required further neurosurgical intervention.

No significant morbidity, mortality, recurrence, or residual neurologic deficit was observed at the 6-month follow-up.

Discussion

Despite the overall reduction in the incidence of sequelae of otogenic infections, serious complications still exist, probably owing to changes in bacterial virulence and sensitivity as well as to the health status of the individual patient. (6,7) The rate of mortality related to these infections ranges between 10 and 25%. (8) In our study, the incidence of intracranial complications accompanied the incidence of ear infection, supporting the findings of some other authors. (2) Otogenic intracranial complications are more common in males; the reason for this gender-related difference is unknown. (9,10)

As was the case in other studies, cerebral abscess in our series was the most common intracranial complication, and all 8 cases (33.3 %) were related to chronic otitis media. (11,12) Cholesteatoma was present in 14 patients (58.3 %). The presence of cerebral abscess is considered a sign of a negative prognosis because of the high mortality rate (33%), and some authors have suggested extensive investigation and early treatment of patients presenting with fever, migraine, and stiffness in the nape of the neck. (2)

No deaths from cerebral abscess occurred in our study, nor were there any other intracranial complications. Otogenic cerebral abscesses typically form in the temporal lobe or in the cerebellum at the rate of 2:1, respectively. (13) Some authors have found meningitis to be the most common intracranial complication, and incidence rates of 34 to 77% have been reported. (2,9,10) Singh and Maharaj recorded a 12% occurrence of meningitis. (1) In our study, meningitis was diagnosed in 7 patients (29.2%). According to Bluestone and Klein, the mortality rate for meningitis caused by otitis media is 10.7%. (14)

Another complication of otogenic infections is sigmoid sinus thrombosis, which occurs in 17.4 to 37% of cases. (10,12) In our study, it occurred in 5 patients (20.8%). This is relatively common in long-term chronic mastoiditis and usually is noted after a radiologic examination. In some cases, the condition is symptomatic and must be treated surgically. The sinus occlusion can naturally recanalize after the ear disease surgery or clinical treatment, (15) but in our opinion the sinus must be approached through a mastoidectomy. All perisinus infection must be removed, and a needle aspiration of the sinus with a thick needle must be performed. If pus comes from the sinus, it should be opened to allow complete drainage.

Extradural empyema is rare. (1,10,12) In our study, it was seen in only 4 cases.

The microorganisms found in our patients were generally the same as those common in developed countries. In CSOM, the most commonly isolated pathogens are P aeruginosa, S aureus, Diphtheroides spp, and Bacteroides spp. In cases of cerebral abscess secondary to CSOM, Bacteroides spp, Proteus spp, P aeruginosa, and Pseudomonas putrefaciens were virtually the only microorganisms found, usually in mixed cultures. (16,17) Streptococcus pneumoniae and P aeruginosa were present in the AOM cases. (18)

Canal-wall-up mastoidectomy is convenient for patients with reversible alterations, such as tenuous granulations or mild edema of the mucous membrane of the middle ear, and in AOM with normal eustachian tube function, even in the presence of intracranial complications. (1) With irreversible alterations such as cholesteatoma or extensive granulated tissue, or with the impossibility of appropriate postoperative care, canal-wall-down mastoidectomy should be performed. (2)

In the past, radical mastoidectomy was considered the treatment of choice in the presence of intracranial complications, (3) and a modified form of radical mastoidectomy is still the treatment of choice in such cases. Whenever a patient's condition allows for it, otologic surgery should be carried out simultaneously with intracranial drainage.

References

(1.) Singh B, Maharaj TJ. Radical mastoidectomy: Its place in otitic intracranial complications. J Laryngol Otol 1993:107:1113-18.

(2.) Kangsanarak J, Fooanant S, Ruckphaopunt K, et al. Extracranial and intracranial complications of suppurative otitis media. Report of 102 cases. J Laryngol Otol 1993;107:999-1004.

(3.) Palva T, Virtanen H, Makinen J. Acute and latent mastoiditis in children. J Laryngol Otol 1985:99:127-36.

(4.) Ludman H. Complications of suppurative otitis media, lh: Kerr AG, Groves J, eds. Scott-Brown's Otolaryngology. London: Butterworths, 1987:264-91.

(5.) Nissen AJ, Bui H. Complications of chronic otitis media. Ear Nose Throat J 1996;75:284-92.

(6.) Glasscock ME III, Shambaugh GE Jr, eds. Surgery of the Ear. Philadelphia: W.B. Saunders, 1990.

(7.) Goycoolea MV, Jung TK. Complications of suppurative otitis media. In: Paparella MM, Shumrick DA, Cluckman JL, MeyerhoffWL, eds. Otolaryngology. Philadelphia: W.B. Saunders, 1991:1381-1401.

(8.) Turgut S, Ercan I, Alkan Z, Cakir B. A case of pneumocephalus and meningitis as a complication of silent otitis media. Ear Nose Throat J 2004;83:50-2.

(9.) Kaplan RJ. Neurological complications of infections of head and neck. Otolaryngol Clin North Am 1976:9:729-49.

(10.) Samuel J, Fernandes CM, Steinberg JL. Intracranial otogenic complications: A persisting problem. Laryngoscope 1986:96:272-8.

(11.) Savic DL, Djeric DR. Facial paralysis in chronic suppurative otitis media. Clin Otolaryngol 1989:14:515-17.

(12.) Mathews TJ, Marus G. Orogenic intradural complications (a review of 37 patients). J Laryngol Otol 1988; 102:121-4.

(13.) Bradley PJ, Manning KR Shaw MD. Brain abscess secondary to otitis media. J Laryngol Otol 1984;98:1185-91.

(14.) Bluestone CD, Klein JO. Intracranial suppurative complications of otitis media and mastoiditis. In: Bluestone CD, Stool SE, Scheetz MD, eds. Pediatric Otolaryngology. Philadelphia: W.B. Saunders, 1990:537-46.

(15.) Agarwal A, Lowry R Isaacson G. Natural history of sigmoid sinus thrombosis. Ann Otol Rhinol Laryngol 2003;112:191-4.

(16.) Kenna MA, Rosane BA, Bluestone CD. Medical management of chronic suppurative otitis media without cholesteatoma in children-Update 1992. Am J Otol 1993; 14:469-73.

(17.) Pit S, Jama F, Cheah FK. Microbiology of cerebral abscess: A four-year study in Malaysia. J Trop Med Hyg 1993;96:191-6.

(18.) Leskinen K, Jero J. Complications of acute otitis media in children in southern Finland. Int J Pediatr Otorhinolaryngol 2004;68: 317-24.

From the Department of Otolaryngology (Dr. Bento and Dr. de Brito) and the Department of Anatomy (Dr. Ribas), University of Sao Paulo School of Medicine, Sao Paulo, Brazil.

Reprint requests: Rubens de Brito, MD, Av. Angelica 1968-Cj. 91, 01228-200, Sao Paulo, Brazil. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

Ricardo Bento, MD; Rubens de Brito, MD; Guilherme Carvalhal Ribas, MD