Mastoiditis

Although it is generally accepted that acute mastoiditis is an uncommon disease, there is evidence that it may be on the increase, although serious complications are still relatively frequent. The aim of the present study was to evaluate the causes and the clinical course of 24 cases of acute mastoiditis treated over a 10-year period.

Eighteen cases were the sequel of acute otitis media, while six cases developed as a complication of cholesteatoma. There were nine cases with intratemporal complications: eight subperiosteal abscesses and one facial nerve paralysis. Two more patients had intracranial complications: a cerebellar abscess and meningitis. Ten patients recovered with conservative therapy consisting of intravenous antimicrobial therapy, combined with myringotomy in some cases. Fourteen patients were treated surgically by cortical (n=8) or modified radical mastoidectomy (n=6). All patients recovered following treatment.

The paper discusses the different approaches used in the management of this disorder.

Acute mastoiditis is no longer a common disease due to the introduction of antimicrobial therapy. However, some authors have noticed that the number of cases has recently increased (Imperei and Sotonyi 1983, Faye-Lund 1989). In addition, other studies have indicated that while acute mastoiditis is less common that previously, its severe complications are still relatively frequent (Ginsburg et al 1980, Luntz et al 1994).

This paper presents our experience with 24 patients treated for acute mastoiditis in our institute over a 10year period.

Our policy in management of this condition is discussed along with the views of other authors.

Patients and Methods

All patients admitted with the diagnosis of acute mastoiditis to King Abdel-Aziz University Hospital, Riyadh, from 1987 through 1996, were included in the study. The diagnosis was based on the presence of retroauricular erythema, edema and tenderness, and auricular displacement. A mastoid subperiosteal abscess was diagnosed if the postauricular swelling was thought to be fluctuant.

A complete history and clinical examination were performed. Bacterial specimens were taken from the external canal if the ear was draining. Mastoid radiographs (CT scans in most instances) were performed on most patients.

All patients were initially treated with intravenous (IV) antibiotics. Myringotomy was performed if the tympanic membrane was intact. Indications for mastoid surgery were underlying chronic suppurative otitis media, the presence of a complication (e.g. subperiosteal abscess, facial palsy) and lack of improvement to conservative therapy. The surgical treatment was a cortical mastoidectomy if the condition had been a sequel of acute middle ear infection, and a modified radical mastoidectomy for patients with chronic suppurative otitis media. At every mastoidectomy, specimens were taken for bacteriological and histopathological evaluation.

Antibiotic therapy was maintained intravenously for patients treated conservatively for 2-3 days after all physical signs of mastoiditis had subsided. Likewise, it was continued for 2-3 days postoperatively in patients treated surgically. Thereafter, it was administered orally for 7 to 14 days.

Results

The study group consisted of 24 patients ranging in age from 9 months to 28 years, with an average of 7.4 years. There were 15 males and 9 females. The duration of the presenting illness prior to admission varied from 2 days to 9 days, with an average of 4.8 days. Six patients were known to have chronic suppurative otitis media. All but four patients had been on antibiotics for several days before admission.

Seven patients were afebrile, fourteen had a low-grade fever (less than 38.4C), and three patients presented with a temperature higher than 39C. The involved ear was draining on admission in 20 patients.

Radiographs revealed clouding of the mastoid air cells in all cases with unequivocal signs of bone destruction in 10 cases. A CT scan demonstrated a cerebellar abscess in one patient.

Ten patients were successfully treated with IV antibiotics. Most of them received amoxicillin and cloxacillin or amoxicillin-clavulinate. Other antimicrobials used were penicillin, cefazolin, cefuroxime, gentamicin, and metronidazole.

Edematous mucosa and pus in the mastoid antrum and air cells were found in all the operated cases. Eight cortical mastoidectomies were carried out. In six cases, modified radical mastoidectomies were performed because of an underlying cholesteatoma. Microorganisms were isolated in 18 (64.3%) instances with two of them showing mixed organisms. The cultured organisms were streptococcus pneumoniae (n=7), Streptococcus pyogenes (n=4), Staphylococcus aureus (n=3), Hemophilus influenzae (n=l), Proteus vulgaris (n=2), Pseudomonas aeruginosa (n=2), and Bacteroides (n=l). The latter three organisms were exclusively isolated from cholesteatomatous ears. Histologically, the main findings were infiltration of the mucosa with polymorphonuclear leucocytes, and varying amounts of granulation tissue. Specimens taken from cases secondary to chronic suppurative otitis media invariably showed cholesteatoma. It is worth mentioning that histological examination revealed two cases of Histiocytosis X that had presented as acute mastoiditis. These were not included in the present study.

All patients recovered following treatment. There were no surgical complications and no deaths. The duration of hospital stay varied from 4 to 12 days with an average of 6 days. The average follow-up period was 2.6 years (range 9 month to 5 years). None of the patients had any recurrence of acute mastoiditis. One patient had a revision modified mastoidectomy for a recurrent cholesteatoma.

The patient with the cerebellar abscess had had no preoperative CT scan due to technical reasons. The condition was diagnosed on the third postoperative day when CT was done because of persistent fever. The abscess was drained through a posterior craniotomy on the same day. He recovered without any sequelae.

Discussion

Acute mastoiditis is viewed as a rare entity by most authors. Palva et al (1985) estimated the annual incidence of acute mastoiditis in Finland at 0.004% (based on an average number of 1.7 cases/year in 1 million population). Prellner and Rydell (1986) reported an incidence of 0.02% in Sweden. Although it seems reasonable to assume that the frequency of the disease is higher in those parts of the world with poor hygienic and social standards, recent studies have shown that the number of cases is rising in some developed countries over the last few years (Imperei and Sotonyi 1983, Faye-Lund 1989).

The dramatic drop in the frequency of acute mastoiditis over the last few decades has been mainly attributed to the use of antimicrobials in the treatment of acute otitis media. However, the routine use of antibiotics cannot be considered as an absolute safeguard against acute mastoiditis. In the present study, 85% of the patients had been on antibiotics for ear or upper respiratory tract infection on presentation. This is higher than other reports which have found that 36%-72% of acute mastoiditis patients developed the disease despite prior antibiotic treatment (Luntz et al 1994, Prellner and Rydell 1986, Hawkins et al 1983, Rosen et al 1986). The reasons are still presumptive and not proven but include low compliance, insufficient dosage, resistant bacteria, and local factors in the middle ear cleft that interfere with the proper diffusion of the drug to the infected area of osteitis (Holt and Gates 1983, Hawkins and Dru 1983).

Acute mastoiditis is usually a sequel of acute otitis media. However, there is a significant group of patients who develop the disease as a complication of chronic suppurative otitis media with cholesteatoma. In the present series, eighteen cases were the sequel of acute otitis media, while 6 cases were found to be associated with cholesteatoma. The development of acute mastoiditis in ears containing cholesteatoma has been described by many authors (Hawkins and Dru 1983, Primrose and Cinnamond 1987). The second author of this paper (A.A) has discussed this association in more detail in a recently published paper (Al-Serhani 1996). An underlying cholesteatoma should therefore be considered if acute mastoiditis occurs in adolescents and young adults.

The predominant causative organisms of acute mastoiditis vary according to the underlying cause and probably vary in different parts of the world. Acute mastoiditis secondary to acute otitis media is usually due to aerobic bacteria, but the relative frequency does not necessarily reflect the etiological agents of middle ear infections. Our results are in accord with many other studies which have shown that streptococcus pneumonia, beta-hemolytic streptococci and staphylococcus aureus are more likely to cause mastoiditis than other pathogens (e.g. hemophilus influenzae) found in acute otitis media (Ginsburg et al 1980, Prellner and Rydell 1986, Mathews and Oliver 1988). On the other hand, patients with cholesteatoma may grow gram-negative bacilli and Bacteroides, often in mixed culture (Mathews and Oliver 1988). In this small series, Proteus vulgaris, Pseudomonas aeruginosa, and Bacteroides were isolated from three cases with chronic suppurative otitis media.

The liberal use of antibiotics for upper respiratory tract infections may affect the clinical signs of manifest mastoiditis. In the present study, 25% of the patients were afebrile. Many other authors have noticed the same finding (Hawkins et al 1983, Rosen et al 1986). Most patients do not look ill or toxic during the course of the disease. The diagnosis is based on the presence of retroauricular erythema, tenderness and edema, posterosuperior meatal wall sagging and auricular displacement. The tympanic membrane usually shows abnormalities that reflect acute middle ear infection. A mastoid subperiosteal abscess is diagnosed if the postauricular swelling is fluctuant.

In the literature, the term "latent mastoiditis" (Faye-Lund 1989, Palva et al 1985) or "masked mastoiditis" (Holt and Gates 1983) are both used to describe a more chronic form of the disease. The condition is characterized by the absence of the clinical signs of pain, fever, and aural discharge. Holt and Gates (1983) reported nine cases of latent mastoiditis: 8 presented with intracranial complications and the ninth with facial paralysis. Similarly, Samuel and Fernandes (1985) reported 21 cases of otogenic complications with an intact tympanic membrane.

Radiographs usually show cloudiness of the air cells. They may demonstrate dissolution of air cell septation and the presence of subperiosteal abscess. Most authors make the diagnosis of mastoiditis on the clinical picture alone and state that they have found radiographs not to be helpful, especially in deciding which cases need surgical intervention (Hawkins et al 1983, Rosen et al 1986). However, we believe CT is mandatory for the assessment of the otological and intracranial pathology. It may detect an early complication that is clinically unnoticed. In the present study, if the CT had been done on presentation, a neurosurgical procedure could have been performed simultaneously with the mastoidectomy under the same anaesthetic in the case with cerebellar abscess. CT also may demonstrate cholesteatoma in certain cases although enhanced MRI in conjunction with CT is probably the investigation of choice in cases suspected of having a complication.

In addition to acute otitis externa, the differential diagnosis should include diseases that may manifest as acute mastoiditis. These include aneurysmal bone cyst (Devries et al 1989), acute myelogenous leukemia (Todd and Bowman 1984), tuberculous mastoiditis (Samuel and Fernandes 1986), Kawasaki's disease (Puczynski et al 1986), and histiocytosis X (Cunningham et al 1988). In our study, we have not included two cases of histiocytosis X that presented as acute mastoiditis.

The treatment of acute mastoiditis is controversial. Some authors advocate simple mastoidectomy as soon as possible after the diagnosis has been established (Faye-Lund 1989, Palva et al 1985). They argue that recovery is rapid, and return of normal hearing is the rule. They believe that conservative treatment is insufficient and is likely to lead to the development of chronic ear disease in one of its various forms. On the other hand, we, as well as others (Rosen et al 1986, Hawkins and Dru 1983), treat all patients initially by intravenous antimicrobial therapy (combined with myringotomy if the ear is not draining spontaneously). We resort to surgery in the presence of clinical signs of subperiosteal abscess or other complications, underlying chronic suppurative otitis media, and in patients not responding to conservative treatment.

In the present series, 10 (35%) cases resolved with conservative treatment. Hawkins et al (1983) reported a response to conservative treatment in 57% (including 5 patients with small subperiosteal abscess) of 54 patients. The response, or otherwise, to conservative treatment is probably related to the clinical stage as suggested by Bluestone and Klein (1983). They suggested that the events leading to the development of acute mastoiditis could be separated into two clinical stages. The first stage (acute mastoiditis with periostitis) occurs when the infection extends to the mastoid periosteum causing erythema and edema of the retroauricular area. In the second stage (acute coalescent mastoiditis), bone destruction occurs which usually manifests as subperiosteal abscess. In the first stage, conservative treatment is usually successful while surgical treatment is required in the second stage.

Two of our patients had intracranial complications (a cerebellar abscess and meningitis). Of interest, acute mastoiditis was the sequel to acute otitis media in both cases. The frequency of serious complications varies considerably in the literature. Prellner and Rydell (1986) and Hawkins et al (1983) had no complications in their series of 24 and 54 patients respectively. Mathews and Marus (1988) reported that 7.1% (4/56) of patients with acute non-cholesteatomatous mastoiditis had concomitant intradural sepsis (3 brain abscesses and 1 meningitis). Luntz et al (1994) reported three (16%) intracranial complications in an 18 patient series. They reviewed nine published studies yielding 891 patients with the study periods from 1937 to 1984 and concluded that severe complications of acute mastoiditis are still relatively frequent.

Conclusion

Acute mastoiditis remains a dangerous disease. Although the diagnosis is a clinical one, CT is a valuable tool for evaluation. The management of acute mastoiditis depends on the clinical situation at presentation and the evolution of symptoms. Intravenous antimicrobials and myringotomy (if the ear is not draining spontaneously) will cure the condition in many instances. Mastoid surgery is undertaken if conservative treatment fails, or if there is a complication or underlying cholesteatoma.

References

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Yousry El-Sayed F.R.C.S. Associate Professor and Consultant

Awad Al-Serhany M.D.

Assistant Professor and Consultant

Department of Otorhinolaryngology King Abdel-Aziz University Hospital PO Box 245, Riyadh 11411 Saudi Arabia Tel: 468 2142 Fax: 477 5748

E-mail: F35N002@KSU.EDU.SA

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