Malignant External Otitis in a Patient With Diabetes Mellitus: Comparison of Bone Scan SPECT/CT and 68Ga-Citrate PET/CT

ABSTRACT

We reported a 66-year-old woman with malignant external otitis who was referred to our department for evaluation of disease extension. Both 99mTc-MDP bone SPECT/CT and 68Ga-citrate PET/CT were done for the patient. Both studies showed concordant areas of increased uptake in the petrous bone. In addition, 68Ga-citrate PET/CT showed soft tissue infection in the nasopharyngeal wall. Our case showed the potential of 68Ga-citrate PET/CT for evaluation of malignant external otitis.

Diagnosing necrotizing external otitis on CT and MRI: assessment of pattern of extension

BACKGROUND AND PURPOSE

Necrotizing external otitis (NEO) is a serious complication of external otitis. NEO can be classified according to-anterior, medial, posterior, intracranial, and contralateral-extension patterns. Currently there is no consensus on the optimal imaging modality for the identification of disease extension. This study compares NEO extension patterns on MR and CT to evaluate diagnostic comparability.

METHODS

Patients who received a CT and MR within a 3-month interval were retrospectively examined. Involvement of subsites and subsequent spreading patterns were assessed on both modalities by a radiologist in training and by a senior head and neck radiologist. The prevalence of extension patterns on CT and MR were calculated and compared.

RESULTS

All 21 included NEO cases showed an anterior extension pattern on CT and MR. Contrary to MR, medial extension was not recognized on CT in two out of six patients, and intracranial extension in five out of eight patients. The posterior extension pattern was not recognized on MR. Overall, single anterior extension pattern (62%) is more prevalent than multiple extension patterns (38%).

CONCLUSION

All anterior NEO extension pattern were identified on CT as well as MR. However, the medial and intracranial spreading patterns as seen on MR could only be identified on CT in a small number of patients. The posterior spreading pattern can be overlooked on MR. Thus, CT and MR are complimentary for the initial diagnosis and work-up of NEO as to correctly delineate disease extent through the skull base.

Malignant otitis externa: An updated review

Malignant otitis externa is a progressive infection of the external auditory canal and skull base. Pseudomonas aeruginosa is the most isolated microorganism and it affects mostly to diabetic, elderly, and immunocompromised individuals. Non-resolving otalgia and chronic otorrhea are the clinical manifestations presented. Facial nerve palsy is a common and well recognized complication. (Computed tomography) CT scan is useful for initial assessment, Technetium-99m is highly sensitive and is part of the protocol for diagnosis. Treatment should be individualized, with multidisciplinary cooperation among specialties. Management involves systemic antipseudomonal antibiotics and monitoring with radiologic techniques, it also involves the strict control of diabetes. It is essential to follow up the patients for at least a year post-treatment. In refractory malignant otitis externa and affection of facial nerve, surgical management is recommended. We reviewed the most recent studies on epidemiology, clinical manifestations, diagnosis, and treatment to provide an update on Malignant Otitis Externa that can offer an overview for clinical practice and future research.

Stratification for Malignant External Otitis

OBJECTIVE: To propose a CT-based method for early identification of severe cases of malignant external otitis (MEO) by correlating between initial CT findings and clinical course.

STUDY DESIGN AND SETTING: Eighteen MEO patients who underwent CT on admission were included in this retrospective study conducted at a tertiary center. The number and extent of anatomical areas involved according to CT were compared to clinical course severity.

RESULTS: The patients were categorized into two groups according to clinical course. There were 13 patients in the “nonsevere” group and 5 in the “severe.” In six out of eight CT anatomical areas the “severe” group had significantly higher scores ( P < 0.05 to P < 0.0005). The average number of areas involved in the “nonsevere” group was 2.9 and in the “severe” 5.4 ( P < 0.0005).

CONCLUSION: We found a clear correlation between clinical course and initial CT findings in MEO patients. Based on these findings it may be possible to predict clinical course severity according to initial CT.

Hypoglossal paresis as the only complication of malignant otitis externa

BACKGROUND

Ipsilateral hypoglossal nerve (XII) paresis has never been reported as the first and only complication of malignant otitis external (MOE).

CASE REPORT

A 73-year-old diabetic male with persistent left temporomandibular joint ache and ear fullness was admitted with the diagnosis of MOE. He received intravenous ciprofloxacin for 14 days and then continued with oral administration (per os). After two months, he returned with otalgia, swallowing difficulty, and ipsilateral XII paresis. He was re-admitted, received intravenous ciprofloxacin for 6 weeks, and continued with per os ciprofloxacin for 6 months. A Ga67-scan 6 months after the first admission revealed no active infection. Two years after his last admission, the patient still has XII paresis. There is no other cranial nerve involvement and inflammatory markers continue to be normal.

CONCLUSION

Doctors should consider MOE in the differential diagnosis when there is XII paresis, especially in diabetic and immunocompromised patients.

Single photon emission computed tomography/computed tomography of the skull in malignant otitis externa

Malignant otitis externa is a severe, rare infective condition of the external auditory canal and skull base. The diagnosis is generally made from a range of clinical, laboratory, and imaging findings. Technetium 99m methylene diphosphonate bone scintigraphy is known to detect osteomyelitis earlier than computed tomography. The authors present a patient with bilateral malignant otitis externa where the extent of skull base involvement was determined on 3-phase bone scintigraphy with single photon emission computed tomography/computed tomography.

Antifungal therapy of Aspergillus invasive otitis externa: efficacy of voriconazole and review

Invasive otitis externa (IOE) due to Aspergillus is a rare, potentially life-threatening, invasive fungal infection affecting immunocompromised patients. The invasive process may lead to skull base osteomyelitis with progressive cranial nerve palsies and can result in irreversible hearing and neurological impairment. We report two cases of Aspergillus IOE treated with voriconazole alone and a literature review of antifungal therapy of Aspergillus IOE. Twenty-five patients, including the two described in the present report, were analyzed. Eighteen patients were treated with amphotericin B, and nine of them received itraconazole as an additional agent. Three patients received initial therapy with itraconazole, and one patient was treated with both voriconazole and caspofungin therapy. The two patients in the present report received voriconazole therapy alone with good clinical and biological tolerance despite prolonged treatment. The last patient did not receive antifungal therapy, as the diagnosis was made postmortem. Eighteen patients underwent an initial extensive surgical debridement. The majority of the patients had a favorable outcome, 17 patients experienced a complete recovery, and 6 showed a partial improvement. Both of the patients reported on here had favorable outcomes, and no aggressive surgical debridement was required. Although voriconazole has been shown to be effective for the treatment of invasive aspergillosis, its precise role in the management of Aspergillus IOE had not been documented. These observations demonstrate that voriconazole could be an effective and well-tolerated therapeutic option for the management of Aspergillus IOE.

Sonography of the ear pinna

OBJECTIVE

This study was undertaken to assess the scope of sonography for the diagnosis of diseases of the external ear.

METHODS

We developed a description of the sonographic anatomy of the normal ear pinna, including the thickness of the normal cartilage and lobule, through systematic scanning of the external ears of 11 healthy volunteers (2 male and 9 female), and reviewed clinical cases with pathologic entities.

RESULTS

Reproducible and recognizable images were collected from normal as well as pathologic cases of the external ear. Images are presented for reference.

CONCLUSIONS

Sonography permits good visualization of the internal structure, including the cartilage, and it is possible to use sonography as a method of study to differentiate between inflammation, vascular lesions, and tumors.

Usefulness of CT scans in malignant external otitis: effective tool for the diagnosis, but of limited value in predicting outcome

Computerized tomography (CT) scanning is a well recognised tool for the diagnosis of malignant external otitis. To investigate the degree of correlation between CT findings scan and the patients clinical status focusing on a subgroup of patients with cranial nerve palsies. Diagnosis of malignant external otitis was confirmed in 23 patients (average age 71 years, age range 39-87) based on criteria of severe pain, otitis externa refractory to conventional treatments and possibly diabetes mellitus and pseudomonas detection. CT was performed on 23 of these patients. Results from these scans were analysed and correlated with patient clinical status. Retrospective analysis of CT images and medical notes were used for data analysis.The CT scans of all 23 patients showed evidence of involvement of disease outside the external auditory canal, confirming the diagnosis. Sixteen out of 23 patients (70%) demonstrated evidence of bone erosion. Four of the 16 showed involvement of the petrous apex. From our subset of ten patients with cranial nerve involvement, eight demonstrated evidence of bone erosion and two showed mastoid and middle ear involvement without bone erosion. All four patients with petrous apical involvement presented with cranial nerve palsies (two lower cranial nerve palsies, one seventh nerve palsy and one combined lower and seventh nerve palsy). CT scanning was found to be a fast and economical tool in the initial assessment of patients with malignant external otitis. Petrous apex involvement was constantly associated with cranial nerve palsies, usually the lower cranial nerves. CT findings of temporal bone in itself however, were not closely correlated to the clinical outcome of the patients.

A case of malignant otitis externa caused by Candida glabrata in a patient receiving haemodialysis

A 74-y-old male receiving haemodialysis presented with right-sided otalgia, otorrhoea and diffuse swelling on the right external auditory canal. Following an initial successful treatment with prolonged intravenous antibiotics, the patient relapsed with a secondary infection in the same site due to Candida glabrata. We report an unusual case of malignant otitis externa caused by the fungus C. glabrata.

Radiological and radionuclide investigation of malignant otitis externa

This study looks at case series of malignant otitis externa, outlines detailed structural (radiological) and functional (radionuclide) investigations, and discusses their utility in the initial diagnosis, patient management and follow up of this condition.

Patients were investigated by computerized tomography (CT), magnetic resonance imaging (MRI), two-phase planar and single-photon emission tomography (SPECT), technetium-99m methylenediphosphonate bone scans, gallium-67 planar and SPECT scans, and indium-111 or technetium-99m labelled WBC planar and SPECT scintigraphy.

We discuss example case reports with the various radiological and scintigraphic findings and outline a protocol for rational investigation.

It is concluded that CT and/or MRI should be supported by routine SPECT bone imaging for initial diagnosis of malignant otitis externa. Routine SPECT bone imaging further supplemented by gallium scintigraphy should be the investigation of choice in the follow up of these cases for assessing response to treatment and disease recurrence.

Malignant (invasive) otitis externa involving the temporomandibular joint

Malignant (invasive) otitis externa (MOE) is an infection involving the external auditory meatus (EAM), most often found in elderly diabetics, which carries a high morbidity and mortality. In advanced cases it may give rise to osteomyelitis and cranial neuropathies. This is a case of MOE, which invaded the posterior wall of the right temporomandibular joint (TMJ), resulting in severe trismus and pain. Subsequently, this required treatment by replacement of the glenoid fossa with a Silastic® prosthesis.

CT and MRI in malignant external otitis: a report of four cases

Malignant external otitis (MEO) is a severe infection of the external auditory canal and skull base which most often affects elderly patients with diabetes mellitus. Early diagnosis and aggressive treatment are important in terms of reducing risks of dissemination. We report four cases of MEO in patients with diabetes mellitus who were observed with computed tomography (CT) and/or magnetic resonance imaging (MRI). MRI was superior to CT in patients with MEO in terms of estimating the anatomic extent of the disease, but it cannot be used for monitoring therapy.

Chronic otitis externa/media with total ear canal ablation and bulla curettage in a North American bison (Bison bison)

An adult female North American bison (Bison bison) with a chronic otitis externa/media of the right ear was examined because of a 4-mo history of intermittent anorexia, apparent painful behavior, and auricular discharge from the right ear. Computerized tomography (CT) demonstrated osteolysis of the tympanic, petrous, and squamous aspects of the temporal bone with soft tissue replacement and sclerosis of the right bulla. A total ear canal ablation with bulla curettage was performed, and cefazolin-impregnated polymethacrylate beads were left within the right bulla and the remnant temporal bone. Six months after the surgery, the bison had no clinical signs of otitis media.

Radical meatoplasty in the treatment of severe chronic external otitis

In the beginning, external otitis is an inflammation of the skin of the external ear canal. Partial or total obliteration of the meatus causes cleaning problems, which worsen the obliteration, and hence, the infection. Immunosuppressive medication or illness, certain dermatological problems or frequent infections may lead to irreversible changes and to the malignant form of external otitis with life-threatening sequelae. Conservative treatments in the beginning are aimed at regaining the normal skin functions by helping the cleaning process and curing the acute infection with repeated irrigation, proper antibacterial medication and corticosteroids and anti-inflammatory analgesics. In rare prolonged cases, surgical procedures are needed to help the cleaning process by removing the irreversibly thickened skin and bone affections, and using grafts. On the basis of our experience, even the removal of the diseased skin and enlarging of the external ear canal are insufficient procedures in the most difficult cases. In the present paper, we describe a new surgical method that we have performed to treat chronic bilateral obliterative external otitis in 2 patients, with favorable results.

Non-pseudomonal malignant otitis externa and jugular foramen syndrome secondary to cyclosporin-induced hypertrichosis in a diabetic renal transplant patient

We present the case of a 58-year-old diabetic renal transplant patient who developed a left jugular foramen syndrome, secondary to an ipsilateral staphylococcal malignant (necrotizing) otitis externa. This followed a protracted episode of uncomplicated otitis externa with no evidence of bone involvement on computed tomography (CT) scanning. Cyclosporin-induced hypertrichosis (excess hair growth) in his external auditory canal contributed greatly to the initial difficulty in managing his otitis externa. Following an initial successful treatment with prolonged intravenous antibiotics the patient relapsed with a secondary infection in the same anatomical site due to Candida parapsilosis. Despite further intensive treatment including antimicrobials, a subtotal petrosectomy and hyperbaric oxygen therapy he eventually succumbed to his disease.

Canalographic evaluation of the external ear canal in dogs

Canalography was performed to measure the diameter of the horizontal ear canal and to assess the clinical relevance of the measurements in identifying abnormalities of the ear canal. The diameter of the proximal and distal end of the annular cartilage in the horizontal ear canal was measured using canalography in 222 ears. The tympanic membrane could not be visualized with otoscopic examination in 70 ears even after ear cleansing. These canals were classified as being stenotic. The diameter of the proximal annular cartilage in the stenotic canals ranged from 0.8 to 3.1 mm (mean = 2.6 +/- 0.8 mm). The proximal annular cartilage was consistently smaller in diameter than the distal annular cartilage. The ratio between the diameter of the proximal and distal annular cartilage varied between dogs. In stenotic ear canals (70 ears) the ratio was less than 0.65. Total ear canal ablations and histopathological analysis were performed in 70 ear canals classified as stenotic after canalography. Hyperplasia of the epidermal layer was found in 56 stenotic canals. Stenosis of the canal due to otitis externa was found in the other 14 canals. Three canals with severe otitis externa were also diagnosed with canalography as having a ruptured tympanic membrane. The results suggest that canalography can be used to measure the diameter of the horizontal ear canal and to assess whether or not the tympanic membrane is ruptured prior to conservative or surgical therapy.

[Benign necrotizing osteitis of the external ear canal. A report of a clinical case]

Benign necrotizing osteitis of the external ear canal is a process of unknown origin. This necrotic process with sequestration of the tympanic bone occurs in healthy, non-diabetic patients. It should be differentiated from malignant otitis externa and radionecrosis of the tympanic bone. A case is reported and the literature on this rare clinical entity is discussed.

[Diagnostic criteria for progressive necrotizing external otitis. Are scintigraphic findings reliable?]

OBJECTIVES

Determine the role of 99m technetium scintigraphy for diagnosis in progressive necrotizing external otitis and assess the diagnostic criteria of this disease.

METHOD

A retrospective study was conducted in 16 patients hospitalized for suspected progressive necrotizing external otitis. Patient characteristics, clinical features, imaging findings and disease course were recorded in order to evaluate the classical criteria of diagnosis.

RESULTS

The clinical course and complementary test results showed that 99m technetium scintigraphy lacked specificity for progressive necrotizing external otitis. These findings are in disagreement with those reported in the literature.

CONCLUSION

Patient characteristics and clinical course are key elements for early diagnosis of this disease. Scintigraphy findings are contributive only when bone lysis (which occurs late) can be evidenced. A prospective study would be required to confirm the lack of specificity of scintigraphy in progressive necrotizing external otitis.

The value of quantitative gallium-67 single-photon emission tomography in the clinical management of malignant external otitis

Malignant external otitis (MEO) is a severe infectious disorder usually caused by Pseudomonas aeruginosa, which most frequently affects diabetic patients. Due to its rarity, the diagnosis of MEO is often not made promptly. Extension into deeper structures or chronic osteomyelitis may occur without signs of infection on local clinical examination. Of the imaging techniques, magnetic resonance imaging provides a fairly adequate picture of the spread of the disease, but, as with computed tomography (CT) scanning and bone scintigraphy, the images remain unchanged for a long time after disease regression. The objective of this study was to establish whether quantitative gallium-67 single-photon emission tomography (SPET) represents an accurate method for the assessment of infection and, moreover, for the monitoring of therapeutic effect. Eight patients (five males, three females) with the clinical diagnosis of MEO were studied. In three patients antibiotic treatment was prolonged for several weeks because visual analysis of gallium scintigraphy still showed slightly increased uptake in the affected area on the first follow-up scan. In one patient, it was decided to stop antibiotic treatment despite a slight increase in uptake on the second follow-up scan. Lesion to non-lesion (L/NL) ratios obtained from 67Ga SPET images at initial diagnosis and during follow-up were assessed in correlation with clinical and biochemical data and with the results of CT scans. In addition to a raised erythrocyte sedimentation rate (ESR), all patients showed increased uptake on the affected side, with L/NL ratios ranging from 1.4 to 3.6 at the time of diagnosis. CT scans failed to demonstrate abnormalities in four patients. Including four scans demonstrating slightly increased uptake in the affected area, L/NL ratios after 6-8 weeks of antibiotic treatment were 1.0+/-0.1. Despite a persistently elevated ESR in the majority of patients, none of them demonstrated local recurrence or complications during follow-up. In all patients, leucocyte count was within the normal range throughout the course. No relation was found between the slightly increased uptake on the follow-up scans and surgical treatment. It is concluded that in addition to the visual analysis of 67Ga SPET imaging, L/NL ratios should be calculated for a more accurate assessment of disease activity in MEO. Despite visually slightly increased uptake, L/NL ratios of 1.0+/-0.1 during follow-up are highly indicative of complete recovery, regardless of ESR values or leucocytosis. CT scans are of little value for diagnosis or for monitoring of therapeutic effect.

Use of gallium-67 in the assessment of response to antibiotic therapy in malignant otitis externa--a case report

Malignant Otitis Externa (MOE) can cause considerable morbidity and mortality in affected individuals. The outlook is now much improved with the use of ciprofloxacin, but it is important to ascertain that the infection has been completely eradicated before stopping treatment, as undertreatment may lead to a recurrence which is usually more resistant than the initial infection. Gallium-67 Single Photon Emmision Computerised Tomography (SPECT) is a sensitive and cost effective tool in monitoring the disease activity of MOE, and should be used in the assessment of the response to antibiotic therapy.

Radiographic appearance of the middle ear after ventral bulla osteotomy in five dogs with otitis media

Radiographs of the middle ear were made in five dogs 60 to 78 months after ventral bulla osteotomy was performed to treat otitis media. The clinical results of surgery were considered satisfactory in four dogs and unsatisfactory in one. In 4 dogs with satisfactory results, radiographs demonstrated complete reformation of the bulla in 3 operated middle ears (3 dogs), with partial bulla reformation in the three middle ears (3 dogs). Radiographs in one dog with unsatisfactory results showed complete bulla reformation with no increase in lumen opacity. The proliferative bony response obliterating the middle ear previously reported in normal dogs after ventral bulla osteotomy was not seen in any of these patients.

SPECT gallium scintigraphy in malignant external otitis: initial staging and follow-up. Case reports

Malignant external otitis (MEO) is a recognized entity characterized by a stubborn Pseudomonas external otitis; it has been most frequently observed in elderly diabetic patients. Early diagnosis is necessary for successful treatment but, despite a widespread inflammatory response, routine plain x-ray studies and computed tomography (CT) scanning show no abnormalities in its early stage. In this report, the clinical value of gallium 67 (Ga 67) single photon emission CT (SPECT) is studied in three patients suspected of having MEO, and the results are compared with findings on CT scan and laboratory tests. These results confirm that the high sensitivity of GA 67 SPECT in the initial recognition of MEO provides a more adequate technique than CT scan. Furthermore, Ga 67 scintigraphy appears to be highly accurate for follow-up evaluation of these patients.

Diabetes mellitus and malignant external otitis: a case study

Malignant external otitis (MEO) is an infection of the external auditory meatus, that affects elderly diabetic patients. As this disease results in a high percentage of deaths, especially if the diagnosis is delayed, we thought that it would be useful to cite a recent case study that was resolved in a positive way, in spite of the extent of the disease.

Necrotizing (malignant) external otitis: prospective comparison of CT and MR imaging in diagnosis and follow-up

PURPOSE

To compare computed tomography (CT) and magnetic resonance (MR) imaging in the diagnosis and follow-up of necrotizing external otitis.

MATERIALS AND METHODS

CT and MR imaging were performed in seven patients at diagnosis and at 6 and 12 months after initiation of therapy. Imaging findings were compared and correlated with the clinical course of the disease.

RESULTS

Cortical bone erosion was best seen on CT scans (n = 5 vs n = 0 on MR images) and failed to normalize with cure. Subtemporal soft-tissue abnormalities (n = 7 with both modalities) were better appreciated with MR imaging and had low signal intensity on T1- and T2-weighted images. Soft-tissue changes improved but did not disappear completely with treatment.

CONCLUSION

CT is preferred at initial diagnosis, as small cortical erosions are better seen. Either modality can be used to follow up soft-tissue evolution. MR imaging may be better for evaluation and follow-up of meningeal enhancement and changes within the osseous medullary cavity.

Indium 111-labeled white blood cell scintigraphy as an unreliable indicator of malignant external otitis resolution

The field of otolaryngology-head and neck surgery has seen many advances in the treatment and prognosis of malignant external otitis (MEO). However, establishing the resolution of the infection remains problematic. A recent report suggests that indium 111-labeled white blood cell scintigraphy may be a reliable and timely indicator of resolution of infection. We present a case of a false-negative white blood cell scan in a patient with persistent MEO. A discussion of this case and a review of the literature illustrate that there continues to be no "gold standard" for establishing MEO resolution.

Bing-Neel syndrome or malignant external otitis in Waldenstrom's macroglobulinaemia?

Malignant external otitis is classically associated with insulin-dependent diabetes mellitus probably due to generalized systemic immunodeficiency (Mowet and Baum, 1971). A unique case of malignant external otitis associated with Waldenstrom's macroglobulinaemia is presented.

Semiquantitative skull planar and SPECT bone scintigraphy in diabetic patients: differentiation of necrotizing (malignant) external otitis from severe external otitis

Early diagnosis of necrotizing external otitis (NEO) includes the use of bone scintigraphy since clinical assessment alone cannot differentiate the necrotizing type of otitis from the severe type of external otitis in which there is no extension to the adjacent bone. Four-hour planar bone scintigraphy may reflect soft-tissue infection, and therefore may not be useful in distinguishing NEO from severe external otitis (SEO). Twenty-four-hour bone scintigraphy using planar or SPECT imaging may better reflect bone uptake and increase the accuracy of the test.

METHODS

Twenty-six diabetic patients (12 diagnosed NEO; 14 SEO) and 10 nondiabetic (ND) patients were studied. Lesion-to-nonlesion (L/N) count ratios obtained from planar and SPECT imaging at 4 hr, 24 hr and 24 hr/4 hr (24/4) were assessed.

RESULTS

Count ratios obtained from the 4- and 24-hr planar and SPECT images were significantly higher in the NEO patients compared to SEO patients for both planar and SPECT studies (p < 0.001, 0.005). The 24/4 count ratio was also significantly higher in the NEO patients on the planar (p < 0.01) and the SPECT studies (p < 0.001). The ND patients were not different from SEO patients on 4-hr planar, 4- and 24-hr SPECT as well as 24/4-hr planar and SPECT studies. The L/N count ratio threshold yielding the best sensitivity for detecting NEO was 1.05 for the 24/4 SPECT study.

CONCLUSION

In diabetic patients, an early distinction between NEO and SEO patients can be reliably made by using L/N count ratios on 24/4 or 24-hr SPECT bone scintigraphy.

Preliminary results on scintigraphic evaluation of malignant external otitis

Malignant external otitis (MEO) is a potentially fatal otitis occurring in diabetic and immunosuppressed patients, which may cause cranial nerve palsies and massive thrombophlebitis of the brain. We studied five diabetic patients with the clinical diagnosis of external otitis who were suspected of having MEO and one diabetic patient presumed cured from MEO. All of them underwent methylene diphosphonate, nanocolloid and gallium single-photon emission tomography studies with quantitative analysis on the basis of regions of interest and count profile curves. This combined assessment helped us to diagnose and follow-up soft tissue and temporal bone infection, especially in the case of transsphenoidal extension of the disease, since conventional radiology and computed tomography were of no particular help. On the basis of these results, we consider scintigraphic demonstration of skull base infection as a fourth criterion of MEO given that the classical Chandler's triad (diabetes, granuloma, and Pseudomonas aeruginosa) is not always present.

Adjuvant hyperbaric oxygen in malignant external otitis

Necrotizing invasive pseudomonal infection of the external auditory canal (malignant external otitis) is an uncommon but important disorder in the elderly. The high morbidity, and even mortality, of this disorder has been reduced by the early and intensive use of combination antipseudomonal antibiotics. However, in severely immunocompromised patients or in infection involving the base of the skull, multiple cranial nerves, or the meninges, conventional therapy has been prolonged, intensive, and relatively ineffective. We treated 16 patients with malignant external otitis with adjuvant hyperbaric oxygen therapy. In six patients, infection was in advanced stages, infections were recurrences after previous treatment, and repeated treatment with antipseudomonal antibiotics had failed. All 16 cases responded promptly when a 30-day course of hyperbaric oxygen was added to the antibiotic regimen, and all patients remained free of infection or neurologic deficit during 1 to 4 years of follow-up. No complications of this treatment modality were noted. Hyperbaric oxygen therapy reverses tissue hypoxia, which enhances phagocytic killing of aerobic microorganisms, and stimulates neomicroangiogenesis. In addition, hyperbaric oxygen augments the action of aminoglycoside antibiotics. Adjuvant hyperbaric oxygen therapy should be considered in advanced or recurrent cases of malignant external otitis.

Necrotizing 'malignant' external otitis caused by Staphylococcus epidermidis

Necrotizing "malignant" external otitis is a life-threatening skull base infection that originates in the external auditory canal and is characterized by otalgia and purulent aural discharge with external auditory canal cellulitis and granulation. Necrotizing external otitis, seen almost exclusively in elderly diabetics, is almost always caused by Pseudomonas aeruginosa. To our knowledge, there have been only six nonpseudomonal cases reported to date. We describe a 70-year-old diabetic man with necrotizing external otitis caused by Staphylococcus epidermidis, confirmed by serial cultures. This case was characterized by otalgia, purulent otorrhea, preauricular swelling, bony external auditory canal erosion, and a conductive hearing loss. Despite prolonged intravenous antistaphylococcal antibiotic therapy and frequent local débridement, the patient's symptoms never completely resolved. As demonstrated by the treatment failure, S epidermidis necrotizing external otitis, may represent a more refractory form of this already virulent disease process. We believe this to be the first reported case of necrotizing external malignant otitis caused by S epidermidis.

[The computed tomography of malignant otitis externa]

Computed tomography was performed preoperatively in 20 patients suffering from malignant external otitis. The CT findings were nearly completely confirmed by the intraoperative findings. A circumscribed or diffuse thickening of the cartilaginous wall of the external auditory canal and an inflammatory infiltration of the subtemporal fossa are, in combination, most suspicious signs of malignant external otitis. Computed tomography enables detailed information on the extension of the pneumatic system and the grade of involvement of bones and soft tissues in malignant external otitis. A modified classification of malignant external otitis based on computed tomographic findings is proposed.

Quantitative bone and 67Ga scintigraphy in the differentiation of necrotizing external otitis from severe external otitis

Qualitative technetium Tc 99m bone scintigraphy using phosphate compounds and gallium 67 scintigraphy were described as a helpful means in diagnosing necrotizing external otitis (NEO). They were, however, claimed to be nonspecific. Quantitative Tc 99m methylene diphosphonate bone scintigraphy and gallium 67 scintigraphy were performed in eight patients with NEO and in 20 patients with severe external otitis, in order to prove usefulness of scintigraphy in the diagnosis of NEO. Ratios of lesion to nonlesion for bone scintigraphy were 1.67 +/- 0.16 in patients with NEO and 1.08 +/- 0.09 in patients with severe external otitis, and for gallium 67 scintigraphy they were 1.35 +/- 0.24 in NEO patients and 1.05 +/- 0.03 in patients with severe external otitis. There was no difference in uptake between diabetic patients with severe external otitis and nondiabetic patients. The scintigraphic studies were also evaluated using a qualitative scoring method (scores 0 to +4), according to the intensity of the radiopharmaceutical uptake. This method was found to be inferior in the diagnosis of NEO compared with the quantitative method. We conclude that lesion-to-nonlesion ratios greater than 1.5 and 1.3 on bone and gallium 67 scintigraphy, respectively, are indicative of NEO. Quantitative bone scintigraphy, which is quicker to perform, may be used as a single imaging modality for the diagnosis of NEO.

Computed tomography in malignant external otitis

Malignant external otitis is a severe infection of the external auditory meatus occurring predominantly in diabetics and usually caused by Pseudomonas aeruginosa. The infection may spread along several routes: directly by bony erosion into the adjacent mastoid bone, anteriorly into the parotid gland and temporomandibular joint and inferiorly into the soft tissues of the infratemporal fossa. We present four cases of malignant external otitis that illustrate the typical patterns of spread of this disease and the role that radiology, and in particular computed tomography, plays in its diagnosis and management.

Malignant external otitis in an infant

Ten cases of malignant external otitis in children have been reported hitherto. These are reviewe, and an eleventh case, a three-month-old infant associated with genetic granulocytopenia, is presented. On the grounds of the reported paediatric cases, the erudition in childhood is compared with the more common form in the adult, and is found to be much less linked with diabetes mellitus and to have a far better prognosis, with practically no mortality.

Malignant external otitis: report on therapy with ceftazidime and review of therapy and prognosis

We report the treatment of 20 patients with malignant external otitis (MEO) since 1980. Ceftazidime was used in 15 patients, with cure achieved in 11 of 12 evaluatable patients. An aminoglycoside and an antipseudomonal penicillin were used in five patients, four of whom were cured. The presentation, radiographic studies, therapy, outcome, and period of follow-up in the 20 patients are reported. The previously reported cases of MEO are also reviewed, with a focus on the changing therapy and prognosis. The frequencies of diabetes mellitus, cranial nerve deficits, and treatment failures in MEO have all declined significantly since 1985 from frequencies in earlier years. We conclude that there has been an overall improvement in the diagnosis and treatment of MEO and that monotherapy with ceftazidime shows promise against this potentially fatal pseudomonal infection.

Malignant external otitis: utility of CT in diagnosis and follow-up

Malignant external otitis is a severe bacterial infection of the bone and soft tissues of the base of the skull that is frequently difficult to diagnose. The effectiveness of antibiotic therapy is likewise difficult to assess. Serial computed tomographic (CT) scans were obtained in 11 consecutive patients with malignant external otitis at time of diagnosis and periodically after conclusion of antibiotic therapy. All patients demonstrated abnormalities of the external auditory canal, with or without bone destruction. Soft tissue or fluid in the middle ear and mastoid, around the eustachian tube, and in the parapharyngeal space (both pre- and poststyloid) was seen in greater than 50% of the cases. While remineralization of bone was not seen, soft-tissue disease improved dramatically, and recurrence or persistence could be corroborated by detection of more extensive soft-tissue changes. By delineating the extra- and intracranial extent of disease, serial CT scans enable one to make the diagnosis, determine the extent of infection, document recurrence, exclude progression, and confirm resolution of malignant external otitis.

Coincidental radiographic findings in severe external otitis in nonimmunocompromised patients

We present the cases of 3 previously healthy patients who became ill with a very sudden and painful external otitis due to Pseudomonas aeruginosa. At the acute stage, diagnosis was difficult in all these patients because of marked periauricular swelling and radiological mastoiditis. The latter sign has not been reported earlier in association with external otitis in nonimmunocompromised patients. All patients made a full recovery with appropriate treatment.

Management of osteomyelitis of the skull base

Osteomyelitis of the skull base is the most severe form of malignant otitis externa. As a result of having treated 13 patients with skull base osteomyelitis over a 4-year period, we have developed a method of staging and monitoring this malady using gallium and technetium scanning techniques. Stage I is localized to soft tissues, stage II is limited osteomyelitis, and stage III represents extensive skull base osteomyelitis. All stages are treated with appropriate antipseudomonal antibiotics. The duration of therapy depends upon the clearing of inflammation as shown on the gallium scan. Each case must be looked at independently and not subjected to an arbitrary treatment protocol.

High resolution CT findings in diseases of the external auditory canal. A review of 31 cases

Thirty-one patients with pathology of the external auditory canal (EAC) were examined with high resolution CT. In this retrospective study we found that CT plays an important role in the diagnosis and especially in the determination of the extent of the disease. CT also offered us a good evaluation of the contiguous bone and it was the best method to visualize the middle ear when complete occlusion of the external auditory canal (EAC) occurred.

Relapsing malignant otitis externa successfully treated with ciprofloxacin

Two cases are presented, both patients with advanced relapsing malignant otitis externa. The antibiotic ciprofloxacin has strong anti-pseudomonal activity. It was given orally for six months to both patients, following administration of the traditional parenteral antibiotic courses, and in each case the disease has been extinguished. We therefore recommend that the management of patients shown to have malignant otitis externa should include strict diabetic control, regular local aural toilet, gentamicin ear drops and a six week course of parenteral antipseudomonal antibiotic agents (usually gentamicin and azlocillin) together with metronidazole to cover any anaerobic element in the infection. This regimen should be followed by a six month course of oral ciprofloxacin (750 mg b.d.). Indium scans should be used to monitor recovery. We believe that this regimen can significantly reduce the morbidity and mortality of patients suffering from malignant otitis externa with cranial nerve involvement.

The evolving treatment of necrotizing external otitis

Necrotizing external otitis, or malignant external otitis, as initially described by Chandler, is a life-threatening Pseudomonas infection of the external auditory canal and skull base, which occurs most commonly in elderly diabetic patients. Historically, radical surgical intervention was the primary method of treatment. The treatment of choice has shifted during the past 20 years to aggressive systemic antibiotic therapy, with surgery reserved for those patients whose disease is resistant to medical therapy. Using this approach, 19 patients with necrotizing external otitis were treated at the Cleveland Clinic Foundation during the past 8 years. A 90% rate of cure was obtained. The diagnostic approach to patients suspected of having necrotizing external otitis, a classification scheme defining the extent of disease, delivery of systemic antibiotic therapy, indications for surgical intervention, and overall effectiveness of treatment are reviewed.

Necrotizing external otitis treated with ciprofloxacin. A case report

Necrotizing (malignant) external otitis is a severe infection caused by Pseudomonas aeruginosa which occurs mainly in elderly diabetics or in immuno-depressed patients (Chandler, 1968). The management of this condition requires the association between an aminoglycoside antibiotic and an antipseudomonal beta-lactamic, given parenterally during a 4 to 6 week period. Sometimes it is necessary to continue the therapy for months until there is no evidence of residual disease (Strauss et al., 1982). Ciprofloxacin is a quinolone with antipseudomonal activity which can be taken orally, and it is a useful alternative to the current treatment. The authors report a case of necrotizing external otitis which was successfully treated with ciprofloxacin.