Malignant external otitis: CT evaluation

Critical infections in the head and neck: A pictorial review of acute presentations and complications

Non-traumatic head and neck emergencies include several disease processes such as infectious, inflammatory, and malignant. Infections are among the most common pathological processes that affect the head and neck, and are particularly important due to their acute, severe, and potentially life-threatening nature. Radiologists need to be well acquainted with these entities because any delay or misdiagnosis can lead to significant morbidity and mortality. Having a general understanding of such diseases is crucial, their prevalence, clinical presentation, common causative pathogens, route of spread, potential complications, and multimodality radiological appearance. Furthermore, understanding the relevant anatomy of the region, including the various fascial planes and spaces, is essential for radiologists for accurate image interpretation and assessment of potential complications. Our aim is to review the most common severe infections affecting the head and neck as well as other rare but potentially life-threatening infections. We will also describe their imaging features while focusing on the anatomy of the regions involved and describing their potential complications and treatment options.

The diagnostic conundrum in necrotizing otitis externa

Necrotizing otitis externa (NOE) is an aggressive and fast-evolving infection of the external auditory canal. Late diagnoses and untreated cases can lead to severe, even fatal consequences and so early diagnosis and treatment are paramount. NOE is a notoriously challenging diagnosis to make. It is therefore important to understand what diagnostic modalities are available and how otolaryngologists can use them to accurately treat such an aggressive disease. This review aims to evaluate the different diagnostic options available in NOE and discuss their advantages and limitations, thus, providing an up-to-date picture of the multimodal approach required in the diagnosis of this disease.

Necrotising Otitis Externa: A Review of Imaging Modalities

Necrotising Otitis Externa (NOE) has often posed some challenges in view of diagnosis and management by clinicians. One such challenge is the appropriate and timely use of imaging techniques since its use is critical not only in diagnosis but also in determining the extent and resolution of the disease. Hence, doctors in both primary and secondary health care need to be familiar with presenting symptoms while specialists need to be appraised of advances in imagining techniques in diagnosis and management of NOE. Whilst there is a general consensus amongst clinicians on some aspects of management of NOE, there is very limited consensus on the use of imaging modalities. There is no single modality of imaging that can provide a complete picture of diagnosis, disease progression and resolution. This review aims to highlight the strengths and weaknesses of various imaging techniques used in the diagnosis and management of NOE over the years and whether a multi-modal imaging technique at particular stages of the disease may provide better management outcomes.

Efficacy of HRCT Imaging vs SPECT/CT Scans in the Staging of Malignant External Otitis

OBJECTIVE

The prognosis of patients with malignant external otitis (MEO) depends on the extent of the inflammatory changes in the temporal bone and skull base. The efficacy of high-resolution computed tomography (HRCT) imaging in accurately assessing the extent of disease is compared with that of single-photon emission computed tomography/computed tomography (SPECT/CT) scan.

STUDY DESIGN

A clinical chart review was conducted with medical records and radiologic images.

SETTING

Tertiary care medical college hospital.

SUBJECTS AND METHODS

This study involved patients with clinically diagnosed MEO who underwent both modalities of imaging of the skull base. Staging of the disease extent was compared between the imaging systems among patients. Symptom control and survival rates were analyzed with respect to the SPECT/CT staging of MEO.

RESULTS

Out of 28 patients included in this study, 72% had SPECT/CT scans showing higher staging than the HRCT imaging. Four patients had mild uptake (stage 1), and 15 had disease confined to the mastoid/temporal bone, not reaching midline (stage 2). All patients in stages 1 and 2 were surviving with good symptom control. Five patients with petrous involvement reaching midline (stage 3) had persistent symptoms, and all 4 cases with SPECT/CT showing sphenoid involvement and crossing midline (stage 4) died within a year of diagnosis.

CONCLUSIONS

SPECT/CT scan is more sensitive than HRCT imaging in detecting the extent of disease and is a better prognosticator for patients with MEO.

Computed Tomography Features of External Auditory Canal Cholesteatoma: A Pictorial Review

Computed tomography (CT) is widely used for evaluation of patients with otologic conditions. External auditory canal cholesteatoma (EACC), although rare, demonstrates characteristic CT appearance. Moreover, the accurate extent of involvement cannot be accurately assessed clinically. This pictorial review aims to illustrate the spectrum of CT features of EACC and highlight the key features that are useful for making an accurate diagnosis of this condition. We have also discussed the radiological and clinical differential diagnoses of external auditory canal lesions that can be mistaken for an EACC.

CT Findings in the External Auditory Canal after Transcanal Surgery

BACKGROUND AND PURPOSE

Middle ear surgery is often performed through the external auditory canal, and the CT appearance of the external auditory canal after transcanal middle ear surgery can mimic erosive pathology such as carcinoma, external auditory canal cholesteatoma, or necrotizing external otitis. We reviewed the CT findings in a group of patients following transcanal surgery to highlight this potential pitfall in interpretation.

MATERIALS AND METHODS

Twenty-seven temporal bones in 25 patients with a history of a transcanal approach to the middle ear and available postoperative CT imaging were identified. Images were assessed for changes along or involving the walls of the external auditory canal, including widening, irregularity, bony defects, and soft tissue opacification.

RESULTS

Osseous changes along the floor of the external auditory canal were demonstrated in 25 of 27 (92.6%) temporal bone CT scans. Similar changes were present in the superior and anterior walls of the external auditory canal in 21 and 18 temporal bones, respectively. The anterior wall was the most common site for complete bony defects (10 of 27 temporal bones). The posterior wall was the least often involved, with osseous changes in 15 of 27 temporal bones and bony defects in 3 cases. Soft tissue thickening was seen most commonly along the floor. No patient was found to have a superimposed pathologic process of the external auditory canal.

CONCLUSIONS

CT findings in the external auditory canal after transcanal surgery include thinning, irregularity and/or flattening of the bone, soft tissue thickening, and bony wall defects. Although these changes may be subtle, they may mimic pathology and should be included in the differential diagnosis of osseous abnormality of the external auditory canal.

Necrotizing otitis externa: 19 cases' report

Necrotizing otitis externa is an uncommon but severe infectious disease of the external auditory canal. Patients at risk are those immunodepressed or having diabetes. The causal germ is often Pseudomonas aeruginosa. Over a period of 10 years (1997-2006), we treated 19 patients: 94.7% had diabetes (insulin dependent in 6 cases). The causal germ was P. aeruginosa in 59% of cases. The pretherapeutic work-up included a computed tomography and a scintigraphy practiced in order to confirm diagnosis and assess the extension. Medical treatment was based on a parenteral antibiotic therapy using a third-generation cephalosporin and a fluoroquinolones. Local treatment of the auditory canal including cleaning and application of antimicrobial agents was performed in all the cases. Surgical debridement of soft tissue and infected bone was performed in one patient who did not respond to medical management. Repeated scintigraphies with gallium were used to follow the course under treatment in only three cases. We had a 89.4% cure rate with only three cases of recurrence. We reviewed the data in the literature on necrotizing otitis externa and present the important diagnostic, imaging, and therapeutic aspects of the disease.

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.

Skull base osteomyelitis interpreted as malignancy

Lesions in the skull base may present difficulties in diagnosis primarily because the access needs to be invasive and one has to rely on imaging that may still be misleading. The case presented here illustrates this example in that the patient had abnormalities on computed tomography (CT) and magnetic resonance image (MRI) scans quite convincing of malignancy but which with time proved, essentially through clinical judgment, to be skull base osteomyelitis secondary to malignant external otitis (OME).

Necrotizing external otitis caused by Aspergillus fumigatus: computed tomography and high resolution magnetic resonance imaging in an AIDS patient

Most necrotizing (malignant) external otitis (NEO) occurs in diabetic patients and is commonly caused by Pseudomonas aeruginosa. We report an acquired immunodeficiency syndrome (AIDS) patient with NEO caused by Aspergillus fumigatus in which computed tomography (CT) showed destructive petrous bone involvement and magnetic resonance imaging (MRI) of the ear discovered extensive soft tissue and facial nerve involvement. Dedicated MRI studies of the ear in this type of pathology provide new insights relating to nerve dysfunction, that cannot be obtained with CT.

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.

Evaluation of Temporal and Facial Osteomyelitis by Simultaneous In-WBC/Tc-99m-MDP Bone SPECT Scintigraphy and Computed Tomography Scan

A reliable imaging technique is needed for follow-up of patients with temporal and facial osteomyelitis. Clinical outcome in 20 patients with suspected osteomyelitis of the temporal/mastoid, calvarium, and mandible facial bones was evaluated with 30 combined In-WBC/Tc-99m MDP bone single photon emission computed tomographic (SPECT) scans and 27 computed tomographic scans. Simultaneous dual-tracer 25-minute SPECT scans were acquired 18 to 20 hours after radiotracer injection by use of a three-detector system. Diagnosis of the 20 patients (age range, 3 to 74 years) included 8 with facial osteomyelitis, 6 with malignant otitis externa, 3 with mandibular osteomyelitis, and 3 with calvarial osteomyelitis. Diagnosis was confirmed by biopsy/culture results in 18 patients and by endoscopic and clinical evaluation in 2 patients with initial negative scans. Of the 30 In-WBC/MDP scans, 15 were true-positive, 13 true-negative, 1 false-negative, and 1 equivocal. Of a total of 27 CT scans, 9 were true-positive, 5 false-negative, and 1 equivocal in patients with biopsy-proven osteomyelitis. Three computed tomographic scans were false-positive and 1 was equivocal in patients without osteomyelitis, because of concurrent postoperative bone abnormalities. Additionally, 8 computed tomographic scans were true-negative. These results suggest that dual In-WBC/Tc-99m MDP bone SPECT scintigraphy provides an accurate imaging modality for diagnosis and follow-up of temporal and facial osteomyelitis when existing clinical or postoperative bone changes make it difficult to detect active osteomyelitis by computed tomographic scan.

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 children

Malignant external otitis in the pediatric population is primarily a disease of children with chronic illness or immunosuppression. The presence of severe, unrelenting otalgia, otorrhea with isolation of Pseudomonas aeruginosa, a markedly elevated erythrocyte sedimentation rate, and evidence of bone destruction on computed tomography scan should alert the clinician to the diagnosis. Unlike adults, children have a higher incidence of seventh nerve paralysis earlier in the course of the infection. They also manifest more frequent involvement of the middle ear with tympanic membrane destruction. The short interval between the onset of symptoms and facial nerve dysfunction highlights the necessity of prompt diagnosis and institution of anti-Pseudomonas therapy. Our review suggests that this destructive bacterial infection is an emerging clinical entity in children; 73% of the cases have been reported since 1980. Pediatricians should therefore be familiar with the clinical presentation of this treatable infection. Substantial morbidity could be alleviated by prompt diagnosis and early antibiotic treatment.

Malignant external otitis: insights into pathogenesis, clinical manifestations, diagnosis, and therapy

Malignant external otitis is an infection of the external ear canal, mastoid, and base of the skull caused by Pseudomonas aeruginosa. The condition occurs primarily in elderly patients with diabetes mellitus. Current theories on pathogenesis and anatomic correlations are reviewed. Severe, unrelenting otalgia and persistent otorrhea are the symptomatic hallmarks of the disease, whereas an elevated erythrocyte sedimentation rate is the only distinctive laboratory abnormality. Iatrogenic causes such as administration of broad-spectrum antibiotics and aural irrigation may play a predisposing role in high-risk populations. The disease can result in cranial polyneuropathies (with facial nerve [VII] paralysis being the most common) and death. The mainstay of treatment is administration of antipseudomonal antibiotics for four to eight weeks. Recurrence is common, and mortality remains at about 20 percent despite antibiotic therapy. Given the increasing longevity of diabetic patients, the frequency of this disease is increasing. Internists, family practitioners, and ambulatory care physicians must now be cognizant of the presenting symptoms, while infectious disease specialists and otolaryngologists need to be appraised of strides in diagnosis and therapy. The role of surgery should be minimized. Use of new diagnostic radiologic modalities and new antipseudomonal antibiotics discussed in this review should lead to improved outcome.