A Rare Case of Malignant Otitis Externa Complicated by Occipital Bone Osteomyelitis

Dr.Sofia Ahmed AlKhatibi AlFalasi  , MBBS  * ¹, Dr.Ali Al-Fraihat - MB BCh BAO^{2 ,} Prof.Jamal Kassouma – MD,FRCS Ed, FRCS orl-hns , ENT Consultant³

1,2,3. Dubai health , otolaryngology department - Dubai hospital.

*Correspondence to: Dr. Sofia Ahmed AlKhatibi AlFalasi, MBBS, otolaryngology department - Dubai Hospital.

Copyright

© 2024 Dr. Sofia Ahmed AlKhatibi AlFalasi, MBBS,. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: 06 April 2024

Published: 01 May 2024

DOI: https://doi.org/10.5281/zenodo.11100529

Introduction

A 65-year-old male with a known case of diabetes mellitus, hypertension, dyslipidemia, and  multiple co-morbidities and a smoker presented to the ENT clinic ,with a 1-year history of  recurrent right ear discharge and ear pain. He developed right otitis externa, which progressed  into right-sided malignant otitis externa, initially affecting osteomastoiditis and further  complicated by severe osteomyelitis involving the occipital bone.

During the first visit, an otologic examination revealed ear congestion, ear discharge, decreased  hearing in bilateral ears, and ear tenderness with edema on the right ear. Regarding his hearing,  he has mentioned that it has been reduced since his childhood, so it is not new to him.

Initially, he was treated with Ciprofloxacin 250mg tablet, Ciprofloxacin-hydrocortisone otic  solution with pain medication Ibuprofen and Paracetamol. It was suggested that he take all his  medications as prescribed.

The patient experienced discomfort, congestion, inflammation, and granulation tissue in his right  ear, but with no discharge. He was advised to be hospitalized but declined. He took prescribed  medications, including the new antibiotic Levofloxacin. Later, he returned with significant  discomfort and impaired hearing. He was advised to be admitted for intravenous therapy, but has  declined. 

He was later hospitalized after failing to improve on outpatient medications. Analgesics and  intravenous ceftazidime 1000 mg for every 12 hours were administered during admission instead  of ciprofloxacin due to him having kidney failure & according to swab culture.

The first CT petrous bone scan of the right side of the ear revealed complete opacification,  indicating chronic otitis media and otitis externa, along with right-side chronic mastoiditis.  After 1 month of treatment, the patient started to improve & he was discharged after two  months.

A microbiological culture of the infected right ear revealed the presence of Escherichia coli,  necessitating a repeat CT scan. Which revealed aggressive infective/inflammatory processes in  the right external auditory canal (malignant otitis externa) with extension and involvement of the  middle ear (otomastoiditis) and erosive changes in the right area of the petrous bone.

A pure tone audiometry test revealed severe to profound mixed hearing loss in the right ear and  mild to profound sensorineural hearing loss in the left ear.

Later a third CT scan was performed due to continued ear discomfort and as a follow-up from  the previous CT scan. In comparison to the previous CT scan done, no significant interval  changes were shown; however, left mastoiditis was developed. He was going to undergo another  ear exploration surgery with bone debridement; however, it was canceled as he was unfit for  anesthesia due to him having severe hypertension which was 210/40 mmhg and taking two  anticoagulants & having multiple co-morbidities.  

Image 1 - CT Scan, Petrous Bone, Coronal View

Image 2 - CT Scan -Petrous Bone, Axial  View

Discussion

Malignant otitis externa is the osteomyelitis of the temporal bone that usually occurs in elderly diabetic or  otherwise immunocompromised patients; occasionally, the infection can spread and cause a skull base  osteomyelitis. In particular, microangiopathy and impaired blood circulation in patients with diabetes may  play a main role in the pathogenesis of the disease. Other causes can favor vascular impairment, such as  radiotherapy or an unhealthy diet[1]. The condition is linked to serious side effects, including cranial nerve  involvement, as well as a high morbidity and mortality rate[1]. MOE has also been shown in  immunocompromised or diabetic children; however, the prevalence is lower than in elderly patients with  diabetes[1].

Symptoms of malignant otitis externa encompass intense ear pain, discharge from the ear, a sense of ear  fullness, and diminished hearing[2]. If the infection extends, it may lead to jaw discomfort (TMJ joint pain),  hemi-facial pain, headaches, and trismus[1]. Facial nerve palsy can also occur in some cases[1]. The Levenson  criteria may be used for diagnosis, which involve factors like persistent otitis externa, severe nocturnal  otalgia, purulent otorrhea, granulation tissue in the external auditory canal,the presence of Pseudomonas  bacteria in ear culture, and underlying conditions like diabetes or immunocompromised patients[2]. All of  these clinical features may aid in making a diagnosis for MOE[2].

The most common microbiological agent for MOE is Pseudomonas aeruginosa. Other bacteria in MOE  include Staphylococcus aureus, S. epidermidis, Proteus mirabilis, Klebsiella oxytoca, and P. cepacia[1]. In  addition, a mycotic superinfection can exacerbate the condition. The most common fungal organism  causing MOE is Aspergillus fumigatus[1]. A bacterial culture provides a base for antibiotic selection.  Ciprofloxacin (with or without rifampin), new-generation fluoroquinolones, or third-generation  cephalosporin are often used if culture findings are negative[2].

Fungal organisms or a combination of bacterial and fungal infections cause MOE; therefore, doctors  recommend antifungal medication[1]. When patients report complications such as facial palsy or  temporomandibular joint discomfort, an imaging scan is required[1]. To assess the occurrence of bony  erosion, a high-resolution CT scan of the temporal bone is typically employed[3]. Magnetic resonance  imaging (MRI) provides higher resolution for evaluating soft tissue, particularly the parotid gland,  meninges, and cranial nerves[4]. When compared to typical MRI sequences, diffusion-weighted MRI gives  greater anatomical resolution[1]. However, combining CT and MRI allows for more sensitive diagnostic  imaging, and diffusion-weighted MRI assists in assessing disease progression[2]. Complications of  malignant otitis externa and osteomyelitis include meningitis, abscess, sagittal, dural, and cavernous sinus  thrombosis[1].

Just like most of the clinical symptoms and features of MOE, the patient in this report was diabetic and  immunocompromised with several co-morbidities. What was different in this case was that the pathogen  from his ear culture was not from the most common organism that causes MOE (Pseudomonas aeruginosa); it was Escherichia coli, which makes this case more unique. Escherichia coli (E. coli) is not  commonly associated with malignant otitis externa (MOE).

MOE is a severe and potentially life-threatening infection of the external ear canal and surrounding  structures, typically seen in elderly individuals with underlying conditions such as diabetes or  immunocompromised systems. Pseudomonas aeruginosa, a bacterium found in soil, water, and damp  environments, typically causes the infection. It is often linked to MOE, causing infections in wounds and  the ear. The presence of Escherichia coli in the ear is unusual, suggesting a more severe or secondary  infection. However, the primary pathogen associated with MOE is usually Pseudomonas aeruginosa.

Our patient had a 1-year history of recurrent right ear discharge and ear pain. His condition began as right  otitis externa, which has developed into right-sided malignant otitis externa that initially involved  osteomastoiditis and was complicated by severe osteomyelitis involving the occipital bone. He was treated  exclusively with antibiotics while being hospitalized, analgesics with ear solutions, and underwent one ear  exploration surgery. He was supposed to undergo ear exploration again with bone debridement after a few  months; however, he was not fit for surgery & anesthesia due to him taking anticoagulants & due to his  health conditions.

In our case, there was a marked progression of right MOE that has developed into osteomyelitis of the  occipital bone.In the CT petrous bone scan, persistent abnormal soft tissue has been shown involving the  outer and inner right ear, with erosive changes of the tegmen tympani ossicles, scutum, middle ear cavity  walls, and mastoid portion of the right temporal bone. Also, irregularity of the facial nerve canal has been  seen along the labyrinthine and tympanic segments of the facial nerve due to erosion or inflammation, and  diffuse opacification of the right mastoid air cells was also seen.

Searching the literature , there has only been one case reported with MOE that has progressed to osteomyelitis of the occipital bone .However, the difference in the case is that it was caused by  Corynebacterium Amycolatum, whereas in our case is that the pathogen from his ear culture was  Escherichia coli . The typical cause of this disease is that it spreads to the skull base, affecting  the lower fourth cranial nerve, and occasionally progresses to the other side of the skull base ,  but in our case it did not go to the skull base and instead it went posteriorly into the occipital  bone, making it rare.

The presence of Escherichia coli in the ear is unusual, suggesting a more severe or secondary infection. The CT petrous bone , revealed aggressive infective and inflammatory processes in the right external  auditory canal which caused malignant otitis externa with extension into the middle ear which caused osteomyelitis of the occipital bone.

Conclusion

In conclusion, the case of malignant otitis externa (MOE) in a diabetic and  immunocompromised patient with multiple co-morbidities is unique due to the presence of Escherichia coli, an uncommon pathogen for MOE. The patient's 1-year history of recurrent  ear issues, progressing from otitis externa to severe MOE involving the mastoid causing  osteomyelitis and extending to the occipital bone, emphasizes the seriousness of the illness.

The standard treatment is hospitalization, antibiotic therapy, analgesics, and an ear exploration surgery. He was going to undergo another ear exploration surgery with bone  debridement on right ear; however, it was canceled as he was unfit for anesthesia due to him having severe hypertension which was 210/40 mmhg and taking 2 anticoagulants & having  multiple co-morbidities.

References

1. Bruschini, L., Berrettini, S., Christina, C., Ferranti, S., Fabiani, S., Cavezza, M., Forli, F., Santoro, A., & Tagliaferri, E. (2019). Extensive Skull Base Osteomyelitis Secondary to Malignant Otitis Externa. The journal of international advanced otology, 15(3), 463–465. 

2. Carlton DA, Perez EE, Smouha EE. Malignant external otitis: The shifting treatment paradigm. Am J Otolaryngol 2018; 39: 41-5. 

3. Rubin J, Yu VL. Malignant external otitis: insights into patho¬genesis, clinical manifestations, diagnosis, and therapy. Am J Med 1988; 85: 391- 8. 

4. Eguchi T, Basugi A, Kanai I, Miyata Y, Nasuno T, Hamada Y. Malignant ex- ternal otitis following radiotherapy for oral cancer: A case report. Medi- cine (Baltimore). 2018; 97: e10898.