|Year : 2013 | Volume
| Issue : 1 | Page : 33-35
Malignant otitis externa with bilateral cranial nerve involvement: Report of a unique case
Somnath Saha1, Kanishka Chowdhury1, Sudipta Pal1, Vedula Padmini Saha2
1 Department of ENT, RG Kar Medical College and Hospital, Kolkata, India
2 Department of Plastic Surgery, RG Kar Medical College and Hospital, Kolkata, India
|Date of Web Publication||6-Mar-2013|
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Source of Support: None, Conflict of Interest: None
Malignant otitis externa is an inflammatory condition caused by pseudomonas infection usually in the elderly diabetics, or an immunosuppressive condition that presents with diffuse otitis externa along with excruciating pain and granulations tissue in the external auditory meatus. Facial paralysis is common along with occasional involvement of other cranial nerves. Case report describing a patient of malignant otitis externa who presented to a tertiary referral hospital of eastern India. This patient had ipsilateral facial and tenth cranial nerve paralysis along with delayed-onset contralateral sixth and twelfth cranial nerve palsy. The patient was treated initially with intravenous anti-pseudomonal antibody followed by tympanic platectomy, facial nerve decompression and medialisation thyroplasty. The contralateral cranial nerve palsy was managed conservatively with partial recovery of function. Malignant otitis externa, though a common disease, may occasionally present with uncommon or unexplained presentations. The management of these cases should be prompt and aggressive and specifically address each of the debilitating complications.
Keywords: Cranial nerve palsy, Facial nerve decompression, Malignant otitis externa, Medialisation thyroplasty, Tympanic platectomy
|How to cite this article:|
Saha S, Chowdhury K, Pal S, Saha VP. Malignant otitis externa with bilateral cranial nerve involvement: Report of a unique case. Indian J Otol 2013;19:33-5
|How to cite this URL:|
Saha S, Chowdhury K, Pal S, Saha VP. Malignant otitis externa with bilateral cranial nerve involvement: Report of a unique case. Indian J Otol [serial online] 2013 [cited 2020 Feb 18];19:33-5. Available from: http://www.indianjotol.org/text.asp?2013/19/1/33/108166
| Introduction|| |
Malignant otitis externa is an uncommon life-threatening disease that occurs in elderly diabetic patients. It is an invasive pseudomonal infection of the external canal and deep peri-auricular tissue that characteristically involves the bone and adjacent cartilaginous structures and may lead to osteomyelitis of the base of the skull. It most commonly affects elderly diabetic (both Type I and Type II) patients who may have an impaired host response to Pseudomonas. Common presentations of malignant otitis externa are otalgia, otorrhoea and seventh cranial nerve palsy. Levenson's criteria can be used for diagnosis, which include: Refractory otitis externa, severe nocturnal otalgia and purulent otorrhea associated with Pseudomonas infection and granulation tissue in an immunocompromised or diabetic patient. In the advanced stage of the disease other cranial nerve palsy and involvement of the temporomandibular joint, parapharyngeal space, central venous sinuses, extradural spaces, meninges can occur. Here we report a case of malignant otitis externa with involvement of multiple cranial nerves.
| Case Report|| |
A 62-year-old male, a known diabetic for 11 years presented with purulent otorrhoea from the right ear for three months with otalgia for the same duration and facial paresis for a duration of two months. On clinical examination external ear canal of the right side was found to be occupied with granulation tissue after dry mopping the discharge. Left ear was normal. The patient also had right seventh nerve palsy (House-Brackmann Scale: Grade VI). On high-resolution computed tomography (HRCT) scan of temporal bone there was paucity of right mastoid air-cells along with sclerosis of the mastoid antrum [Figure 1]. There was also soft tissue attenuation in the right external auditory canal. Ear ossicles and internal auditory canal was found to be normal. Left-sided HRCT finding was normal. Provisional diagnosis of malignant otitis externa was made and the patient was put on intravenous antipseudomonal antibiotics (pipeacillin-tazobactum with ciprofloxacin) along with strict diabetic control. As the disease was not controlled on conservative management, we planned for tympanic platectomy with facial nerve decompression at its exit from the stylomastoid foramen. Post surgery the facial nerve status improved (HB Scale: Grade II) with subsidence of otalgia and patient was discharged with long-term oral ciprofloxacin. Nine months after the surgery, the patient developed deviation of tongue and hoarseness of voice and diplopia along with dry cough. On clinical examination there was left-sided sixth and twelfth nerve palsy [Figure 2] and [Figure 3] and right-sided vocal cord palsy along with Grade 2 right seventh nerve palsy. Magnetic resonance imaging (MRI) was advised which revealed increased signal in the soft tissue beneath the skull base at the right side [Figure 4]. On Technetium (99mTc-MDP) bone scan in delayed phase there was diffusely increased concentration of radiotracer over the periphery of the anterior and inferior aspect of the right temporal bone [Figure 5]. To prevent aspiration and for improvement of voice, Type 1 (medialisation) thyroplasty was done. There was marked improvement of vocal quality postoperatively along with reduction in the cough which was probably due to aspiration.
|Figure 1: HRCT temporal bone showing paucity of right mastoid air-cells along with sclerosis of mastoid antrum and soft tissue attenuation in the right external auditory canal|
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|Figure 2: Clinical photograph of the patient showing deviation of tongue towards the left side|
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|Figure 3: Clinical photograph of the patient showing left-sided medial rectus palsy|
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|Figure 4: MRI scans showing increased signal in the soft tissue beneath the skull base at the right side|
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|Figure 5: 99mTc-MDP bone scan in delayed phase showing diffusely increased concentration of radiotracer over the periphery of the anterior and inferior aspect of the right temporal bone|
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| Discussion|| |
Malignant otitis externa is an aggressive and potentially life-threatening infection of the soft tissues of the external ear and surrounding structures, quickly spreading to involve the periostium and bone of the skull base. The first reported case was published in 1836,  and the term 'malignant otitis externa' was coined in 1968,  because of its high mortality. Predisposing factors include immunologic abnormalities including diabetes, dermatitis, medication, neoplasm, iatrogenic procedures and chronic infection of the ear canal.  It is the end-stage of a severe infection that originates from the external auditory canal and progresses through cellulitis, chondritis, peri-osteitis, osteitis and finally osteomyelitis. Once peri-osteitis develops it progresses rapidly across the skull base. As a result, facial nerve and other cranial nerve palsies are sustained. Pseudomonas aeruginosa is the most common pathogen and is responsible in over 95% of cases.  The terms 'osteomyelitis of the temporal bone', 'skull base osteomyelitis' and 'malignant otitis externa› have not been clearly defined, and have in the past often been used interchangeably in the literature. The presence of cranial nerve palsy is a sign of advanced disease and these patients can still have mortality rates of up to 80%.  If the disease progresses, extensive skull base osteomyelitis becomes established. The clivus and contralateral temporal bone can be involved and infection can spread anteriorly into the sphenoid and to the carotid. Anterior infection can involve the temporomandibular joint and parapharyngeal space. The facial nerve is the most commonly affected cranial nerve (60% of cases with palsies)  and thereafter the ninth, tenth and eleventh cranial nerves. Paralysis of the sixth or twelfth cranial nerves is rare, but has been reported.  Finally, disease can spread to the central venous sinuses, extradural space and meninges. Mani et al., demonstrated in their study that 43.5% patients had cranial nerve involvement. In their series of 23 cases, facial nerve was involved in 6 patients, lower cranial nerves (combination of 9, 10, 11, 12) in 3, and extended nerve palsy (6, 7, 9, 10, 11) was found in 1 patient. However 13 (56.5%) of their patients were free from any neural palsy.  Multiple cranial nerve palsy can occur due to extensive skull base osteomyelitis secondary to malignant otitis externa. Skull base osteomyelitis can lead to thrombosis of the jugular bulb and subsequent paralysis of cranial nerves 7, 9, 10 and 12. Extensive disease with involvement of the petrous apex may even cause paralysis of the fifth and sixth cranial nerves.
In the present case report, diagnosis of malignant otitis externa was based on Levenson's criteria of purulent otorrhoea, otalgia along with facial nerve palsy in an elderly diabetic patient along with finding of granulation tissue in the external auditory canal, and presence of Pseudomonas as confirmed by microbiological examination. HRCT, MRI and Technetium bone scan helped to strengthen the diagnosis. The case is unique in the sense that there was left-sided sixth and twelfth nerve palsy along with right vocal cord palsy without involvement of the ipsilateral sixth and twelfth cranial nerve. The explanation behind this might be that there can be chances of skip lesion in advanced malignant otitis externa extending to the skull base area. We performed tympanic platectomy (removal of the floor of the external auditory canal) because in malignant otitis externa, there is extensive granulation tissue only at the external auditory canal and when the disease becomes extensive, granulation tissue may also present at the skull base region. Hence mastoid exploration is very rarely necessary. We also performed facial nerve decompression at the site of exit of the nerve from the stylomastoid foramen where it lies in close proximity to the tympanic plate of temporal bone and can be affected easily due to extensive inflammation secondary to granulation tissue. The palsy of lower cranial nerves usually recovers on long-term oral medication as suggested by Mani et al., in their study.  The patient in our report underwent medialisation thyroplasty for vocal cord palsy to give relief for dry cough probably due to chronic aspiration. We also performed the procedure to improve the voice quality as part of rehabilitation to improve the quality of life. The other cranial nerve palsies were managed conservatively.
| Conclusion|| |
In the advanced stage of the disease, the skull base can be involved often with multiple lower cranial nerve palsies. There is only one reference of involvement of the sixth and twelfth cranial nerve in a case of malignant otitis externa and that too of the ipsilateral side. In the present case, the contaralateral sixth and twelfth nerve were involved which is a unique situation. Similar kind of presentation in a case of malignant otitis externa is yet to be reported in world literature. The probable cause was involvement of the contarlateral nerves by skip lesions of micro-abscesses at the skull base. However, this is hypothetical assumption and more research is required to elucidate the probable causes and proper management.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]