Abstract
Diseases of the temporal bone causing lower cranial nerve palsies are uncommon. In the presence of bony erosion, they are highly suggestive of a malignant process. However, when there is a clear history of otitis externa in an immunocompromised or diabetic patient, a diagnosis of osteomyelitis and secondary inflammatory mass should be considered. We report 4 separate cases of infective skull base lesions causing multiple lower cranial nerve palsies in elderly patients who were not immunocompromised or diabetic, highlighting that this condition is not exclusive to this population.
1
Introduction
A wide variety of soft tissue masses may be encountered in the skull base, such as cholesterol granuloma, schwannoma, and meningioma . Interestingly, they have been described to be associated with lower cranial nerve palsies (CNP) . Malignant disease including primary nasopharyngeal carcinoma extending into the skull base or secondary bony metastasis can also present in a similar fashion .
Osteomyelitis of the skull base remains rare. It was first described by Meltzer in 1959 and was thought to be a complication of otitis externa caused by Pseudomonas aeruginosa in elderly diabetic or immunocompromised patients . A potentially life-threatening illness, it requires aggressive antibiotic treatment for a prolonged period. Atypical non–pseudomonas infections have also been isolated, but rarely and are not associated with aural pathology . As the infection spreads through the skull base, bone erosion occurs with the formation of soft tissue granulomas and abscesses . The resulting nerve weakness, initially thought to be reversible, is secondary to the pressure effect of the inflammatory tissue surrounding the nerve as it exits the corresponding foramen . The most commonly affected nerve is the facial nerve followed by the glossopharyngeal, vagal and accessory nerves at the jugular foramen, and the hypoglossal nerve through its own canal . This may lead to sigmoid sinus or cavernous sinus thrombosis if the disease extends through the petrous apex as well as potentially involving the fifth and sixth cranial nerves. Further complications can also occur, including meningitis, brain abscess, or even death.
We present 4 cases of lower CNP caused by necrotising otitis externa in patients without a history of diabetes or immunocompromise and discuss the management of these significant cases.
2
Case reports
2.1
Case 1
A 75-year-old nondiabetic man presented with a 4-week history of left-sided otalgia and mild deafness. Ear examination revealed a swollen external auditory canal (EAC) full of debris. A microbiology swab taken from the ear grew Proteus species. Although reviewed regularly, 2 months later, a left EAC polyp was seen. Histological examination of the polyp revealed nonspecific chronic inflammatory changes. Otoscopy of the ear returned to normal. Despite repeated local and systemic treatment, the patient continued to report mild left otalgia and headache. A computed tomography (CT) scan did not identify any mastoid or skull base pathology.
Five months after his initial visit, the patient developed additional symptoms of facial pain, hoarseness, dysarthria, dysphagia, and weight loss. Physical examination revealed left sided VII, X, XI, and XII CNP. Otoscopy at the time was unremarkable. Markers of infection were significantly elevated C-reactive protein (CRP) greater than 200 mg/L. A CT scan did not identify any obvious skull base lesion. Subsequent magnetic resonance imaging (MRI) showed a submucosal mass in the postnasal space, extending to the petrous apex of the left temporal bone ( Fig. 1 ). T2-weighted MRI images showed high signal changes in the left middle ear cavity and mastoid air cells consistent with inflammation or infection.
A nasopharyngeal biopsy showed inflammatory changes consistent with the diagnosis of rhinoscleroma. This histology showed characteristic features of infection due to the bacillus Klebsiella rhinoscleromatis .
The patient was treated with 8 weeks of oral ciprofloxacin and doxycycline. A percutaneous endoscopic gastrostomy (PEG) was inserted for long-term enteral feeding. He also benefited from a left lateral tarsorraphy. There was rapid reduction in pain after the introduction of the antibiotics.
After 2 years, he no longer required his PEG. A MRI performed at this time showed almost complete resolution of the high signal lesion seen in the petrous bone on T2-weighted images. The same lesion however was apparent and isointense on T1-weighted images ( Fig. 2 ). A further CT scan performed 3 years after presentation showed no evidence of bony destruction at the skull base. Inflammatory markers (CRP, erythrocyte sedimentation rate [ESR]) returned to normal values.
Five years after the initial presentation, there remained paralysis of his left vocal cord, tongue, palate, and facial muscles.
2.2
Case 2
A 66-year-old nondiabetic woman was referred to the ENT clinic with left otalgia and headache. Left otitis externa was diagnosed and treated with antibiotic eardrops. She was admitted 5 weeks later with a worsening headache. A thorough ear, nose, and throat examination failed to show any significant abnormality. Noncontrast CT of the head was unremarkable.
A week later, the patient developed difficulty with talking and swallowing. Examination revealed that she had developed left-sided IX, X, and XII CNP. There were no signs of active ear infection. Initial investigations showed raised ESR and CRP (36 mm/h and 122 mg/L, respectively). T2-weighted MRI scan showed high signal in the mastoid air cells compatible with mastoiditis. It also suggested the possibility of a base of skull lesion. The CT scan confirmed soft tissue lesion on the left side of the skull base measuring 5 cm across. The lesion was infiltrating the tissues of the nasopharynx, descending into the oropharynx at the level of the anterior arch of C1 and superiorly reaching the infratemporal fossa around the left pterygoid plate.
Ear microbiological swabs grew Pseudomonas species. A nasopharyngeal biopsy showed acute and chronic inflammation with necrosis but no evidence of neoplasia. The patient showed steady clinical improvement with a prolonged course of intravenous cefuroxime and metronidazole. After a period of feeding through nasogastric tube, she returned to oral feeding.
After the initial clinical response, she relapsed. Antibiotics were changed to oral ciprofloxacin, and a 7-week course of meropenem (initially 1 g TDS until discharge, then 1 g BD) by a long intravenous line. The patient had most of her treatment in her own home with the help of outreach nursing support. She had a good clinical response, followed by intermittent symptoms. Two months later she started to deteriorate again and was started on a prolonged course of meropenem (dose as before) through a long line for 11 months. Electrolytes were checked monthly once initial treatment had commenced.
Three years after presenting with multiple lower cranial palsies, a repeat MRI scan showed that the inflammatory mass had resolved and that the inflammatory blood markers had returned to normal values. Although the patient still shows evidence of left vocal cord palsy and tongue weakness, she had no significant problems with her speech and swallowing.
2.3
Case 3
An 86-year-old nondiabetic man presented with a 3-month history of severe right otalgia and occasional discharge. He had been treated with multiple ear drops before this by his general practitioner. Examination revealed an aural polyp in the deep meatus. Cranial nerve examination was normal, and audiological assessment revealed symmetrical high-frequency sensorineural hearing loss. Urgent biopsy was arranged, after which oral ciprofloxacin (500 mg BD) was started and a CT scan organized. On admission, the white cell count was raised (15.1 10 9 /L—differential neutrophil count 12.62 10 9 /L). Histology confirmed chronic inflammatory tissue, and the CT showed a mass eroding the skull base suggestive of nasopharyngeal carcinoma. Urgent MRI however revealed the likely diagnosis of osteomyelitis secondary to necrotising otitis externa. A long line was inserted for the administration intravenous meropenem (initially 1 g TDS until discharge, then 1 g BD). Inflammatory markers, plasma viscosity and CRP, were raised (1.83 mPa s and 25 mg/L, respectively). Cranial nerve examination identified an isolated right hypoglossal nerve palsy.
After 2 weeks of treatment, the hypoglossal palsy was improved. After 3 months of treatment at home, the inflammatory markers had also improved to normal levels. The long line was removed at this point and the inflammatory markers monitored. These continue to be in their reference ranges 4 months after stopping antibiotic treatment. A further MRI scan has been arranged to assess the skull base.
2.4
Case 4
A 78-year-old nondiabetic patient was referred by his general practitioner to the medical unit with a presumed right-sided cerebrovascular accident. He presented with a history of dysphagia, otalgia on chewing, one stone weight loss over the preceding year, and hoarseness for 3 weeks. Examination revealed right-sided tongue wasting and right vocal cord palsy along with pooling of saliva in the hypopharynx. An urgent CT of the skull base revealed a large soft tissue mass in the right side of the nasopharynx (3.5 × 3 cm) involving the prevertebral muscle. Bony erosion of the right carotid canal and jugular foramen was evident together with enlargement of posterior lymph nodes. A fine-needle aspirate was taken of the post nasal swelling. An axial T1- and T2-weighted MRI was performed to supplement the CT scan. T1 images confirmed the presence of the lesion with effacement of the right fossa of Rosenmüller and loss of normal fat planes. The lesion encased the internal carotid artery and jugular vein. Postgadolinium fat saturated T2 images showed the mass to extend through the hypoglossal foramen into the posterior cranial fossa and along the floor of the middle cranial fossa ultimately involving the margins of the temporomandibular joint.
The results of the fine-needle aspirate showed only a benign cyst, and therefore, a postnasal space biopsy was performed. This unfortunately was unhelpful, and deep biopsies were repeated, which showed chronic inflammatory tissue only. A microbiological swab taken at the same time however grew Pseudomonas species.
Finally, a diagnosis of osteomyelitis of the skull base was made. The gentleman was started on intravenous meropenem (1 g TDS) and enteral ciprofloxacin via his PEG (inserted during his admission). Discussion with his wife after the diagnosis was made revealed a history of ear discharge approximately 6 months earlier.
Although he was actively treated and kept nil by mouth throughout, the patient deteriorated significantly over the next 3 weeks and eventually dying from pneumonia.
2
Case reports
2.1
Case 1
A 75-year-old nondiabetic man presented with a 4-week history of left-sided otalgia and mild deafness. Ear examination revealed a swollen external auditory canal (EAC) full of debris. A microbiology swab taken from the ear grew Proteus species. Although reviewed regularly, 2 months later, a left EAC polyp was seen. Histological examination of the polyp revealed nonspecific chronic inflammatory changes. Otoscopy of the ear returned to normal. Despite repeated local and systemic treatment, the patient continued to report mild left otalgia and headache. A computed tomography (CT) scan did not identify any mastoid or skull base pathology.
Five months after his initial visit, the patient developed additional symptoms of facial pain, hoarseness, dysarthria, dysphagia, and weight loss. Physical examination revealed left sided VII, X, XI, and XII CNP. Otoscopy at the time was unremarkable. Markers of infection were significantly elevated C-reactive protein (CRP) greater than 200 mg/L. A CT scan did not identify any obvious skull base lesion. Subsequent magnetic resonance imaging (MRI) showed a submucosal mass in the postnasal space, extending to the petrous apex of the left temporal bone ( Fig. 1 ). T2-weighted MRI images showed high signal changes in the left middle ear cavity and mastoid air cells consistent with inflammation or infection.
