Malignant Otitis Externa Complicated by Skull Base Osteomyelitis Presenting as Vernet's Syndrome with Central Venous Thrombosis

Abstract

Skull base osteomyelitis (SBO) is a rare disease that often has delayed presentation in clinical settings. SBO is often misinterpreted as skull base malignancy, thus posing a challenge in diagnosis. We submit a case that presented with chronic otitis media with multiple cranial nerve palsies. His diagnosis was challenged in view of nonspecific imaging findings and odd presentation, which caused a delay in diagnosis. Methicillin-resistance coagulase-negative Staphylococcus (MRCONS) was isolated from the drained pus. MRCONS usually presents with an indwelling medical device or in severe burn cases. However, isolating and documenting organisms in SBO is needed for rare cases. A final diagnosis of SBO complicated with Vernet's syndrome and sigmoid sinus thrombosis was made. He made good recovery with microbial-specific antibiotics and drainage of abscess with the least improvement on cranial nerve palsies.

Keywords

skull base osteomyelitis - methicillin-resistant coagulase-negative Staphylococci (MRCONS) - central vein thrombosis - chronic suppurative otitis media - Vernet's syndrome

Introduction

Meltzer and Kelemen were the first to discover skull base osteomyelitis (SBO) in 1959, representing a rare clinical entity characterized by low incidence rates, largely attributing to the widespread implementation of antibiotics. This infectious disease of the skull bone base is characterized by multiple cranial nerve palsies with intracranial arterial thrombosis in advanced diseases. Although microorganisms are rarely isolated in SBO, Urbančič et al have documented a comprehensive catalog of pathogen spread in SBO.[1] While SBO is typically associated with Pseudomonas aeruginosa and other Gram-negative bacteria, emerging reports highlight unusual pathogens.[2] In this case, methicillin-resistance coagulase-negative Staphylococcus (MRCONS) typically associated with implant-related infections were isolated despite the absence of prosthetic devices or foreign material in patient's clinical history, highlighting the pathogenic potential beyond device-associated infections. This case highlights a rare spectrum of manifestations, including Vernet's syndrome, cerebral venous thrombosis, and isolation of MRCONS despite the absence of implants.

Case Presentation

A 64-year-old man presented with complaints of left ear pain with mild discharge and left-sided headache following which the patient had difficulty in swallowing, nasal regurgitation, slurring of speech, and angle of deviation of mouth to the right side for 1 month. Initially treated at another hospital where a magnetic resonance imaging (MRI) brain with an angiogram showed abnormal signals in the left skull base extending to the nasopharynx. Also, enclosing the left internal carotid artery (ICA) with infiltration of temporal bone involving the left stylomastoid foramen and left clivus. Narrowing of the left ICA was noted. These radiological features were suggestive of skull base malignancy. His medical history highlighted chronic suppurative otitis media (CSOM) for 2 years and diabetes mellitus for 15 years. With worsening of general condition, he was referred for further management. On arrival, he was lethargic, confused, and in septic shock. Neurological examination showed left sided LMN type of facial palsy (CN VII), along with CN XI to XI palsy, ipsilateral bulbar palsy, absent gag reflex, whispering voice and uvula deviation to right side. Muscle wasting with fasciculations of the left trapezius and sternocleidomastoid muscle with drooping and absent shrugging of the left shoulder was noted. Based on clinical features a diagnosis of Vernet's syndrome was made and differential diagnosis of malignant tumor of the temporal bone, malignant otitis externa (MOE), and SBO was considered. Initial blood results showed mild hyponatremia 132 mEq/L (ref range: 135–145 mEq/L), hypokalemia (3.0 mEq/L) (ref range: 3.5–5.5 mEq/L), decreased hemoglobin levels (10.7 g/dL) (ref range: 12–15 g/dL), and elevated glycated hemoglobin level (7.9%) (nondiabetic < 5.5%). Other hematological results were within the normal range.

MRI of brain with contrast showed marrow edema with enhancement noted in the left petrous apex, clivus, left occipital condyle, around jugular foramen, and hypoglossal canal. Moderate narrowing of the distal segment of the left ICA was noted, smooth dural thickening was noted in the left cerebellopontine angle and clival region, left ICA, left jugular foramen, and hypoglossal canal, and complete occlusion of the left distal sigmoid sinus and proximal internal jugular vein ([Fig. 1]). Multiple irregularly rim-enhancing abscesses are seen anteroinferior to the clivus and left petrous apex and in the left prevertebral space measuring 2.9 × 0.8 cm and 1.2 × 0.6 cm, respectively ([Fig. 2]). Ill-defined soft tissue thickening with enhancement noted in the skull base on the left side, involving the prevertebral space, left parapharyngeal space, and inferior to mastoid ([Fig. 3]). Soft tissue thickening with enhancement was noted in the left external auditory canal (EAC) and middle ear ([Fig. 4]).

Fig. 1 Edema surrounding the skull base on the left side medially enclosing within the clivus and condyles along with narrowing of the left internal carotid artery (ICA). Arrow indicating narrowing of the left internal carotid artery (ICA) and surrounding inflammatory tissue.

Fig. 2 Peripheral enhancement surrounding abscess anteroinferior to the clivus and 2.9 × 0.8 cm and 1.2 × 0.6 cm, respectively. Arrow indicating an irregularly contrast rim-enhancing abscess inferior to the clivus.

Fig. 3 Magnetic resonance imaging (MRI) shows the spread of inflammatory signals into the nasopharynx.

Fig. 4 Ill-defined soft tissue thickening with enhancement noted in the skull base on the left side, involving the prevertebral space, left parapharyngeal space, and inferior to mastoid. Arrow indicates edematous tissue along the paravertebral space and inferior to mastoid.

A diagnosis of SBO with complications of VIIth cranial nerve palsy, Vernet's syndrome, and central venous thrombus was made. Initially, he was started on broad-spectrum antibiotics (piperacillin + tazobactam for 3 days). The neurosurgeon and otorhinolaryngologist suggested surgical drainage of SBO with abscess. After preanesthetic evaluation, the patient underwent transnasal transsphenoidal drainage of the abscess with mastoid exploration, pus sample was collected from the abscess and sent for culture and sensitivity, and tissue samples were collected from mastoid and abscess wall, which were sent for culture sensitivity and histopathological examination. The biopsy report showed features consistent with CSOM ([Fig. 5]). Tissue culture showed Staphylococcus species (MRCONS), and antibiotics were modified accordingly. Culture-specific antibiotics (imipenem + vancomycin) were given for 15 days. Even after antibiotic therapy, the patient still had multiple lower cranial nerve palsies. Speech-language pathologist was consulted, as the patient could not tolerate oral feeding, and developed an event of aspiration during oral trial. Percutaneous endoscopic gastrostomy tube placement was done by a gastroenterologist, as dysphagia was persisting. After 1 month of follow-up, the patient had only mild improvement in aspects of VII and bulbar palsy, as he still had difficulty swallowing, and percutaneous endoscopic gastrostomy tube feeding was continued. Concluding, he had an atypical presentation of SBO with cranial nerve complications of VIIth cranial nerve palsy, Vernet's syndrome, and central venous thrombus.

Fig. 5 This histopathology image shows signs of chronic inflammation with granulation tissue along with fibrosis that is in consistence with chronic suppurative otitis media. (A) The area in the upper left and central region of the image shows dense infiltration of small, dark-staining cells. These are lymphocytes and plasma cells, typical of chronic inflammation in chronic suppurative otitis media (CSOM). (B) The central region, with a loose, pink, and somewhat disorganized matrix, represents granulation tissue. This area shows proliferation of fibroblasts and new blood vessels. (C) The lower part of the image shows a denser, more organized pink matrix, indicative of fibrous tissue formation, another hallmark of chronic inflammation.

Discussion

SBO is a rare yet potentially life-threatening condition that necessitates early recognition and appropriate treatment to mitigate its severe consequences. A comprehensive review of the literature across various online platforms yielded a total of 153 articles on this subject that gives an outline of all the plethora of symptoms that SBO can present.[3] [4] A study conducted in a teaching hospital in South India over the span of 10 years (2006–2018) identified a total of 41 patients diagnosed with SBO.[5] Consequently, the incidence of SBO is considered rare.

The reported case presented with inactive CSOM and worsening multiple cranial nerve palsies affecting cranial nerves VII, IX, X, and XI, one of the syndrome of jugular foramen compression. SBO cases typically exhibit delayed presentation due to the absence of prominent external symptoms unless cranial nerves are initially involved. Base of the skull osteomyelitis carries a mortality rate of 10%, with one-third of patients experiencing long-term neurological deficits, despite appropriate management.[6]

SBO is broadly classified into typical and atypical forms. Typical SBO arises secondary to uncontrolled infection in the temporal bone region, most frequently due to necrotizing otitis externa. In contrast, atypical SBO occurs in absence of evident temporal bone or EAC infections, often involving the sphenoid and occipital bone, particularly the clivus.[6] [7] [8] Typically, SBO is preceded by destructive otitis externa; however, atypical cases may present without aural symptoms.[7] [9] [10] In a study of 42 atypical cases, the most common presenting features included headaches, facial pain, and cranial nerve palsies.[6] This case exemplifies typical SBO.

In case of MOE, the infection spreads from the EAC via the Santorini fissures to the cartilage. External infections of the EAC can lead to osteal infections of the temporal bone, which may progress into the skull base. The spread of infection from the temporal bone occurs through a combination of air cells and Haversian nutrient channels. Consequently, involvement of the stylomastoid foramen can elicit facial nerve palsy, while involvement of the jugular foramen results in lower cranial nerve palsies.[11] Despite advancements in imaging technologies, diagnosing SBO remains challenging, as there is no single criterion that can effectively differentiate between MOE and SBO. Apparently, our case had a history of CSOM that progressed to malignant otitis media, which complicated into SBO. This pathophysiology was clearly noted in the MRI in our patient.

Apparently 78% of cranial nerve palsies are associated with ear infections, with facial nerve being the most frequently involved.[5] Various jugular foramen syndromes have been reported in SBO across numerous studies. Vernet's syndrome refers to paralysis of cranial nerves IX, X, and XI traversing the jugular foramen, which was first described by Vernet in the Paris Medical Journal in 1917.[10] This case involved SBO surrounding the jugular foramen, hypoglossal canal, carotid canal, and extending along the paravertebral and parapharyngeal spaces.

Pseudomonas aeruginosa, a Gram-negative aerobe, colonizes the EAC, particularly in conditions of high moisture content. It is considered the etiological agent in 50 to 90% of MOE cases; however, various microorganisms can also be isolated, especially in a nondiabetic patient, including Staphylococci (Staphylococcus aureus, particularly methicillin-resistant S. aureus, Staphylococcus epidermidis), Streptococci, and Gram-negative bacteria (Klebsiella species, Proteus mirabilis, or Raoultella ornithinolytica). Conversely, fungi rarely cause MOE, with an incidence of approximately 10%, where Aspergillus species and Candida albicans are the most implicated fungi (including Candida glabrata, C. parasilosis, and Candida ciferrii).[12] [13] In our case, we isolated Staphylococcus MRCONS without the presence of a medical device implant or severe burns, conditions where these species are found.[10] We initially started treatment with broad-spectrum antimicrobials, subsequently adjusting based on sensitivity reports. This helped in decreasing the febrile spikes and inflammatory markers.

Currently, there are no established protocols regarding the duration or dosage of antibiotic courses for SBO cases; however, the Infectious Disease Society of America recommends a minimum of 6 weeks of intravenous antibiotics, potentially extending up to 6 months.[14] Surgical debridement is the most recommended first-line management strategy, as it provides source control, reduces the infectious load, and allows for the collection of samples for culture to identify etiological organisms. Whenever feasible, debridement of source control should be performed in all patients with SBO.[5]

Conclusion

Isolation of staphylococcus MRCON is uncommon, particularly in cases without prosthetic devices. Elderly diabetic patients presenting with CSOM, have higher susceptibility to SBO. Untreated or refractory cases have reported to carry mortality rates of up to 60% in the literature. This case underscores the necessity of including infectious etiologies even in patients with no classical signs of infection. Documentation of such rare clinical presentations enhances clinician's ability to recognize atypical manifestations of SBO and supports the therapeutic protocol through multidisciplinary approach.

Conflict of Interest

None declared.

• References

• 1 Urbančič J, Vozel D, Battelino S. et al. Atypical skull-base osteomyelitis: comprehensive review and multidisciplinary management viewpoints. Trop Med Infect Dis 2023; 8 (05) 254
• 2 Dusini N, Buchek GM. Skull base osteomyelitis: a case report and literature review. Cureus 2025; 17 (07) e88466
• 3 Khan MA, Quadri SAQ, Kazmi AS. et al. A comprehensive review of skull base osteomyelitis: diagnostic and therapeutic challenges among various presentations. Asian J Neurosurg 2018; 13 (04) 959-970
• 4 Das S, Iyadurai R, Gunasekaran K. et al. Clinical characteristics and complications of skull base osteomyelitis: a 12-year study in a teaching hospital in South India. J Family Med Prim Care 2019; 8 (03) 834-839
• 5 Johnson AK, Batra PS. Central skull base osteomyelitis: an emerging clinical entity. Laryngoscope 2014; 124 (05) 1083-1087
• 6 Clark MP, Pretorius PM, Byren I, Milford CA. Central or atypical skull base osteomyelitis: diagnosis and treatment. Skull Base 2009; 19 (04) 247-254
• 7 Berbari EF, Kanj SS, Kowalski TJ. et al; Infectious Diseases Society of America. 2015 Infectious Diseases Society of America (IDSA) clinical practice guidelines for the diagnosis and treatment of native vertebral osteomyelitis in adults. Clin Infect Dis 2015; 61 (06) e26-e46
• 8 Chandler JR, Grobman L, Quencer R, Serafini A. Osteomyelitis of the base of the skull. Laryngoscope 1986; 96 (03) 245-251
• 9 Das JM, Al Khalili Y. Jugular Foramen Syndrome. [Updated 2023 Jul 31]. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; ; January 2025
• 10 Khan A, Riaz AA, Ahmad S, Shabbir A, Anjum AS. Skull base osteomyelitis due to Staphylococcus epidermidis in the absence of indwelling medical devices presenting with bilateral internal carotid artery thrombosis. Cureus 2024; 16 (08) e66563
• 11 Sokołowski J, Lachowska M, Karchier E, Bartoszewicz R, Niemczyk K. Skull base osteomyelitis: factors implicating clinical outcome. Acta Neurol Belg 2019; 119 (03) 431-437
• 12 Akhtar F, Iftikhar J, Azhar M, Raza A, Sultan F. Skull base osteomyelitis: a single-center experience. Cureus 2021; 13 (12) e20162
• 13 Spielmann PM, Yu R, Neeff M. Skull base osteomyelitis: current microbiology and management. J Laryngol Rhinol Otol 2013; 127 (Suppl. 01) S8-S12
• 14 Blyth CC, Gomes L, Sorrell TC, da Cruz M, Sud A, Chen SC. Skull-base osteomyelitis: fungal vs. bacterial infection. Clin Microbiol Infect 2011; 17 (02) 306-311

Publication History

Article published online:
20 November 2025