Endoscopic Transnasal Navigation Guided Treatment of Clivus Abscess in Adult with Mucormycosis: A Rare Report

Abstract

Osteomyelitis and abscess of the clivus are rare conditions thought to arise from contiguous spread of infection from the paranasal sinuses. Clival osteomyelitis is a rare potentially life-threatening skull base infection which is generally challenging to diagnose and treat. It is typically seen in the pediatric population and is very rare in the adult population. The exact pathophysiology of osteomyelitis of the clivus is relatively uncertain. Here, we describe a case of a 32-year-old immunocompetent female with a primary complaint of headache, with no significant medical history of diabetes, hypertension or rhinosinusitis or SARS COV-2 for the past 18 months. This case report demonstrates an image-guided and endoscopic approach to surgical localization and treatment of abscesses in the clival area.

Introduction

Osteomyelitis of the cranial bones with a sub-pericranial abscess as a result of the frontal bone injury was first described by Percival Pott in 1775 [1]. It is a rare entity and relatively uncommon in adults as compared to the pediatric population in whom the infection is thought to be due to contiguous spread from adjacent infections from the paranasal sinuses or temporal bone. Other primary sources of infection may include retropharyngeal abscess or spinal epidural abscess and rarely via hematogenous spread.

Skull base osteomyelitis (SBO) is not only the result of progression of inflammation of the external auditory canal [2] but also inflammation of the face, nose, paranasal sinuses, oral cavity, and pharynx [3, 4]. It is associated with high mortality and morbidity rates especially if left untreated. Atypical skull-base osteomyelitis (ASBO) is a rare but fatal disease and usually involves infection of the ethmoid, sphenoid, occipital, or temporal bones that make up the skull base. Unlike typical SBO, which is usually the result of advanced necrotizing external otitis (so-called otogenic), ASBO does not have an otogenic cause. ASBO can occur as a result of advanced or untreated infection of the deep tissues of the face, oral cavity, pharynx, nasal and paranasal sinuses more commonly the sphenoid sinus. According to literature Pseudomonas aeruginosa is seen to be the most common pathogen associated with SBO in recent times, but the incidence of other organisms, like Aspergillus spp, Staphylococcus aureus, etc. has increased. Fungi are a rare cause of skull base osteomyelitis, especially clivus abscess.

In this report, we have documented a rare case of Clivus abscess caused by Aspergillosis fumigatus in a young immunocompetent patient without significant clinical findings who was managed promptly by endoscopic transnasal navigation guided drainage of clivus abscess and started on antifungal treatment.

Case Presentation

A 32-year-old immunocompetent female presented to the primary health center with complaints of headache and left otalgia 18 months back and had no significant medical history of diabetes mellitus, hypertension, sinusitis, ear discharge or SARS COV-2. The patient was referred to an Otorhinolaryngologist and was thoroughly examined. Neurological examination revealed no central nervous system involvement or cranial nerve involvement. The patient had no history of ear, nose or throat infection or any sinonasal infection and had no evidence of rhinosinusitis on examination. The patient was treated conservatively with antibiotics. In view of persistent symptoms at follow-up, a contrast-enhanced computed tomography of paranasal sinuses was advised which revealed ill-defined osteolysis involving clivus, associated with enhancing collection withing the walls and septations within it. Osteolysis was found extending to involve wall of right sphenoid sinus with sphenoid sinus mucosal thickening. Rest of the sinuses were normal on radiological imaging. The CT scan of paranasal sinuses findings were confirmed on magnetic resonance contrast imaging of the brain showing collection involving clivus and base of right sphenoid with peripheral enhancement (films of previous investigations not available). The patient kept follow up at primary health center and had underwent multiple courses of antibiotics. The symptoms were relieved temporarily under antibiotic coverage. The patient later lost follow up to primary health center.

The patient reported to our hospital after 18 months with complaint of headache without any associated rhinosinusitis or any otorhinolaryngological complaints or any cranial nerve involvement. Otorinolaryngological examination revealed mild congestion of the pharynx which aroused a suspicion of exacerbation of previous detected pathology. The patient underwent contrast enhanced magnetic resonance imaging of brain which was suggestive of lytic collection involving entire clivus with peripheral enhancement and central necrosis (Fig. 1A and B), increase in size of clivus with increase in soft tissue size in posterior wall of nasopharynx, with significant airway narrowing (compared to previous scan).The findings were suggestive of infective pathology involving skull base – clival and sphenoidal osteomyelitis with intra-osseous abscesses narrowing the nasopharyngeal airway.

Fig. 1.

 A) Preoperative MRI of Brain sagittal cut showing lytic collection in clivus. B) Preoperative MRI of Brain coronal cut showing lytic collection in entire clivus with peripheral enhancement. C) Preoperative CT of Brain sagittal cut (parenchymal window) showing extent of lesion. D) Preoperative CT of Brain sagittal cut (bone window) showing near-complete lytic destruction of the clivus. E) and F) Postoperative CT of Brain sagittal cut showing complete excision of clival abscess

Contrast enhanced CT scan of brain confirmed the dimensions and extent of lesion. It also showed near complete lytic destruction of the clivus (Fig. 1C and D).

The location of abscess created a dilemma because of its eloquent location, potential risk of injurying the vital structures, which include the basilar artery, the brainstem and spinal cord. The patient was planned for navigation guided (Medtronics S8 Navigation System: Electromagnetic system) surgical drainage of abscess. Contrast enhanced CT was used for reference in the navigation system. The patient underwent Endoscopic Transnasal Navigation Guided aspiration and drainage of the clival abscess. For locating and localizing the abscess, universal tracer instrument was calibrated with syringe and needle, and after the location of abscess was confirmed, the needle was inserted into abscess cavity and 10 cc of abscess was aspirated. A sickle knife and suction tip were used to wide open the abscess and drain the remaining abscess. Using the endoscope, the defect in the clival wall was visualized and multiple abscess wall biopsies were taken. The advantages of navigation guidance in this case are: advantage of deciding the extent of the abscess, precise point of entry into abscess cavity (Fig. 2E and F) and as the bone of wall of clivus was deficient, it also helped to delineate the posterior extent of the abscess.

Fig. 2.

 A) Intraoperative image showing obliterated nasopharynx with abscess seen bulging. B) Intraoperative image showing draining abscess. C) Intraoperative image showing drained clival abscess cavity. D) Intraoperative image showing abscess cavity post irrigation. E) Intraoperative image showing navigation probe confirmation of the abscess location prior to abscess drainage. F) Neuronavigation image (Stealth) confirmation within the abscess cavity. G) Hematoxylin and Eosin staining showing purple stained fungal hyphae. H) Giemsa staining showing stained branching linear fungal hyphae

In the postoperative period, the patient’s headache and pharyngeal congestion subsided. The patient was kept on parenteral antibiotics postoperatively. Post-operative CT scan of brain was done, showing complete excision of the abscess (Fig. 1E and F).

Histopathological examination showed predominant necrotic material surrounded by scanty neutrophils, lymphocytes, plasma cells and macrophages. The necrotic material showed numerous fungal elements in the form of broad septate hyphae with obtuse angle branching (Fig. 2G and H). The acute on chronic inflammatory pathology with fungal elements morphologically was suggestive of Mucormycosis. Culture report showed growth of Aspergillus Fumigatus.

The patient was started on Intravenous infusion of Liposomal Amphotericin B treatment (antifungal drug) administered at dose of 5 mg/kg in 300 cc of Dextrose 5% (@60ml/hr), which was initiated with no complications and was continued for 6 weeks. The patient was discharged on Tablet Posoconazole 300 mg once a day which was started 5days prior to discharge and has to be continued for long term. At follow up 3months period, the patient had no persistent complaints.

Discussion

Clivus abscess is basically a form of skull base osteomyelitis. Osteomyelitis of clivus is a very rare entity in adults and its diagnosis and treatment is very challenging. Clivus osteomyelitis may lead to potential mortality and morbidity due to risk of meningitis, if not treated and intervened early. Typical locations of skull base osteomyelitis are the temporal and sphenoid bone and involvement of clivus bone is relatively rare and atypical [5]. This patient presented with sole complaint of headache without rhinosinusitis or any cranial nerve involvement, hence spread was postulated to be from the other adjacent bones of the skull base [6]. The symptoms of osteomyelitis of the clivus in this case is typically nonspecific as the patient had no pre-existing comorbidities like diabetes mellitus. Patient was immunocompetent with no history of SARS COV-2 without any cranial nerve involvement. Typical SBO clinically presents with headache, otalgia, aural discharge, conductive hearing loss, external auditory canal swelling, granulation tissue and usually affects VIIth cranial nerve, whereas ASBO clinically presents with nonspecific symptoms: headache and facial pain and the clinical picture of rhinosinusitis, facial cellulitis, furuncle, or pharyngitis with frequent involvement of VIth, IXth, Xth cranial nerves [3, 7–9]. Atypical or central SBO invades the sphenoidal and occipital bones, with nonrelated previous otic infection. Staphylococcus aureus and Pseudomonas aeruginosa are some of the most frequently reported bacterial pathogens in atypical SBO.

Fungi are rarely seen to cause SBO. Aspergillus spp and Candida albicans are most occasionally reported fungal organisms. The pathophysiology of fungal SBO is not well understood. The local complications are more frequently associated with fungal SBO compared to bacterial SBO, as evident in our report where Aspergillus fumigatus produced an invasive clinical condition with consequent clinical evolution and considerable local aggressiveness.

Aspergillus fumigatus is the mycotic pathogen most frequently reported in the literature [10]. The known mechanism of skull base invasion by these microorganisms is through contiguous translocation through Santorini fissures and hematologic translocation through the venous plexus located within the temporal bone [11]. A prominent navicular fossa, which is a known anatomical variant of clival morphology, is established anatomical risk factor for clival osteomyelitis.

The most used diagnostic study and the first imaging study is the CT scan, as it is most accessible and efficient modality to observe the skull and its bony changes. The most significant benefit is that CT scan allows for visualization of bone erosion and demineralization. Contrast-enhanced CT can show changes signifying ill-defined contrast enhancement, obliteration of fat planes or a frank abscess of affected soft tissues [3, 12].

Magnetic resonance imaging (MRI) is beneficial for visualizing soft tissue components near the skull. MRI is superior to CT in depicting the extent and presence of bone marrow involvement, soft tissue changes, and possible intracranial complications like thrombosis and intracranial spread.

Histopathologic examination (HPE) in patients with osteomyelitis is an essential diagnostic tool. HPE can provide information regarding acute and chronic inflammatory cell infiltration, necrosis, proliferation of the granulation tissue, fibrosis and edema. Additionally, HPE may help to determine the etiological factor too.

A microbiological examination is a much-needed tool in case of clivus osteomyelitis or abscess. Isolation of the causative agent from primarily sterile specimens is confirmative of invasive infection. The confirmation of the etiology of the disease on microbiological examination, allows the clinician to initiate targeted antifungal or antimicrobial treatment.

The aim of surgical treatment is to drain the abscess, reduce microbial load, decompress vital neurovascular structures (brainstem, basilar artery, optic nerve decompression), tissue biopsy, drainage of the paranasal cavities, sequestrectomy and for better penetration of antifungal or antimicrobial agents.

The advantage of the navigation guidance helps in preventing inadervent injury to surrounding vital structures.

Long-term pathogen-specific antifungal therapy remains the mainstay of treatment even though early empirical therapy with broad-spectrum intravenous antibiotics is to be started. After stopping the antifungal or antimicrobial therapy, careful follow-up with close monitoring of the patient’s clinical symptoms is necessary due to the risk of recurrence [7, 13].

Conclusion

Skull base osteomyelitis (SBO) is a very rare potentially life threatening chronic infectious disease in adults with an uncharacteristic presentation. SBO is usually suspected in immunodeficient adult patients with comorbidities like diabetes mellitus and untreated chronic infection of the nasal cavities or paranasal sinuses. Fungal pathogen should always be considered amongst the differential diagnosis of unusual intracranial and skull base lesions, with an uncharacteristic presentation, even in immunocompetent patients. This case highlights the aggressiveness and meticulous management of invasive CNS fungal infection. The treatment should be based on maximal lesion removal associated with long-term antifungal therapy. Early clinical examination, diagnostic imaging, drainage and collection of abscess by the neurosurgeon, and pathological and microbiological examination are the key factors to diagnosis. Due to the location of the abscess in close proximity to the brainstem, spinal cord, basilar artery and deep to the nasopharynx, the surgical approach to clival abscess is difficult and risky. In this case, we have demonstrated the utility of an image-guidance system in localizing and endoscopic drainage of clivus abscess effectively and safely. The rarity of this case and its uncharacteristic presentation prompted us to report the case.

Declaration

Competing interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Conflicts of interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests.

All Sources of Financial and Material Support Including the Following

NA.

Consent to Publication

I, Mrs. Surekha Jadhav grant permission to Dr. Apurva Lachake and team for publishing case report in journal. I do not have objection regarding the above mentioned.

Any portion of the contents of the paper may have not been presented or published previously.