Non-invasive fungal sinusitis resulting in multiple cranial nerve neuropathies

Abstract

A 33-year-old man presented to the emergency department with a right-sided facial paralysis and maxillary division (V2, trigeminal nerve) paraesthesia. He had been suffering with upper respiratory tract symptoms in the preceding 2 months, including rhinorrhoea, fever and headache. The patient was otherwise fit and immunocompetent. Urgent radiological investigation revealed extensive fungal sinusitis with sphenoid sinus dehiscence and skull base osteitis. The patient underwent emergency endoscopic sinus surgery revealing concretions and debris in the ethmoid and sphenoid sinuses. He was commenced on systemic antifungal therapy and made a full recovery with resolution of his cranial neuropathies. The fungus Schizophyllum commune was isolated and is a rare cause of fungal sinusitis, but with the potential for invasive disease in immunosuppressed individuals.

Background

This case represents a rare pathogen causing non-invasive fungal sinusitis and associated cranial neuropathies. There is minimal literature on this particular fungus resulting in sinus disease and serves as an important reminder as to the potential severity of fungal sinusitis both in immunocompetent and immunosuppressed individuals. Prompt diagnosis and treatment is essential if invasive fungal disease is suspected.

Case presentation

The 33-year-old man presented to the emergency department acutely after awaking with a right-sided facial nerve paralysis. He also described a 1-week history of right-sided maxillary division (V2) paraesthesia. The patient had been unwell in the preceding 8 weeks, suffering from intermittent right-sided clear rhinorrhoea, nasal congestion and headaches.

His medical history included hypercholesterolaemia of which he was on atorvastatin. He had no known allergies. The patient was a diesel mechanic predominately based in Perth, Western Australia, but had recently been working in a copper mine several hours north of Perth. There was no history of overseas travel. The patient was a non-smoker and consumed minimal amounts of alcohol.

On examination, the patient’s vital observations were within normal limits. However, he appeared unwell with obvious facial pallor. Cranial nerve examination demonstrated a right-sided facial nerve palsy (House-Brackmann 5) and right-sided V2 paraesthesia. His other cranial nerves were intact. Anterior rhinoscopy and flexible nasoendoscopy revealed a deviated nasal septum to the right with a small amount of mucopus seen at the middle meatus.

Investigations

A full blood count and electrolyte and C reactive protein levels were obtained, all of which were within normal limits.

Urgent CT and MRI were organised, demonstrating demineralisation of the right lamina papyracea with extensive hyperdense secretions within the ethmoidal and right sphenoid sinuses with right sphenoid sinus bony dehiscences involving the foramen rotundum and the vidian canal. Additionally, a 1.2 cm bony dehiscence was seen at the lateral aspect of the opacified right pterygoid sinus recess. Extensive skull base osteitis was reported; however, there was no evidence of orbital or intracranial abscess.

Histopathological slides were obtained and examined demonstrating reactive bone running through the centre of the specimen lined on one side by nasal mucosa while also abutting fibroinflammatory tissue on the opposing side (see figures 1–5).

Figure 1.

Axial CT demonstrating right-sided fungal sinusitis with sphenoid sinus dehiscence and skull base osteitis.

Figure 2.

Coronal CT demonstrating the extent of disease at the skull base.

Figure 3.

Coronal MRI demonstrating extensive disease in the posterior ethmoid air cells bilaterally extending into the sphenoid sinus.

Figure 4.

Low-power (10×) H&E-stained section showing reactive bone running through the centre of the specimen lined on one side (bottom right) by nasal mucosa while abutting fibroinflammatory tissue on the opposing side (top left).

Figure 5.

Low-power (250×) H&E-stained section showing reactive bone (left) abutting fibroinflammatory tissue rich in eosinophils, histiocytes and plasma cells (right).

Treatment

The patient was admitted under the ear, nose and throat (ENT) surgical team. He underwent urgent endoscopic sinus surgery revealing concretions and debris in the ethmoid and sphenoid sinuses, which were debrided. Multiple specimens and biopsy samples were obtained during the surgery and were used for urgent evaluation. He was commenced on oral fluconazole on advice from the infectious diseases physicians.

Outcome and follow-up

The patient remained in the hospital for 1 week until the causative fungus was isolated in case of an invasive pathogen due to the occurrence of cranial neuropathies and skull base erosion. He continued oral fluconazole throughout this time with rapid recovery of his V2 paraesthesia within 5 days. Schizophyllum commune was isolated on microscopy, and given the patient’s quick initial neurological recovery, he was deemed safe for discharge and to continue with antifungal therapy for a minimum of 3 months. Follow-up with the ENT surgeons and infectious diseases doctors 1 month postoperatively demonstrated a resolving facial nerve palsy (House-Brackmann 2).

Discussion

Fungal sinusitis can be categorised as invasive or non-invasive. Invasive disease can be devastating with subsequent orbital and intracranial involvement and typically affects immunosuppressed individuals. In contrast, non-invasive fungal sinusitis is usually more chronic.¹ We present the rare case of an immunocompetent patient presenting with multiple cranial nerve palsies secondary to a non-invasive fungal sinus infection.

The Aspergillus and the Mucoracea families of fungi are the the most common causative pathogens resulting in invasive fungal sinusitis, and the sequelae can be fatal. Rarely, chronic non-invasive disease can erode the skull base and cause intracranial complications such as those presented in this case.

The mould S. commune was isolated on microscopy in this case, and a review of the literature demonstrates this pathogen as a rare cause of fungal sinusitis but with the potential for invasive disease in immunosuppressed individuals.²

S. commune is ubiquitous in nature and is predominately found in trees and rotting wood, with infection in humans (especially immunocompetent individuals) limited to a small number of case reports. The mould has been reported to result in both invasive and non-invasive disease in the sinuses, lungs and brain.³ Given the rarity of disease caused by Schizophyllum, the optimal treatment is largely unknown; however, surgical intervention followed by systemic antifungal therapy appears to be the mainstay of treatment for fungal sinusitis and has demonstrated good results with this particular fungus.⁴

The patient’s facial nerve paralysis is interesting in this case, given the absence of other cranial nerve palsies that are anatomically in closer proximity to the affected V2 nerve. Our hypothesis is that the widespread skull base osteitis was the aetiology underlying the facial nerve paralysis, and for reasons unknown, this did not appear to affect the other cranial nerves (excluding V2). Histopathological slides were examined, supporting this hypothesis demonstrating reactive bone running through the specimen. Despite not showing frank invasion, we assume these reactive changes were causative of the paralysis, especially in the absence of other obvious aetiologies.

Learning points.

• Non-invasive fungal sinusitis can mimic more invasive disease as evident in this case report with skull base erosion and multiple cranial neuropathies.

• A low index of suspicion for invasive fungal sinusitis is crucial, given the potential sequelae.

• Prompt radiological investigation and the attainment of cultures is paramount in characterising the nature of the fungal infection so that optimal treatment can be administered.

• We have presented the rare case of an immunocompetent individual presenting with serious complications of non-invasive fungal sinusitis.

• To our knowledge, this is one of the few case reports of an immunocompetent individual suffering from fungal sinusitis due to Schizophyllum commune.