Changing Spectrum of Invasive Fungal Infections of Anterior Skull Base

Objective: The purpose of this study was to evaluate the change in clinical spectrum and outcomes of invasive fungal disease involving the anterior skull base region.

Study Design: This study represents a retrospective review of the patients diagnosed with acute and chronic invasive fungal rhinosinusitis based on imaging, fungal staining and culture, biochemical analysis, and histopathology report. Assessment of anterior, central skull base including orbital involvement was done clinicoradiologically and/or intraoperative findings.

Setting: A tertiary referral hospital.

Results: There was a total of 79 patients, of which 67% had skull base mucormycosis, 33% had invasive aspergillosis. In the skull base mucormycosis group, there were 53 patients, with 33 males and 20 females. 88% of patients had a history of COVID-19 infection. 98% of patients had type 2 diabetes mellitus. The mean duration of symptoms was 36 days, and 68% of them presented 30 days after onset of symptom. Mortality was seen in 7 (14%) patients. The most common symptom of the presentation was facial swelling followed by facial numbness, vision loss and headache. The most common area of skull base involved was pterygopalatine fossa (88%), followed by infratemporal fossa (71%), anterior and posterior cribriform area (60% each). The most common vessel involved was the sphenopalatine artery (75%), and the neural structure involved was infraorbital nerve (64%) and maxillary division of trigeminal nerve (52%). 13 patients had an intracranial disease, with 2 having cerebritis and rest with parenchymal abscess including one patient with cerebellar abscess. All patients had radical debridement with antifungal treatment.

In the invasive aspergillosis group, there were 26 patients with 12 males and 14 females with a mean age of 42 years. The mean duration of presentation after the onset of the symptom was 33 weeks. Only 26% of patients had diabetes mellitus (type 2), and one patient had COVID-associated aspergillosis who presented within 28 days after onset of symptom with intracranial extension. Tissue diagnosis for confirmation of aspergillosis was obtained in 62% of patients, while the use of galactomannan assay and clinicoradiological diagnosis was done in 38%. A similar trend of skull base involvement was seen in mucormycosis, where the most common area involved was pterygopalatine fossa (65%) and infratemporal fossa (57%), superior orbital fissure (38%). All patients were treated with oral voriconazole, and all patients responded well to the treatment.

Conclusion: It is essential to acknowledge the changing trend in the presentation of mucormycosis, which was earlier known to have a fulminant course, but now have presented as a chronic invasive form with good short-term prognosis; long term prognosis is yet to be studied. Contrast enhancing pattern in T1 contrast MRI sequences and sequestral changes of skull base bones on CT plays an essential role in surgical decision making. Chronic invasive skull base aspergillosis where tissue specimen is difficult to obtain, radiology and galactomannan assay is to be used along with clinical assessment to diagnose aspergillosis. If disease load is significant, debulking of disease compliments antifungals’ action and resolves the disease faster ([Figs. 1]–[3]).

Fig. 1 (A) A 57-year-old male diagnosed with Mucormycosis had sequestra over basisphenoid, greater wing of the sphenoid and posterior part of the lateral wall of orbit (B) Postoperative CT showing removal of sequestra using endoscopic endonasal and lateral orbital approaches. (C) 2-month postoperative MRI T1 contrast shows a well-controlled and non-progression of the disease.

Fig. 2 (A) A 56-year-old male diagnosed with Mucormycosis had cribriform involvement, which is enhancing on T1 contrast (B) left ethmoidal roof showing the preserved cribriform area (Star), frontal sinus (F), Anterior fovea (AF), posterior fovea (PF), medial wall of the orbit (O) and anterior ethmoidal artery (Arrow). (C) There is no progression of intracranial extension on 3 week post-op MRI.

Fig. 3 (A,B) A 45-year-old male diagnosed with invasive aspergillosis his CT shows disease involving right orbital contents and left ethmoidal sinus. (C,D) After completion of 4 months of Voriconazole therapy his MRI T1 contrast shows complete resolution of disease.

Publication History

Article published online:
15 February 2022