AIFRS is a severe and life-threatening condition. In this study, a systematic reporting approach is used by both the reading otolaryngologist and the reading radiologist to understand the clinical-radiological relevance of findings. Patients had a wide range of imaging characteristics. It varied from subtle mucosal thickening of sinuses up to cerebral extension. In our patients, sinonasal soft tissue necrosis was detected in 54/54 patients, inflammatory soft tissue changes extending from the sinuses into the facial subcutaneous tissue (25/54) as well as into the infratemporal and in 49/54 patients into the temporal fossa. Orbital (16/54 patients) and cerebral involvement (22/54 patients) were frequent in our study leading to neurological complications and bony destruction in 22/54 cases; cranial nerve involvement was not uncommon (14 patients).
The degree of mucosal opacification of sinuses and nasal cavity and nasopharynx had relatively poor sensitivity and specificity. Extrasinus soft tissue involvement correlated most strongly with involvement in the pterygopalatine fossa. The correlation between mucosal opacification and infiltrations was very weak. Unilateral predominance existed. Bilateral AIFR was present in one case with a strong predilection of the disease on the left side. Nasal Septal ulceration was reported in 31.5% only. We found unenhanced mucosal areas at the middle turbinate (black turbinate) as well as in the ethmoidal sinuses in 10 patients,
The CT findings presented hypodense opacification of the sinuses, unlike chronic fungal infections where the sinuses are hyperdense due to the build-up of mineral-rich fungal waste products. The cross-sectional imaging features of AIFRS associated with COVID-19 infections do not differ from those reported in the literature for AIFRS associated with other risk factors [8]. This is in concordant with the study of Middlebrooks et al. [1, 7].
The black turbinate sign described by Baumgartner et al. [9] refers to a lack of contrast enhancement of invaded mucosa due to occlusion of small vessels. The sign could also be called the black mucosa sign.
Middlebrooks et al. [7] recently proposed a simple and robust diagnostic model to serve as an easily applicable screening tool for at-risk patients with 23 variables that allow for three levels of involvement: (1) nasal cavity, paranasal sinuses, (2) rhino-orbital disease, rhino-orbito-cerebral. MRI contrast administration allows delineation of subtle areas of invasion, recognition of necrosis, and thrombosis of structures such as the cavernous sinus [1, 10, 11].
Seo et al. [12] found that (74%) of patients already had sinonasal soft tissue infarction. 100% of patients had intrasinonasal infarction and 13/17 patients also had extrasinonasal infarction and directly died of disease. Various locations of extrasinonasal infarction, including the orbit (n = 8/17), infratemporal fossa (n = 7/17), intracranial cavity (n = 3/17), and oral cavity and/or facial soft tissue (n = 4/17). Variable signal intensities were noted in the area of sinuses on T1- and T2-weighted images. Bone destruction was found on CT scans in 3/17 patients.
Ashour et al. [8] examined 8 patients and record extrasinus extensions as follows: pterygopalatine fossa (n = 5/8), and periantral fat (n = 7/8) were also noticed as well as bone dehiscence (n = 7/8), septal ulceration (n = 7/8). Bilateral disease detected in (n = 5/8). Orbital infiltration was unilateral in 4/8 patients. Intracranial complications were: perineural spread (n = 6/8), cavernous sinus involvement (n = 6/8), meningeal/epidural infiltration (n = 3/8), ICA thrombosis (n = 4/8), intracerebral abscess (n = 2/8), and a high mortality rate of 37.5%.
In the current study, we obtain the mean age of 48.06 ± 16.5 years younger than that recorded by Shintani in the USA [13]. The mean age was 58.0 ± 2.2 years, with nearly the same sex predilection of 55.9% male (55.6% male, 44.4 female).
The most common presenting symptoms of patients with AIFRS were unilateral facial pain, tingling, and numbness in the malar areas 92.6% in concordance with Turner et al. [14] who recorded facial swelling (64.5%), fever (62.9%), and nasal congestion (52.2%. Extension into the orbit results in proptosis, deterioration in vision or even visual loss (70.4%), facial skin infarction, and ulceration in 46.3%. In addition, Yin et al. [15] described that unilateral facial swelling, pain, or erythema were the most common presentations, involvement of the orbit or pterygopalatine fossa on imaging, and mucosal necrosis is seen on endoscopy.
As expected, the most commonly associated predisposing conditions were diabetes mellitus in concordance with the study of Malleshappa et al. [16] found that 78.4% patients were diabetic in concordance with the study of Wandell et al. [17] aggressive infection occurring in immunocompromised patients.
In this study 2/54 patients had haematologic malignancy on the contrary Malleshappa et al. [16] found that 17.6% had haematologic malignancies.
Mucor species (77.8%) was the most commonly isolated fungal pathogens followed by Aspergillus fumigatus (22.2%). As Raab et al. [6] pointed out, Mucorales is not the only fungi, which can infect the sinuses, Aspergillus spp. can also lead to invasive fungal sinusitis.
The aim of surgery is to excise the necrotic tissue thus maxillectomy is done in 5 patients and orbital exenteration in 13/54 patients. Systemic antifungal was described for 50 patients. This is discordant with Turner et al. [14], who described external debridement for 37.2%, endoscopic debridement in 37% and combined open and endoscopic debridement for 24.1% and Malleshappa et al. [16] who recorded partial/total maxillectomy (29.4%), orbital exenteration (7.8%) and craniotomy (2%), while Allensworth et al. [18] found that ten patients underwent maxillectomy, six with orbital exenteration. In concordance with a study done by Yin et al. [15], most patients were treated with a combination of intravenous antifungal medication and surgery. Two patients passed away before surgery.
Despite improvements in medical and surgical therapy, survival remains limited. The overall mortality in the AIFR was 40.7% in concordance with the study of Turner et al. [14] who stated an overall survival rate equalled 49.7% and Allensworth et al. [18] recorded (68%) survived which was nearly the same mentioned in the study of Malleshappa et al. [16] that gave a survival rate of 68.2% overall.
Strength of the study, up to our knowledge and the published data, is that it had a large sample and our patients were a good representative of the medical problem. Second, multidisciplinary reporting expanded the scope of data analysis.
AIFRS in COVID-19 patients is a matter of urgency; consequently, this study had some limitations. First, it was a single institutional study. Second, patient selectivity bias was possible due to rapid disease progression and poor prognosis. Third, the lack of a comparator control group limited our findings. Finally, the availability of long-term clinical outcomes was modest. The international longitudinal study is necessary for future studies.