There were few specific features of Covid-19 seen in the second wave of the pandemic, firstly, a tendency to cause capacious pulmonary disease followed by analveolo-interstitial pathology that may aggravate the risk of invasive fungal infections. Secondly, the immune derangement linked with Covid-19, with reduced T lymphocytes, CD4+T, and CD8+T cells, may amend innate immunity making the patient more vulnerable to opportunistic fungal infections [3]. Mainly, neutrophils are responsible for protection against fungi, and any change in the number or function of these white cells leads to an escalate the risk of infection.

Letters or articles were searched on Pubmed with the search letter mucormycosis," "Mucor, " and "Covid-19" to spot any additional reported cases. Only a few case reports of secondary mucormycosis with perineural spread have been reported till now. Hanley et al. have reported a case of a young male with Covid-19 pneumonia and a middle cerebral artery (MCA) infarct in whom dispersed mucormycosis involving the lungs and brain was incidental during a postmortem study [4]. Mucormycosis is a potentially lethal opportunistic infection of immunocompromised patients. Rhino-orbito-cerebral mucormycosis is a rare assertive fungal infection. Around 80% of cases occurred in patients with diabetes and it had been declared endemic in India after the surge of the second wave. In diabetes, an elevated blood glucose levels augment fungal growth. The serum of a patient with ketoacidosis is not able to stop the growth of the fungus. Many probable explanations of this resurgence were given, like immunomodulation by Covid-19 itself, extensive steroid use, industrial oxygen usage and prolonged wearing and reuse of the same mask over a long period [1,2]. It is an acute, lethal infection caused by fungi of the order mucorales in the class zygomycetes [2]. Specifically, the hyphae infiltrate the vessel walls with ensuing local thrombotic infarction [4]. This action often headway from the sinus cavity to the orbit and then cavernous sinus. Central nervous system (CNS) connivance may occur from the hematogenous route or direct infiltration and have a bare prognosis with a five-year survival rate of 20% to 45% [3]. The extend of established rhino-orbito-cerebral mucormycosis is a bit expected. The spread is from the paranasal sinuses; mucor fungi invade the orbits and then into the cavernous sinus.

Nevertheless, straightway of infection through the cribriform plate into the anterior cranium may also occur, and it was suggested as a perineural spread [5]. Direct fungal invasion of the seventh and eighth cranial nerves from the internal auditory canal subarachnoid space has been documented in the former studies. However, it arises in the environs of fulminant meningitis from Cryptococcus or Aspergillus organisms [6]. There was no fungal involvement seen in the sensory ganglion [7]. The use of MRI to evaluate rhino-orbito-cerebral mucormycosis was first reported in 1988 by G.A. Press et al. in his study [4]. For evaluation of extracranial perineural spread, both CT and MRI imaging give sufficient information. However, MRI is proved to be superior for the cisternal segment, brain stem and skull base involvement and other potential routes of intracranial fungal invasion [8]. MRI has proved to be the most helpful technique for cavernous sinus involvement. Multiplanar ability and high tissue resolution make MRI the modality of choice for studying the entire intracranial pathway of the cranial nerve. MRI findings described in the R.O.C.M. include an abnormal hyperintense sinus mucosal wall, T2-W hyperintense lesion expanding from paranasal sinus across orbital apex then into intracranial structures encasing the vessel walls leading to slow flow in the ipsilateral vessel in the vicinity of mucor invasion. MRI well exhibited all these characteristic features in our cases. We further more noticed hyperintense signal intensity on D.W.I. and simultaneous hypointense signal on A.D.C. maps in the lesion lengthen from orbit to cavernous sinus, congenial with restricted diffusion [9]. D.W.I. of the brain also showed small infarcts in the watershed distribution in the high parietal region.

Our cases of perineural spread of rhino-orbito-cerebral mucormycosis are distinct in that fungal elements involved multiple cranial nerves, with no apparent leptomeningitis. Spread of infections to the hard and soft palate can easily ingress the greater and lesser palatine nerves, while these infections in the cheek and orbital soft tissues can encase the infraorbital nerve. Above mentioned nerves ascend to form the maxillary nerve, which through pterygopalatine fossa, enters into the cavernous sinus via the foramen rotundum. This fungal infection can also spread to Meckel's cave from the cavernous sinus and then by the sides of the cisternal portion of the trigeminal nerve to the lateral side of the pons or the trigeminal nucleus.

Hematogenous extend from the cavernous sinus or internal carotid may cause distant cerebral infarction and abscess, normally ipsilateral to the initial disease. Bone involvement is relatively rare in acute disease. However, the infection spreads from one bone or fascia into another via inherent dehiscences in the fascia or through fissures, canals and foramina within the bone [5]. The direct spread of the infection may invade the CNS through the cribriform plate, orbital fissure or basal foramina [2,6].

Radiological affirmation of the perineural spread of rhino-orbito-cerebral mucormycosis is very rare, and there were only two other cases (also involving the mandibular part of the trigeminal nerve) reported in the previous literature as per our knowledge. McLean et al. [6] described the radio-pathologic findings, while Press et al. told about the MRI findings of expansion of the disease from the cavernous sinus to the pons. With the presence of characeteristic MRI findings, it seems reasonable to assume the perineural spread for rhino-orbito-cerebral mucormycosis, especially when there is evidence of thickening and enhancement of the trigeminal nerve along its path and association of pons.

Aggressive surgical epithelialization, intravenous Amphotericin-B therapy, control of blood glucose, and correction of the weakened immune response are the treatment strategies for invasive mucormycosis. The prognosis of cerebral mucormycosis is indigent, with 5-year survival rates of just 20%–45%. Health is essential for an individual’s well-being; it is also necessary for all productive activities in a society (Goel, 2002). Therefore, the Rajasthan State has ensured strong delivery of health and family welfare services throughout the peripheral areas of Rajasthan via voluntary workers, community health workers, and ASHA (Accredited Social Health Activists) etc. Continuous attempts are being made to supply the primary health care to these areas, conceding some issues like gender imbalance, inequality, availability, accessibility, and delivery of quality health care services and major one i.e., affordability. In order to build up the potency and quality of this primary health care delivery systems, Rajasthan Health System Development Project is being executed in all the 32 districts with financial encouragement from the World Bank. The prime goal is to strengthen secondary-level medical institutions. One of the significant issues in providing good medical care in India is the untrained/unqualified quacks providing unlicensed medical services. Since our institute is also located in the tribal area of southern Rajasthan where these quack practices, lack of healthcare services and health hygiene are major issues, so, we get a maximum number of patients who came up in the end-stage of the disease or are in a worsened state due to lack of awareness and are treated wrongly by these quacks.