Rhinocerebral mucormycosis: a rare cause of cerebral infarct

A 48-year-old female patient with history of uncontrolled diabetes presented with acute onset right sided hemiparesis. She gave a history of pain in her left eye in the previous days.

MR images of brain showed infarcts in the left internal carotid artery territory. MR sections of paranasal sinuses showed altered signal intensity areas in the left ethmoid sinus with T2 hypointense areas within. Infiltration of fat in left orbital apex and left cavernous sinus with absent flow void in cavernous segment of left internal carotid artery noted.

Enucleation was done for this patient and histopathology and fungal culture results were consistent with mucormycosis.

First described by Paultauf in 1885, mucormycosis is a lethal opportunistic infection with poor prognosis [1]. Found in soil, spoiled food, oral cavity, nasal passages and paranasal sinuses, these saprophytic fungi can spread to orbit, meninges and brain by direct extension and cause infection in immunocompromised individuals [2]. Based on the anatomic area of involvement it can be classified as rhino cerebral, pulmonary, cutaneous, gastrointestinal, disseminated and miscellaneous forms [3].

This fulminant fungal infection has the propensity to invade the walls of blood vessels resulting in vascular thrombus and infarction and thus may disseminate to the central nervous system. It initially presents with fever, headache, facial pain, nasal obstruction, discharge and crusting and rapidly progresses to involve central nervous system in few hours to days. Central nervous system involvement has dismal survival rates [2]. Imaging has a crucial role in early diagnosis.

Paranasal sinus opacification in CT with areas of increased density and markedly hyperdense foci due to calcium phosphate and calcium sulphate deposits in necrotic areas of mycetoma are early features. Obliteration of fat planes in infratemporal and pterygopalatine fossa, orbital involvement with cellulitis or abscess, cavernous sinus thrombus and intracranial features including infarcts, emboli, abscess and sinus thrombus are seen in advanced cases [4]. MR can better depict intracranial and intraorbital extension.

Surgical debridement and systemic amphotericin therapy are the recommended treatment options [1]. Treatment of underlying predisposing factor is also necessary. Case fatality rate often exceed 80% when cerebral involvement occurs [5].

Mucormycosis is a relatively rare cause of cerebral infarction and a high index of clinicoradiologic suspicion is needed to not overlook the possibility. Rapidity of diagnosis and early initiation of treatment can be life-saving for this highly lethal opportunistic infection. Increasing awareness on association of mucormycosis with COVID 19 infection adds to its relevance in the present era of the pandemic [6].