Retrospective Clinical Study of Eighty-One Cases of Intracranial Mucormycosis

Invasive fungal rhinosinusitis: current evidence and research opportunities

PURPOSE OF REVIEW

To summarize the evidence surrounding diagnosis, treatment, prognosis, and surveillance of patients with acute invasive fungal sinusitis (AIFS) and discuss future research needs.

RECENT FINDINGS

New risk factors for AIFS such as COVID have been identified, and a new prognostic staging system has been developed.

SUMMARY

Most patients who develop AIFS are immunocompromised, with the majority having a history of diabetes or a hematologic malignancy. Unfortunately, there are not any highly sensitive and specific diagnostic tools. Therefore, a combination of signs and symptoms, imaging, endoscopy, biopsy, and labs should be used to diagnosis AIFS. Although surgery and systemic antifungals are known to improve outcomes, there is limited data on time to intervention, duration of antifungals, and surveillance patterns. There is also limited information on factors that can predict outcomes in AIFS patients. However, sensory/perceptual changes, prolonged neutropenia duration, and comorbidity burden may be associated with a poor prognosis.

Duration of antifungal treatment in mold infection: when is enough?

PURPOSE OF REVIEW

Although invasive mold infections (IMI) are a major complication in high-risk populations, treatment duration has not yet been well defined.

RECENT FINDINGS

Guidelines suggest documenting clinical/radiological resolution and immunological recovery before stopping antifungal treatment, after a minimum duration of treatment of 3 months for invasive pulmonary aspergillosis, while longer (up to 6 months) duration is proposed for the treatment of invasive mucormycosis. However, data on and definitions of clinical/radiological resolution and immune recovery remain scarce. Limited real-life data suggest that often much longer courses of treatment are given, generally in the context of continuous immunosuppression, occasionally defined as secondary prophylaxis. However, clearcut definition and distinction of secondary prophylaxis from antifungal treatment remain to be defined.

SUMMARY

Decisions to stop antifungal treatment are based on poorly defined treatment responses and immune reconstitution and experts' opinions. More evidence is needed to determine the optimal duration of treatment of IMI. Well designed, easy to use, and realistic algorithms to help clinicians decide when to stop antifungal treatment are urgently needed.

Imaging spectrum in rhino-orbito-cerebral mucormycosis: a cross-sectional study

Background

Rhino-orbital-cerebral mucormycosis (ROCM) is a life-threatening condition caused by a saprophytic fungus that predominately affecting immune-compromised patients. Early diagnosis of ROCM is of utmost importance to start the treatment as early as possible to prevent early and horrible complications of the disease.

Materials and methods

This retrospective study evaluated the imaging findings of 21 patients with biopsy and KOH mount-based evidence of invasive ROCM. The imaging was obtained from a Siemens Magnetom Amira 1.5T system with a strength of 1.5T or more. The spectrum of findings was evaluated for the sites of involvement, signal intensity, contrast characteristics, necrotic component as well as orbital, infratemporal, and intracranial extensions, especially cavernous sinuses, Meckel's cave, and the brain parenchyma.

Results

The mean age of the patients was 55.8±10.9 years and included 71% male. All the patients were positive for COVID-19 and the majority were diabetic. MRI showed predominant involvement of the maxillary sinus (17, 81%) and the ethmoidal sinus (15, 71.4%). The orbital extension was present in 18 cases (86%). T1-weighted imaging showed iso to low signal intensity in involved sinuses in the majority of the patients (9, 42.9%). Heterogeneously high signal intensity was observed in T2-weighted and short tau inversion recovery images in all the patients. Heterogenous contrast enhancement was present in 20 (95.2%) patients.

Conclusion

The imaging spectrum of ROCM is variable. Multiplanar MRI with postcontrast images is a very useful complementary tool to the clinical evaluation to assess the extent of disease and its complications, which has a high mortality. Clinicians and radiologists should be aware of the imaging spectrums of ROCM.

Part 2: Mucormycosis: Focus on Therapy

INTRODUCTION

Mucormycosis (MCR) a rare but life-threatening infection occurs primarily in immunocompromised hosts. Mortality rates with invasive MCR are high (>30-50%), up to 90% with disseminated disease, but lower (10-30%) with localized cutaneous disease. Due to the rarity of MCR, randomized, controlled therapeutic trials are lacking. Lipid formulations of amphotericin B (LFAB) are the mainstay of therapy but oral triazoles (posaconazole and isavuconazole) may be effective as step-down therapy or in MCR cases refractory to or intolerant of LFAB. Early surgical debridement or excision play important adjunctive roles in localized invasive disease. Control of hyperglycemia in diabetic patients, correction of neutropenia and reduction of immunosuppressive therapy is critical for optimal survival.

AREAS COVERED

The authors discuss various therapeutic options for mucormycosis. A literature search of mucormycosis therapies was performed via PubMed (up to December 2022), using the key words: invasive fungal infections; mold; mucormycosis; Mucorales; amphotericin B; isavuconazole; posaconazole.

EXPERT OPINION

Randomized, controlled therapeutic trials are lacking. Lipid formulations of amphotericin B (LFAB) are the mainstay of therapy but oral triazoles (posaconazole and isavuconazole) may be effective as step-down therapy, in MCR cases refractory to or intolerant of LFAB. We encourage early surgical debridement or excision as adjunctive measures.

Emergence of Cerebral Mucormycosis in the Post-COVID Period: A Detailed Analysis of Risk Factors, Clinical Progression, and Management of This Opportunistic Fungal Infection

BACKGROUND

An epidemic of Mucorales was reported following the second wave of COVID-19 in India, and intracranial extension of the same was one of the most dreadful complications.

METHODS

A total of 62 patients with cerebral mucormycosis were recruited and followed up till 12 weeks to evaluate the risk factors, incidence, clinical manifestations, management, and prognosis of cerebral mucormycosis.

FINDINGS

A median age of 51.5 years with male predominance (74%) was noted. The majority of subjects reported a history of COVID infection (93.5%) and diabetes mellitus (83.87%). The first symptom of mucormycosis appeared after a mean period of 17.63 ± 8.9 days following COVID. Facial swelling and ptosis were the most common symptoms. Only 55% of patients had neurological presentations, and hemiparesis was the most common neurological sign (30.6%). Radiologically, the involvement of maxillary sinus (90.32%) and ethmoid sinus (87.10%) was commonly noted. Cerebral findings included temporal lobe (50%) and parietal lobe (30.06%) involvement, cavernous sinus thrombosis (30.06%), and internal carotid artery thrombosis (22.58%). Acute cerebral infarction was notable in 37% of subjects (p-value=0.0015, significant association with the outcome). Conventional and liposomal amphotericin B were used in 91.94% and 53.23% of patients, respectively. Retrobulbar amphotericin injections used in 11.3% of subjects significantly affected the outcome (p-value=0.03, significant). Posaconazole step-down therapy was used in 72.5% of subjects (p-value=0.0005, significant). Surgical interventions were performed in 53 (85.48%) subjects (p-value=0.004, significant). Functional endoscopic sinus surgery was the most common (in 64.52% of subjects), followed by maxillectomy (20.97% of subjects) and craniotomy (17.7% of subjects). At the end of 12 weeks, 33.87% of patients died and 59.68% were alive; the rest (6.45%) were lost to follow-up.

INTERPRETATION

The absence or late presentation of neurological symptoms led to a delayed diagnosis of cerebral mucormycosis. The presence of acute cerebral infarction indicated a worse prognosis. However, there was a significant influence of step-down posaconazole therapy, retrobulbar amphotericin injections, and surgical intervention on the prognosis of cerebral mucormycosis.

Metagenomic next-generation sequencing of cell-free and whole-cell DNA in diagnosing central nervous system infections

Background

Central nervous system (CNS) infections pose a fatal risk to patients. However, the limited sample volumes of cerebrospinal fluid (CSF) and low detection efficiency seriously hinder the accurate detection of pathogens using conventional methods.

Methods

We evaluated the performance of metagenomics next-generation sequencing (mNGS) in diagnosing CNS infections. CSF samples from 390 patients clinically diagnosed with CNS infections were used for the mNGS of cell-free DNA (cfDNA) (n =394) and whole-cell DNA (wcDNA) (n =150).

Results

The sensitivity of mNGS using cfDNA was 60.2% (237/394, 95% confidence interval [CI] 55.1%–65.0%), higher than that of mNGS using wcDNA (32.0%, 95% [CI] 24.8%–40.2%, 48/150) and conventional methods (20.9%, 95% [CI] 16.2%–26.5%, 54/258) (P < 0.01, respectively). The accuracy of mNGS using cfDNA in positive samples was 82.6%. Most of viral (72.6%) and mycobacterial (68.8%) pathogens were only detected by the mNGS of cfDNA. Meningitis and encephalitis with Streptococcus pneumoniae infection might be more likely to result in critically ill diseases, while Human alphaherpesvirus 3 was prone to cause non-critically ill diseases.

Conclusions

This is the first report on evaluating and emphasizing the importance of mNGS using CSF cfDNA in diagnosing CNS infections, and its extensive application in diagnosing CNS infections could be expected, especially for viral and mycobacterial CNS infections.

Imaging features of rhinocerebral mucormycosis: from onset to vascular complications

Rhinocerebral mucormycosis (RCM) may result in severe intracranial ischemic and hemorrhagic lesions. Both computed tomography (CT) and magnetic resonance imaging (MRI) play an essential role in the diagnosis of RCM, but whereas CT is better for assessing bone erosion, MRI is superior in evaluating soft tissue, intraorbital extension, and in assessing intracranial and vascular invasion. Specific CT and MRI techniques, such as CT angiography or enhanced MR angiography, and more advanced MRI sequences such as gadolinium-3D Black Blood imaging, contribute to the assessment of the extension of vascular invasion.In this pictorial review, we describe specific CT and MRI signs of RCM, mainly focusing on its life-threatening complications due to vascular involvement.

Rhino-orbito-cerebral Mucormycosis: Pictorial Review

Mucormycosis (MCR) is a fulminant, potentially lethal, opportunistic fungal infection. Diabetes, immunocompromised states and elevated serum iron levels are the most important risk factors for contracting MCR infection. Recently, MCR co-infections have been observed in patients with COVID-19 disease owing to a complex interplay of metabolic factors and corticosteroid therapy. Rhino-orbito-cerebral mucormycosis (ROCM) is the most common clinical form of MCR infection and refers to infection of the nasal cavities, paranasal sinuses, neck spaces, orbits and intracranial structures. Sinonasal inoculation is typically the primary site of infection; the necrotising and angioinvasive properties of the fungus facilitate its spread into adjacent structures. In this review, we discuss the pertinent mycology and risk factors of MCR infection. The review also aims to acquaint the reader with the cross-sectional imaging appearances of ROCM and its complications. All the cases discussed in this pictorial essay are microbiologically and/or histopathologically proven cases of ROCM with concomitant COVID-19 infection.

Imaging features of perineural and perivascular spread in rapidly progressive rhino-orbital-cerebral mucormycosis: A case report and brief review of the literature

Background:

Rhinocerebral mucormycosis (ROCM) is an opportunistic fungal infection originating from the paranasal sinuses with extension to the brain. A delayed diagnosis can rapidly result in a poor prognosis. ROCM commonly affects patients with diabetes or immunocompromised states with a variable progression.

Case Description:

We report the case of a 59-year old patient with an untreated diabetes who developed a ROCM with rapidly progressive neurological symptoms. From the onset of sinus pain, nasal congestion, he rapidly developed facial swelling and masticatory dysfunction. The patient underwent sinus surgery which allowed Rhizopus oryzae to be isolated. Accordingly, a systemic therapy by intensive intravenous amphotericin B was started. Nevertheless, the infection rapidly resulted in bilateral cavernous sinuses thrombosis and occlusion of the left internal carotid artery providing the subsequent patient death.

Conclusion:

Mucormycosis is a life-threatening fungal infection in diabetic and/or immunosuppressed patients. Our case demonstrates the three main mechanisms for infection spreading that are direct, perineural, and perivascular diffusion. Clear identification of the main risk factors, proper assessment of clinical features, and radiological findings may improve the chance for an early diagnosis and patient survival.

Host Immune Defense upon Fungal Infections with Mucorales: Pathogen-Immune Cell Interactions as Drivers of Inflammatory Responses

During the last few decades, mucormycosis has emerged as one of the most common fungal infections, following candidiasis and aspergillosis. The fungal order responsible for causing mucormycosis is the Mucorales. The main hallmarks of this infection include the invasion of blood vessels, infarction, thrombosis, and tissue necrosis, which are exhibited at the latest stages of the infection. Therefore, the diagnosis is often delayed, and the rapid progression of the infection severely endangers the life of people suffering from diabetes mellitus, hematological malignancies, or organ transplantation. Given the fact that mortality rates for mucormycosis range from 40 to 80%, early diagnosis and novel therapeutic strategies are urgently needed to battle the infection. However, compared to other fungal infections, little is known about the host immune response against Mucorales and the influence of inflammatory processes on the resolution of the infection. Hence, in this review, we summarized our current understanding of the interplay among pro-inflammatory cytokines, chemokines, and the host-immune cells in response to mucoralean fungi, as well as their potential use for immunotherapies.

Fatal and Rapid Progressive Isolated Cerebral Mucormycosis Involving the Bilateral Basal Ganglia: A Case Report

Isolated cerebral mucormycosis is a clinical type of mucormycosis that is estimated to account for 8% of all mucormycosis cases. The clinical symptoms of isolated cerebral mucormycosis are elusive, and thus conventional techniques often lake sensitivity and specificity. Moreover, cultures are often negative, even when direct microscopy examination is positive. Although histopathology will probably remain the gold standard for the diagnosis of mucormycosis, obtaining a biopsy specimen is not always feasible in most vulnerable populations. Thus, molecular approaches are currently used as an advantageous assistant examination method to improve the early identification of the causative agent and subsequently guide therapy to improve the prognosis of patients. Here, we report a case of isolated cerebral mucormycosis caused by Rhizopus microspores in a healthy young adult that was identified using next-generation sequencing technology.

Global guideline for the diagnosis and management of mucormycosis: an initiative of the European Confederation of Medical Mycology in cooperation with the Mycoses Study Group Education and Research Consortium

Mucormycosis is a difficult to diagnose rare disease with high morbidity and mortality. Diagnosis is often delayed, and disease tends to progress rapidly. Urgent surgical and medical intervention is lifesaving. Guidance on the complex multidisciplinary management has potential to improve prognosis, but approaches differ between health-care settings. From January, 2018, authors from 33 countries in all United Nations regions analysed the published evidence on mucormycosis management and provided consensus recommendations addressing differences between the regions of the world as part of the "One World One Guideline" initiative of the European Confederation of Medical Mycology (ECMM). Diagnostic management does not differ greatly between world regions. Upon suspicion of mucormycosis appropriate imaging is strongly recommended to document extent of disease and is followed by strongly recommended surgical intervention. First-line treatment with high-dose liposomal amphotericin B is strongly recommended, while intravenous isavuconazole and intravenous or delayed release tablet posaconazole are recommended with moderate strength. Both triazoles are strongly recommended salvage treatments. Amphotericin B deoxycholate is recommended against, because of substantial toxicity, but may be the only option in resource limited settings. Management of mucormycosis depends on recognising disease patterns and on early diagnosis. Limited availability of contemporary treatments burdens patients in low and middle income settings. Areas of uncertainty were identified and future research directions specified.

De Novo Blister Aneurysm Formation in 16 Days Associated with Mucorales Fungi

Although blister aneurysms represent a small percentage of all intracranial aneurysms, they are generally considered to be a more morbid and challenging entity than the more common saccular intracranial aneurysms. Despite this, the etiology of blister aneurysms is still unknown, though there are several theories. We present the case of a 54-year-old man who initially presented with vision loss and normal intracranial computed tomography angiography imaging. Only 16 days thereafter, he underwent rapidly progressive clinical decline, which was found to be due to the development and rupture of a de novo supraclinoidal blister aneurysm. Autopsy results showed fungal infection of the arterial wall by Mucorales fungi at the site of the aneurysm. Our case report supports the theory that blister aneurysms can be caused by fungal infection of the wall of the internal carotid artery.

An indolent case of isolated cerebral mucormycosis: an uncommon presentation

Introduction

This case is a presentation of isolated central nervous system (CNS) Mucormycosis in an immunocompetent patient. This case is unique in its demonstration of isolated CNS involvement while lacking clear evidence elucidating an entry point.

Case presentation

The patient is a 36-year-old man without a pertinent past medical history, who initially presented with altered mental status and a 5-day history of progressively slurred speech. His social history is significant for intravenous drug use and outdoor pest control work. The patient's head computed tomography (CT) scan without contrast demonstrated the presence of possible bilateral infarcts or masses involving the basal ganglia and periventricular white matter. The patient then progressed to facial diplegia with new onset hemiplegia. High-dose steroids were initiated due to concern for neurosarcoidosis. A lumbar puncture was ordered due to minimal improvement and suggested an inflammatory process. A stereotactic brain biopsy was then performed, demonstrating non-caseating granulomatous inflammation with giant cells. Liposomal amphotericin B was added to cover possible fungal etiology. The pathology report was consistent with an isolated cerebral mucormycosis infection. The etiology remained elusive with clear paranasal sinuses and no cutaneous manifestations. Due to extensive gray matter involvement, the patient was not a candidate for surgery.

Conclusion

This is a report of mucormycosis in a seemingly immunocompetent patient with either isolated CNS involvement or disseminated mucormycosis without an identifiable source. Although this patient did have two risk factors including intravenous drug use and outdoor working history, his lack of peripheral involvement demonstrates an uncommon presentation.

Ruptured Mycotic Aneurysm of the Distal Circulation in a Patient with Mucormycosis Without Direct Skull Base Extension: Case Report

BACKGROUND AND IMPORTANCE

Infectious intracranial aneurysms are a rare subset of intracranial aneurysms caused by bacterial, fungal, or viral sources. Intracranial aneurysms of fungal etiology carry a high mortality risk and typically occur in immunocompromised patients via direct extension of skull base infections, or more rarely, after intracranial surgery.

CLINICAL PRESENTATION

We present the case of a 27-yr-old female with systemic lupus erythematous and primary pulmonary mucormycosis, who suffered a subarachnoid hemorrhage from a ruptured fusiform distal middle cerebral artery aneurysm. Despite undergoing a successful extracranial-to-intracranial bypass and aneurysm excision, the patient ultimately died following progressive disseminated infection and a secondary intracranial hemorrhage of unknown etiology. Pathological examination of the excised artery confirmed Mucor infection.

CONCLUSION

To the best of our knowledge, this case represents one of the first mycotic cerebral aneurysms from mucormycosis in a patient without an underlying skull base infection or previous intracranial surgery. Despite optimal surgical management, clinical outcomes for mycotic cerebral aneurysms are largely dependent on the success of medical therapies at controlling systemic disease.

Successful treatment of primary cerebral mucormycosis: Role of microbiologist

Fungal brain abscess is rare with a rapidly progressive disease with fulminant course and invariably fatal outcome, unless diagnosed early and treated rapidly. We report a 56-year-old woman diagnosed to have fungal abscess who recovered completely following amphotericin B treatment. She presented with weakness of the right hand, deviation of mouth to left and aphasia for 2 days. Computed tomography of the brain revealed a left frontal capsuloganglionic hypodense lesion. Stereotactic biopsy was performed, and microbiological confirmation of non-septate fungal hyphae from pus from aspirate within 2 h helped initiate timely and appropriate treatment leading to cure. Histopathology and culture later confirmed mucormycosis.